Replacing J Bolts in a lead Keel

[scobie]

Hi All,

I want to replace the J Bolts in a Lead Keel. The boat is a Cape Vickers 41.

My problem is I'm in NSW Au. and cannot find anyone here, I wouldn't mind doing it myself as I have a Metal Fab Factory, I have been researching on how to extract the leaded in bolts, Some say drill out from the top and some say melt them out from the side of the Keel.
The other problem is how to lead back in the the new bolts so that the new lead fuses in with the old lead.

Is a flux needed?

Do I need to undercut the old keel if so what profile should it be?

I was intending on making a template with tube /pipe which fit over the old bolts welded on to a flat plate so exact position of bolts can be replicated when leading in new bolts so correct alignment can be achieved.

Thanks in anticipation.
John

[Matt Johnson]

Ours were done by melting the lead away from the J-bolt on one side of the keel keeping the cavity in place on the other. New bolts were bent to the shape of the old, then set back in the mold. As to the heating of the new lead and "welding" it to the old, unfortunately, I wasn't there for that and don't know the particulars.

Matt

[Matt Johnson]

John at Oasis Boat Yard in St Augustine FL was the one that did ours. Maybe he'll explain it to you. (904) 824-2520

Matt

[scobie]

Thanks Matt,
Would you know what was used to keep the cavity in the keel so the new bolts could be inserted,
Cheers.

[Matt Johnson]

Originally Posted by scobie

Thanks Matt,
Would you know what was used to keep the cavity in the keel so the new bolts could be inserted,
Cheers.

Nothing was used. He just melted down to the bolt on one side, careful to not melt further, and pulled the old one out. The other half of the keel mold was retained without issue.


He did also make a plywood template of the keel bolt locations just incase.

Matt

[scobie]

Excellent,
I'm half way there.
Cheers Matt.
John

[UNCIVILIZED]

Originally Posted by funjohnson

Nothing was used. He just melted down to the bolt on one side, careful to not melt further, and pulled the old one out. The other half of the keel mold was retained without issue.


He did also make a plywood template of the keel bolt locations just incase.

Matt

I'm thinking that a plywood template with attached vertical tubes for each bolt would be wise. So that you have the bolts precisely aligned when they're reinstalled. Meaning that the jig is fabricated so that each bolt's exact orientation in all 3 planes is utterly the same as when they were removed. Otherwise refitting the keel will be "fun".

[UNCIVILIZED]

IIRC, another way to redo keel bolts is to pull out the old ones, after making a template which shows their placement, as well as their precise vertical orientations. And then to cut pockets into the keel wall, well below where the old bolts ended. Then drill the keel from above, down to these pockets. Install longer bolts, & permanently affix plates & nuts to them inside of the pockets. After which all of the cutouts in the keel, top & sides, are refilled with lead.

[scobie]

I'm just concerned that the lead might solidify before reaching all of the void to fill. I suppose that I could heat threaded rod to help the fast rate of cooling upon newly poured lead touching the cold old surfaces which cannot be reached with a torch, What about shrinkage?

[UNCIVILIZED]

Man, it's been a REALLY long time since I fiddled around with keels & hot lead. So much of this is conjecture, pulled from long dead brain cells. However, I'm an exceptional guesser

That said, I think that when you repour in order to fill such spaces in a keel like we're talking about, the keel in the vicinity of the pour is warmed up prior to pouring. So as to somewhat mitigate overly rapid curing at the juncture of the old & new lead. Along with one's building cofferdams around the area of the pour, so that you can pour in enough molten lead for it to stand proud when it's liquid/still soft. And then when it's cool, do the final shaping. Probably by hand in this case.

But as I said, the above's conjecture on my part. And no doubt there's plenty of info out there on this topic, gratis. That, or just call Mars Metals & have them machine you a new keel complete

Might it be possible instead to sister in some bolts? It would help to know what the situation with the keel is that's necessitating this maintenance. As well as the design of the keel/her footprint, along with that of the sump, weight of the ballast package, length of current bolts, their size & number, bolt offsets, etc. And of course, pics.


Note that there are a few retired boatbuilders on the thread, ditto on surveyors, so you might try contacting them directly on this.

[scobie]

Cheers Mate,
I would love to get Marrs to do the bolts. Can you imagine the freight cost from Sydney to Florida��
The guestimate weight 4 ton, 17x bolts M16 and M24. With the longest about 800mm.

[groundtackle]

I want to replace the J Bolts in a Lead Keel.
scobie, I'd like to ask why you want to replace them and if you have any pics of the imagined poor condition?
ce

[Crew of Turning]

FIW MarsMetals/MarsKeels is a Canadian company based in Burlington Ontario Canada who do custom and keel designs for builders. A friend of mine wanted to shorten the keel on his Catalina30 ten years ago. We all thought he had gone a little crazy when he took a chain saw to his keel and lopped off 2 feet. He gave the cut to Mars and they remolded it into 2 half torpedos that he rebolted to the stub. He never grounded out again going in or out of his yatch club.

[Dougtiff]

I have done this job, if there is no reason to remove the keel, lay out the the line the new bolts will be in on the keel [outside], cut or drill a hole all the way thru the keel, drill down thru the keel until the you reach the hole, install washer and nut, back fill with thickened epoxy, did this on a 40 footer.