# Lifting strakes and spray rails

> What do lifting strakes do?

- 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/lifting-strakes/ · JSON: https://xemstudio.com/api/geometry?object=lifting-strakes · Plain text: https://xemstudio.com/objects/lifting-strakes/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

- Lifting strakes are lengthwise steps on each side of the keel that add small flat surfaces, raising running attitude and top speed at the cost of weight and wetted area (Boat Blurb).
- Spray rails are lengthwise additions that knock spray down before it reaches occupants (Boat Blurb).
- 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 |
|---|---|---|
| Effect | higher running attitude, more top speed | Boat Blurb |

## Where the files are

- Boat Blurb: [Where is a chine on a boat and what does it do?](https://www.boatblurb.com/post/where-is-a-chine-on-a-boat-and-what-does-it-do) — web — Publisher's page; dimensions are facts

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

Index: https://xemstudio.com/files/hardware/lifting-strakes/index.json · license: https://xemstudio.com/files/hardware/lifting-strakes/LICENSE.md

- lifting-strakes-hull: [STEP](https://xemstudio.com/files/hardware/lifting-strakes/lifting-strakes-hull.step) · [STL](https://xemstudio.com/files/hardware/lifting-strakes/lifting-strakes-hull.stl) — deep v hull, 585 × 181 mm, deadrise 22° (sections illustrative, scale to your boat)

## Questions

**Any downside?**

Added weight and wetted surface (Boat Blurb).

## 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/)
- [Three-point hydroplane](https://xemstudio.com/objects/three-point-hydroplane/)