diff --git a/.gitignore b/.gitignore
index cf61a3a3d..615890856 100644
--- a/.gitignore
+++ b/.gitignore
@@ -28,8 +28,10 @@ test/plugin-test-config/plugin-config-data/
 test/plugin-test-config/ssl-cert.pem
 test/plugin-test-config/ssl-key.pem
 test/plugin-test-config/baseDeltas.json
+test/plugin-test-config/unitpreferences/
 
 test/server-test-config/applicationData/
+test/server-test-config/unitpreferences/
 test/server-test-config/ssl-cert.pem
 test/server-test-config/ssl-key.pem
 test/server-test-config/plugin-config-data/
diff --git a/src/config/config.ts b/src/config/config.ts
index cd8294085..5e4f605de 100644
--- a/src/config/config.ts
+++ b/src/config/config.ts
@@ -159,8 +159,8 @@ export function load(app: ConfigApp) {
 
   // Load unit preferences
   try {
-    loadUnitPreferences()
     setApplicationDataPath(app.config.configPath)
+    loadUnitPreferences()
     debug('Unit preferences loaded')
   } catch (err) {
     console.error('Failed to load unit preferences:', err)
diff --git a/src/interfaces/unitpreferences-api.js b/src/interfaces/unitpreferences-api.js
index 382d6cec9..10c0836c6 100644
--- a/src/interfaces/unitpreferences-api.js
+++ b/src/interfaces/unitpreferences-api.js
@@ -124,26 +124,6 @@ function validatePreset(preset, definitions) {
   return null
 }
 
-/**
- * Check if a preset name already exists
- * @param {string} presetName - The preset filename (without .json)
- * @returns {object|null} - { type: 'builtin'|'custom' } if exists, null if not
- */
-function checkPresetExists(presetName) {
-  const builtInPath = path.join(UNITPREFS_DIR, 'presets', `${presetName}.json`)
-  if (fs.existsSync(builtInPath)) {
-    return { type: 'builtin' }
-  }
-  const customPath = path.join(
-    UNITPREFS_DIR,
-    'presets/custom',
-    `${presetName}.json`
-  )
-  if (fs.existsSync(customPath)) {
-    return { type: 'custom' }
-  }
-  return null
-}
 const {
   getConfig,
   getCategories,
@@ -156,9 +136,31 @@ const {
   getDefaultCategory
 } = require('../unitpreferences')
 
-const UNITPREFS_DIR = path.join(__dirname, '../../unitpreferences')
+const PACKAGE_UNITPREFS_DIR = path.join(__dirname, '../../unitpreferences')
 
 module.exports = function (app) {
+  const configUnitprefsDir = path.join(app.config.configPath, 'unitpreferences')
+
+  function checkPresetExists(presetName) {
+    const builtInPath = path.join(
+      PACKAGE_UNITPREFS_DIR,
+      'presets',
+      `${presetName}.json`
+    )
+    if (fs.existsSync(builtInPath)) {
+      return { type: 'builtin' }
+    }
+    const customPath = path.join(
+      configUnitprefsDir,
+      'presets/custom',
+      `${presetName}.json`
+    )
+    if (fs.existsSync(customPath)) {
+      return { type: 'custom' }
+    }
+    return null
+  }
+
   const router = express.Router()
 
   // GET /signalk/v1/unitpreferences/config
@@ -175,7 +177,7 @@ module.exports = function (app) {
   // PUT /signalk/v1/unitpreferences/config
   router.put('/config', (req, res) => {
     try {
-      const configPath = path.join(UNITPREFS_DIR, 'config.json')
+      const configPath = path.join(configUnitprefsDir, 'config.json')
       fs.writeFileSync(configPath, JSON.stringify(req.body, null, 2))
       reloadPreset()
       app.emit('unitpreferencesChanged', { type: 'global' })
@@ -212,7 +214,7 @@ module.exports = function (app) {
   router.get('/custom-definitions', (req, res) => {
     try {
       const customPath = path.join(
-        UNITPREFS_DIR,
+        configUnitprefsDir,
         'custom-units-definitions.json'
       )
       if (fs.existsSync(customPath)) {
@@ -238,7 +240,7 @@ module.exports = function (app) {
       }
 
