Originally Posted by boden36
Do you need to key it at all? The reason I ask is that our Aquadrive propeller
shaft coupling is split axially and has six high tensile allen head
set screws to clamp it to the prop shaft. Despite years of full engine
thrust and forward/reverse shock loading it has never moved. Maybe you could have something along these lines made up.
I think that couplings do not get as much torque as a ruddershaft, although coupling bolts get sheared all the time (and it is no fun getting the studs out!!!). Normally, the rudder is not normally loaded much provided the sails
are well balanced. Those times when runninig or broad reaching in heavier weather
with seas to match, even with small balanced fore and aft sails
REALLY load the rudder and that could be for many hours. Boats with semi balanced rudders will get even more loading.
As far as welding a key to the shaft, it is a bit like the proverbial ultimate test of welding skill: weld a razor blade to a railroad track...When the shaft get preheated, the fiberglass
"seal" around the top of the rudder (that keeps the water
from getting in the rudder) will probably burn as well as the packing material in the packing gland
and maybe the bearing material...whew!