Mistake made: Lead Keel construction #2

[chuckm]

I have posted recently for help with "Lead keel Construction" with many needed and helpful tips and advice. But recently I became aware that I made a critical mistake in hull-deadwood thickness; The lofted plan calls for a 5" keel to 5" deadwood area to bolt to. I know what probably happened. I had been so prizing and wanting to use an excellent piece of truly old growth, tight grained, very resonous Long Leaf Pine. Perfect dimension's and quality for the deadwood. I saw it, and said great; perfect. It looked right. I had already lofted and ice picked in the frame lines to make the frames. All was good, planking was a; I don't know; 1 1/2 ---2 year project.


One of the problems with extended multi year projects is loss of information. So I have a problem. Let's work the problem.......http://im1.shutterfly.com/media/47a0df34b3127ccef94ae659612200000040O08QcMnDZwzcA9 vPhA/cC/f%3D0/ps%3D50/r%3D0/rx%3D550/ry%3D400/IThttp://im1.shutterfly.com/media/47a0df34b3127ccef94b057801a600000040O08QcMnDZwzcA9 vPhA/cC/f%3D0/ps%3D50/r%3D0/rx%3D550/ry%3D400/

[chuckm]

This could be fun. Can I, should I;
1) Increase the hight of the lead keel balast; add more of a "bulb"
like bump. Would have to determine the area needed and re-
build my cast mold.
2) Increase the seat size to, as called for and clearly shown by de-
signer, by adding a 1 inch wood shim, with thicken epoxy.
3) Deepen the overall lead keel mold to compensate loss of
volume. Kinda of like a deeper bump all along the deadwood
seat.
4) Write Oughtred and pray for forgiveness?

Will deepening the lead keel, should actually benefit the boats stability because the weight is further down?

http://im1.shutterfly.com/media/47a0df34b3127ccef94b82d8c0ed00000040O08QcMnDZwzcA9 vPhA/cC/f%3D0/ps%3D50/r%3D0/rx%3D550/ry%3D400/

[chuckm]

Thinking out loud. If I go with a thinner lead balast; 3 inches instead of 5 inches, a deeper more pear shaped cast, I would have to single bolt to every floor. Still talking 1400#. A different designed keel. How serious an error.

[chuckm]

Here's the deadwood to lead keel slot.http://im1.shutterfly.com/media/47b9cc07b3127ccef8a11944e42300000040O08QcMnDZwzcA9 vPhA/cC/f%3D0/ps%3D50/r%3D0/rx%3D550/ry%3D400/

[paladin]

Keep the same mold, use gold instead of lead, 1200 PPcF instead of 716...

[Timo_N62.9_E27.7]

First thing that comes to my mind is that you would increase the forces in the join considerably if you would have a deeper and thinner ballast.

The increase in depth would increase the bending moment at the join and there would be less width to transfer it doubling the effect.

I would increase the width of the deadwood as designed.

[wizbang 13]

Depleated Uranium,Didn't Tabarly do it?

[Roger Long]

How serious an error.

Very, very, serious. Lofting is the most important step in boatbuilding.:(

However, no big deal:) If the boat was designed so light and close to the bone that that you can't make the keel deeper as you show (going from the straight profile to the curved one if I'm interpreting your drawing correctly) than it needed some beefing up. I would bolt every floor anyway. Few boats can not use some beefing up in the garboard area. The weight of extra structure doesn't hurt and this is where strains first show up as a wooden boat ages.

I would keep the keel profile mostly straight to simplify blocking when hauling out and introduce a bit more of a knuckle at the forward end of the keel.

All you've done here is mistake yourself into a boat that will go better to windward with almost no increase in draft. Don't let anyone scare you about sail balance. You'll never notice the difference.

I wish I could remember who said "The mark of a good boatbuilder is his ability to build his way out of his mistakes." Atkin? Culler?

[chuckm]

OK; thank you Roger, but I must snail-mail Oughtred; added pictures and summary of above, and ask for his input. He does call for and drew the outer curve. The straight line is there for measurements. I am essentially missing 2/5's of vol/weight, WOW that's a hard one to admit to. I see only two directions I can go. Add 1 inch on each seat side, return to 5" thickness, or, increase the curve-bump and make up the vol/wt by deepening the lead keelhttp://im1.shutterfly.com/media/47b9cc06b3127ccef8a20b6e1d5000000040O08QcMnDZwzcA9 vPhA/cC/f%3D0/ps%3D50/r%3D0/rx%3D550/ry%3D400/

[Rich Jones]

It ain't a mistake if it can be fixed.

