Phillip –

I have a Skerry, but the construction of the rudder is similar.  You had to sand down the top part of the rudder blade, reducing its thickness so it wouldn’t bind in the rudder head.  The break is in a perfectly straight line.  I don’t know how much you sanded it down, but I suspect you left a sharp corner between the sanded down part and the full thickness part, which resulted is a stress concentration along that line.  You can avoid this stress concentration by blending in the transition from thin to thick.

You might want to call CLC and see how much they would charge for a replacement. rudder blade.

hokker 

Thanks Hokker - I'm  pretty sure that's what I must have done  wrong.  At least now I know better and can hopefully avoid a repeat performance!

I would order a new blank from CLC, but I'm in Bermuda & getting things shipped here is a pain (and bank breaking). I also thought I might try laminating some local cedar together and making it out of that... is that a bad idea? I can probably source some decent marine ply here if I have to.

I do still have the top of the rudder, so I guess I really just need to know the width at the bottom and overall length...

Thanks for your help 

Phillip

I have not built the PMD but i looked at your picture and have built similar craft in the past.

one thing is clear is that the blade was not glassed...and not sure if the PMD instructions call for that.  but for any blade like this, glassing would substantially improve the strength....particularly for relatively thin sections.

on your cedar question, i routinely build cedar blades for fins....but they are always glassed/or carbon fibre. 

fwiw, you don't need to be going fast to break a rudder that does not have the right strength. the lateral force of simply tacking the boat (as the boat rolls from one side to the other) can cause a lot of lateral force.  i used to be a dinghy sailor and in a light breeze we would often 'roll-tack' agressively to 'swim' the boat forward where the propulsive force was basically coming from the rudder being pushed agressively against the water.

h    

   Well, the CLC team came to my rescue! They've sent me a new Rudder piece (which came as very welcome news after getting hit by 2 hurricanes in a week!). You just can't beat the folks at CLC. Amazing.

I'm sure I'll have better luck with this one thanks to the advice above.

Phillip

For the curious