Jammed rudder on V10

I have both a standard layup and an V10 Ultra. The intention was to use the standard ski for training and the light one for racing but the Ultra is such a pleasure that the standard tends to be used only occassionally. Last week I took the standard ski out after a 6 week layup and found the rudder had jammed. This had happened before but few minutes in water was enought to get it moving so I tried this again. This time however the rudder remained jammed so I resorted to as much hammering & twisting as I felt I could without breaking the rudder shaft out of the hull.

My initial conclusion was that the jamming was due to salt crystalisation so at first I tried to dissolve the salt with water. When this failed I concluded the problem had to be a build up of aluminum oxide on the rudder shaft (the V10 is unusual in that it has an aluminum rudder shaft). So I tried sodium hydroxide which did not seem to produce a reaction. Vinegar (ascetic acid) produced an intial reaction (indicating the presence of aluminum oxide) but then went inert without releasing the rudder.

My choices now are either to find new solvents or break the rudder out of the hull. Before I resort to drastic measures I thought I might first check whether others have had the same problem and found a solution. Are there any chemists out there who can advise?

I think your best bet is to cut the rudder off and drill out the shaft.

The real problem is tht this is a major design flaw. Anyone in the marine industry knows that aluminium, stainless and seawater are a bad combination. The difference in galvanic potential between the metals means that you have a little battery on the back of your ski.

When you put your new rudder in, either get one with a stainless shaft from another manufacturer or isolate the rudder shaft as best as you can with something like Tefgel. the best would be to take the rudder out if you are not using the ski for a while.

Good luck
stuart

Thanks for the suggestions. I have sorted out my jammed rudder problem and thought it might be helpful to post my solution to help others who might experience the same thing.

All attempts to use solvents for aluminum oxide (sodium hydroxide, ascetic acid etc) produced a mild reaction but no result even after days. Release agents and solvents such as Q10, WD40 etc also had no effect.

Clearly breaking the rudder out would give rise to major reconstruction to say nothing of the hassles of sourcing a new shaft sleeve. I also discarded the suggestion of drilling the shaft out as it would almost impossible to drill out a solid structural grade aluminum shaft out of a soft tight fitting fiberglass sleeve nearly 200mm long without destroying the sleeve. I can only assume that this suggestion was based on the assumption that the sleeve was made of stainless. So I decided to erode the shaft using hydrochloric acid. The reaction was very vigorous but it still took nearly 6 hours. The only adverse effect that I can see is a small amount of crazing of the gelcoat inside the rudder box caused either by heat (the reaction is quite exothermic) and/or the extended exposure to the acid. Based on a lot of trial & error I believe this is the best solution.

Glad you had a good result - you are right, I didn't realise that the rudder tube was GRP. I would still recomend tefgel as an inhibitor around the new rudder shaft.

Stuart

Next one, soak with Simple Green and micro move it as you soak it ....... it will let go once you get a tiny bit of movement in there ...... no need for heavy handed powertool techniques.