Add unit settings, wind particles toggle, and recenter-to-top

- New UnitPrefs: persisted C/F, ft/m, hPa/inHg, kt/mph/kph — defaults to °F
- InstrumentHandler now accepts raw values (knots, metres, hPa, °C) and formats
  via UnitPrefs on every update
- LayerPickerSheet expanded with wind particles toggle and unit chip selectors;
  wrapped in ScrollView to handle the additional height
- MapLayerManager tracks particlesEnabled (persisted); setParticlesEnabled() added
- MainActivity: caches last raw values so refreshUnits() can reformat everything
  instantly when the user changes a unit without waiting for new sensor data
- Recenter button moved to top (below HUD strip) so it's never obscured by the
  bottom sheet or bottom nav
- Unit label TextViews given IDs in HUD and instrument sheet for live updates

https://claude.ai/code/session_01HXPjBsogsJVRwCiekDGkJX

9 files changed, 643 insertions, 189 deletions

diff --git a/android-app/app/src/main/kotlin/org/terst/nav/MainActivity.kt b/android-app/app/src/main/kotlin/org/terst/nav/MainActivity.kt
index 21aa55b..86dd531 100644
--- a/android-app/app/src/main/kotlin/org/terst/nav/MainActivity.kt
+++ b/android-app/app/src/main/kotlin/org/terst/nav/MainActivity.kt
@@ -37,6 +37,7 @@ import org.terst.nav.ui.map.ParticleWindView
 import org.terst.nav.ui.safety.SafetyFragment
 import org.terst.nav.ui.voicelog.VoiceLogFragment
 import java.util.*
+import org.terst.nav.data.model.MarineConditions
 import org.terst.nav.safety.AnchorWatchState
 
 class MainActivity : AppCompatActivity(), SafetyFragment.SafetyListener {
@@ -60,12 +61,35 @@ class MainActivity : AppCompatActivity(), SafetyFragment.SafetyListener {
     private lateinit var bottomNav: BottomNavigationView
     private lateinit var mapCrosshair: View
 
-    // HUD TextViews — wired to layout_nav_hud.xml
+    // HUD value TextViews
     private lateinit var hudSog: TextView
     private lateinit var hudCog: TextView
     private lateinit var hudBsp: TextView
     private lateinit var hudDepth: TextView
 
+    // HUD unit label TextViews
+    private lateinit var unitHudSog: TextView
+    private lateinit var unitHudBsp: TextView
+    private lateinit var unitHudDepth: TextView
+
+    // Instrument sheet unit label TextViews
+    private lateinit var unitTws: TextView
+    private lateinit var unitTemp: TextView
+    private lateinit var unitBaro: TextView
+    private lateinit var unitCurrSpd: TextView
+    private lateinit var unitWaveHt: TextView
+    private lateinit var unitSwellHt: TextView
+
+    // Unit preferences
+    private lateinit var unitPrefs: UnitPrefs
+
+    // Cached raw values for unit-change refresh
+    private var lastConditions: MarineConditions? = null
+    private var lastBaroHpa: Float? = null
+    private var lastSogKnots: Double? = null
+    private var lastBspKnots: Double? = null
+    private var lastDepthMeters: Double? = null
+
     private val safetyFragment = SafetyFragment().apply { setSafetyListener(this@MainActivity) }
 
     private val viewModel: MainViewModel by viewModels()
@@ -85,6 +109,7 @@ class MainActivity : AppCompatActivity(), SafetyFragment.SafetyListener {
         MapLibre.getInstance(this)
         setContentView(R.layout.activity_main)
 
+        unitPrefs = UnitPrefs(this)
         checkForegroundPermissions()
         initializeUI()
     }
@@ -99,24 +124,37 @@ class MainActivity : AppCompatActivity(), SafetyFragment.SafetyListener {
         bottomNav = findViewById(R.id.bottom_navigation)
         mapCrosshair = findViewById(R.id.map_crosshair)
 
-        // HUD views (inside the included layout_nav_hud)
+        // HUD value views
         hudSog   = findViewById(R.id.hud_sog)
         hudCog   = findViewById(R.id.hud_cog)
         hudBsp   = findViewById(R.id.hud_bsp)
         hudDepth = findViewById(R.id.hud_depth)
 
-        // Initialise HUD with dashes
+        // HUD unit label views
+        unitHudSog   = findViewById(R.id.unit_hud_sog)
+        unitHudBsp   = findViewById(R.id.unit_hud_bsp)
+        unitHudDepth = findViewById(R.id.unit_hud_depth)
+
+        // Instrument sheet unit label views
+        unitTws     = findViewById(R.id.unit_tws)
+        unitTemp    = findViewById(R.id.unit_temp)
+        unitBaro    = findViewById(R.id.unit_baro)
+        unitCurrSpd = findViewById(R.id.unit_curr_spd)
+        unitWaveHt  = findViewById(R.id.unit_wave_ht)
+        unitSwellHt = findViewById(R.id.unit_swell_ht)
+
+        // Init HUD with dashes; apply correct unit labels from stored prefs
         hudSog.text   = "—"
         hudCog.text   = "—"
         hudBsp.text   = "—"
         hudDepth.text = "—"
+        applyUnitLabels()
 
         setupBottomSheet()
         setupBottomNavigation()
         setupHandlers()
         setupMap()
 
-        // Single tap starts; long press stops (requires deliberate intent mid-sail)
         fabRecordTrack.setOnClickListener {
             if (!viewModel.isRecording.value) viewModel.startTrack()
         }
@@ -129,12 +167,9 @@ class MainActivity : AppCompatActivity(), SafetyFragment.SafetyListener {
         }
 
         fabMob.setOnClickListener { onActivateMob() }
-
-        fabRecenter.setOnClickListener {
-            mapHandler?.recenter()
-        }
-
+        fabRecenter.setOnClickListener { mapHandler?.recenter() }
         btnQuit.setOnClickListener { onQuitRequested() }
+
         lifecycleScope.launch {
             viewModel.isRecording.collect { recording ->
                 val icon = if (recording) R.drawable.ic_close else R.drawable.ic_track_record
@@ -151,11 +186,73 @@ class MainActivity : AppCompatActivity(), SafetyFragment.SafetyListener {
         }
     }
 