[Canoeyawl]

Generally the "curve" is in the ballast to lower it and concentrate the weight amidships to reduce hobbyhorsing.
As Roger said, your proposed changes will improve the boat.
You could cast the lead into an exagerated foilshape/taper ala Chuck's "Scheel Keel"? and gain some thickness down low.
Google >Scheel keel
http://www.tartanownersweb.org/models/t33/images/t33_06a.jpg

[George Ray]

Apprentice:
Learns how to not make mistakes ....

Journeyman:
Learns how to cover up his mistakes .....

[Roger Long]

Add 1 inch on each seat side, return to 5" thickness, or, increase the curve-bump and make up the vol/wt by deepening the lead keel

The keel is already the width that it is and it is the stress on the wooden member that is critical. Making the seat wider isn't going to fix that. If you want to make up for the higher stresses on the narrower wood keel, you have to add floors and supporting structure inside.

Deeper is better for reasons beyond raw area going to windward. Unless you have a critical draft issue, you'll be happier with a deeper boat. If the wind has been blowing from the same direction for a long time, there will be quite a bit of surface drift set up and a deeper keel will get farther below that. I've seen a witch of a schooner with 19 foot draft hampered by this effect.

http://www.pointseast.com/template.shtml?id=EEuApppyplMkENKsEG&style=story

That said, I have a shoal draft boat but, at 32 feet, the ability to get into tight places makes up for the deficiency in windward ability in my mind. I can't imagine another few inches making a big difference in your size of boat although the additional wetted surface will slow her down a bit in light air. If you haven't built the rig, you could add a bit to it. Don't worry about upsetting any magic balance. Your boat in the 1800's would have had twice the sail area and most of it hanging over the stern on a boom you couldn't reach the end of. Somehow, they managed to live with it:)

[Roger Long]

Here's a keel that comes within a couple of % of recovering the volume you need if I'm reading your posts right. Areas measured with CAD assuming constant thickness.

http://www.rogerlongboats.com/images/Keelfix.jpg

She would feel different than the original design if you sailed one right after the other but would be fine. Most boats end up stern heavy so the more forward ballast location won't hurt anything unless the original design had bow trim. Easier to haul out, easier to handle if drying out after a grounding, nice to have lead running all the way back under the sternpost. You probably would want to make that a small separate casting. Be sure to get a good radius and taper on the front of the keel. That additional "leading edge" will help her to windward.

[chuckm]

WOW: Yes constant 3" thickness, that looks like the 2/5's that I need. Thank you for rescueing a complete novice like myself. I have a feeling that other's will benefit from my mistake. here's a pic of floors, mostly oakhttp://im1.shutterfly.com/media/47b9ce00b3127ccef83ef120564800000030O08QcMnDZwzcA9 vPhA/cC/f%3D0/ps%3D50/r%3D0/rx%3D720/ry%3D480/

[Roger Long]

here's a pic of floors, mostly oak

Nice floors! From what I can see, you should be just fine with the 3" siding. That construction looks like it should hold a fin keel. There's a lot more beef there than on a lot of fiberglass boats with thin fins that hang way down.

Just be sure not to skimp on proper material for keel bolts. Tobin Bronze. Buy rod stock and invest in the die to thread them yourself.

[chuckm]

So, above look's very do-able; 7 floor's tied with 3/4 inch bolt to the 7 foot, 8 inch lenght of lead keel. 1400#'s. Do I need 1" bolt? Designer calls for double bolting 1/2 in SS bolt, but centerboard version requires one bolt on each side of CB. This feels like, or I feel like the AA chapter of boatbuilder's anonymous, where I have fallen off the wagon or scaffold, and I need guidence, prayer, and passages from the big book of Boatbuilding by Steward, McIntosh, ect.... Roger please be my sponsor.:o

[Roger Long]

Do I need 1" bolt? Designer calls for double bolting 1/2 in SS bolt...

What! Designer calls for stainless? Bad, very bad. Many get away with it. He may not have had a keel fall of yet but you wouldn't be able to sleep at night if you fully understood what was involved.