       const customPath = path.join(
-        UNITPREFS_DIR,
+        configUnitprefsDir,
         'custom-units-definitions.json'
       )
       fs.writeFileSync(customPath, JSON.stringify(req.body, null, 2))
@@ -265,7 +267,7 @@ module.exports = function (app) {
   // PUT /signalk/v1/unitpreferences/custom-categories
   router.put('/custom-categories', (req, res) => {
     try {
-      const customPath = path.join(UNITPREFS_DIR, 'custom-categories.json')
+      const customPath = path.join(configUnitprefsDir, 'custom-categories.json')
       fs.writeFileSync(customPath, JSON.stringify(req.body, null, 2))
       reloadCustomCategories()
       app.emit('unitpreferencesChanged', { type: 'global' })
@@ -279,13 +281,13 @@ module.exports = function (app) {
   // GET /signalk/v1/unitpreferences/presets
   router.get('/presets', (req, res) => {
     try {
-      const presetsDir = path.join(UNITPREFS_DIR, 'presets')
-      const customDir = path.join(presetsDir, 'custom')
+      const presetsDir = path.join(PACKAGE_UNITPREFS_DIR, 'presets')
+      const customDir = path.join(configUnitprefsDir, 'presets', 'custom')
 
       const builtIn = []
       const custom = []
 
-      // List built-in presets
+      // List built-in presets from package dir
       const builtInFiles = fs.readdirSync(presetsDir)
       for (const file of builtInFiles) {
         if (file.endsWith('.json')) {
@@ -299,7 +301,7 @@ module.exports = function (app) {
         }
       }
 
-      // List custom presets
+      // List custom presets from config dir
       if (fs.existsSync(customDir)) {
         const customFiles = fs.readdirSync(customDir)
         for (const file of customFiles) {
@@ -332,9 +334,9 @@ module.exports = function (app) {
         return
       }
 
-      // Check custom first
+      // Check custom presets in config dir first
       const customPath = path.join(
-        UNITPREFS_DIR,
+        configUnitprefsDir,
         'presets/custom',
         `${presetName}.json`
       )
@@ -344,9 +346,9 @@ module.exports = function (app) {
         return
       }
 
-      // Fall back to built-in
+      // Fall back to built-in in package dir
       const builtInPath = path.join(
-        UNITPREFS_DIR,
+        PACKAGE_UNITPREFS_DIR,
         'presets',
         `${presetName}.json`
       )
@@ -388,7 +390,7 @@ module.exports = function (app) {
         return
       }
 
-      const customDir = path.join(UNITPREFS_DIR, 'presets/custom')
+      const customDir = path.join(configUnitprefsDir, 'presets/custom')
       if (!fs.existsSync(customDir)) {
         fs.mkdirSync(customDir, { recursive: true })
       }
@@ -413,7 +415,7 @@ module.exports = function (app) {
       }
 
       const presetPath = path.join(
-        UNITPREFS_DIR,
+        configUnitprefsDir,
         'presets/custom',
         `${presetName}.json`
       )
@@ -435,7 +437,24 @@ module.exports = function (app) {
   router.get('/active', (req, res) => {
     try {
       const preset = getActivePreset()
-      res.json(preset)
+      const definitions = getMergedDefinitions()
+      const result = {
+        ...preset,
+        categories: { ...preset.categories }
+      }
+      for (const [category, catDef] of Object.entries(result.categories)) {
+        const unitDef = definitions[catDef.baseUnit]
+        const conversion = unitDef?.conversions?.[catDef.targetUnit]
+        if (conversion) {
+          result.categories[category] = {
+            ...catDef,
+            formula: conversion.formula,
+            inverseFormula: conversion.inverseFormula,
+            symbol: conversion.symbol
+          }
+        }
+      }
+      res.json(result)
     } catch (err) {
       debug('Error getting active preset:', err)
       res.status(500).json({ error: 'Failed to get active preset' })
@@ -443,10 +462,12 @@ module.exports = function (app) {
   })
 
   // GET /signalk/v1/unitpreferences/default-categories
-  // Returns the full default-categories.json data
   router.get('/default-categories', (req, res) => {
     try {
-      const defaultCatPath = path.join(UNITPREFS_DIR, 'default-categories.json')
+      const defaultCatPath = path.join(
+        PACKAGE_UNITPREFS_DIR,
+        'default-categories.json'
+      )
       if (fs.existsSync(defaultCatPath)) {
         const data = JSON.parse(fs.readFileSync(defaultCatPath, 'utf-8'))
         res.json(data)
@@ -460,7 +481,6 @@ module.exports = function (app) {
   })
 