+    /** Updates all static unit label TextViews to match current [unitPrefs]. */
+    private fun applyUnitLabels() {
+        unitHudSog.text   = unitPrefs.speedUnitLabel()
+        unitHudBsp.text   = unitPrefs.speedUnitLabel()
+        unitHudDepth.text = unitPrefs.depthUnitLabel()
+        unitTws.text      = unitPrefs.speedUnitLabel()
+        unitTemp.text     = unitPrefs.tempUnitLabel()
+        unitBaro.text     = unitPrefs.pressureUnitLabel()
+        unitCurrSpd.text  = unitPrefs.speedUnitLabel()
+        unitWaveHt.text   = unitPrefs.depthUnitLabel()
+        unitSwellHt.text  = unitPrefs.depthUnitLabel()
+    }
+
+    /**
+     * Re-formats every cached raw value with the current unit prefs.
+     * Called after the user changes a unit in the settings sheet.
+     */
+    private fun refreshUnits() {
+        applyUnitLabels()
+        lastSogKnots?.let    { hudSog.text   = unitPrefs.formatSpeed(it) }
+        lastBspKnots?.let    { hudBsp.text   = unitPrefs.formatSpeed(it) }
+        lastDepthMeters?.let { hudDepth.text = unitPrefs.formatDepth(it) }
+        lastConditions?.let  { applyConditions(it) }
+        lastBaroHpa?.let     { instrumentHandler?.updateConditions(baroHpa = it) }
+    }
+
+    private fun applyConditions(c: MarineConditions) {
+        instrumentHandler?.updateConditions(
+            twsKt         = c.windSpeedKt,
+            twsBearingDeg = c.windDirDeg?.toFloat(),
+            tempC         = c.tempC,
+            currSpdKt     = c.currentSpeedKt,
+            currDirDeg    = c.currentDirDeg?.toFloat(),
+            waveHeightM   = c.waveHeightM,
+            waveDirDeg    = c.waveDirDeg?.toFloat(),
+            swellHeightM  = c.swellHeightM,
+            swellDirDeg   = c.swellDirDeg?.toFloat(),
+            swellPeriodS  = c.swellPeriodS
+        )
+        instrumentHandler?.updateWaveState(
+            swellHeightM    = c.swellHeightM?.toFloat() ?: 0.9f,
+            swellPeriodSec  = c.swellPeriodS?.toFloat() ?: 10f,
+            windWaveHeightM = c.waveHeightM?.toFloat() ?: 0.45f,
+            windSpeedKt     = c.windSpeedKt?.toFloat() ?: 0f
+        )
+    }
+
     private fun setupBottomSheet() {
         bottomSheetBehavior = BottomSheetBehavior.from(bottomSheet)
         bottomSheetBehavior.state = BottomSheetBehavior.STATE_COLLAPSED
     }
 
+    private fun buildLayerPickerSheet(): LayerPickerSheet {
+        val currentStyle = loadedStyleFlow.value
+        return LayerPickerSheet(
+            manager           = layerManager,
+            onBaseChanged     = { preset -> currentStyle?.let { layerManager.setBasePreset(it, preset) } },
+            onWindChanged     = { enabled -> currentStyle?.let { layerManager.setWindEnabled(it, enabled) } },
+            onParticlesChanged = { enabled ->
+                layerManager.setParticlesEnabled(enabled)
+                particleWindView?.visibility = if (enabled) View.VISIBLE else View.GONE
+            },
+            unitPrefs         = unitPrefs,
+            onUnitsChanged    = { refreshUnits() }
+        )
+    }
+
     private fun setupBottomNavigation() {
         bottomNav.setOnItemSelectedListener { item ->
             when (item.itemId) {
@@ -167,14 +264,7 @@ class MainActivity : AppCompatActivity(), SafetyFragment.SafetyListener {
                     true
                 }
                 R.id.nav_layers -> {
-                    val currentStyle = loadedStyleFlow.value
-                    if (currentStyle != null) {
-                        LayerPickerSheet(
-                            manager = layerManager,
-                            onBaseChanged = { preset -> layerManager.setBasePreset(currentStyle, preset) },
-                            onWindChanged = { enabled -> layerManager.setWindEnabled(currentStyle, enabled) }
-                        ).show(supportFragmentManager, "layer_picker")
-                    }
+                    buildLayerPickerSheet().show(supportFragmentManager, "layer_picker")
                     bottomNav.post { bottomNav.selectedItemId = R.id.nav_map }
                     true
                 }
@@ -253,20 +343,18 @@ class MainActivity : AppCompatActivity(), SafetyFragment.SafetyListener {
             bearingCurr  = findViewById(R.id.bearing_curr),
             bearingWaves = findViewById(R.id.bearing_waves),
             bearingSwell = findViewById(R.id.bearing_swell),
-            waveView = findViewById(R.id.wave_divider)
-        )
-        instrumentHandler?.updateConditions(
-            tws = "—", baro = "—", currSpd = "—"
+            waveView  = findViewById(R.id.wave_divider),
+            unitPrefs = unitPrefs
         )
     }
 
     private fun Int.dpToPx(): Int = (this * resources.displayMetrics.density).toInt()
 
     private fun checkForegroundPermissions() {
-        val fineLocationPermission = ContextCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION)
-        val coarseLocationPermission = ContextCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION)
+        val fineLocation   = ContextCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION)
+        val coarseLocation = ContextCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION)
 
-        if (fineLocationPermission == PackageManager.PERMISSION_GRANTED || coarseLocationPermission == PackageManager.PERMISSION_GRANTED) {
+        if (fineLocation == PackageManager.PERMISSION_GRANTED || coarseLocation == PackageManager.PERMISSION_GRANTED) {
             startServices()
         } else {
             requestPermissionLauncher.launch(arrayOf(
@@ -299,6 +387,12 @@ class MainActivity : AppCompatActivity(), SafetyFragment.SafetyListener {
         layerManager = MapLayerManager(this)
         mapView = findViewById(R.id.mapView)
         particleWindView = findViewById(R.id.particle_wind_view)
+
+        // Apply persisted particles preference immediately
+        if (!layerManager.particlesEnabled) {
+            particleWindView?.visibility = View.GONE
+        }
+
         if (NavApplication.isTesting) return
 
         mapView?.onCreate(null)
@@ -325,9 +419,9 @@ class MainActivity : AppCompatActivity(), SafetyFragment.SafetyListener {
 
             maplibreMap.setStyle(styleBuilder) { style ->
                 loadedStyleFlow.value = style
-                val anchorBitmap = rasterizeDrawable(R.drawable.ic_anchor)
-                val arrowBitmap = rasterizeDrawable(R.drawable.ic_tidal_arrow)
-                val userBitmap = rasterizeDrawable(R.drawable.ic_ship_arrow)
+                val anchorBitmap   = rasterizeDrawable(R.drawable.ic_anchor)
+                val arrowBitmap    = rasterizeDrawable(R.drawable.ic_tidal_arrow)
+                val userBitmap     = rasterizeDrawable(R.drawable.ic_ship_arrow)
                 val windArrowBitmap = rasterizeDrawable(R.drawable.ic_wind_arrow)
                 mapHandler?.setupLayers(style, anchorBitmap, arrowBitmap, userBitmap)
                 mapHandler?.setupWindLayer(style, windArrowBitmap)
@@ -346,19 +440,13 @@ class MainActivity : AppCompatActivity(), SafetyFragment.SafetyListener {
                         corners.minOf { it.longitude }, corners.maxOf { it.longitude }
                     )
                 }
-                // Refresh conditions for current map center (works in both follow + pan mode)
                 maplibreMap.cameraPosition.target?.let { center ->
                     viewModel.loadConditions(center.latitude, center.longitude)
                 }
             }
 
