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Holman 26 Keel Bolt Replacement

DD1871

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4 Oct 2019
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I'm just about to embark on the replacement of the keel bolts on my Holman 26 (when I'm allowed out again) . They are so corroded that the best option appears to be to cut through them at the join between the wooden hull and the cast iron ballast keel. I think the original bolts were mild steel. I've been advised that I need a diamond wire cutter. Any suggestions as to where I could get such a tool suitable for the job?
 

DD1871

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4 Oct 2019
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Tried knocking the first one out and it doesn't budge. Don't want to risk damaging wood. Assuming the rest will be the same as they all appear to be in a similar condition
 

DD1871

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4 Oct 2019
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Yes - with some help from the boatyard. I'm hoping that the bolts will be easier to drift out if they are half the size. If not, then it might be easier to drill out the iron keel section and potentially cut a hole round the bits left in the wood. I'm not confident that the one I've tried to drift out is straight now either.
 

johnlilley

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30 May 2001
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South Dorset/moored Poole/lay up Wareham
Have you confirmed that they are through keel bolts & not tapped into keel & thus studs. Some ballast keels are attached that way on some timber vessels.
Do you know what size they are...possibly 3/4". Anything smaller does tend to buckle if they are through bolts with corrosion when drifted through. If they are corroded badly it will be at the ballast keel/timber keel interphase. They can take a considerable initial force to get moving, usually with a good drift and sledgehammer...is that what you have tried so far. If you can get the bolt to move downwards even slightly then make sure there is an equivalent movement at the base of the bolt. If there is not then the bolt has parted & the points are passing in the keel & jamming so in that case try & use the nut to pull the remnants out from the top using washers and ever thicker spacers. Make sure you do not lose the top of the bolt by knocking through too deeply if there is no base movement. You then use a drift of slightly smaller dia. with a hole drilled in the base of the drift to accommodate the spike that remains otherwise this turns over and jams the bolt or damages the wood. The problem with folkboat type keelbolts is that they are usually quite slender, (sometimes under 3/4") very long & the ballast keel drillings are too tight for the bolt causing the bolt to lock in the ballast keel. Some vessels have the keel drillings about 12% larger than the bolt meaning the bolt very seldom locks in the keel.
 

DD1871

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They are definitely bolts rather than threaded studs as we've uncovered the bottom of the one we've worked on. I'd say they are around 3/4 inch but can't get to the boat for a while to check. The one that I've looked at doesn't have any nut left on it just a short spike of corroded bolt shaft. It wasn't visible until I had the engine lifted out.
Thanks for the advice - I could have another go at drifting the bolts out with a bit more welly when I can get to the boat again but my gut feeling is that I will need to be ready to cut the bolts if that doesn't work. The yard have said that they would need to source a diamond wire cutter (which they haven't been able to so far) if they were doing the job hence my original post.

Not sure I follow the question about xray - sounds expensive and would it help me? I already know I need to replace the bolts and reseal the keel. .I could ask around locally (totnes) and see if anyone does it.
 

johnlilley

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30 May 2001
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South Dorset/moored Poole/lay up Wareham
Quite obvious to see the problem now. It looks likely the bolt also passes through the stern knee as well as the keel and timber keel. My guess is that the whole of the bolt in the timber has probably disappeared.looking at the staining residue I am wondering if a hollow tube type drill would actually clear the residue in the timber section. Simply a thin walled tube the outside diameter close to the bolt diameter with teeth cut on the end and a drill arbor fitted on the other end. This is gradually fed down the outside of the remnants of the existing bolt using this bolt and the original drilled hole as a guide and hopefully will not run off line. This could free the corroded bolt in the timber leaving just the section in the ballast keel. Simply drilling the corroded remains of the bolt out is tricky as all that happens is the drill takes the easy route through the timber leaving the bolt still in position but irreparable damage to the stern timber. Ultimately the tube drill might end up creating a new drilling about 1/4inch larger but straight. A testing time....
 

