What bedding for new Keel Bolts

T

tillergirl

Well-Known Member
Joined
5 Nov 2002
Messages
8,782
Location
West Mersea
Visit site
I have dropped all my old keel bolts now and am waiting for the new ones to be made. What should I bed in the new ones with. Previously I have used a polysulphide but it has been suggested that I use a thin bitumen poured down the holes as the bolts are driven up (be messy no doubt) - not that I know where to get such a thing at the moment. Then what about some preservative down the holes a few days before? Oh yes and strands of caulking round the heads of course.

When the old ones came out two had the heads (underneath) bedded in white lead stopping which was in pretty good condition. Curiously these were the worse two, one having given up completely. Several were wet but the liquid smelt strongly of creosote so I'm pursuading myself that this is some original preservative that was used in 1964 which has survived to today. Am I deluding myself and I really ought to be dropping the keel because the main joint has seriously gone?

We are talking a wooden boat here by the way and no she didn't make more than a bead of moisture!

Comments gratefully received (Mirelle any views please)
 
Er, well, Martin Evans has just told me that Mirelle's keel really ought to be re-bedded next time we do the bolts (i.e., in 8 years time, as we do them every 10 years or so) because there is now evidence of a weep at the forward end. Beyond commending Martin's services, not much I can add about re-bedding keels, never having tried it, but when Chris Briggs did his he used "Black Pudding" from the people in Lowestoft, and it seems to work.

As to what to put the bolts in with, we've used epoxy pitch the last two times and it seems to work pretty well, so I commend that (I am assuming iron keel, here).
 
Yes iron keel is right. Am I right in concluding a weep at the keel = a failure in the keel bedding. Last time I was surveyed, the surveyor was quite casual about some rust weeps talking of raking out anything loose on the outside of the joint and putting stopping back in the resulting crack. I didn't think much of it at the time.

Dropping the keel is not the most popular thing I've ever thought of. I'd have to get a crane in (£200+) and hope to get the keel dropped, cleaned, rebedded all in the half day or pay for two visits or extra hours. In theory of course, now there's nothing holding it it ought to stay in place while the boat is lifted but I can see all sorts of nastiness if the front lets go while the back end doesn't causing it to jam aainst the deadwoods, or, needs great effort to break the seal. Have you done it before?
 
Nope, never done it. Saw Chris do it to Cecelia, a little sister of ours. Awful job.

I share your trepidation. Suggest putting it off to next keelbolt time...
 
Recommendations to avoid doing something nasty are always welcome! I am kind of reasoning that if the first lot lasted 41 years, I ought to get 10/15 years out of these (on the basis that she isn't as water tight around there as the early part of her life) which is not unreasonable. Will the boatyards that do this sort of work be around in 15 years time? Mine is great, I do the work with the owner - he is really excellent at the little tricks of the trade which ease the task.

Thank you for the answer. Do you think the lack of replies is a measure of how infrequently this sort of job is tackled? Might repeat this on the PBO forum.
 
Well, its interesting, isn't it!

I was brought up nicely in these matters, by reading Michael Verney and consulting Ben Clarke, who forty years ago had a yard in The Lane in West Mersea, and it was very much the done thing to pull a bolt every decade and if it looked at all tired, re-do the lot. So Mirelle's keel bolts get done every ten years or so - mind you, previous lot were steel, but this time Robertsons (free plug for good yard!) got some wrought iron from the nice people at the Real Wrought Iron Company so we ought to do better.

I've noticed that Americans never seem to do their keelbolts. But I wonder if Tillergirl's really were 40+? I reckon someone probably did them 20 odd years ago. Mirelle's lower shrouds were reckoned to be original until Stewart White told me that he and Alan Dale made them in 1977!
 
You might be right about the age of the bolts but I have a 1988 survey which talks of examining X rays taken in 1985 (which showed no significant wastage) so I was kind of working on the basis that if the guy that bought her in 1985 had her X rayed, the previous owner presumably told him that he hadn't had the bolts done. Since that previous owner had had her since 1980 if the bolts had been replaced it must have been in the first 16 years of the boats life which I kind of doubted. If they were, the second set have lasted well! All of which is supposition I guess.

There's no doubt that there is no subsitute for regular checking and presumably they are easier to knock out after ten years than twenty or certainly forty. One thing is certain, they haven't been done since 1980 so even though one had gone, the overall position wasn't too bad.
 
I defer to the evidence!