             maplibreMap.addOnMapLongClickListener { _ ->
-                val currentStyle = loadedStyleFlow.value ?: return@addOnMapLongClickListener true
-                LayerPickerSheet(
-                    manager = layerManager,
-                    onBaseChanged = { preset -> layerManager.setBasePreset(currentStyle, preset) },
-                    onWindChanged = { enabled -> layerManager.setWindEnabled(currentStyle, enabled) }
-                ).show(supportFragmentManager, "layer_picker")
+                buildLayerPickerSheet().show(supportFragmentManager, "layer_picker")
                 true
             }
         }
@@ -371,8 +459,9 @@ class MainActivity : AppCompatActivity(), SafetyFragment.SafetyListener {
                 mapHandler?.centerOnLocation(gpsData.latitude, gpsData.longitude)
                 mapHandler?.updateUserPosition(gpsData.latitude, gpsData.longitude, gpsData.cog.toFloat())
                 viewModel.addGpsPoint(gpsData.latitude, gpsData.longitude, gpsData.sog, gpsData.cog)
-                // HUD — SOG and COG come from GPS
-                hudSog.text = "%.1f".format(Locale.getDefault(), gpsData.sog)
+                // HUD — SOG and COG from GPS
+                lastSogKnots = gpsData.sog
+                hudSog.text = unitPrefs.formatSpeed(gpsData.sog)
                 hudCog.text = "%.0f°".format(Locale.getDefault(), gpsData.cog)
                 if (!conditionsLoaded) {
                     conditionsLoaded = true
@@ -400,41 +489,28 @@ class MainActivity : AppCompatActivity(), SafetyFragment.SafetyListener {
         lifecycleScope.launch {
             LocationService.barometerStatus.collect { status ->
                 if (status.history.isNotEmpty()) {
-                    instrumentHandler?.updateConditions(baro = status.formatPressure())
+                    lastBaroHpa = status.currentPressureHpa
+                    instrumentHandler?.updateConditions(baroHpa = status.currentPressureHpa)
                 }
             }
         }
         lifecycleScope.launch {
             viewModel.marineConditions.collect { c ->
                 if (c == null) return@collect
-                instrumentHandler?.updateConditions(
-                    tws          = c.windSpeedKt?.let { "%.1f".format(Locale.getDefault(), it) },
-                    twsBearingDeg = c.windDirDeg?.toFloat(),
-                    tempC        = c.tempC,
-                    currSpd      = c.currentSpeedKt?.let { "%.1f".format(Locale.getDefault(), it) } ?: "—",
-                    currDirDeg   = c.currentDirDeg?.toFloat(),
-                    waveHeightM  = c.waveHeightM,
-                    waveDirDeg   = c.waveDirDeg?.toFloat(),
-                    swellHeightM = c.swellHeightM,
-                    swellDirDeg  = c.swellDirDeg?.toFloat(),
-                    swellPeriodS = c.swellPeriodS
-                )
-                val swellHtFt   = c.swellHeightM?.let { (it * 3.28084f).toFloat() } ?: 3f
-                val windHtFt    = c.waveHeightM?.let  { (it * 3.28084f).toFloat() } ?: 1.5f
-                val swellPeriod = c.swellPeriodS?.toFloat() ?: 10f
-                val windKt      = c.windSpeedKt?.toFloat() ?: 0f
-                instrumentHandler?.updateWaveState(swellHtFt, swellPeriod, windHtFt, windKt)
+                lastConditions = c
+                applyConditions(c)
             }
         }
         lifecycleScope.launch {
             LocationService.nmeaDepthDataFlow.collect { depthData ->
-                // Update HUD depth (converted to feet)
-                hudDepth.text = "%.1f".format(Locale.getDefault(), depthData.depthMeters * 3.28084)
+                lastDepthMeters = depthData.depthMeters
+                hudDepth.text = unitPrefs.formatDepth(depthData.depthMeters)
             }
         }
         lifecycleScope.launch {
             LocationService.nmeaBoatSpeedData.collect { bspData ->
-                hudBsp.text = "%.1f".format(Locale.getDefault(), bspData.bspKnots)
+                lastBspKnots = bspData.bspKnots
+                hudBsp.text = unitPrefs.formatSpeed(bspData.bspKnots)
             }
         }
         lifecycleScope.launch {
diff --git a/android-app/app/src/main/kotlin/org/terst/nav/UnitPrefs.kt b/android-app/app/src/main/kotlin/org/terst/nav/UnitPrefs.kt
new file mode 100644
index 0000000..8d60ae0
--- /dev/null
+++ b/android-app/app/src/main/kotlin/org/terst/nav/UnitPrefs.kt
@@ -0,0 +1,83 @@
+package org.terst.nav
+
+import android.content.Context
+import java.util.Locale
+
+enum class TempUnit     { CELSIUS, FAHRENHEIT }
+enum class DepthUnit    { FEET, METERS }
+enum class PressureUnit { HPA, INHG }
+enum class SpeedUnit    { KNOTS, MPH, KPH }
+
+/**
+ * Persists and applies the user's preferred display units.
+ * Defaults: Fahrenheit, feet, hPa, knots.
+ */
+class UnitPrefs(context: Context) {
+
+    private val prefs = context.getSharedPreferences("unit_prefs", Context.MODE_PRIVATE)
+
+    var tempUnit: TempUnit
+        get() = TempUnit.valueOf(prefs.getString(KEY_TEMP, TempUnit.FAHRENHEIT.name)!!)
+        set(v) { prefs.edit().putString(KEY_TEMP, v.name).apply() }
+
+    var depthUnit: DepthUnit
+        get() = DepthUnit.valueOf(prefs.getString(KEY_DEPTH, DepthUnit.FEET.name)!!)
+        set(v) { prefs.edit().putString(KEY_DEPTH, v.name).apply() }
+
+    var pressureUnit: PressureUnit
+        get() = PressureUnit.valueOf(prefs.getString(KEY_PRESSURE, PressureUnit.HPA.name)!!)
+        set(v) { prefs.edit().putString(KEY_PRESSURE, v.name).apply() }
+
+    var speedUnit: SpeedUnit
+        get() = SpeedUnit.valueOf(prefs.getString(KEY_SPEED, SpeedUnit.KNOTS.name)!!)
+        set(v) { prefs.edit().putString(KEY_SPEED, v.name).apply() }
+
+    fun formatTemp(tempC: Double): String = when (tempUnit) {
+        TempUnit.CELSIUS    -> "%.0f".format(Locale.getDefault(), tempC)
+        TempUnit.FAHRENHEIT -> "%.0f".format(Locale.getDefault(), tempC * 9.0 / 5.0 + 32.0)
+    }
+
+    fun tempUnitLabel(): String = when (tempUnit) {
+        TempUnit.CELSIUS    -> "°C"
+        TempUnit.FAHRENHEIT -> "°F"
+    }
+
+    fun formatDepth(metres: Double): String = when (depthUnit) {
+        DepthUnit.FEET   -> "%.1f".format(Locale.getDefault(), metres * 3.28084)
+        DepthUnit.METERS -> "%.1f".format(Locale.getDefault(), metres)
+    }
+
+    fun depthUnitLabel(): String = when (depthUnit) {
+        DepthUnit.FEET   -> "ft"
+        DepthUnit.METERS -> "m"
+    }
+
+    fun formatPressure(hpa: Float): String = when (pressureUnit) {
+        PressureUnit.HPA  -> "%.1f".format(Locale.getDefault(), hpa)
+        PressureUnit.INHG -> "%.2f".format(Locale.getDefault(), hpa * 0.02953f)
+    }
+
+    fun pressureUnitLabel(): String = when (pressureUnit) {
+        PressureUnit.HPA  -> "hPa"
+        PressureUnit.INHG -> "inHg"
+    }
+
+    fun formatSpeed(knots: Double): String = when (speedUnit) {
+        SpeedUnit.KNOTS -> "%.1f".format(Locale.getDefault(), knots)
+        SpeedUnit.MPH   -> "%.1f".format(Locale.getDefault(), knots * 1.15078)
+        SpeedUnit.KPH   -> "%.1f".format(Locale.getDefault(), knots * 1.852)
+    }
+
+    fun speedUnitLabel(): String = when (speedUnit) {
+        SpeedUnit.KNOTS -> "kt"
+        SpeedUnit.MPH   -> "mph"
+        SpeedUnit.KPH   -> "kph"
+    }
+
+    companion object {
+        private const val KEY_TEMP     = "temp_unit"
+        private const val KEY_DEPTH    = "depth_unit"
+        private const val KEY_PRESSURE = "pressure_unit"
+        private const val KEY_SPEED    = "speed_unit"
+    }
+}
diff --git a/android-app/app/src/main/kotlin/org/terst/nav/ui/InstrumentHandler.kt b/android-app/app/src/main/kotlin/org/terst/nav/ui/InstrumentHandler.kt
index 48ebb3b..ccb3a91 100644
--- a/android-app/app/src/main/kotlin/org/terst/nav/ui/InstrumentHandler.kt
+++ b/android-app/app/src/main/kotlin/org/terst/nav/ui/InstrumentHandler.kt
@@ -1,19 +1,11 @@
 package org.terst.nav.ui
 
