Bent keel on a Catspaw

[Mrleft8]

I had the keel all clamped to the moulds, the skeg bedded and bolted on, the ribs bent around the ribbands, and nailed/screwed to the keel. everything was arrow straight and fair... 2 days go by and I'm back at it and I started spiling for the garboards... Something was off, so I sighted down the keel again. It's bent. If I crank the transome over about 3/4" it gets close to straight again, but the center line on the transom is off the centerline of the strongback. So the question is: Do I live with the bend in the keel, and have the centerlines on the strongback/transome line up, or do I live with the centerlines out of whack, and have a straight keel? I can't see removing the keel at this point, it took too long to rabbet, and I'd destroy a bunch of ribs... :mad:

[rbgarr]

Crank the transom over 3/4". Most boats have assymmetries anyway.

[Paul Denison]

Ouch! Don't know enough to help. Was it laminated? What made it warp?

[Mrleft8]

Paul Denison
.
Member # 4174

posted 03-15-2003 01:59 PM
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Ouch! Don't know enough to help. Was it laminated? What made it warp?
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From: Knoxville, TN | IP: Logged

I blame El Nino..... The tree grew up in a bad neighborhood.... The sun was hotter on one side than the other..... Dubya threatened it...... The French came by in the night and did it just to sabotage me.... Hell if I know, it just happened.

[ishmael]

Tempted to go with what rbgarr says, though I think it's six of one, half dozen of another. And whichever, don't let it unnerve ya. smile.gif rbgarr's right, traditional wooden boats are rarely rock solid on their lines.

[Ross Faneuf]

Fudge it around until it's whatever you can bear. Avoid a twist in the transom - that is, so the centerline of the transom is no longer parallel to the centerline of the stem; a twist like that is easy to see, while a non-straight keel is not.

Consider if unbolting and unbedding will give you better alignment. Might be worth it, even though it will feel like a step back.

Resign yourself to the fact that you will always be aware of this problem - or any problem that gets built into this boat, or any boat. Train yourself to focus on the things you get right - there will be lots. And it's perfectly true - no wooden boat is ever perfectly symmetrical, or perfect, for that matter.

[ishmael]

The more I think about this, the more I think you ought to let it be. The boat is framed right? You start cranking stuff around who knows what you're gonna wopperjaw. Build it the way it's settled. It wants to be a little crooked. It'll go to windward better on one tack. ;) And you'll have to pull a little harder on one oar. ;) ;)

[ 03-17-2003, 07:28 AM: Message edited by: ishmael ]

[Mrleft8]

The "perfectionist" furniture maker in me cringes at letting something "go". But.... I think I will. I've nudged the transom over about 5/8", still plumb, and square to the strongback, but off center by 5/8"....
As Krenov once told me... "It's not that I never make mistakes. It's that I've been making mistakes for so long, that I've gotten REALLY good at hiding them"
Still bugs me though... :(

[ishmael]

The unfairness in a chine of a skiff I built twenty years ago still bugs me. No one else, save a boatbuilder notices it, ever. Get used to it. Stradivarii boats ain't.

[Mrleft8]

I just keep telling myself that it's a first time project, and to try my best, and learn as I go.... Sigh...

[ishmael]

Ah, ya have to get beyond that Lefty. The project'll lose steam if ya don't.

Boats aren't like anything else. The fact that you have a 3/4 inch run out over what, 10 feet, isn't gonna matter a hill of beans, to either the boat's performance or its looks. There, feel better? No I didn't think so.

This is just the thorn in your side, the imperfection in the fabric. Where would we be without it?

[Cedarhill Boatworks]

It aint how bad you f**ck it up, it's how good you cover it up.
Crank the transom around and live with it.

[Walcheren]

I have been thinking about your Post quite a bit. First I must tell you that I can imagine how it felt when you discovered that the damned thing had bent itself out of place. I did not immediately reply as I had no idea what to say regarding what to do about it. I built a Catspaw about 10 years ago. What happened to me created a similar emotional response I think. I am telling you this so that it won't happen, for sure, to you. They say quite clearly that you have to put spreaders across the boat before you take her off the mould. Well I thought I could wait a day. Well, several days later I noticed that the stem was displaced forward at a joint by 3/8 of an inch or so. Damn. It took a bit of brainwork to realise that I had not put the spreaders in immediately and as it appears the desire of the planking to straighten out was greater than the ribs straightening themselves out, the boat had to become longer and "narrower". So the stem had to give. So watch out. I fixed it by putting a large bolt through the stem to stabilise the "fracture" and some epoxy inside and out did the job. She is just fine and nobody would notice except a surveyor. My Dad used to say "nobody lives there so it won't be noticed" If the keel is out sufficiently so that the boat does not track straight when rowing, a small tab on the skeg will eliminate that. You can'put the spreaders in untill after the boat is off the moulds but have them ready, all three of them.

[Mrleft8]

Thanks Walcheren!
I've already been thinking about that!
I figured I would mark cross spalls while the hull was still fastened to the form, cut it free flip it over and attach the spalls as fast as possible. I guess I was thinking it would want to "widen", good point on the "lengthen" issue...
So, my spalls need to be able to deal with compression, as well as tension... (I guess 3/4"x3/4" stock won't do!)

[Walcheren]

No, Dirk

[ 03-21-2003, 03:49 PM: Message edited by: Walcheren ]

[Mrleft8]

No Dirk?

[Figment]

This happened to me once, and I was able to fudge it back into shape by "influencing" the keel back into line on a station-by-station basis and securing on same basis to moulds. My thinking at the time was that, once the hull was planked to this shape, the keel could be released from this torture and would probably not spring back into its bent shape.

From what I could tell, it worked. Once off the moulds, the keel was visually straight. I never bothered to check for what the cost was in terms of hull shape, but I assume that SOMETHING was sacrificed in terms of symmetry, etc. in order to make this happen. I didn't check because I don't want to know. What I knew was that I didn't want to have a curved keel staring me in the face every time I turned the boat over. Lesser of two evils.

Anyway, if this is the biggest challege you face on this project you're doing damn fine.

Did you ever get that station 3 (IIRC) misalignment thing figured out, or did you just cut your losses and recut the mould?

[Walcheren]

I am still thinking. I said No..... but it depends. Depends on what wood one uses I guess. I used yew for the ribs and once that wood is steamed and bent in place it just stays there. So in my case the 9/16 cedar planking, sometimes steamed sometimes not, I would blame for my problems. I have no idea what happens when one uses other wood for ribs like oak. So maybe it does depend. But measuring in your cross spalls (thanks for reminding me of the term) before hand seems a very good idea. (I have no clean workshop!)

[ 03-22-2003, 10:33 PM: Message edited by: Walcheren ]

[Mrleft8]

The station #3 issue was resolved Mike. It was not fastened properly to the strong back. Curiously enough, as I plank the hull, the bend in the keel seems to lessen. Perhaps the eqalizing forces of the planking are working to make it straight. That, or I'm getting so used to the bend that it's becoming less traumatic...