Perhaps in its initial conception the Sea King was designed to allow water operations. However, as the gross weight of the aircraft has steadily climbed to 21,400lbs over the years, the nose bay has been stuffed with electronics and the radar has been added under the rear freight floor in the bathtub below the theoretical water line, the aircraft sits considerably lower in the water allowing significant water ingress.
If you look at the Shearwater picuter above all seals are protected with water proof tape.
Whilst the normal aircraft will not take long time immersion in water, the boat hull and SEWTO (Single Engine Water T/O) capability does allow for engine failures in the hover when heavy to be recovered if dealt with in a reasonable amount of time. The aircraft can also be water taxied over long distances if
required, as happened to a friend of mine in Mounts Bay many years ago.
As to the Mi 14, it looks as if the pilot tries to apply full power with forward cyclic into the swell
The resulting tip strike would be fairly catastrophic in all helos. Water is HARD! The course at Shearwater teaches, wait for the aircraft to stabalise, if possible run with the swell, gently trim the rotor disc forward, always watching the distance of the tips to the water surface. When the bow wave reaches to bottom of the windscreen, blip the collective to break the surface suction of the water, ride the bow wave, over pitch the collective to get airborne, nose down, gain airspeed, reduce collective as you enter the ground cushion. Continue gently trimming forward to increase the airspeed whilst attempting to maintain an NR in excess of 91%. As translation lift comes in to force climb away slowly whilst recovering NR. Brains a bit rusty but thats what I remember.
W2P