 import android.widget.TextView
+import org.terst.nav.UnitPrefs
 import java.util.Locale
 
 // ── Pure formatting helpers (top-level for testability) ──────────────────────
 
-private const val M_TO_FT = 3.28084
-
-/** Converts metres to feet. */
-fun metresToFeet(metres: Double): Double = metres * M_TO_FT
-
-/** Formats a feet value to one decimal place. */
-fun formatFt(ft: Double, locale: Locale = Locale.getDefault()): String =
-    "%.1f".format(locale, ft)
-
 /** Formats a bearing to zero decimal places with a degree symbol. */
 fun formatBearing(deg: Double, locale: Locale = Locale.getDefault()): String =
     "%.0f°".format(locale, deg)
@@ -31,11 +23,9 @@ fun formatPeriod(sec: Double, locale: Locale = Locale.getDefault()): String =
  * All boat-instrument data (SOG, COG, BSP, Depth) is handled directly
  * in MainActivity via the HUD strip.
  *
- * Units contract:
- *  - Speed values: pre-formatted strings in knots (caller's responsibility)
- *  - Height values: caller passes raw metres; this class converts to feet
- *  - Bearing values: raw degrees as Float, rotated into arrows and formatted
- *    into bearing TextViews by this class
+ * All numeric values are accepted in SI / nautical base units:
+ *   speeds in knots, heights in metres, pressure in hPa, temperature in °C.
+ * [unitPrefs] is consulted on each update to produce the correct formatted string.
  */
 class InstrumentHandler(
     // ── Conditions header ────────────────────────────────────────────────
@@ -58,47 +48,60 @@ class InstrumentHandler(
     private val bearingWaves: TextView,
     private val bearingSwell: TextView,
     // ── Wave view ────────────────────────────────────────────────────────
-    private val waveView: WaveView
+    private val waveView: WaveView,
+    // ── Unit preferences ─────────────────────────────────────────────────
+    private val unitPrefs: UnitPrefs
 ) {
     init {
         arrowCurr.arrowStyle  = DirectionArrowView.ArrowStyle.OCEAN
         arrowWaves.arrowStyle = DirectionArrowView.ArrowStyle.OCEAN
         arrowSwell.arrowStyle = DirectionArrowView.ArrowStyle.OCEAN
+        valueTws.text     = "—"
+        valueTemp.text    = "—"
+        valueBaro.text    = "—"
+        valueCurrSpd.text = "—"
+        valueWaveHt.text  = "—"
+        valueSwellHt.text = "—"
     }
 
     /**
-     * Updates all area-conditions fields.
-     * Null arguments leave the current value unchanged.
-     * [waveHeightM] and [swellHeightM] are raw metres — converted to feet internally.
+     * Updates all area-conditions fields. Null arguments leave the current value unchanged.
+     *
+     * @param twsKt      True wind speed in knots
+     * @param tempC      Air temperature in degrees Celsius
+     * @param baroHpa    Barometric pressure in hPa
+     * @param currSpdKt  Ocean current speed in knots
+     * @param waveHeightM  Wind-wave height in metres
+     * @param swellHeightM Swell height in metres
      */
     fun updateConditions(
-        tws: String?          = null, twsBearingDeg: Float? = null,
+        twsKt: Double?        = null, twsBearingDeg: Float? = null,
         tempC: Double?        = null,
-        baro: String?         = null,
-        currSpd: String?      = null, currDirDeg: Float?    = null,
+        baroHpa: Float?       = null,
+        currSpdKt: Double?    = null, currDirDeg: Float?    = null,
         waveHeightM: Double?  = null, waveDirDeg: Float?    = null,
         swellHeightM: Double? = null, swellDirDeg: Float?   = null,
         swellPeriodS: Double? = null
     ) {
-        tws?.let  { valueTws.text  = it }
-        baro?.let { valueBaro.text = it }
-        tempC?.let { valueTemp.text = "%.0f".format(Locale.getDefault(), it) }
+        twsKt?.let   { valueTws.text   = unitPrefs.formatSpeed(it) }
+        tempC?.let   { valueTemp.text  = unitPrefs.formatTemp(it) }
+        baroHpa?.let { valueBaro.text  = unitPrefs.formatPressure(it) }
         twsBearingDeg?.let {
             arrowTws.bearing = it
             bearingTws.text  = formatBearing(it.toDouble())
         }
 
-        currSpd?.let { valueCurrSpd.text = it }
+        currSpdKt?.let { valueCurrSpd.text = unitPrefs.formatSpeed(it) }
         currDirDeg?.let {
             arrowCurr.bearing = it
             bearingCurr.text  = formatBearing(it.toDouble())
         }
-        waveHeightM?.let { valueWaveHt.text = formatFt(metresToFeet(it)) }
+        waveHeightM?.let { valueWaveHt.text   = unitPrefs.formatDepth(it) }
         waveDirDeg?.let {
             arrowWaves.bearing = it
             bearingWaves.text  = formatBearing(it.toDouble())
         }
-        swellHeightM?.let { valueSwellHt.text = formatFt(metresToFeet(it)) }
+        swellHeightM?.let { valueSwellHt.text = unitPrefs.formatDepth(it) }
         swellDirDeg?.let {
             arrowSwell.bearing = it
             bearingSwell.text  = formatBearing(it.toDouble())
@@ -108,26 +111,28 @@ class InstrumentHandler(
 
