Weeping O rings

colind3782

colind3782

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The O rings on my logwheel transducer were letting seawater past them as a slow weep. I seem to have stopped the leak by applying a liberal dollop of Vaseline to the O rings but I'm sure there must be a more suitable sealant? The sealant must be non-setting as the logwheel takes taken out regularly for cleaning.

Any recommendations apart from replacing the O rings?
 
colind3782 said:
The O rings on my logwheel transducer were letting seawater past them as a slow weep. I seem to have stopped the leak by applying a liberal dollop of Vaseline to the O rings but I'm sure there must be a more suitable sealant? The sealant must be non-setting as the logwheel takes taken out regularly for cleaning.

Any recommendations apart from replacing the O rings?
Click to expand...

Silicone grease
 
They should seal without any grease which is used only to make it easier to insert. Check that the skin fitting is perfectly clean. Unless the o rings are perished they be no trouble. If they are old and perished, replace them - they're very cheap.
 
The O rings look to be in good condition which is why I was wondering why they have started weeping. Hard to check the skin fitting and clean it in the water unfortunately and I'm loath to lift her again as I have only just had her antifouled last week. Could be that the pressure washing disturbed something?. I'll replace the O rings but the logistics involved (I'm back in the UK for the next three weeks and the boat is in Empuriabrava) make it difficult.
 
Earlier in the year, just as I was about to hand over my old boat to the new owner, the log transducer developed a persistent leak. Eventually fixed it with a new O-ring, but only after trying about 5 O-rings which looked the right size but weren't. There are lots of different sizes, I found.
 
Went through this a couple of years ago with a Raymarine ST50 transducer. Could only get O rings from Raymarine if I bought the complete service kit. Could not find or get any information on their exact size, and 'close match' didn't work. Eventually got a couple of O rings direct from Airmar.
 
I used to have an o ring kit comprising various diameters of rubber on a roll, sharp knife, alignment jig and superglue. This kit was a bought item. I could make up o rings in any thickness and diameter. The jig was to align the two cut ends while gluing. Superglue sticks rubber extremely well.
Don't know if these kits are still available. Saves carrying zillions of different sizes around.
http://m.ebay.co.uk/itm?itemId=130394316999
 
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>I used to have an o ring kit comprising various diameters of rubber on a roll, sharp knife, alignment jig and superglue. This kit was a bought item. I could make up o rings in any thickness and diameter. The jig was to align the two cut ends while gluing. Superglue sticks rubber extremely well.

I had one of those too, it works fine. You would think that superglue would affect the integrity of the O ring but it doesn't.
 
I shouldn't think it has caused your problem, but its worth saying that it's always better to take a log impeller out, and fit the blank, before pressure washing.
 
NormanS said:
I shouldn't think it has caused your problem, but its worth saying that it's always better to take a log impeller out, and fit the blank, before pressure washing.
Click to expand...
Apart perhaps that you can do a better job of cleaning it - why do you need to take it out? or is the impeller damaged by a very high apparent speed?
 
The last time I needed some O rings I just popped into the local bearing specialist and got the right ones, they measure them to make sure the replacement is correct and no extra charge for marine.

Good luck and fair winds. :)
 
As soon as you get an O-ring leak it's a wake up call to fit new O-rings - whilst using silicone grease is an adequate stop-gap those O-rings only last about 5-6 years.
It is difficult to find exactly the right section and the correct diameter, so the suggestion of a cut to cut to size is a good one - you have to be pretty good with a micrometer to read off the exact section, though the diameter is pretty simple. I fit all my O-rings with a little silicon grease.
 
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