I have a Tohatsu 3.5, and I have been having the same shear pin problem. The first
time it happened was awkward because I didn't have a spare shear pin. A kindly guy
on a dock improvised on for me from some brass welding rod that happened to be the
same or near the same diameter. The second time it happened was awkward because of
the size of the following waves in San Francisco Bay. I don't think I hit anything
either time.
But I start in neutral and shift from idle. What is amazing to me is that the prop
is plastic or some such, not metal. It seems to me that there is excessive play of
the prop on the spindle such that there is significant lash when shifting into
gear. I have taken the prop off expectantly and found wear deformation of the
shear pin where it exits from the spindle. My interpretation is that it is a
design flaw, and the solution is either get a new engine or carry a supply of shear
pins which I inspect frequently.
Bryan McNutt
P15 Smee