Displacement hull and hull speed — dimension sheet
Source: Xem Studio, https://xemstudio.com/objects/displacement-hull/  (sheet CC BY 4.0; files Xem Studio Design License, https://xemstudio.com/license/)
Basis: Design rules and figures from the cited sources; example geometry by Xem Studio
Catalog version: 2026-10-20

Sizes: see table below
- A displacement hull is supported by buoyancy. Its bow wave lengthens with speed, and when the wave length equals the waterline length the boat is trapped climbing its own wave, so speed is limited by length (Good Old Boat).
- Hull speed in knots is 1.34 x sqrt(waterline in feet); some designers use 1.4. Doubling length does not double speed.
- Used on: Most large monohull sailboats (Good Old Boat).
- The file is a reference example built by Xem Studio from the numbers above (Length = IOM hull length 1000 mm (onemetre.net); beam and deadrise illustrative.). Sizes the sources do not fix are illustrative; scale the example to your own vehicle.

parameter  value or range  source
Hull speed  S (kn) = 1.34 x sqrt(LWL ft)  Good Old Boat
Alternative constant  1.4  Good Old Boat
20 ft LWL  ~6.0 kn  Good Old Boat
40 ft LWL  ~8.5 kn  Good Old Boat
IOM RC yacht hull length  1000 mm  onemetre.net

Files elsewhere (not hosted by Xem Studio; license as stated by the publisher):
- Good Old Boat: Displacement hull speed 101 — web — Publisher's page; dimensions are facts — https://goodoldboat.com/displacement-hull-speed-101/
- onemetre.net: The IOM class — web — Publisher's page; dimensions are facts — https://onemetre.net/OtherTopics/IOMclass/IOM.htm

Free files (Xem Studio Design License, Xem Studio; STEP + STL, 1 parts): https://xemstudio.com/files/hardware/displacement-hull/index.json
API: https://xemstudio.com/api/geometry?object=displacement-hull