I had to go into the office this afternoon. Nevins rules call for 1 square inch of sectional area per 1500 pounds of ballast. Bolts should be no more than 1/3 of the floor timber thickness so 1/2" is probably about right. Cross section area is .196 so you need a minimum of 5 for 1400 pounds of ballast. Stagger them port and starboard. Nothing wrong with putting additional bolts through just the keel between the floors. If you can reasonably get more bolts in, go for it. As long as you don't weaken the other structure, there is no downside except work to having plenty.

I always liked the idea of drilling the lead and tapping the holes. Drill 8 diameters down and a minimum of 7 diameters (3.5" in this case) thread length. Water will have a harder time getting into blind holes and the effort of tapping should be less than drilling all the way through the lead. You can also cut in through the sides for nuts in pockets but that also seems like a lot more work than tapping.

Don't buy bolts. You want nuts and threads on top for tightening and you'll end up having to rework threads anyway so you may as well have the die and tools on hand.

[chuckm]

There old plans I have, I'm sure he advocates the better Silicone Bronze metals today. In fact I believe someone stated using NAB. Nichel Aluminum Bronze. Also Merton's marine supply advocates using NAB, or some alloy of Brass because silicon Bronze is SO expensive. But thats another post. Oh my floors are 3 inches wide. Could safely use 5/8's.

[gert]

Nevins rules call for 1 square inch of sectional area per 1500 pounds of ballast
Does this mean (in theory) that 3 - 1" bolts would be sufficient to hold this keel on? Not that I would go there; the 10 - 1/2" bolts the designer calls for gives greater peace of mind. In the designers defence, he calls for bronze or stst "fastenings"; I dont think he was refering to the keel bolts.


I always liked the idea of drilling the lead and tapping the holes

You Can do this? Is this conventional machine thread or a special coarse thread?
This certaily would be easier than drilling all the way through; I think.

[Canoeyawl]

(A 1-inch diameter bolt = 7/8 sq.in.)
A little 1400 lb keel, One bolt would hold it on!

[chuckm]

What a mess I have Gert; Yea can you give me Oughtred's address.

[Roger Long]

Does this mean (in theory)...

Guidance rules of thumb like 1 sq. inch / 1500 pounds assume that everything else is done properly. A good distribution of bolts is part of that. 10 bolts are probably what is required to achieve the necessary distribution. If this was a weight critical area, such as up in the rig, the designer might have reduced them to 3/8", about half the cross sectional area. However, there is no downside in a location where they are just ballast and thicker bolts have a better ratio of corrosion prone surface to cross section. 10 1/2 half inch bolts sounds quite reasonable for this keel. Just figure out where you need the bolts and stick with the 1/2". It will be easier to drill and tap for that size. If you find a good deal on 5/8" rod, go with that. This isn't a space shuttle.

Use a coarse thread. There are some special tricks to make drilling and tapping lead easier but I don't know them off the top of my head. Herreshoff describes the process in one of his books in detail but I can't remember which one. Perhaps someone will remember and post. You will probably have to get the tap welded to a long steel rod and have a "T" handle welded to the other end at the same time. You will need to drill twice, first through timber and lead at the proper size for the tap. When you hit the lead, put tape on the drill 8 diameters (4" in this case) up the shaft and continue. Take it slow and pull to clear chips often. Then drill the 1/2" hole for the bolts through the wood. It may help to get the tap started if you continue that hole about 1/4" into the lead. Tape a piece of the largest piece of tubing or pipe that will fit down the hole to a shop vac hose to help clear out chips.

[Roger Long]

What a mess I have Gert; Yea can you give me Oughtred's address.

Relax. It's all under control. Always nice to give the original designer a chance to weight in on changes. I would appreciate it if it were my boat. However, if round trip mail is going to take weeks though or he is slow in responding, don't get you knickers in a wad. Keep working on your boat.

[donald branscom]

Generally the "curve" is in the ballast to lower it and concentrate the weight amidships to reduce hobbyhorsing.
As Roger said, your proposed changes will improve the boat.
You could cast the lead into an exagerated foilshape/taper ala Chuck's "Scheel Keel"? and gain some thickness down low.
Google >Scheel keel
http://www.tartanownersweb.org/models/t33/images/t33_06a.jpg

I would not do that.
It will be like those ill fated wing keels.
When it gets stuck in the mud you will not get it unstuck.

Read C.A. Marche's "THE AEROHYDRODYNAMICS OF SAILING"
Do ANYTHING else.