   // GET /signalk/v1/unitpreferences/default-category/:path
-  // Returns the default category for a specific SignalK path
   router.get('/default-category/*', (req, res) => {
     try {
       const signalkPath = req.params[0]
@@ -473,7 +493,6 @@ module.exports = function (app) {
   })
 
   // POST /signalk/v1/unitpreferences/presets/custom/upload
-  // Upload a custom preset file (admin only)
   const MAX_PRESET_SIZE = 100 * 1024 // 100KB
 
   router.post('/presets/custom/upload', (req, res) => {
@@ -569,7 +588,7 @@ module.exports = function (app) {
         }
 
         // Ensure custom directory exists
-        const customDir = path.join(UNITPREFS_DIR, 'presets/custom')
+        const customDir = path.join(configUnitprefsDir, 'presets/custom')
         if (!fs.existsSync(customDir)) {
           fs.mkdirSync(customDir, { recursive: true })
         }
diff --git a/src/unitpreferences/index.ts b/src/unitpreferences/index.ts
index 7be8133de..797337903 100644
--- a/src/unitpreferences/index.ts
+++ b/src/unitpreferences/index.ts
@@ -10,6 +10,7 @@ export {
   getActivePreset,
   getActivePresetForUser,
   getDefaultCategory,
+  getConfigUnitprefsDir,
   setApplicationDataPath,
   DEFAULT_PRESET
 } from './loader'
diff --git a/src/unitpreferences/loader.ts b/src/unitpreferences/loader.ts
index e06ad0db7..07c9c60b1 100644
--- a/src/unitpreferences/loader.ts
+++ b/src/unitpreferences/loader.ts
@@ -7,7 +7,7 @@ import {
   UnitPreferencesConfig
 } from './types'
 
-const UNITPREFS_DIR = path.join(__dirname, '../../unitpreferences')
+const PACKAGE_UNITPREFS_DIR = path.join(__dirname, '../../unitpreferences')
 export const DEFAULT_PRESET = 'nautical-metric'
 
 let categories: CategoryMap
@@ -18,51 +18,109 @@ let activePreset: Preset
 let config: UnitPreferencesConfig
 let defaultCategories: { [path: string]: string } = {}
 let applicationDataPath: string = ''
+let configUnitprefsDir: string = ''
 
 export function setApplicationDataPath(configPath: string): void {
   applicationDataPath = path.join(configPath, 'applicationData')
+  configUnitprefsDir = path.join(configPath, 'unitpreferences')
+  ensureConfigDir()
+}
+
+export function getConfigUnitprefsDir(): string {
+  return configUnitprefsDir
+}
+
+function ensureConfigDir(): void {
+  if (!configUnitprefsDir) return
+
+  // Create directory structure
+  fs.mkdirSync(path.join(configUnitprefsDir, 'presets', 'custom'), {
+    recursive: true
+  })
+
+  // Seed mutable files from package dir if not present in config dir
+  const mutableFiles = [
+    'config.json',
+    'custom-units-definitions.json',
+    'custom-categories.json'
+  ]
+  for (const file of mutableFiles) {
+    const destPath = path.join(configUnitprefsDir, file)
+    if (!fs.existsSync(destPath)) {
+      const srcPath = path.join(PACKAGE_UNITPREFS_DIR, file)
+      if (fs.existsSync(srcPath)) {
+        fs.copyFileSync(srcPath, destPath)
+      }
+    }
+  }
+
+  // Migrate custom presets from package dir if any exist
+  const pkgCustomDir = path.join(PACKAGE_UNITPREFS_DIR, 'presets', 'custom')
+  if (fs.existsSync(pkgCustomDir)) {
+    const configCustomDir = path.join(configUnitprefsDir, 'presets', 'custom')
+    for (const file of fs.readdirSync(pkgCustomDir)) {
+      if (file.endsWith('.json')) {
+        const destPath = path.join(configCustomDir, file)
+        if (!fs.existsSync(destPath)) {
+          fs.copyFileSync(path.join(pkgCustomDir, file), destPath)
+        }
+      }
+    }
+  }
 }
 
 export function loadAll(): void {
-  // Load categories
+  // Load categories (read-only, from package)
   categories = JSON.parse(
-    fs.readFileSync(path.join(UNITPREFS_DIR, 'categories.json'), 'utf-8')
+    fs.readFileSync(
+      path.join(PACKAGE_UNITPREFS_DIR, 'categories.json'),
+      'utf-8'
+    )
   )
 
