ratio is as follows:

0< SLR < 0.9: With increasing speed the flow separates from the transom so that is completely ventilated to the atmosphere. The hull squats slightly and trims up slightly.

0.9< SLR < 2.0: The hull attains its maximum squat (substantially less that for a displacement hull) and maximum trim (approximately 2 degrees). There is some evidence that the transverse flow from the bottom is clinging to the round bilges due to the negative pressures in this area. In this speed range however there is only a small effect on hull resistance.

2.0 < SLR <3.0: The hull rises to essentially its original static draft and the trim angle decreases with increasing speed. The round bilges develop a spray formation that rises rapidly with increasing speed. This spray climbs up on the sides of the hull and can reach to the deck level at SLR approaching 3.0. For further increases in speed, the trim is further reduced, the spray is intensified and the total wetted area becomes significantly larger that the static wetted area. For SLR > 3, the resistance of the hull usually increases very rapidly. Although properly designed spray rails can attenuate the bow spray there is insufficient dynamic lift for the craft to plane."

Then further on: 

• 􏰜  Complete avoidance of convex surfaces (except for the bow area which is out of the water at planing speeds) to avoid the development of bottom suction pressures.

• 􏰜  Sharp edge chines at the intersection of the bottom and sides to insure complete separation of the transverse flow component from the bottom.

• 􏰜  A deeply submerged wide transom with a sharp trailing edge to insure complete separation of the longitudinal flow from the bottom- thus insuring that the entire transom is ventilated to the atmosphere."