Failure of Rudder Tube. |
I don't know if the problem I've had is likely to occur on other models, but I would strongly recommend other Snapdragon 24 owners to check the condition of their rudder tubes as a matter of urgency. Access is extremely difficult as it involves a certain amount of gymnastics to get between the cockpit sole and the top of the engine, so I'd never been in there and I suspect I'm not the only one. The tube on Jissel, a Snapdragon 24 of 1970 vintage turned out to be a simple copper tube - basically a length of water pipe with walls no more than a couple of mm thick - glassed into the bottom of the hull. |
On Jissel, it had completely corroded through just above the top of the GRP reinforcing. The top of the tube is not attached to anything. The glassing came up to about the static waterline, certainly no more than an inch or so above, so had it failed at sea, the result could have been catastrophic. With access so difficult, there's no way I would risk squeezing into the space under the cockpit with the boat taking on water! |
| The repair was relatively straightforward, helped by the presence of an old windsurfer mast in the yard's junk pile and hindered by the access. It involved cutting the corroded stub off at the top of the glass reinforcing and abrading the glass reinforcement with an angle grinder where I could get the grinder in, - a horrible dusty job, so wear a mask and eye & ear protection if you have to do it, — and coarse sandpaper where I couldn't. |
I cut out a length of the windsurfer mast so it would fit over the top of the remains of the old tube and its reinforcing with a reasonable overlap, coated the inside of the new tube and the outside of the stub liberally with epoxy and left it to go tacky. I them mixed up a dose of epoxy thickened to where it wouldn't run with microfibres and slathered the inside of the tube with it and twisted the tube into place. A fair bit of the epoxy mix was pushed up into the tube, so I pushed a wad of cloth through the tube to clean it up. This had the effect of forcing the mix back into the joint and leaving it very neat inside. It looked like a good joint, so I left it to go off. The next day I sealed the bottom of the tube and filled it with water to make sure the joint was waterproof properly. Sealing was a much more difficult job than I'd expected because the hole wasn't round and I never did get a complete seal, but as the water didn't show up inside the engine compartment, I was happy that I'd made a waterproof joint. If the joint hadn't been waterproof, plan B involved another painful visit below the cockpit and an epoxy-glass bandage.
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TECHNICAL OFFICER'S NOTE.
This warning applies to all Snapdragons and Mirages except those with externally hung rudders.
I am used to the problem of corrosion by dezincification of brass, but have not met a problem with copper except when used in hot exhaust lines. However, in view of this report, I would strongly suggest keying the surface of your rudder tube and wrapping it from the hull to the top with 4 layers of glass mat and polyester resin. In that way the remains of the tube acts a former and the tube is in effect replaced by corrosion proof glassfibre tube. Extend the glassing for 3 inches all round over the hull as well. |
Whilst on the topic of corrosion and I know I have mentioned this before it is timely to state that all seacock’s hose tails and skin fittings should be replaced if there is any doubt about their age or condition. Use Bronze or DZR material (not Tonval) Aquafax is a reliable supplier. Most fittings sold in chandlers are just ordinary brass and potentially lethal in my experience. |
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