The ram air affect which affords the Flats® Cat to run smoothly across the top of the waves also serves another function when entering shallow water. As air passes under the bow and approaches the inside walls of the Cat Hulls, the water under the boat is compressed slightly and in turn rebounds up into the water channel of the twin hulls. It is here that the water comes in contact with the sub-hull. The sub-hull is a slightly downward curve about one third of the way back from the bow. The purpose of the sub hull is to purge most of the air out of the water that is flowing into the Cat Hulls. The water is then wedged or trapped in between the Cat Hulls by the patented reverse angle inside hull wall. When the water passes under the transom, a jet effect is formed compacting the water even more and aiding in forward motion. When the water exits the transom it explodes up into the lower unit and propeller of the outboard which allows for good handling characteristics, and more than adequate water pressure for engine cooling. At speeds exceeding 20 MPH the Flats® Cat Hull has 1/2" draft, meaning the boat is on top of the water, not pushing through it. When entering water that is 7" or less in depth, the water is compacted between the hull and the bottom creating a lifting effect which raises the boat to about 1/2" plus draft. This means that the keel-less Flats Cat will not hit sub surface strata while there is any water below the boat at speed. However, when equipped with a tilt and trim engine and a standard 5" Jack Plate, skeg drag will occur in about 3 1/2" of water, signaling the boat operator to seek deeper water. This is a built-in safety factor for shallow water running, which has been well received and appreciated by our boat owners.