Come to think of it, Mirelle had one bolt that was covered by the mast step, which went clean over the top of it. It was found in the course of replacing the mast step, so that fellow had been in for 64 years!

Certainly the cost of a keelbolt is the cost of knocking it out - which is minimal after ten years.
 
What about the bolts through the deadwoods (if that's the right term. I have two large ones forward and two aft of the ballast keel. The nuts inside look fine but the keel bolts have just shown that to be a poor guide. I'm not too keen on disturbing the timber. There's no sign of starting or weeping in way of these bolts. I'm planning to leave them alone. Good or poor idea?
 
Thin bituminous compounds can be obtained from asphalt spreading companies. This can be in the form of 'Cutback Bitumen" [which may be an Australian term; the British version may be different] which is a btiumen containing a sovent. An alternative is Bituminous Emulsion, which is sprayed on the gravel course of a road before the asphalt is spread. This is especially so if the road is wet. You may be asked how many tons do you want!
Peter.
 
Possible source for bitumin

Hi,
Roofing contractor specializing in flat roofs might give you some bitumin,
if you offer to buy some. After explaining what you needed for so they don't feel you are trying to fix your own roof.
I would not use white lead in contact with steel or iron, I don't have any
test data but composition of white lead I suspect will be more noble
when in contact with steel or iron.
Good luck
Muzaffer
 
Re: Possible source for bitumin

Yes you are right about the nobility of lead -0.2 volts against Mild Steel/Cast Iron at -0.6. so it might be best to avoid it. Could that be why the two bolts obviously stoppered up (if that's the right term) with white lead underneath were the worst two? I am assuming the putty had white lead in it. It does make sense to stopper up the bottom nut and recess - what's the alternative do you think?
 
Re: Possible source for bitumin

A disc of roofing lead sheet placed over the hole and then peened arouns the edges should blend in with the lead of the ballast keel. Oh, but then I think that you said in a early posting that you have an iron keel. Hmmm, back to the drawing board!
Peter.
 
Re: Possible source for bitumin

I was pondering this again as I was trying to get to sleep last night - How about using a polysulphide around the caulking and head of the bolt as it is finally pulled up and then filling in around the bottom with the same, using a piece of ply or similar helf against the bottom of the keel until it goes off - peel away the ply and abrade flush. I'm sure it will messy.
 
I wouldn\'t do that

Hi Tillergirl,
if I understand Your description correctly You are trying to make some washers from Pollysulfite but I am surprised that You have not mentioned if You have regular washers under the bolt-heads. Because of the enormous forces involved with this bolts, I would not use the technique You mentioned in this particular instance which will be acceptable in any other case which is suitable.

Please understand these are very difficult to analyze from a distance specially without any photos or drawings, therefore any suggestions I am making in good faith is to be discussed with local engineer or professional who is familiar with this matters.
If it was my boat this is what I would consider doing, after verifying I have enough threads I will have extra thick washers largest possible for the available flat area made with one or two O-Ring grooves properly sized, made by your local machine shop.
More than likely I would consider using plumbers pudey smeared on the threads I will replace the bolts one at a time and torque them down to specified torque setting, after weekend of sailing they should be torqued again.
If the bilge water is also a problem, I would after drying the area, cover each bolt with liberal amount of plumbers pudey (the kind that comes in a tube it is sticky and off white Color).
Please consider discussing these ideas with your local engineer. I have used above techniques successfully.
Regards
Muzaffer
 
We have just had Cornish Maid's keel lowered, and new keel bolts fabricated and the whole lot rebonded. The initial problem was a weep from the keel/hull join, and another weep from inside where I removed a very deeply placed and over-long screw holding down the strum box of the bilge pump. So, off came the keel at Dell Quay, (about £750 labour, + new stainless steel keel bolts and washers). The top of the keel was cleaned off and painted with a protective paint, then the boat was lowered back down onto the keel with what the guys call 'stickyflex', which I believe is just a marine sealant like sikkaflex. They used lots so that it ouzed all around the bolts, and made doughnuts of sealant around the washers. They then painted the join between keel and hull with epoxy sealant to make it neat. It is a really lovely job, with all the bilges where they worked freshly painted. Not worth doing it yourself for the price they charged (and the gaurantee).
 
Original bolts were of mild steel. The keel is cast iron. The yard apparently use stainless steel bolts, like Westerly did, because they have never had any problems.
 
You must log in or register to reply here.

Share this page

Top