Tunnel hull (tunnel catamaran) — dimension sheet
Source: Xem Studio, https://xemstudio.com/objects/tunnel-hull-catamaran/  (sheet CC BY 4.0; files Xem Studio Design License, https://xemstudio.com/license/)
Basis: Design rules and figures from the cited sources; example geometry by Xem Studio
Catalog version: 2026-10-20

Sizes: see table below
- A tunnel hull has two sponsons joined by a deck whose underside forms a tunnel. The deck and tunnel roof act as a wing in ground effect with the sponsons as endplates, so some of the boat's weight is carried by air (Powerboat & RIB / AeroMarine Research).
- Air lift is cheap: every pound carried by air lets the planing surfaces shrink, cutting water drag. Some tunnel hulls make 30-50% of their lift aerodynamically.
- A lower tunnel improves lift-to-drag; a wider tunnel (higher aspect ratio) is more efficient.
- 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.

parameter  value or range  source
Aero share of lift  30-50% on some tunnel hulls  Powerboat & RIB
Sponson deadrise  about 10-15 deg  Powerboat & RIB
Typical vee-hull deadrise (comparison)  18-22 deg  Powerboat & RIB
Worked example  6% air lift cuts water drag ~9% at 50 mph  Powerboat & RIB

Files elsewhere (not hosted by Xem Studio; license as stated by the publisher):
- Powerboat & RIB (Jim Russell, AeroMarine Research): High flyers: aerodynamic lift on tunnel hulls — web — Publisher's page; dimensions are facts — https://powerboatandrib.com/tuition/high-flyers

Free files (Xem Studio Design License, Xem Studio; STEP + STL, 1 parts): https://xemstudio.com/files/hardware/tunnel-hull-catamaran/index.json
API: https://xemstudio.com/api/geometry?object=tunnel-hull-catamaran