Boats with an inflatable keel bottom

Keel and inflatable (NDND)

— inflatable bottom of low pressure (NDND), having a protruding keel.

In general, keel bottoms (of all types) are more complex and more expensive than flat bottoms, but they are better suited for high speeds and long-distance transitions: the keel provides good course stability and allows the boat to “cut the waves”, so that hitting the water at speed is not so strong. However a keel boat needs more power than a flat-bottom boat to go on planing, but the design of such boats usually allows the installation of sufficiently powerful motors.

The keel NDND differs from the inflatable keel (see the relevant paragraph) in that in this case the entire surface of the bottom is inflated, and not just the keelson. This allows to achieve higher rigidity, such bottoms can be used without additional coatings. On the other hand, keel boats with NDND turn out to be less stable, they sit higher in the water and ideally require additional loading to lower draft; Yes, and such bottoms are somewhat more expensive than analogues with an inflatable keel.