This "phenomenon" is not related to the shape of the stearn. It is ore likely related to the steepness and size of the wave as it relates to the length and shape of your bow. What you are describibg is called a "broach" or broaching. It can happen with big boats as well. The bow basically buries itself into whatever is in front of the boat while the stern continues to be pushed by the wave. The force of the pushing wave overcomes the ability of the bow to "clear itself" and then the stern comes around. It is very similar to a tractor trailer jacknifing....the back part continues at a speed greater than the front part....simple as that. All boats will do it given the right conditions. But full displacement boats are probably less likely.
IMO... from past experiences.
A. Primarily, for a boat's heading to be "turned" by "following" sea waves - means:
1A. The "following" wave is going faster than the boat is [maybe just an inkling faster or maybe somewhat faster]. The faster than the boat that the wave is traveling, then the more energy that wave places against the boat's transom as it
pushes the boat's bow forward - forcing the bow to
slice into the back of the wave ahead.
2A. For whatever reason; the boat is not traveling perpendicular to the waves in the following seas. Making broaching more easy to occur. Especially if the following wave is moving faster than the boat [i.e. the wave's energy is being applied against the transom while pushing the boat into the next wave's rear
at the speed the following wave creats].
3A. As the following wave's energy pushes [forces] the boat's transom forward and the bow then slices into the wave ahead, the boat's pilot does not have good control of rudder angle and/or engine power in relationship to energy hitting the stern and the veering off of directional energy possibly occurring by the angle of the bow slicing into the forward wave.
B. Primarily, for a boat's heading to
NOT repeatedly be "turned" by "following" sea waves - means:
1B. The "following" wave is going slower than the boat is [maybe just an inkling slower or maybe somewhat slower]. When going slower than the boat that the wave is traveling, then there can be no forward pushing energy that wave can place against the boat's transom. The wave is being left behind while the boat moves forward via its own propulsion; forcing the bow to
slice into the back of the wave ahead
at the speed desired by the pilot.
2B. The boat is traveling perpendicular to the waves in the following seas. Making broaching less likely to occur.
3B. As the boat's propulsion energy keeps it ahead of the following wave the bow slices into the wave ahead. If the boat's pilot has good control of rudder angle and engine power in relationship to riding up upon the wave ahead, then veering of direction energy occurring by the bow slicing into the forward wave can be well controlled. Thus, by carefully manipulating throttle levels as well as rudder angles the pilot can suddenly reduce speed of bow hitting rear of front wave and therefore create better conditions as the boat passes through the next wave for riding down that wave's slope... to repeat the same type of wave handling sequence... time after time!
C. In Context:
1C. No matter the hull design [D, SD or P] in following seas the pilot must always be on key to constantly maneuver the boat by adjusting rudder angles, propulsion rpms and entry angles into the forward wave.
2.C. In general, canoe stern of a D hull reduces the "energy" effects of following sea waves that are overtaking the boat. D hulls with flat transoms can be greatly affected by the energy of following waves.
3C. SD and P hull boats usually have propulsion-power capability to go faster than the following waves and therein enable handling conditions mentioned in 3B.
4C. There is no really easy way to pilot any boat in a heavy conditions of "following seas"
If conflicting seas [regarding wind direction, wave direction, current direction] are encountered... well... be sure to see this video!!
