# Trim tabs

> How do trim tabs work and what size do I need?

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

- Trim tabs are adjustable plates at the transom that push the stern up and the bow down, and can correct list (West Marine).
- West Marine's rule of thumb: at least 1 in of tab span per foot of boat length. On an RC mono, one builder runs tabs about 1-3 mm below the hull bottom (SV Design).
- The file is a reference example built by Xem Studio from the numbers above (1 x 1.5 in RC tab (SV Design); deflection illustrative.). Sizes the sources do not fix are illustrative; scale the example to your own vehicle.

## Sizes

| parameter | value or range | source |
|---|---|---|
| Span rule | >=1 in per ft of boat length | West Marine |
| RC tab drop | 1-3 mm below bottom | SV Design (Stealthwake) |
| RC tab size example | 1 x 1.5 in metal tabs | SV Design (Stealthwake) |

## Where the files are

- West Marine: [Selecting and Installing Trim Tabs](https://www.westmarine.com/west-advisor/Selecting-and-Installing-Trim-Tabs.html) — web — Publisher's page; dimensions are facts
- SV Design: [Pro Boat Stealthwake upgrades info (Feb 2022)](https://myplace.frontier.com/~sv_design/Pro%20Boat%20Stealthwakes%20Upgrades%20Info%20SVC_Feb-2022.pdf) — web — Publisher's page; dimensions are facts

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

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

- trim-tabs-tab: [STEP](https://xemstudio.com/files/hardware/trim-tabs/trim-tabs-tab.step) · [STL](https://xemstudio.com/files/hardware/trim-tabs/trim-tabs-tab.stl) — Hinged plate 38 × 25 mm deflected 5°

## Questions

**How wide?**

At least 1 in per foot of length (West Marine).

## 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/)