Keel Modification: Increase stability

[fourlyons]

If you do cut the keel, definitely use the chainsaw. I have done this a number of times and it works well. Don't use a circular saw, the carbide blades we use now don't have enough set to the teeth. You run the risk of melting lead and binding the blade. The sawzall is ok, but very slow.

[Fore and Aft]

I have found a hire chainsaw works well for keel modifications. Blow out the chainsaw with compressed air afterwards and no one is any wiser.
Cheers

[Capt Ben]

Great PHOTO! Thanks for sharing.
Personally, I have no experience w/chain saws (bucket list haha) though I'm quite experienced with many other cutting methods/tools. My concern with the chain saw is the ability to be somewhat accurate. I'm also concerned re the minimum cut. I think my drawing shows horizontal cuts of about 7". These horizontal cuts are where I need the most control so I can stop ±3" from where the bolts are. I'll look into one. Maybe a small electric one.

Originally Posted by nmuir

Chainsaw is the way to go.


If you do you will be in good company. I attach a photo for fun. It is Bent Jespersen mid-series modifying the lead keel of Canada II, the 12 meter entry to the 1987 America's Cup in Fremantle. Not a computer model, test tank (or safety gear) in sight.


Things were a bit different back then.....

[Capt Ben]

Thanks. OK. I'm hoping to find a small electric chainsaw that might work. The blade width needs to be kinda small so I can stay away from keel bolts ±3. I'd like too have a rounded cut left in the corners from the 1" auger drills.

Originally Posted by Fore and Aft

I have found a hire chainsaw works well for keel modifications. Blow out the chainsaw with compressed air afterwards and no one is any wiser.
Cheers

[Capt Ben]

Wow, can you speak to the ability to control the cut with a chain saw? I'm leaning this way. Considering a small electric chainsaw.
Thank you.
Ben

Originally Posted by fourlyons

If you do cut the keel, definitely use the chainsaw. I have done this a number of times and it works well. Don't use a circular saw, the carbide blades we use now don't have enough set to the teeth. You run the risk of melting lead and binding the blade. The sawzall is ok, but very slow.

[fourlyons]

Originally Posted by Capt Ben

Wow, can you speak to the ability to control the cut with a chain saw? I'm leaning this way. Considering a small electric chainsaw.

Thank you.

Ben

With good sharp blades on hand, an electric chainsaw should work fine. Keep the oil topped up, it's the oil and wide, sloppy kerf that keeps it from binding in lead.

With practice, you can actually get quite accurate with a chainsaw, but, I think you should count on having to clean up the cuts, they will be rough. One challenge you will have is all your cuts are plunge cuts, that's tough because the tip will want to bounce around until you have a kerf started. Watch out for kick back, always a risk when cutting with the tip. Get a big chunk of hardwood to practice on.

Be careful with the auger, go very slow with lots of cutting oil or even water. The problem with lead is it melts at a really low temperature and you run the risk of binding in the cut. You can break a wrist if you're using a powerful drill, which you will have to to drill a decent size hole, and it binds up. Ideally your auger will taper down a bit from the tip so there is clearance.

Just to be clear, I agree with the other comments questioning whether this makes sense for the amount of work and risk involved.

[Bowdrie]

Beware when drilling lead freehand, most bits/augers will try to grab, and as a previous poster said, it's easy to break your wrist.
I've had good success drilling bolt holes in lead keels by taking an auger bit and grinding down the tapered threads and slightly dulling the cutting edge.
Then the auger will only cut when pressure is applied and will have less tendency to try and screw itself thru the material.
Twist drill bits will also grab, the angles ground into them are generally made for steel/ferrous metals, and not suitable for lead, a slight>moderate dulling of the edge helps.
A machine shop could re-configure the bit(s) so that they have the proper cutting and clearance angles for lead, (recommended).
Kerosene is a good lube.
Back out the swarf from the cuts often or the lead will clog the bit.
Go easy.

[grahamb]

Ben Lexcen had a chainsaw used to remove lead from the keel of Australia 2....prior to her leaving for the U.S........the edges of the cuts looked almost as smooth as a saw cut...perhaps the chap using the saw was a tree trimmer.......

[Capt Ben]

Yep, it sounds like with practice, this is doable. I'll watch some ice and tree carving with chainsaw videos for hints (haha).

My last concern re this project is that the lead keel will still have sufficient structural integrity once cutouts have been made. At this point, I plan on staying at least 3" from the edges of any bolts and from the top edge of the keel. Not removing any lead from the forward two bolt sections should maintain the strength of the keel from a slight grounding...

Originally Posted by grahamb

Ben Lexcen had a chainsaw used to remove lead from the keel of Australia 2....prior to her leaving for the U.S........the edges of the cuts looked almost as smooth as a saw cut...perhaps the chap using the saw was a tree trimmer.......

[Fore and Aft]

Leads pretty soft and a sharp power planer cuts it like butter.
My biggest concern is levering a ton of weight on a honeycomb section? It's not just a static load, there's going to be plenty of bouncing up and down. Worst case scenario the keel bends, I doubt it would drop of.
Cheers

[Capt Ben]

Yes, that's the concern! I may have to remove less lead than I wanted. Farr office has now advised me 'no cutouts' below bolt ends!

Originally Posted by Fore and Aft

Leads pretty soft and a sharp power planer cuts it like butter.
My biggest concern is levering a ton of weight on a honeycomb section? It's not just a static load, there's going to be plenty of bouncing up and down. Worst case scenario the keel bends, I doubt it would drop of.
Cheers

[Fore and Aft]

Capt Ben if the keel bends it should be easy to spot the problem..........LOL
Cheers

[Capt Ben]

Made some design changes. Made cutouts a bit smaller such that the lower edge of cutouts is near lower edge of keel bolts. Hopefully, there's minimal bending...

[wyb2]

I wouldn’t worry about bending. If that was going to happen with the amount of material you have left, keel bolt washers (the ones inside the keel) would have to be so big, they wouldn’t fit inside the keel.

Looks like the yield strength of lead is around 800 psi (correct number of zeros). You could run the numbers based on the remaining surface area. Use 1/3 of the SA in tension to approximate bending, and 2x the weight of the keel to approximate dynamic loading.

If you hit a rock on the other hand…

[MicHughV]

if it were me......I'd make a mold for the lead shoe addition...then pour the one side followed by the other side...at this point I'm assuming both sides will have the same shape...
here is the tricky part...the bottom of the mold needs to replicate the shape of the keel.....easy enough to do.
once the lead is out of the mold, it will be easy enuff to shape the lead with a chainsaw, angle grinder, etc...
once the two pieces are complete.....another difficult part....is to drill some recessed bolt holes thru' the two mold pieces and the keel to fasten the mold pieces using some S/S bolts. The recessed holes can be filed with putty.

Some time back when I was building my boat, I came to a point where I needed to find lead for the ballast. To this end I salvaged an old wood sailboat with a 6,000 ld shoe bolted to the bottom.
As I was somewhat distant from my hometown the logistics of moving this chunk of lead was a problem.
But I found a local equipment rental store, and rented a chainsaw. With this I sawed the keel into 3 parts. It went surprisingly quick. The challenge was explaining to the rental shop why the blades on the rented chainsaw were so blunt.