[donald branscom]

Depleated Uranium,Didn't Tabarly do it?

Yes - it was done and then outlawed, when one of the racing sailboats sunk.
Rich people will not be allowed to poison the waters. Only the military.

[donald branscom]

I have posted recently for help with "Lead keel Construction" with many needed and helpful tips and advice. But recently I became aware that I made a critical mistake in hull-deadwood thickness; The lofted plan calls for a 5" keel to 5" deadwood area to bolt to. I know what probably happened. I had been so prizing and wanting to use an excellent piece of truly old growth, tight grained, very resonous Long Leaf Pine. Perfect dimension's and quality for the deadwood. I saw it, and said great; perfect. It looked right. I had already lofted and ice picked in the frame lines to make the frames. All was good, planking was a; I don't know; 1 1/2 ---2 year project.


One of the problems with extended multi year projects is loss of information. So I have a problem. Let's work the problem.......http://im1.shutterfly.com/media/47a0df34b3127ccef94ae659612200000040O08QcMnDZwzcA9 vPhA/cC/f%3D0/ps%3D50/r%3D0/rx%3D550/ry%3D400/IThttp://im1.shutterfly.com/media/47a0df34b3127ccef94b057801a600000040O08QcMnDZwzcA9 vPhA/cC/f%3D0/ps%3D50/r%3D0/rx%3D550/ry%3D400/

You did not say what really happened.
You stated the keel deadwood thickness was 5 inches wide.
You did not tell us what the width of the keel that you poured WAS.
Can you tell us what the difference WAS?

[donald branscom]

Very, very, serious. Lofting is the most important step in boatbuilding.:(

However, no big deal:) If the boat was designed so light and close to the bone that that you can't make the keel deeper as you show (going from the straight profile to the curved one if I'm interpreting your drawing correctly) than it needed some beefing up. I would bolt every floor anyway. Few boats can not use some beefing up in the garboard area. The weight of extra structure doesn't hurt and this is where strains first show up as a wooden boat ages.

I would keep the keel profile mostly straight to simplify blocking when hauling out and introduce a bit more of a knuckle at the forward end of the keel.

All you've done here is mistake yourself into a boat that will go better to windward with almost no increase in draft. Don't let anyone scare you about sail balance. You'll never notice the difference.

I wish I could remember who said "The mark of a good boatbuilder is his ability to build his way out of his mistakes." Atkin? Culler?

I like this solution - but we still do not know what the difference is we are talking about. Also if more hot lead is added it will melt into and become part the original piece. We need a better idea of what is really going on.

[gert]

Donald:

Chuck hasn't poured his keel yet; but where it mates to the dead wood it's supposed to be 5" wide. Chuck built his dead wood at this point only 3" wide. That's the problem.

[donald branscom]

Donald:

Chuck hasn't poured his keel yet; but where it mates to the dead wood it's supposed to be 5" wide. Chuck built his dead wood at this point only 3" wide. That's the problem.

That is only ONE inch less on each side.
I would just calculate the weight difference and add some internal ballast.
Need to know what that number is.
Fair the deadwood by adding or subtracting HIS CHOICE. Less wetted surface.
If it was me I would just shave the deadwood one inch on a 45º angle.
I have seen much worse problems.
If he has not poured the keel why not just make a new mold or modify it?

[chuckm]

This has been fun for me guy's, cause I have learned alot. This is what its all about; posting a problem, big or small depending on one's level of expertise. And getting results and answers. My area Boatbuilding Master is John Vardiman; he's building a 44 ft Malabar, nuff said; anyway he look at the problem , glanced at the plans, saw the problem, studied it for maybe 90 secounds and said "no big deal" here's what you do. It was almost dead on to what Roger Long designed. He also said if your not making mistakes your not building. Us newbyies can't help but get our panties in a wad. But that's how I learn. I really like the idea of taping into the the keel with a Tap and Die set. Vardiman had one, now that I see it, and how to use it, what a great method. Yea, it's labour intensive, but, I can see it through. Once the lead keel is poured, position it under the seat and drill maybe just a little, inch or three, then bring out the Tap and die set following that angle and direction. Simplisity is Zen. So I will build the Roger Long fin keel, (hope it is,nt patended), take pics, send them to Oughtred and ask for is blessing. Thanks again all, this has been fun.:)

[gert]

Try out the tap & die on some of your lead ingots before you commit, that's what I'm going to do.
4" is a long tap.