     /**
      * Updates the WaveView with current sea state. Call once when conditions load.
-     *
-     * View height is set here to reflect swell scale: 1ft → 56dp, 8ft → 160dp.
+     * Heights are passed in metres; the WaveView scale is computed internally.
      * [windSpeedKt] gates whitecap rendering (Beaufort 4 threshold = 12 kt).
      */
     fun updateWaveState(
-        swellHeightFt: Float,
+        swellHeightM: Float,
         swellPeriodSec: Float,
-        windWaveHeightFt: Float,
+        windWaveHeightM: Float,
         windSpeedKt: Float = 0f
     ) {
-        waveView.swellHeightFt    = swellHeightFt
+        val swellHtFt    = swellHeightM    * 3.28084f
+        val windWaveHtFt = windWaveHeightM * 3.28084f
+
+        waveView.swellHeightFt    = swellHtFt
         waveView.swellPeriodSec   = swellPeriodSec
-        waveView.windWaveHeightFt = windWaveHeightFt
+        waveView.windWaveHeightFt = windWaveHtFt
         waveView.windSpeedKt      = windSpeedKt
 
         // Size the view to the swell — bigger swell = taller window
-        val density = waveView.resources.displayMetrics.density
-        val heightDp = (32f + swellHeightFt * 16f).coerceIn(56f, 160f)
-        val lp = waveView.layoutParams
-        lp.height = (heightDp * density).toInt()
+        val density  = waveView.resources.displayMetrics.density
+        val heightDp = (32f + swellHtFt * 16f).coerceIn(56f, 160f)
+        val lp       = waveView.layoutParams
+        lp.height    = (heightDp * density).toInt()
         waveView.layoutParams = lp
     }
 }
diff --git a/android-app/app/src/main/kotlin/org/terst/nav/ui/LayerPickerSheet.kt b/android-app/app/src/main/kotlin/org/terst/nav/ui/LayerPickerSheet.kt
index 48dc808..78fd70f 100644
--- a/android-app/app/src/main/kotlin/org/terst/nav/ui/LayerPickerSheet.kt
+++ b/android-app/app/src/main/kotlin/org/terst/nav/ui/LayerPickerSheet.kt
@@ -7,30 +7,33 @@ import android.view.ViewGroup
 import com.google.android.material.bottomsheet.BottomSheetDialogFragment
 import com.google.android.material.chip.ChipGroup
 import com.google.android.material.switchmaterial.SwitchMaterial
+import org.terst.nav.DepthUnit
+import org.terst.nav.PressureUnit
 import org.terst.nav.R
+import org.terst.nav.SpeedUnit
+import org.terst.nav.TempUnit
+import org.terst.nav.UnitPrefs
 
 class LayerPickerSheet(
     private val manager: MapLayerManager,
     private val onBaseChanged: (MapBasePreset) -> Unit,
-    private val onWindChanged: (Boolean) -> Unit
+    private val onWindChanged: (Boolean) -> Unit,
+    private val onParticlesChanged: (Boolean) -> Unit,
+    private val unitPrefs: UnitPrefs,
+    private val onUnitsChanged: () -> Unit
 ) : BottomSheetDialogFragment() {
 
     override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View =
         inflater.inflate(R.layout.layout_layer_picker_sheet, container, false)
 
     override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
-        val chipGroup  = view.findViewById<ChipGroup>(R.id.chip_group_base)
-        val windSwitch = view.findViewById<SwitchMaterial>(R.id.switch_wind)
-
-        // Set initial state from manager
-        val chipId = when (manager.basePreset) {
+        // ── Base layer chips ──────────────────────────────────────────────────
+        val chipGroup = view.findViewById<ChipGroup>(R.id.chip_group_base)
+        chipGroup.check(when (manager.basePreset) {
             MapBasePreset.SATELLITE -> R.id.chip_satellite
             MapBasePreset.CHARTS    -> R.id.chip_charts
             MapBasePreset.HYBRID    -> R.id.chip_hybrid
-        }
-        chipGroup.check(chipId)
-        windSwitch.isChecked = manager.windEnabled
-
+        })
         chipGroup.setOnCheckedStateChangeListener { _, checkedIds ->
             val preset = when (checkedIds.firstOrNull()) {
                 R.id.chip_satellite -> MapBasePreset.SATELLITE
@@ -41,8 +44,76 @@ class LayerPickerSheet(
             onBaseChanged(preset)
         }
 
-        windSwitch.setOnCheckedChangeListener { _, checked ->
-            onWindChanged(checked)
+        // ── Wind overlay switch ───────────────────────────────────────────────
+        val windSwitch = view.findViewById<SwitchMaterial>(R.id.switch_wind)
+        windSwitch.isChecked = manager.windEnabled
+        windSwitch.setOnCheckedChangeListener { _, checked -> onWindChanged(checked) }
+
+        // ── Particles switch ──────────────────────────────────────────────────
+        val particlesSwitch = view.findViewById<SwitchMaterial>(R.id.switch_particles)
+        particlesSwitch.isChecked = manager.particlesEnabled
+        particlesSwitch.setOnCheckedChangeListener { _, checked -> onParticlesChanged(checked) }
+
+        // ── Temperature chips ─────────────────────────────────────────────────
+        val chipTemp = view.findViewById<ChipGroup>(R.id.chip_group_temp)
+        chipTemp.check(when (unitPrefs.tempUnit) {
+            TempUnit.FAHRENHEIT -> R.id.chip_fahrenheit
+            TempUnit.CELSIUS    -> R.id.chip_celsius
+        })
+        chipTemp.setOnCheckedStateChangeListener { _, ids ->
+            unitPrefs.tempUnit = when (ids.firstOrNull()) {
+                R.id.chip_fahrenheit -> TempUnit.FAHRENHEIT
+                R.id.chip_celsius    -> TempUnit.CELSIUS
+                else -> return@setOnCheckedStateChangeListener
+            }
+            onUnitsChanged()
+        }
+
+        // ── Depth chips ───────────────────────────────────────────────────────
+        val chipDepth = view.findViewById<ChipGroup>(R.id.chip_group_depth)
+        chipDepth.check(when (unitPrefs.depthUnit) {
+            DepthUnit.FEET   -> R.id.chip_feet
+            DepthUnit.METERS -> R.id.chip_meters
+        })
+        chipDepth.setOnCheckedStateChangeListener { _, ids ->
+            unitPrefs.depthUnit = when (ids.firstOrNull()) {
+                R.id.chip_feet   -> DepthUnit.FEET
+                R.id.chip_meters -> DepthUnit.METERS
+                else -> return@setOnCheckedStateChangeListener
+            }
+            onUnitsChanged()
+        }
+
+        // ── Pressure chips ────────────────────────────────────────────────────
+        val chipPressure = view.findViewById<ChipGroup>(R.id.chip_group_pressure)
+        chipPressure.check(when (unitPrefs.pressureUnit) {
+            PressureUnit.HPA  -> R.id.chip_hpa
+            PressureUnit.INHG -> R.id.chip_inhg
+        })
+        chipPressure.setOnCheckedStateChangeListener { _, ids ->
+            unitPrefs.pressureUnit = when (ids.firstOrNull()) {
+                R.id.chip_hpa  -> PressureUnit.HPA
+                R.id.chip_inhg -> PressureUnit.INHG
+                else -> return@setOnCheckedStateChangeListener
+            }
+            onUnitsChanged()
+        }
+
+        // ── Speed chips ───────────────────────────────────────────────────────
+        val chipSpeed = view.findViewById<ChipGroup>(R.id.chip_group_speed)
+        chipSpeed.check(when (unitPrefs.speedUnit) {
+            SpeedUnit.KNOTS -> R.id.chip_knots
+            SpeedUnit.MPH   -> R.id.chip_mph
+            SpeedUnit.KPH   -> R.id.chip_kph
+        })
+        chipSpeed.setOnCheckedStateChangeListener { _, ids ->
+            unitPrefs.speedUnit = when (ids.firstOrNull()) {
+                R.id.chip_knots -> SpeedUnit.KNOTS
+                R.id.chip_mph   -> SpeedUnit.MPH
+                R.id.chip_kph   -> SpeedUnit.KPH
+                else -> return@setOnCheckedStateChangeListener
+            }
+            onUnitsChanged()
         }
     }
 }
diff --git a/android-app/app/src/main/kotlin/org/terst/nav/ui/MapLayerManager.kt b/android-app/app/src/main/kotlin/org/terst/nav/ui/MapLayerManager.kt
index 83cfa70..855233f 100644
--- a/android-app/app/src/main/kotlin/org/terst/nav/ui/MapLayerManager.kt
+++ b/android-app/app/src/main/kotlin/org/terst/nav/ui/MapLayerManager.kt
@@ -26,6 +26,9 @@ class MapLayerManager(context: Context) {
     var windEnabled: Boolean = prefs.getBoolean(KEY_WIND, true)
         private set
 