-  // Load standard definitions
+  // Load standard definitions (read-only, from package)
   standardDefinitions = JSON.parse(
     fs.readFileSync(
-      path.join(UNITPREFS_DIR, 'standard-units-definitions.json'),
+      path.join(PACKAGE_UNITPREFS_DIR, 'standard-units-definitions.json'),
       'utf-8'
     )
   )
 
-  // Load custom definitions (if exists)
-  const customPath = path.join(UNITPREFS_DIR, 'custom-units-definitions.json')
+  // Load custom definitions from config dir
+  const customPath = configUnitprefsDir
+    ? path.join(configUnitprefsDir, 'custom-units-definitions.json')
+    : path.join(PACKAGE_UNITPREFS_DIR, 'custom-units-definitions.json')
   if (fs.existsSync(customPath)) {
     customDefinitions = JSON.parse(fs.readFileSync(customPath, 'utf-8'))
   } else {
     customDefinitions = {}
   }
 
-  // Load custom categories (if exists)
-  const customCatPath = path.join(UNITPREFS_DIR, 'custom-categories.json')
+  // Load custom categories from config dir
+  const customCatPath = configUnitprefsDir
+    ? path.join(configUnitprefsDir, 'custom-categories.json')
+    : path.join(PACKAGE_UNITPREFS_DIR, 'custom-categories.json')
   if (fs.existsSync(customCatPath)) {
     customCategories = JSON.parse(fs.readFileSync(customCatPath, 'utf-8'))
   } else {
     customCategories = {}
   }
 
-  // Load config
-  const configPath = path.join(UNITPREFS_DIR, 'config.json')
-  if (fs.existsSync(configPath)) {
-    config = JSON.parse(fs.readFileSync(configPath, 'utf-8'))
+  // Load config from config dir
+  const cfgPath = configUnitprefsDir
+    ? path.join(configUnitprefsDir, 'config.json')
+    : path.join(PACKAGE_UNITPREFS_DIR, 'config.json')
+  if (fs.existsSync(cfgPath)) {
+    config = JSON.parse(fs.readFileSync(cfgPath, 'utf-8'))
   } else {
     config = { activePreset: DEFAULT_PRESET }
   }
 
-  // Load default categories
-  const defaultCatPath = path.join(UNITPREFS_DIR, 'default-categories.json')
+  // Load default categories (read-only, from package)
+  const defaultCatPath = path.join(
+    PACKAGE_UNITPREFS_DIR,
+    'default-categories.json'
+  )
   if (fs.existsSync(defaultCatPath)) {
     const defaultCatData = JSON.parse(fs.readFileSync(defaultCatPath, 'utf-8'))
     // Build flat lookup: path -> category
@@ -84,28 +142,34 @@ export function loadAll(): void {
 function loadActivePreset(): void {
   const presetName = config.activePreset
 
-  // Check custom presets first
-  const customPresetPath = path.join(
-    UNITPREFS_DIR,
-    'presets/custom',
-    `${presetName}.json`
-  )
-  if (fs.existsSync(customPresetPath)) {
-    activePreset = JSON.parse(fs.readFileSync(customPresetPath, 'utf-8'))
-    return
+  // Check custom presets in config dir first
+  if (configUnitprefsDir) {
+    const customPresetPath = path.join(
+      configUnitprefsDir,
+      'presets/custom',
+      `${presetName}.json`
+    )
+    if (fs.existsSync(customPresetPath)) {
+      activePreset = JSON.parse(fs.readFileSync(customPresetPath, 'utf-8'))
+      return
+    }
   }
 
-  // Fall back to built-in presets
-  const builtInPath = path.join(UNITPREFS_DIR, 'presets', `${presetName}.json`)
+  // Fall back to built-in presets in package dir
+  const builtInPath = path.join(
+    PACKAGE_UNITPREFS_DIR,
+    'presets',
+    `${presetName}.json`
+  )
   if (fs.existsSync(builtInPath)) {
     activePreset = JSON.parse(fs.readFileSync(builtInPath, 'utf-8'))
     return
   }
 
