Rudder Failure - builder error!

Posted by Frogsider on
URL: http://uk-hbbr-forum.61.s1.nabble.com/Rudder-Failure-builder-error-tp3338284.html

In an effort to economise on materials when finishing off my Selway Fisher Greenshank, I made the fundamental mistake of using 9mm marine ply instead of  the specified 12mm for the rudder blade.  I just couldn't believe that 12mm was really necessary, anyway, and laughed inwardly, as I shaped the elegant profile of my slim foil, at what I thought was Paul Fisher's ultra cautious over-engineering.

I'm not laughing so much now, as yesterday the rudder snapped cleanly off along the line of the lower edge of the rudder stock cheeks causing an instant, and, no doubt, spectacularly funny capsize.

The wind was blowing about 15 knots, quite fresh for an 8ft dinghy, and I had been enthusiastically short tacking against the incoming tide in the estuary, but I never dreamt that the rudder blade could be under such a load.  I certainly didn't feel it through the tiller (made slightly shorter than designer spec. to gain space inboard)  I know better now - the designer was right - it's the builder who is to blame!

Obviously I have to make a new blade, but to fit a 12mm blade I will have to alter the stock to take  the extra thickness.  This leads me to two questions.

1. I could presumably simply replace the 9mm blade with a new 9mm blade made of stronger material.  But what material?  Obviously steel would be one possibility, but are there any other lighter materials of adequate strength that I could cut and shape myself, using ordinary woodworking tools?

2. If I have to fit a 12mm blade I will have to either make a new stock or disassemble and alter the existing stock to accommodate the extra thickness.  The stock was glued up with thickened epoxy.  Is there any way to unglue it without breaking it?

Any suggestions will be welcomed.