I'm just anticipating a combination of worn out pivot bearings, wave direction and amplitude,  inertia of the outboard motor all conspiring to rack the tender on the upswing and hit something. 

For the sled/tender to swing upward  from a high enough amplitude wave while under steam  what safeguards are in place to smooth the entry of the transom end of the sled to rotate between the beams so that the corners of the tender don't scrape the beam surfaces?