DD1871

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Indeed.. but at least I've got some time to think about it now before I start. Thanks very much for your posts
 

Wansworth

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8 May 2003
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SPAIN,Galicia
They are definitely bolts rather than threaded studs as we've uncovered the bottom of the one we've worked on. I'd say they are around 3/4 inch but can't get to the boat for a while to check. The one that I've looked at doesn't have any nut left on it just a short spike of corroded bolt shaft. It wasn't visible until I had the engine lifted out.
Thanks for the advice - I could have another go at drifting the bolts out with a bit more welly when I can get to the boat again but my gut feeling is that I will need to be ready to cut the bolts if that doesn't work. The yard have said that they would need to source a diamond wire cutter (which they haven't been able to so far) if they were doing the job hence my original post.

Not sure I follow the question about xray - sounds expensive and would it help me? I already know I need to replace the bolts and reseal the keel. .I could ask around locally (totnes) and see if anyone does it.
Thought it might indicate the condition of the bolts
 

Keith 66

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21 Jun 2007
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Benfleet Essex
Removing keelbolts is nearly always a nightmare. I have done quite a few. A hollow tube drill to cut around the outside can work but is very slow as you have to pull it to clear the teeth every few seconds. Main thing is to try & knock it out first. Make sure that the underside of the ballast keel is blocked & wedged up tight right next to the bolt you are working on. You will need a big heavy drift to start it at least as fat as the bolt or fatter. The drift can be held in a wooden handle by an assistant if there is room or tied to a crosspiece if there isnt. You will need a big hammer preferably a 14 pounder, dont piss about, really smite it as hard as you can. If you are lucky it will move in the first few whacks. If it starts to move go outside & make damn sure its moving outside as well. The risk is that if it is heavily waisted it will shear & the tapered ends will drive past each other causing a jam up. Once they start to move you can go to a thinner drift & keep going.
Repeat for the others!
If none of this works you can try sawing though the keel to ballast join, never heard of a diamond wire saw being used but i have used a reciprocating saw with demolition blades in it, that works! Good luck.
 

Dan Tribe

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3 Jun 2017
Messages
744
I'm just about to embark on the replacement of the keel bolts on my Holman 26 (when I'm allowed out again) . They are so corroded that the best option appears to be to cut through them at the join between the wooden hull and the cast iron ballast keel. I think the original bolts were mild steel. I've been advised that I need a diamond wire cutter. Any suggestions as to where I could get such a tool suitable for the job?
Probably the same vintage as my old Stella. I was told that the keel bots were wrought iron, heated to cherry red and dipped in bitumen when fitted. Not sure how that helps though.
 
Last edited:

Keith 66

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21 Jun 2007
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1,151
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Benfleet Essex
A friend removed bolts to check them on a 45ft Robert clark yacht, Iron keel with wrought iron bolts. They were big & at least 2ft 6" long, they came out easily & smoothly & were still shiny. They had been coated in white lead paste.
 

Redwing228

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7 Jan 2010
Messages
152
Location
Pembrokeshire
Getting keel bolts out can be quite a fight. Here’s a write-up with pictures of what we had to do on our Finesse 24 to replace hers...

Finesse 24 Sailing Yacht


The Finesse had the added complication of having to remove the centreplate case to access the bolts along each side of the slot.

Bill
 

johnlilley

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Joined
30 May 2001
Messages
350
Location
South Dorset/moored Poole/lay up Wareham
A small bit of thread drift... Ref. The Finesse 24..I read your keelbolt replacement procedure with interest and looks like a very good job. You noted some degrading of the inner end of the stern tube timber. Forgive me for commenting but you perhaps relate the damage to the anode not being properly connected to the stern tube. I note that you fitted the anode back and carefully connected everything up. The reason the timber degraded in the first place is usually a direct resut of having an anode connected . What has probably happened is that the connection gradually deteriorated after the damage was done.. This damage will almost certainly continue with the new anode connected with additional damage at the plank internal where the anode is planted. The indicator of damage will be a gradual increase of white crud around the internal housing and the anode fastenings. Basically as the anode works a strong alkaline base chemical surrounds the protected metal and destroys the timber. The white crud is often mistaken for dried up salt, which it definitely is not. Consider cutting the electrical connections to protect the timber. Anodes can and often do cause serious damage to timber vessels.
 
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