Mike it is most defiantly a drainage hole, you should block it before putting it in the water. One way I found is to put a bolt but larger than the size you have now, thread the hole in the rudder and screw in the bolt with some sealant, at the end of the season just remove the bolt, that simple.
Philip & Johanne Williams
Majestic Phoenix
Nonsuch 354 #73
Treadwell Bay marina
Plattsburgh NY
Lake Champlain Fleet
When I bought my boat the surveyor discovered water in the rudder. If you go on the Nonsuch website there are photos under “general maintenance/rudder information/rudder pictures” of a rudder that was taken apart to remove the core and clean up the soggy core material.
There is (was?) quite a bit of water in the rudder. I know because I drill holes in it each fall and let it run out. Then I seal them up in the spring. The first year after I bought the boat loads of rusty water came out. Last fall, my third winter, almost no water ran out but the core material still looked damp and what came out was very rusty.
Yes the crack around the shaft was likely the place the water came in and this was sealed with 4200 the first year.
When I fix the rudder as per the Nonsuch web site I will use core material that will not absorb water. I am not complaining, the boat is 30 years old this summer and with a little care will go another 30.
Tom
26C 28
North Star
Penetanguishene