Tunnels are similar to hydroplanes as they also rely on an air trap of tunnel to create the air pressure needed to help these boats ride on top of the water. Tunnels differ from hydroplanes in the fact that the air traps extend to the full length of the hull.
The WASBC runs 3 classes of Tunnel boat, the Open Unlimited Class (F1), 2000cc (F2) and 1250cc (F3).
