# Three-point hydroplane

> What is a three-point hydroplane?

- Category: Boat design › Hull types
- Kind: Standard part
- Basis: Design rules and figures from the cited sources; example geometry by Xem Studio
- Page: https://xemstudio.com/objects/three-point-hydroplane/ · JSON: https://xemstudio.com/api/geometry?object=three-point-hydroplane · Plain text: https://xemstudio.com/objects/three-point-hydroplane/sheet.txt
- License: dimension sheet CC BY 4.0 (Xem Studio); files Xem Studio Design License (free to use and sell from, not to redistribute as files: https://xemstudio.com/license/)
- Use in every chat: add https://xemstudio.com/mcp as a connector (https://xemstudio.com/use-with-ai/)

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

## Notes

- A three-point hydroplane rides on two forward sponsons and the lower half of its semi-submerged propeller, lifting most of the hull clear of the water (Wikipedia).
- Lift at speed comes from planing forces, not buoyancy. The design set records such as Slo-Mo-Shun IV's 160.323 mph in 1950.
- RC hydro set-up centres on strut angle, tail weight and turn-fin angle (Model Gas Boats).
- Used on: Slo-Mo-Shun IV, Spirit of Australia.
- 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.

## Sizes

| parameter | value or range | source |
|---|---|---|
| Slo-Mo-Shun IV record | 160.323 mph (1950) | Wikipedia |
| RC strut angle (manufacturer default) | 0 deg | Model Gas Boats |
| Strut shim, 1.75 in strut | 0.030 in per 1 deg | Model Gas Boats |
| RC rudder | 90 deg to table unless specified | Model Gas Boats |

## Where the files are

- Wikipedia: [Hydroplane (boat)](https://en.wikipedia.org/wiki/Hydroplane_(boat)) — web — Publisher's page; dimensions are facts
- Model Gas Boats: [Some tips on setting up a hydroplane hull](https://modelgasboats.com/magazine/tech-articles-mainmenu-608/369-hydro-setup-tips) — web — Publisher's page; dimensions are facts

## Free STEP/STL (1 parts, Xem Studio Design License, Xem Studio)

Index: https://xemstudio.com/files/hardware/three-point-hydroplane/index.json · license: https://xemstudio.com/files/hardware/three-point-hydroplane/LICENSE.md

- three-point-hydroplane-hull: [STEP](https://xemstudio.com/files/hardware/three-point-hydroplane/three-point-hydroplane-hull.step) · [STL](https://xemstudio.com/files/hardware/three-point-hydroplane/three-point-hydroplane-hull.stl) — Three-point hydroplane: centre hull + two forward sponsons, 585 × 181 mm (illustrative)

## Questions

**What is tail weight?**

Weight at the strut with the boat level on a table; a key RC hydro number (Model Gas Boats).

## Fits with

- [Deep-V hull](https://xemstudio.com/objects/deep-v-hull/)
- [Modified-V (semi-V) hull](https://xemstudio.com/objects/modified-v-hull/)
- [Flat-bottom hull](https://xemstudio.com/objects/flat-bottom-hull/)
- [Cathedral (tri-hull)](https://xemstudio.com/objects/cathedral-tri-hull/)
- [Tunnel hull (tunnel catamaran)](https://xemstudio.com/objects/tunnel-hull-catamaran/)
- [Stepped hull](https://xemstudio.com/objects/stepped-hull/)