Heavy metal

Apr 29

Written by: Tom Daniels
4/29/2009 9:39 PM 

Karl and Joel have been slowly moving the lead into position for drilling and bolting.



There's a filler piece above the lead there, as well as deadwood at the aft end.



They moved the lead under the boat and have been adjusting the poppets to subtly fine tune the boat's position over the lead.  When they get the orientation just right and fit the filler and deadwood precisely, they will bed everything and set the boat on top of the ballast keel.  After that, everything gets drilled and bolted together.

You may remember seeing the chain plate earlier:



That's been cleaned up and drilled to accept the fittings for the shrouds.



There's a plate that connects the chain plate to a bridle that will run beneath the mast.  The rigging pulls the mast down into the keel, and this is the source of a huge amount of stress on a boat's backbone.  Some designers addressed this problem by adding a bridle that counteracts these downward forces by essentially pulling up on the bottom of the mast.  Here's the plate after being welded up, getting some clearance holes drilled in the top.



To install this plate, we drill a series of holes that go through the plate, the chain plate, and the hull.  Six bolts connect the two plates, and four other bolts connect the chain plate to the sheer clamp.  The top three bolts also go through the lodging knees, so they're very long (over 8").  We'll custom make these ourselves.



Here's the port side plate after installation.  



The junky stuff on the hull is bedding compound that hasn't been cleaned up yet.  The tab coming out towards the center of the boat is the attachment point for the bridle.  We should be installing that soon.

Luckily the weather has been excellent... just perfect for working outside.  Launch day is one month away, and we're hoping for more of these mild temperatures and sunny days.

Location: Blogs Cherokee Blog
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11 comment(s) so far...

Re: Heavy metal

So in the end did the shrinkage of the keel casting cause any problems? You were relying on a certain dimension from the forefoot to the rudder heel.

By Tim Booth on   5/1/2009 2:16 PM

Re: Heavy metal

HI Tim,
The keel's looking good, so the shrinkage didn't turn out to be an issue. I was talking with another builder about this the other day, and it seems that most folks don't worry too much about shrinkage in a keel this small. In a much larger boat, say a NY 50, the shrinkage would be a much bigger issue since the shrinkage is expressed as a percentage of the dimension of the piece. Larger dimension, larger shrinkage. Here's an interesting discussion of the issue I found the other day:
www.boatdesign.net/forums/fiberglass-composite-boat-building/shrinkage-lead-25165.html

Tom

By Tom Daniels on   5/1/2009 2:21 PM

Re: Heavy metal

So I ran into somebody who called Cherokee 'ugly'. When I regained consciousness and asked some questions, it turned out that what she meant was that the woodwork was so beautiful it seemed a shame to cover it up with paint.

I have often thought, as I followed the blog, that if this whole racing thing didn't work out, Cherokee would certainly be considered artwork. One of the twelves, Easterner, I think, is finished naturally above the waterline. I wouldn't want to be the one keeping all that brightwork bright, but she is a handsome boat.

Why is Cherokee painted above the waterline?

By Duncan Hannah on   5/7/2009 9:14 PM

Re: Heavy metal

Hi Duncan,
I think a large part of the painting scheme is to keep her as close to original as possible, and she was painted white with a bright covering board originally. Certainly upkeep is a consideration, and I seriously doubt that any of her new owners wants to keep up with that kind of brightwork. I've really liked seeing Cherokee in her current state because the monochromatic hull makes her shape more clear. Your eye isn't tricked by waterlines, contrasting paint and boot stripes. It's just the raw form of the boat, almost like a lines drawing come to life.

No fear, though, paint's coming soon!

By Tom Daniels on   5/7/2009 9:21 PM

Re: Heavy metal

That's pretty funny about the 'ugly' comment. Tom - you're right about keeping to original. Olin wasn't much on 'bright' boats and his sixes of the 30's were all painted - every one of them. These purpose built S&S designs were created with one thing in mind - performance. Practicality came as a close second, and paint is a lot easier to maintain. If the boats were aesthetically pleasing, this was a natural result the previous 2 characteristics. With this said, there are examples of S&S sixes finished bright, all of them built outside the USA - "May Be VII" (1952 - Sweden), "Toogie V" (1971 - Australia), and "Gitana Senior" (1982 Switzerland).

By Matt Cockburn on   5/8/2009 6:05 PM

Re: Heavy metal

Tom:

I understand that there are 3 common methods for installing keel bolts: Embed the bolts in the lead; provide cores in the lead for through bolts, and drill and tap for threaded bolts. It seems that the later was used for Cherokee. What did you use to tap the holes? Special tap? How deep did you run the tap? Was drilling the lead problematic, especially clearing the chips up through the deadwood?

By Dennis Dunn on   9/29/2011 6:17 PM

Re: Heavy metal

You're correct about us drilling for the keel bolts. I'm not recalling tapping however. There's a formula for drilling keel bolt holes that allows for the lead to essentially squish in around the keel bolt threads as the bolt is turned in. Essentially the bolt taps itself. I don't have that formula at hand right now. Drilling isn't particularly difficult, you just do it the same way you usually drill, pull the bit up frequently to prevent the lead chips from galling and jamming. Some people will use a lubricant when drilling like vaseline or dish soap.

By Tom Daniels on   9/29/2011 6:21 PM

Re: Heavy metal

Tom:

Lubricant, ahh. Do you also use some form of lubricant when installing long bolts?

By Dennis Dunn on   10/1/2011 2:10 PM

Re: Heavy metal

At the Mystic Seaport Museum we'll often use white lithium grease to ease in big bolts and sometimes even when driving lags. At MP&G we'd often used red metal primer paint to help seal the grain in the hole as well as to lube up a big keel bolt.

By Tom Daniels on   10/1/2011 2:12 PM

Re: Heavy metal

Tom:

Did you use a traditional bedding compound between the ballast keel and the keel plank? Did you paint the keel plank with red lead first? Thanks.

By Dennis Dunn on   11/13/2011 11:18 AM

Re: Heavy metal

We didn't use red lead on this boat, although it's great stuff. I believe that we just used a red oxide primer to seal the wood. It's more common to use tar as the bedding compound between ballast and keel, some folks will use tarred felt if the mating surfaces are particularly uneven. You want to seal the wood well when using any bedding compound as the oil can suck up into the wood, leaving your compound dry and ineffective. One of the great things about using tar is that it takes ages to dry out, if it dries at all.

By Tom Daniels on   11/13/2011 11:25 AM

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