-  // Default to nautical
+  // Default to nautical-metric
   activePreset = JSON.parse(
     fs.readFileSync(
-      path.join(UNITPREFS_DIR, `presets/${DEFAULT_PRESET}.json`),
+      path.join(PACKAGE_UNITPREFS_DIR, `presets/${DEFAULT_PRESET}.json`),
       'utf-8'
     )
   )
@@ -137,16 +201,20 @@ export function getConfig(): UnitPreferencesConfig {
 }
 
 export function reloadPreset(): void {
-  // Re-read config from file to get updated activePreset
-  const configPath = path.join(UNITPREFS_DIR, 'config.json')
-  if (fs.existsSync(configPath)) {
-    config = JSON.parse(fs.readFileSync(configPath, 'utf-8'))
+  // Re-read config from config dir
+  const cfgPath = configUnitprefsDir
+    ? path.join(configUnitprefsDir, 'config.json')
+    : path.join(PACKAGE_UNITPREFS_DIR, 'config.json')
+  if (fs.existsSync(cfgPath)) {
+    config = JSON.parse(fs.readFileSync(cfgPath, 'utf-8'))
   }
   loadActivePreset()
 }
 
 export function reloadCustomDefinitions(): void {
-  const customPath = path.join(UNITPREFS_DIR, 'custom-units-definitions.json')
+  const customPath = configUnitprefsDir
+    ? path.join(configUnitprefsDir, 'custom-units-definitions.json')
+    : path.join(PACKAGE_UNITPREFS_DIR, 'custom-units-definitions.json')
   if (fs.existsSync(customPath)) {
     customDefinitions = JSON.parse(fs.readFileSync(customPath, 'utf-8'))
   } else {
@@ -155,7 +223,9 @@ export function reloadCustomDefinitions(): void {
 }
 
 export function reloadCustomCategories(): void {
-  const customCatPath = path.join(UNITPREFS_DIR, 'custom-categories.json')
+  const customCatPath = configUnitprefsDir
+    ? path.join(configUnitprefsDir, 'custom-categories.json')
+    : path.join(PACKAGE_UNITPREFS_DIR, 'custom-categories.json')
   if (fs.existsSync(customCatPath)) {
     customCategories = JSON.parse(fs.readFileSync(customCatPath, 'utf-8'))
   } else {
@@ -207,18 +277,24 @@ function loadPresetByName(presetName: string): Preset | null {
     return null
   }
 
-  // Check custom presets first
-  const customPresetPath = path.join(
-    UNITPREFS_DIR,
-    'presets/custom',
-    `${presetName}.json`
-  )
-  if (fs.existsSync(customPresetPath)) {
-    return JSON.parse(fs.readFileSync(customPresetPath, 'utf-8'))
+  // Check custom presets in config dir first
+  if (configUnitprefsDir) {
+    const customPresetPath = path.join(
+      configUnitprefsDir,
+      'presets/custom',
+      `${presetName}.json`
+    )
+    if (fs.existsSync(customPresetPath)) {
+      return JSON.parse(fs.readFileSync(customPresetPath, 'utf-8'))
+    }
   }
 
-  // Fall back to built-in presets
-  const builtInPath = path.join(UNITPREFS_DIR, 'presets', `${presetName}.json`)
+  // Fall back to built-in presets in package dir
+  const builtInPath = path.join(
+    PACKAGE_UNITPREFS_DIR,
+    'presets',
+    `${presetName}.json`
+  )
   if (fs.existsSync(builtInPath)) {
     return JSON.parse(fs.readFileSync(builtInPath, 'utf-8'))
   }
diff --git a/unitpreferences/default-categories.json b/unitpreferences/default-categories.json
index 8371bb9ba..f958ae210 100644
--- a/unitpreferences/default-categories.json
+++ b/unitpreferences/default-categories.json
@@ -120,6 +120,9 @@
         "steering.rudderAngleTarget",
         "steering.autopilot.targetHeadingTrue",
         "steering.autopilot.targetHeadingMagnetic",
+        "steering.autopilot.target.headingMagnetic",
+        "steering.autopilot.target.headingTrue",
+        "steering.autopilot.target.windAngleApparent",
         "sails.*.reefState"
       ]
     },
diff --git a/unitpreferences/standard-units-definitions.json b/unitpreferences/standard-units-definitions.json
index 6b0a0067f..e91e98678 100644
--- a/unitpreferences/standard-units-definitions.json
+++ b/unitpreferences/standard-units-definitions.json
@@ -36,16 +36,6 @@
         "formula": "value * 3.280839895013124",
         "inverseFormula": "value / 3.280839895013124",
         "symbol": "fps"
-      },
-      "knot": {
-        "formula": "value * 1.943844494119952",
-        "inverseFormula": "value / 1.943844494119952",
-        "symbol": "knot"
-      },
-      "kph": {
-        "formula": "value * 3.5999999971200007",
-        "inverseFormula": "value / 3.5999999971200007",
-        "symbol": "kph"
       }
     }
   },