Keel bolt leak - how to fix

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JimC

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I have a slow leak from the rearmost bolt securing my port keel - naturally this is the most awkward to reach. The bolt (actually a stud) is 20 mm diameter, over it is fitted a galvanised steel plate about 4" x 2", then a washer, then the nut. There is about 1" of stud protruding through the nut. The plate is bedded-down on Sikaflex with more Sikaflex glooped over the nut, washer and the protruding end of the stud. The water is coming up the stud and escaping either between the plate and washer or between the washer and nut, or both. The nut and stud are rusty. The Sikaflex that was glooped over the nut, washer and stud has been undermined and loosened by the rust and was easily pulled off.

I would appreciate some advice on how to fix this. My first thought, having brought the boat ashore, is to remove nut, washer and, if possible, plate; dry, clean up and reassemble using fresh Sikaflex. The problem I foresee is that the Sikaflex will only stick to the pre-existing rust on the nut and stud and will come away again taking me back to square one. I could get a new nut but not much chance of replacing the stud. I've been considering rust converters but don't know if these are any good long-term or if compatible with Sikaflex. Any advice very welcome.
 
Your could do as you suggest and it may stop the water coming into the boat. You really need to drop the keel and seal the keel to the hull to do a proper job. You don't want water in contact with the stud there and so causing hidden corrosion.

It is not as big a job as it might sound if you can find a helpful yard and will allow you to inspect the stud for corrosion too. I undertook this work on my last boat at Ridge Warf near Wareham and was well worth it for the peace of mind.

Steve
 
You may succeed in stopping the influx by putting fresh mastic into the assembly, but in an ideal world there wouldn't be water coming up the stud! Long-term, you should re-bed the keel so that no water is getting between the keel and hull. Unless there is any damage and distortion form a hard grounding, it's likely that the bedding has become brittle and cracked. If you're looking for a short term fix, I would rake out the mastic fairing the keel to the hull and renew it - rather like repointing a brick wall - then reseal the nut assembly in the bilges. It may work or it may not, that will depemd on whether there is any movement in the keel.

Rob.
 
A long life has convinced me that leaks cannot be fixed from the inside! You can bodge it up for a while but as others have suggested the presence of water between keel and hull is going to produce corrosion in the medium term. The cost of repair will by then have escalated. Drop the keel, or in your case it sounds like both of them, and rebed them. Not so urgent that you have to do it next weekend, but definitely next winter.
 
If you are able to take the nut and 'washers' off I would re-bed them in arbo mast br sealant (non setting) By applying this after cleaning off the old sealant to the hull and then re-using the washers some of the sealant will hopefully be forced down the bolt thread and stop the leak. This should last until the winter when a proper job can be carried out ashore.
 
vyv_cox said:
A long life has convinced me that leaks cannot be fixed from the inside! You can bodge it up for a while but as others have suggested the presence of water between keel and hull is going to produce corrosion in the medium term. The cost of repair will by then have escalated. Drop the keel, or in your case it sounds like both of them, and rebed them. Not so urgent that you have to do it next weekend, but definitely next winter.
Click to expand...

+1
 
Thanks everyone for your advice. So the offending keel will have to be completely re-seated. Being at an angle to the vertical and weighing the best part of a ton I don't think I'll be tackling it myself.
 
That's the deluxe way of doing it! DIY versions in our club's yard have involved shoring the boat, digging a pit and building an inclined plane for the keel to slide down. I hope after the expenditure you'll have the driest boat in the village!

Rob.
 
I was getting 20L a week through my keelbolts on my Ruffian 23. I was dreading trying to drop keel as the bolts looked very seized but a good quality spanner and a mash hammer made very light work of the bolts. I then raised the boat on the trailer by 2 inches and scraped the old seal away.

I am now trying to decide what to use to seal it. Some say sikaflex and some say definitely dont use it.

Any suggestions for what is best would be greatly appreciated

Cheers

Pete
 
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