{
 "version": "2026-10-20",
 "license": "Dimension sheets: CC BY 4.0. Standard and published-size files: CC BY 4.0. Xem Studio's own designs (files_license = Xem Studio Design License): free to use and sell things from, not to redistribute as files — https://xemstudio.com/license/. Other publishers' files: their own license, linked beside them.",
 "slug": "skeg-hung-rudder",
 "name": "Skeg-hung rudder",
 "kind": "standard",
 "category": "Boat design",
 "group": "Sailboat appendages",
 "year": null,
 "question": "Why use a skeg-hung rudder instead of a spade?",
 "tags": [
  "vehicle design",
  "sailboat appendages",
  "rc design",
  "aerodynamics"
 ],
 "aliases": [
  "skeg hung rudder",
  "skeg rudder",
  "partial skeg",
  "rudder skeg",
  "cruising rudder",
  "skeg vs spade",
  "full skeg rudder",
  "skeg rudder stall"
 ],
 "overall_mm": {
  "length": null,
  "width": null,
  "height": null
 },
 "official_cad": false,
 "xem_status": "free-files",
 "les": false,
 "free_files": 1,
 "url": "https://xemstudio.com/objects/skeg-hung-rudder/",
 "sheet_txt": "https://xemstudio.com/objects/skeg-hung-rudder/sheet.txt",
 "sheet": {
  "basis": "Design rules and figures from the cited sources; example geometry by Xem Studio",
  "overall_mm": {
   "length": null,
   "width": null,
   "height": null
  },
  "notes": [
   "A skeg ahead of the rudder supports a lower bearing, protects the blade and helps tracking; because the skeg sees a lower angle of attack, the combination stalls later than a spade (Good Old Boat).",
   "A full skeg leaves no balance area, so helm loads get high on big boats; Perry's compromise is a half-depth partial skeg.",
   "The file is a reference example built by Xem Studio from the numbers above (Illustrative.). Sizes the sources do not fix are illustrative; scale the example to your own vehicle."
  ],
  "table": {
   "columns": [
    "parameter",
    "value or range",
    "source"
   ],
   "rows": [
    [
     "Partial skeg",
     "about half rudder depth (Perry)",
     "Good Old Boat"
    ],
    [
     "Upwind weather helm optimum",
     "2-4 deg",
     "Good Old Boat"
    ]
   ]
  }
 },
 "sheet_text": "Skeg-hung rudder — dimension sheet\nSource: Xem Studio, https://xemstudio.com/objects/skeg-hung-rudder/  (sheet CC BY 4.0; files Xem Studio Design License, https://xemstudio.com/license/)\nBasis: Design rules and figures from the cited sources; example geometry by Xem Studio\nCatalog version: 2026-10-20\n\nSizes: see table below\n- A skeg ahead of the rudder supports a lower bearing, protects the blade and helps tracking; because the skeg sees a lower angle of attack, the combination stalls later than a spade (Good Old Boat).\n- A full skeg leaves no balance area, so helm loads get high on big boats; Perry's compromise is a half-depth partial skeg.\n- The file is a reference example built by Xem Studio from the numbers above (Illustrative.). Sizes the sources do not fix are illustrative; scale the example to your own vehicle.\n\nparameter  value or range  source\nPartial skeg  about half rudder depth (Perry)  Good Old Boat\nUpwind weather helm optimum  2-4 deg  Good Old Boat\n\nFiles elsewhere (not hosted by Xem Studio; license as stated by the publisher):\n- Good Old Boat: The rudiments of rudders — web — Publisher's page; dimensions are facts — https://goodoldboat.com/the-rudiments-of-rudders/\n\nFree files (Xem Studio Design License, Xem Studio; STEP + STL, 1 parts): https://xemstudio.com/files/hardware/skeg-hung-rudder/index.json\nAPI: https://xemstudio.com/api/geometry?object=skeg-hung-rudder\n",
 "sources": [
  {
   "publisher": "Good Old Boat",
   "title": "The rudiments of rudders",
   "url": "https://goodoldboat.com/the-rudiments-of-rudders/",
   "formats": [
    "web"
   ],
   "license": "Publisher's page; dimensions are facts",
   "license_verified": true,
   "hosted": false
  }
 ],
 "xem": {
  "status": "free-files",
  "sheet_free": true,
  "mesh_price_usd": null,
  "step_price_usd": null,
  "tolerance_mm": null
 },
 "related": [
  "fin-keel-bulb",
  "spade-rudder",
  "daggerboard",
  "centreboard",
  "canting-keel",
  "wing-sail"
 ],
 "fits": [],
 "dimensions": "exact (nominal, no printing tolerance)",
 "dimension_rule": "All geometry on Xem Studio is exact (nominal, true size) with no printing tolerance. Where a part meets another part, the object lists its mating features (feature, exact size, what it mates with, fit class: press, slide, run, socket, clamp or designed). Apply your process's allowance to those features only; 'designed' gaps are part of the design and stay as drawn.",
 "mating": [],
 "faq": [
  {
   "q": "Why later stall?",
   "a": "The skeg's leading edge sees a lower angle of attack (Good Old Boat)."
  }
 ],
 "files_license": {
  "name": "Xem Studio Design License",
  "holder": "Xem Studio",
  "url": "https://xemstudio.com/license/",
  "note": "Xem Studio's own design: free to use, print, modify and sell things made from it; not to be republished or redistributed as files."
 },
 "offers": [
  {
   "file": "skeg-hung-rudder-appendage",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "Xem Studio Design License",
   "step": "https://xemstudio.com/files/hardware/skeg-hung-rudder/skeg-hung-rudder-appendage.step",
   "stl": "https://xemstudio.com/files/hardware/skeg-hung-rudder/skeg-hung-rudder-appendage.stl",
   "note": "rudder spade: 300 mm deep, 60 mm chord, NACA 00-series foil"
  }
 ],
 "markdown": "https://xemstudio.com/objects/skeg-hung-rudder/index.md"
}