+    var particlesEnabled: Boolean = prefs.getBoolean(KEY_PARTICLES, true)
+        private set
+
     // ── Source / Layer IDs ────────────────────────────────────────────────────
 
     companion object {
@@ -39,8 +42,9 @@ class MapLayerManager(context: Context) {
         const val LAYER_WIND        = "wind-layer"
         const val LAYER_SEAMARKS    = "openseamap-layer"
 
-        private const val KEY_BASE  = "base_preset"
-        private const val KEY_WIND  = "wind_enabled"
+        private const val KEY_BASE      = "base_preset"
+        private const val KEY_WIND      = "wind_enabled"
+        private const val KEY_PARTICLES = "particles_enabled"
 
         // Tile URLs
         private const val URL_SATELLITE =
@@ -106,6 +110,12 @@ class MapLayerManager(context: Context) {
         }
     }
 
+    /** Toggle wind particles (Canvas overlay — no style interaction needed). */
+    fun setParticlesEnabled(enabled: Boolean) {
+        particlesEnabled = enabled
+        prefs.edit().putBoolean(KEY_PARTICLES, enabled).apply()
+    }
+
     /** Toggle wind overlay on a live style. */
     fun setWindEnabled(style: Style, enabled: Boolean) {
         windEnabled = enabled
diff --git a/android-app/app/src/main/res/layout/activity_main.xml b/android-app/app/src/main/res/layout/activity_main.xml
index 5147506..5943949 100644
--- a/android-app/app/src/main/res/layout/activity_main.xml
+++ b/android-app/app/src/main/res/layout/activity_main.xml
@@ -90,10 +90,10 @@
                 android:visibility="gone"
                 app:cornerRadius="20dp"
                 app:elevation="20dp"
-                app:layout_constraintBottom_toBottomOf="parent"
+                app:layout_constraintTop_toBottomOf="@id/nav_hud"
                 app:layout_constraintEnd_toEndOf="parent"
                 app:layout_constraintStart_toStartOf="parent"
-                android:layout_marginBottom="24dp" />
+                android:layout_marginTop="8dp" />
 
         </androidx.constraintlayout.widget.ConstraintLayout>
 
diff --git a/android-app/app/src/main/res/layout/layout_instruments_sheet.xml b/android-app/app/src/main/res/layout/layout_instruments_sheet.xml
index faec826..03cefb7 100644
--- a/android-app/app/src/main/res/layout/layout_instruments_sheet.xml
+++ b/android-app/app/src/main/res/layout/layout_instruments_sheet.xml
@@ -56,7 +56,7 @@
                     android:id="@+id/value_tws"
                     style="@style/InstrumentPrimaryValue"
                     tools:text="15.5" />
-                <TextView style="@style/InstrumentUnit" android:text="kts" />
+                <TextView android:id="@+id/unit_tws" style="@style/InstrumentUnit" android:text="kt" />
                 <org.terst.nav.ui.DirectionArrowView
                     android:id="@+id/arrow_tws"
                     android:layout_width="14dp"
@@ -95,7 +95,7 @@
                     android:id="@+id/value_temp"
                     style="@style/InstrumentPrimaryValue"
                     tools:text="18" />
-                <TextView style="@style/InstrumentUnit" android:text="°C" />
+                <TextView android:id="@+id/unit_temp" style="@style/InstrumentUnit" android:text="°F" />
             </LinearLayout>
         </LinearLayout>
 
@@ -123,7 +123,7 @@
                     android:id="@+id/value_baro"
                     style="@style/InstrumentPrimaryValue"
                     tools:text="1013" />
-                <TextView style="@style/InstrumentUnit" android:text="hPa" />
+                <TextView android:id="@+id/unit_baro" style="@style/InstrumentUnit" android:text="hPa" />
             </LinearLayout>
         </LinearLayout>
 
@@ -175,7 +175,7 @@
                     android:id="@+id/value_curr_spd"
                     style="@style/ForecastValue"
                     tools:text="0.8" />
-                <TextView style="@style/ForecastUnit" android:text="kts" />
+                <TextView android:id="@+id/unit_curr_spd" style="@style/ForecastUnit" android:text="kt" />
             </LinearLayout>
             <LinearLayout
                 android:layout_width="wrap_content"
@@ -214,7 +214,7 @@
                     android:id="@+id/value_wave_ht"
                     style="@style/ForecastValue"
                     tools:text="3.5" />
-                <TextView style="@style/ForecastUnit" android:text="ft" />
+                <TextView android:id="@+id/unit_wave_ht" style="@style/ForecastUnit" android:text="ft" />
             </LinearLayout>
             <LinearLayout
                 android:layout_width="wrap_content"
@@ -253,7 +253,7 @@
                     android:id="@+id/value_swell_ht"
                     style="@style/ForecastValue"
                     tools:text="5.2" />
-                <TextView style="@style/ForecastUnit" android:text="ft" />
+                <TextView android:id="@+id/unit_swell_ht" style="@style/ForecastUnit" android:text="ft" />
             </LinearLayout>
             <LinearLayout
                 android:layout_width="wrap_content"
diff --git a/android-app/app/src/main/res/layout/layout_layer_picker_sheet.xml b/android-app/app/src/main/res/layout/layout_layer_picker_sheet.xml
index c424606..fdfbb7a 100644
--- a/android-app/app/src/main/res/layout/layout_layer_picker_sheet.xml
+++ b/android-app/app/src/main/res/layout/layout_layer_picker_sheet.xml
@@ -1,104 +1,310 @@
 <?xml version="1.0" encoding="utf-8"?>
-<LinearLayout
+<ScrollView
     xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
     android:layout_width="match_parent"
     android:layout_height="wrap_content"
-    android:orientation="vertical"
-    android:paddingStart="24dp"
-    android:paddingEnd="24dp"
-    android:paddingBottom="32dp"
     android:background="?attr/colorSurface">
 
