Turn fins (RC boats) — dimension sheet
Source: Xem Studio, https://xemstudio.com/objects/turn-fins/  (sheet CC BY 4.0)
Basis: Design rules and figures from the cited sources; example geometry by Xem Studio
Catalog version: 2026-10-20

Sizes: see table below
- Turn fins are small vertical blades near the chine that give the hull grip in turns. On a deep-V mono a racer places a right-turn fin as close to the chine line as possible at 90 deg to the V surface (Model Gas Boats forum).
- On hydros, forward tilt makes the boat track left and lifts the starboard sponson; backward tilt does the opposite (Model Gas Boats).

parameter  value or range  source
Mono fin placement  near chine, 90 deg to V surface  Model Gas Boats forum
Hydro fin forward tilt  tracks left, lifts starboard sponson  Model Gas Boats

Files elsewhere (not hosted by Xem Studio; license as stated by the publisher):
- Model Gas Boats forum: Need help setting up a mono for the first time — web — Publisher's page; dimensions are facts — https://www.modelgasboats.com/forum/13-ask-the-editors-discuss-articles-general-boat-questions/21138-need-help-setting-up-a-mono-for-the-first-time
- Model Gas Boats: Some tips on setting up a hydroplane hull — web — Publisher's page; dimensions are facts — https://modelgasboats.com/magazine/tech-articles-mainmenu-608/369-hydro-setup-tips

No true-size file yet: the published figures do not fix the whole shape; a measured scan is planned.
API: https://xemstudio.com/api/geometry?object=turn-fins