Rudder osmosis

ashtead

ashtead

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looking for any advice forum items might have on osmosis in a 2001 rudder.
Any advice on 1 costs of treatment 2) reliable repairers anyone has used in Solent area; steps and timescales to sort this out to satisfy a survey; 3) if repaired doesn't it just return as high moisture readings in rudders seem like a standard clause in surveyors reports nowadays .
Ideally a list of reputable repairers to contact on Monday would be great but all sensible advice welcome
 
I think most rudders would return a wetter than average reading due to their construction and the difficulty in sealing them from water ingress. If the rudder is wet but shows no sign of osmosis then you can usually drill a few pilot holes in the very bottom of it to allow any trapped water to escape and promote drying. I even know someone who took their rudder home and stored it in their airing cupboard to dry it out over winter! If osmosis has set in then the rudder needs to be dried, peeled and epoxied when moisture levels have reduced to a low enough level. There will be no guarantee that the problem won't return. In extremis, the rudder should be removed, split along its edges into two halves, the core rebuilt and then re glassed and epoxied - over a grand for that one! Has the problem come up as you are a buyer or a seller?
 
How bad ? is the structure compromised or is it just a few blisters? if the later then 'normal' osmosis treatment is indicated, made easier as it is just a small area. Easier to take off and treat in a warm place or by tenting and heating in situ. You are right in that readings will not come down until every thing is dried out. drain holes may be a first start. When dry small area makes applying epoxy easy if this is required.
 
ashtead said:
looking for any advice forum items might have on osmosis in a 2001 rudder.
Any advice on 1 costs of treatment 2) reliable repairers anyone has used in Solent area; steps and timescales to sort this out to satisfy a survey; 3) if repaired doesn't it just return as high moisture readings in rudders seem like a standard clause in surveyors reports nowadays .
Ideally a list of reputable repairers to contact on Monday would be great but all sensible advice welcome
Click to expand...

Suggest you look more closely as to what the problem is. "osmosis" - that is blisters under the gel coat caused by incomplete curing is unlikely on a 2001 boat. If it is high moisture readings it is much more likely to be water inside the rudder which is much more common. The cause is either coming in down the stock where it goes into the blade or a crack in the outer skin. Water gets in and soaks into the foam. First thing to do is drill a hole at the bottom and see if water drains out. some people live with this and dry out every year, filling the hole(s) before the boat is launched. Alternatively you can have the rudder rebuilt and resealed. Any competent shipwright should be able to advise and carry out the repairs.
 
When I bought my Westerly Fulmar, the surveyor commented that water runs from where the rudder stock joined the blade was typical of water inside the blade. He suggested I cut panels to inspect the tangs and take remedial action according to what I saw. Well checking the rudder more carefully, I could not get a dull ring to show water was present inside the blade. Watching water run off the deck and down the hull, I noticed it always stopped by the rudder stock and then ran down the blade, not the hull. So observation solved what the surveyor incorrectly diagnosed as a problem.

Your original comments are too brief as to why you say you have osmosis in the rudder. Before you start to do anything to the blade, do try and establish if any work is really necessary. As another poster said it is unlikely that the resin used would suffer from osmosis. If there is a problem it is far more likely to be a bad join between the two halves of the blade that is letting water in. Drill a hole in the bottom of the blade, if any water drains out then you have a leak. To find the leak is easy. Cover the blade with soapy water and then use a foot pump to push air in through the drilled hole, any leak will show as bubbles.
 
ashtead said:
looking for any advice forum items might have on osmosis in a 2001 rudder.
Any advice on 1 costs of treatment 2) reliable repairers anyone has used in Solent area; steps and timescales to sort this out to satisfy a survey; 3) if repaired doesn't it just return as high moisture readings in rudders seem like a standard clause in surveyors reports nowadays .
Ideally a list of reputable repairers to contact on Monday would be great but all sensible advice welcome
Click to expand...
Both my Beneteaus suffer ed from it. The 351, someone ground the blisters out, filled and covered with tar stuff, no further probs
The 381, one blister that comes and goes, I ignore it.
Apparently, according to the surveyor, they mostly all suffer from it, it is an inherent with the design.
Dont worry about it if it is an AWB
S
 
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