-    <View
-        android:layout_width="36dp"
-        android:layout_height="4dp"
-        android:layout_gravity="center_horizontal"
-        android:layout_marginTop="12dp"
-        android:layout_marginBottom="20dp"
-        android:background="@color/md_theme_outline" />
-
-    <TextView
-        android:layout_width="wrap_content"
-        android:layout_height="wrap_content"
-        android:layout_marginBottom="16dp"
-        android:text="MAP LAYERS"
-        android:textSize="11sp"
-        android:textAllCaps="true"
-        android:letterSpacing="0.12"
-        android:fontFamily="sans-serif-light"
-        android:textColor="@color/instrument_text_secondary" />
-
-    <!-- Base map selection -->
-    <com.google.android.material.chip.ChipGroup
-        android:id="@+id/chip_group_base"
+    <LinearLayout
         android:layout_width="match_parent"
         android:layout_height="wrap_content"
-        android:layout_marginBottom="24dp"
-        app:singleSelection="true"
-        app:selectionRequired="true"
-        xmlns:app="http://schemas.android.com/apk/res-auto">
-
-        <com.google.android.material.chip.Chip
-            android:id="@+id/chip_satellite"
-            style="@style/Widget.Material3.Chip.Filter"
+        android:orientation="vertical"
+        android:paddingStart="24dp"
+        android:paddingEnd="24dp"
+        android:paddingBottom="40dp">
+
+        <View
+            android:layout_width="36dp"
+            android:layout_height="4dp"
+            android:layout_gravity="center_horizontal"
+            android:layout_marginTop="12dp"
+            android:layout_marginBottom="20dp"
+            android:background="@color/md_theme_outline" />
+
+        <!-- ── MAP LAYERS ──────────────────────────────────────────── -->
+
+        <TextView
             android:layout_width="wrap_content"
             android:layout_height="wrap_content"
-            android:text="Satellite" />
+            android:layout_marginBottom="12dp"
+            android:text="MAP LAYERS"
+            android:textSize="11sp"
+            android:textAllCaps="true"
+            android:letterSpacing="0.12"
+            android:fontFamily="sans-serif-light"
+            android:textColor="@color/instrument_text_secondary" />
 
-        <com.google.android.material.chip.Chip
-            android:id="@+id/chip_charts"
-            style="@style/Widget.Material3.Chip.Filter"
-            android:layout_width="wrap_content"
+        <!-- Base map selection -->
+        <com.google.android.material.chip.ChipGroup
+            android:id="@+id/chip_group_base"
+            android:layout_width="match_parent"
             android:layout_height="wrap_content"
-            android:text="Charts" />
+            android:layout_marginBottom="20dp"
+            app:singleSelection="true"
+            app:selectionRequired="true">
 
-        <com.google.android.material.chip.Chip
-            android:id="@+id/chip_hybrid"
-            style="@style/Widget.Material3.Chip.Filter"
-            android:layout_width="wrap_content"
+            <com.google.android.material.chip.Chip
+                android:id="@+id/chip_satellite"
+                style="@style/Widget.Material3.Chip.Filter"
+                android:layout_width="wrap_content"
+                android:layout_height="wrap_content"
+                android:text="Satellite" />
+
+            <com.google.android.material.chip.Chip
+                android:id="@+id/chip_charts"
+                style="@style/Widget.Material3.Chip.Filter"
+                android:layout_width="wrap_content"
+                android:layout_height="wrap_content"
+                android:text="Charts" />
+
+            <com.google.android.material.chip.Chip
+                android:id="@+id/chip_hybrid"
+                style="@style/Widget.Material3.Chip.Filter"
+                android:layout_width="wrap_content"
+                android:layout_height="wrap_content"
+                android:text="Hybrid" />
+
+        </com.google.android.material.chip.ChipGroup>
+
+        <View
+            android:layout_width="match_parent"
+            android:layout_height="1dp"
+            android:layout_marginBottom="16dp"
+            android:background="@color/md_theme_surfaceVariant" />
+
+        <!-- Wind overlay toggle -->
+        <LinearLayout
+            android:layout_width="match_parent"
             android:layout_height="wrap_content"
-            android:text="Hybrid" />
+            android:orientation="horizontal"
+            android:gravity="center_vertical"
+            android:layout_marginBottom="12dp">
 
-    </com.google.android.material.chip.ChipGroup>
+            <LinearLayout
+                android:layout_width="0dp"
+                android:layout_height="wrap_content"
+                android:layout_weight="1"
+                android:orientation="vertical">
+                <TextView
+                    android:layout_width="wrap_content"
+                    android:layout_height="wrap_content"
+                    android:text="Wind overlay"
+                    android:textSize="15sp"
+                    android:textColor="@color/instrument_text_normal" />
+                <TextView
+                    android:layout_width="wrap_content"
+                    android:layout_height="wrap_content"
+                    android:text="Wind speed colour map"
+                    android:textSize="12sp"
+                    android:textColor="@color/instrument_text_secondary" />
+            </LinearLayout>
 
-    <!-- Wind divider -->
-    <View
-        android:layout_width="match_parent"
-        android:layout_height="1dp"
-        android:layout_marginBottom="16dp"
-        android:background="@color/md_theme_surfaceVariant" />
+            <com.google.android.material.switchmaterial.SwitchMaterial
+                android:id="@+id/switch_wind"
+                android:layout_width="wrap_content"
+                android:layout_height="wrap_content" />
 
-    <!-- Wind toggle -->
-    <LinearLayout
-        android:layout_width="match_parent"
-        android:layout_height="wrap_content"
-        android:orientation="horizontal"
-        android:gravity="center_vertical">
+        </LinearLayout>
 
