Question re attachment of chine, sheer and battens - Bo-Jest

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tsmitherman
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Question re attachment of chine, sheer and battens - Bo-Jest

Post by tsmitherman » Sun Apr 27, 2008 6:37 pm

I have the frames built, and am working on the stem and transom. I had decided to let the chine, stem and bottom battens all stand proud of the frames by 1/4", so I have not cut any notches yet. It has occurred to me that if I do this, I'll need to make the transom 1/4" larger on the bottom and both sides so the battens will be flush with the transom edge and the planking will lie flat it.

Am I on the right track :?:

I assume that the 1/4" difference at the stem won't be a problem, since I can just adjust the curvature of the longitudinals, but at the transom, the transom edge needs to be even with the bottom battens in order for the bottom planking to lie flat. If I made the transom as shown on the plans and faired off the bottom battens to match, this would alter (increase) the curvature of the bottom.

I have the transom rough-cut, leaving enough room to make it 1/4" oversize.

Hoping someone can help me over this hurdle so I can get everything on the building form.

Tom Smitherman
Tom
------------------------------
36' 1969 Willard Aft-Pilothouse Trawler
Blog: www.genesisboat.blogspot.com


Knot-So-Fast (BoJest) SOLD

"It's amazing what one can do when one doesn't know what one can't do." - Garfield

Jones
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Post by Jones » Sun Apr 27, 2008 7:55 pm

I'll make an attempt:

1. The members (chine, sheer, battens, etc) will be received into the notched 1" thick sub-frame that is attached to the inboard surface of the transom. If you haven't already detected it, the members meet the transom in a long taper that is difficult for the eye to detect, but the transom is cut with a bevel... inboard dimension greater than outboard. If you notch to the point that the members are flush with the inboard surface you're good to go... just a bit of planing to match the transom taper. In other words, you'll desire a flat mating surface for the planking to land on the transom perimeter; it only needs to be flush when you're done.

2. When landing the chine to the stem, scribing a line on the forward surface right down the middle of the stem gives an aiming point for the chine. Ultimately, you are aiming for the outboard surface of the chine to intersect the middle of the stem after all fairing is done. It's hard to explain in writing, but because the stem ends up being the finale of the boat's forward taper (the bow) the members attached to the stem are just a long taper that needs to end gracefully at a specific point... that being the "front" surface of the stem, hence the line scribed (I used dividers) right down the middle of the stem.

When you "plank" the boat you'll want continuous support along all members and landing "fairly" onto the transom of the stem and transom... so "flush" landings are the way to go in this man's opinion. If you visit my pages in the customer photos section you'll see a goofy looking "hook" on the end of a batten. It's used to reach around unfaired wood to see how close to the line you're getting as you bring a member into fairness. Alternatively, you can aim a rasp at what you think is the fair line and take off material (from stem) in small bites as you land the member into the stem. Some guys have wrapped sandpaper around an old saw blade to fine-fit members, but that's getting pretty "devoted" :lol:

MJ
Avoid Haste.

Amm
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Post by Amm » Sun Apr 27, 2008 8:07 pm

You might want to read this, http://glen-l.com/phpBB2/viewtopic.php?t=4893
I am assuming you feel that it is a superior method? Either way has advantages, but the the expert says the design should be for that particular method.

That being said, my guess is that it will turn out fine. I don't know much about the Bo-Jest, but its a semi-displacement hull. You probably should study what makes a semi-displacement hull a semi-displacement hull. Then make a decision.

Regarding introducing a 1/4" rise in the aft planking between the transom and next frame, I would think that is a bad idea. Seems like that would introduce a compound curve. Methinks you would have to adjust the transom to suit. With the transom on an angle it won't just be 1/4". 1/4" divided by the sin(angle). At least I think so.

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tsmitherman
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Post by tsmitherman » Wed Apr 30, 2008 6:36 pm

I guess I'm not very good at explaining things with text when a picture or drawing is needed. :oops:

Basically, if I let the chine, sheer and battens stand 1/4" above the surface of all the frames, then that would effectively increase the width of the boat by 1/4" on each side, and the depth by 1/4".

My question should have been, do I need to make the transom bigger to match the new dimensions, or is that a small enough variation that I can just ignore it and fair the longitudinals down to match the transom as sized in the plans?
Tom
------------------------------
36' 1969 Willard Aft-Pilothouse Trawler
Blog: www.genesisboat.blogspot.com


Knot-So-Fast (BoJest) SOLD

"It's amazing what one can do when one doesn't know what one can't do." - Garfield

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Bill Edmundson
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Post by Bill Edmundson » Wed Apr 30, 2008 6:50 pm

This is not a high speed boat so it probably won't have much ettect. But, I think I'd add to the transom.

Bill
Mini -Tug, KH Tahoe 19 & Bartender 24 - There can be no miracle recoveries without first screwing up.
Tahoe 19 Build

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tsmitherman
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Post by tsmitherman » Wed Apr 30, 2008 6:54 pm

Thanks Bill. I got the building form up today & should get the frames mounted and braced to it tomorrow. Maybe you'll have a change to ride down and see it sometime soon.

Tom
Tom
------------------------------
36' 1969 Willard Aft-Pilothouse Trawler
Blog: www.genesisboat.blogspot.com


Knot-So-Fast (BoJest) SOLD

"It's amazing what one can do when one doesn't know what one can't do." - Garfield

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Bill Edmundson
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Post by Bill Edmundson » Wed Apr 30, 2008 6:59 pm

Tom,

Once you have your frames up, you might cut a card board transom. If you have a long thin strip, lay it on the frames and see how it lines up with the transom.

Bill
Mini -Tug, KH Tahoe 19 & Bartender 24 - There can be no miracle recoveries without first screwing up.
Tahoe 19 Build

Jones
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Post by Jones » Wed Apr 30, 2008 7:04 pm

tsmitherman wrote:
Basically, if I let the chine, sheer and battens stand 1/4" above the surface of all the frames, then that would effectively increase the width of the boat by 1/4" on each side, and the depth by 1/4".
It only seems that you would be doing so. The plans are designed for the amount you've left proud.

The multiple angles of the keel/chine/sheer will not change (effectively) when you end up removing the material to fair the "landings" for the planking. You'll end up with a beautiful landing by leaving them a bit "proud" and you'll achieve the designer's intention that the planking not rest on the frames between stations. I think you'll be amazed how much material comes off in the process.

I hope my comments aren't confusing you.

MJ
Avoid Haste.

Jones
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Post by Jones » Fri May 02, 2008 6:53 am

Tom,

I hope you start posting photos in the customer pages, I was glad I did so from the very beginning. Good luck with your build.

- MJ
Avoid Haste.

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tsmitherman
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Post by tsmitherman » Fri May 02, 2008 11:09 am

MJ --
#1. No, your comments aren't confusing me - I can confuse myself pretty well :?

I appreciate your comments and suggestions - especially since you've just finished the Bo-Jest and have faced all the issues I'm encountering.

#2. I have all the frames mounted, and plan to take pictures as soon as the stem and transom are added. I will post them and try to keep the Customer Photos section updated as the project progesses.

I'm starting to get a lot of people coming by to see it now, and I'm keeping a list so I can call them when it's time for the "Roll-Over Party".

Tom
Tom
------------------------------
36' 1969 Willard Aft-Pilothouse Trawler
Blog: www.genesisboat.blogspot.com


Knot-So-Fast (BoJest) SOLD

"It's amazing what one can do when one doesn't know what one can't do." - Garfield

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