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Stepped hull

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

How does a stepped hull make a boat faster? · Standard part · basis: Design rules and figures from the cited sources; example geometry by Xem Studio

Also called: step hull, ventilated step, stepped bottom boat, rc stepped hull, hull steps, two step hull, stepped vee, stepped hull speed

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

sizes: 3 in table

Notes

Steps break the planing bottom into several high-pressure leading edges, reducing wetted area and friction drag. Each step must be ventilated, or the step face stays wet and drag rises (BoatTest).
Steps can add roughly 8-12% performance but are not worthwhile at low planing speeds, about 35 knots for a 30 ft boat. Poor designs can hook in turns (BoatTest).
Twin steps tolerate CG variation better than a single step (BoatTest).
Used on: White Iveco (Fabio Buzzi, 1984).
The file is a reference example built by Xem Studio from the numbers above (Reference RC mono: 585 mm length and 20 deg transom deadrise (SV Design Stealthwake data); 181 mm is an unlabelled width in the same source's deadrise diagram.). Sizes the sources do not fix are illustrative; scale the example to your own vehicle.

Stepped hull size chart

parameter	value or range	source
Performance gain	roughly 8-12%	BoatTest
Worthwhile above (30 ft boat)	about 35 knots	BoatTest
Early hydro step	75 mm step, 2/3 aft	Wikipedia (Hydroplane)

Where the files are

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

BoatTest	Watch your step (stepped hulls)	web	Publisher's page; dimensions are facts
Wikipedia	Hydroplane (boat)	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

stepped-hull-hull

stepped hull, 585 × 181 mm, deadrise 22°, 2 steps (sections illustrative, scale to your boat)

STEP · STL

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