+        <!-- Wind particles toggle -->
         <LinearLayout
-            android:layout_width="0dp"
+            android:layout_width="match_parent"
             android:layout_height="wrap_content"
-            android:layout_weight="1"
-            android:orientation="vertical">
+            android:orientation="horizontal"
+            android:gravity="center_vertical"
+            android:layout_marginBottom="8dp">
+
+            <LinearLayout
+                android:layout_width="0dp"
+                android:layout_height="wrap_content"
+                android:layout_weight="1"
+                android:orientation="vertical">
+                <TextView
+                    android:layout_width="wrap_content"
+                    android:layout_height="wrap_content"
+                    android:text="Wind particles"
+                    android:textSize="15sp"
+                    android:textColor="@color/instrument_text_normal" />
+                <TextView
+                    android:layout_width="wrap_content"
+                    android:layout_height="wrap_content"
+                    android:text="Animated particle overlay"
+                    android:textSize="12sp"
+                    android:textColor="@color/instrument_text_secondary" />
+            </LinearLayout>
+
+            <com.google.android.material.switchmaterial.SwitchMaterial
+                android:id="@+id/switch_particles"
+                android:layout_width="wrap_content"
+                android:layout_height="wrap_content" />
+
+        </LinearLayout>
+
+        <!-- ── UNITS ───────────────────────────────────────────────── -->
+
+        <View
+            android:layout_width="match_parent"
+            android:layout_height="1dp"
+            android:layout_marginTop="8dp"
+            android:layout_marginBottom="16dp"
+            android:background="@color/md_theme_surfaceVariant" />
+
+        <TextView
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:layout_marginBottom="12dp"
+            android:text="UNITS"
+            android:textSize="11sp"
+            android:textAllCaps="true"
+            android:letterSpacing="0.12"
+            android:fontFamily="sans-serif-light"
+            android:textColor="@color/instrument_text_secondary" />
+
+        <!-- Temperature -->
+        <LinearLayout
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:orientation="horizontal"
+            android:gravity="center_vertical"
+            android:layout_marginBottom="10dp">
             <TextView
+                android:layout_width="0dp"
+                android:layout_height="wrap_content"
+                android:layout_weight="1"
+                android:text="Temperature"
+                android:textSize="14sp"
+                android:textColor="@color/instrument_text_normal" />
+            <com.google.android.material.chip.ChipGroup
+                android:id="@+id/chip_group_temp"
                 android:layout_width="wrap_content"
                 android:layout_height="wrap_content"
-                android:text="Wind overlay"
-                android:textSize="15sp"
+                app:singleSelection="true"
+                app:selectionRequired="true">
+                <com.google.android.material.chip.Chip
+                    android:id="@+id/chip_fahrenheit"
+                    style="@style/Widget.Material3.Chip.Filter"
+                    android:layout_width="wrap_content"
+                    android:layout_height="wrap_content"
+                    android:text="°F" />
+                <com.google.android.material.chip.Chip
+                    android:id="@+id/chip_celsius"
+                    style="@style/Widget.Material3.Chip.Filter"
+                    android:layout_width="wrap_content"
+                    android:layout_height="wrap_content"
+                    android:text="°C" />
+            </com.google.android.material.chip.ChipGroup>
+        </LinearLayout>
+
+        <!-- Depth / height -->
+        <LinearLayout
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:orientation="horizontal"
+            android:gravity="center_vertical"
+            android:layout_marginBottom="10dp">
+            <TextView
+                android:layout_width="0dp"
+                android:layout_height="wrap_content"
+                android:layout_weight="1"
+                android:text="Depth / height"
+                android:textSize="14sp"
                 android:textColor="@color/instrument_text_normal" />
+            <com.google.android.material.chip.ChipGroup
+                android:id="@+id/chip_group_depth"
+                android:layout_width="wrap_content"
+                android:layout_height="wrap_content"
+                app:singleSelection="true"
+                app:selectionRequired="true">
+                <com.google.android.material.chip.Chip
+                    android:id="@+id/chip_feet"
+                    style="@style/Widget.Material3.Chip.Filter"
+                    android:layout_width="wrap_content"
+                    android:layout_height="wrap_content"
+                    android:text="ft" />
+                <com.google.android.material.chip.Chip
+                    android:id="@+id/chip_meters"
+                    style="@style/Widget.Material3.Chip.Filter"
+                    android:layout_width="wrap_content"
+                    android:layout_height="wrap_content"
+                    android:text="m" />
+            </com.google.android.material.chip.ChipGroup>
+        </LinearLayout>
+
+        <!-- Pressure -->
+        <LinearLayout
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:orientation="horizontal"
+            android:gravity="center_vertical"
+            android:layout_marginBottom="10dp">
             <TextView
+                android:layout_width="0dp"
+                android:layout_height="wrap_content"
+                android:layout_weight="1"
+                android:text="Pressure"
+                android:textSize="14sp"
+                android:textColor="@color/instrument_text_normal" />
+            <com.google.android.material.chip.ChipGroup
+                android:id="@+id/chip_group_pressure"
                 android:layout_width="wrap_content"
                 android:layout_height="wrap_content"
-                android:text="OpenWeatherMap wind speed"
-                android:textSize="12sp"
-                android:textColor="@color/instrument_text_secondary" />
+                app:singleSelection="true"
+                app:selectionRequired="true">
+                <com.google.android.material.chip.Chip
+                    android:id="@+id/chip_hpa"
+                    style="@style/Widget.Material3.Chip.Filter"
+                    android:layout_width="wrap_content"
+                    android:layout_height="wrap_content"
+                    android:text="hPa" />
+                <com.google.android.material.chip.Chip
+                    android:id="@+id/chip_inhg"
+                    style="@style/Widget.Material3.Chip.Filter"
+                    android:layout_width="wrap_content"
+                    android:layout_height="wrap_content"
+                    android:text="inHg" />
+            </com.google.android.material.chip.ChipGroup>
         </LinearLayout>
 
-        <com.google.android.material.switchmaterial.SwitchMaterial
-            android:id="@+id/switch_wind"
-            android:layout_width="wrap_content"
-            android:layout_height="wrap_content" />
+        <!-- Speed -->
+        <LinearLayout
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:orientation="horizontal"
+            android:gravity="center_vertical">
+            <TextView
+                android:layout_width="0dp"
+                android:layout_height="wrap_content"
+                android:layout_weight="1"
+                android:text="Speed"
+                android:textSize="14sp"
+                android:textColor="@color/instrument_text_normal" />
+            <com.google.android.material.chip.ChipGroup
+                android:id="@+id/chip_group_speed"
+                android:layout_width="wrap_content"
+                android:layout_height="wrap_content"
+                app:singleSelection="true"
+                app:selectionRequired="true">
+                <com.google.android.material.chip.Chip
+                    android:id="@+id/chip_knots"
+                    style="@style/Widget.Material3.Chip.Filter"
+                    android:layout_width="wrap_content"
+                    android:layout_height="wrap_content"
+                    android:text="kt" />
+                <com.google.android.material.chip.Chip
+                    android:id="@+id/chip_mph"
+                    style="@style/Widget.Material3.Chip.Filter"
+                    android:layout_width="wrap_content"
+                    android:layout_height="wrap_content"
+                    android:text="mph" />
+                <com.google.android.material.chip.Chip
+                    android:id="@+id/chip_kph"
+                    style="@style/Widget.Material3.Chip.Filter"
+                    android:layout_width="wrap_content"
+                    android:layout_height="wrap_content"
+                    android:text="kph" />
+            </com.google.android.material.chip.ChipGroup>
+        </LinearLayout>
 
     </LinearLayout>
-
-</LinearLayout>
+</ScrollView>
diff --git a/android-app/app/src/main/res/layout/layout_nav_hud.xml b/android-app/app/src/main/res/layout/layout_nav_hud.xml
index 4623bb1..90119fa 100644
--- a/android-app/app/src/main/res/layout/layout_nav_hud.xml
+++ b/android-app/app/src/main/res/layout/layout_nav_hud.xml
@@ -39,6 +39,7 @@
                 android:fontFamily="sans-serif-medium"
                 tools:text="7.1" />
             <TextView
+                android:id="@+id/unit_hud_sog"
                 android:layout_width="wrap_content"
                 android:layout_height="wrap_content"
                 android:text="kt"
@@ -110,6 +111,7 @@
                 android:fontFamily="sans-serif-medium"
                 tools:text="6.8" />
             <TextView
+                android:id="@+id/unit_hud_bsp"
                 android:layout_width="wrap_content"
                 android:layout_height="wrap_content"
                 android:text="kt"
@@ -149,6 +151,7 @@
                 android:fontFamily="sans-serif-medium"
                 tools:text="42.0" />
             <TextView
+                android:id="@+id/unit_hud_depth"
                 android:layout_width="wrap_content"
                 android:layout_height="wrap_content"
                 android:text="ft"