Project of motor boat which uses planing hull has a simple idea: build a fast motor yacht, empowered by big engine. Planing hull must fly over the water – that’s the point.
Fast and fun!
The planing hull flows faster when more power is applied, without a clear upper speed limit, because this hull rises and its bottom is supported by water pressure, just as the aircraft wings are supported by air pressure. The only practical speed limit for this hull depends in fact on the size of the waves, the size of the boat, the shape of the bottom and the integrity of the structure.
Compared to the displacement hull, the sliding hull is characterised by relatively shallow draught, rectangular corners and flat, not sloping aft buttocks, which provide lift and allow acceleration above the bow wave. The planing hull appears very stable, but this is due to the distribution of buoyancy – called form stability – rather than weight and has a narrower range of positive stability. A typical planing hull is not able to physically survive extremely harsh conditions, as it is built on lighter canals than many displacement trawlers (like houseboat). So, the sliding boat has to float above water instead of facing the biggest waves.
In all but the harshest sea conditions, a well-designed V hull is an excellent choice when the goal is to travel from A to B. You’ll get there much faster and come back with a drink in a few hours before the displacement yacht arrives home. And if you have to cross the bar on your way home, the superiority of the planing hull gives you better control as you choose the wave you want to go on.
A good planing motor boat must be able to sail well in all directions. A moderately sharp entrance and a generous deadrise with a high chin lift in the front half of the hull allows the boat to sail at high speed in rough water without submissive passengers. The stern should be properly secured to ensure that the boat is sailing in a straight line rather than constantly yawning off course. The forefoot should not be so delicate or deep that the bow dives deep into the back of each wave. Excessive bow draught, especially when swimming down the sea, turns the bow into a rudder and makes it very difficult to steer the boat, which easily leads to a stall that can lead to capsizing in very rough water. Thus, the well-designed sliding boat is not so flat that it hits the sea, and has sufficient buoyancy and dynamic floatation so immersion is minimized down-sea.