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Displacement hull and hull speed

Name: Displacement hull and hull speed dimension sheet
Creator: Xem Studio
License: https://creativecommons.org/licenses/by/4.0/

What is hull speed and why can't displacement boats go faster? · Standard part · basis: Design rules and figures from the cited sources; example geometry by Xem Studio

Also called: hull speed, displacement hull, hull speed formula, 1.34 sqrt lwl, speed length ratio, waterline length speed, displacement speed, rc sailboat hull speed, maximum hull speed

Exact dimensions. True size, with no printing tolerance added.

sizes: 5 in table

Notes

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.

Displacement hull and hull speed size chart

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

Where the files are

Other publishers' files are linked, not hosted. "verify" = check the license at the link before commercial use.

Good Old Boat	Displacement hull speed 101	web	Publisher's page; dimensions are facts
onemetre.net	The IOM class	web	Publisher's page; dimensions are facts

Free files

★ Free files 1 parts. Xem Studio design: free to use, print and sell things from; not to be republished as files. Xem Studio Design License. index.json

displacement-hull-hull

displacement hull, 1000 × 181 mm, deadrise 0° (sections illustrative, scale to your boat)

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Plain text: sheet.txt · JSON: /api/geometry?object=displacement-hull