Wooden Boat People

By McKenzieDriftBoat.com

Transom size vs rocker angle

Hello all -

Looking for a little advice. I am on my first build, making a hybrid of a Don Hill and a Honky Dory. I just finished seting up my last scarph joint and am going to start making my transom while it cures.

Here is the question. I have stretched my plans to make an 18' (gunnel) and 56" bottom boat. the plans I am using (both sets) call out for different size transoms although both are for a

16' (gunnel) boat. I understand that the wider the transom, the less rocker, the narrower,the more rocker, but am hoping that someone else out there has done something similer and can give me a little advice..

I was going to stick with the measurements from the Don Hill, mainly because it has all af the measurements there, but I "think" that I am making a mistake.

Any suggestions???

Greg

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Replies to This Discussion

Permalink Reply by Dave Z on January 16, 2012 at 12:13pm

Welcome Greg.

Mmmm.... I'm sure you can design about any boat with any width transom and get the desired amount of rocker. Now, If I assume correctly, you are sticking with the side panel dimensions in your plans, or stretching them too?

Transom angle should not dictate rocker. It's the entire design of the boat that dictates the rocker. The frame bottom bevels, side panels and frame locations.

I woud start with a desired profile view, fore and aft rocker and the ever important side height at the 'locks, and then fit it into a panel size so that you can cut both panels out of one big old scarfed sheet.

What you can do is build your transom dead last, during assembly of the hull. get all of your frames in, stem, etc, then pull your sides in to where you like them, brace them in place wiht a spanish windlass or rope and turnbuckle, design it in air, make it fit perfectly.

....or.....

Make a transom, make a stem. put them on th ehull first, twist and torture th ehull shape to where you want it, then brace it in place. make your frames cusotm to the shape to hold the rocker and profile. This is sketchy, as you don't know how it is going to look or balance once right side up.

I would revert back to making a scale model of the desired build. Much easier to scrap 2 bucks worth of poster board versus plywood. Go 1" = 1 foot, lay it all out, cut it out and tape it together. remeasure the "hull" model, adjust frame placements, then build her in real wood.

Good luck.

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Permalink Reply by Greg Jensen on January 16, 2012 at 6:30pm

Dave,

thank you for responding and let me describe what I am doing.

I have multiple sets of plans, for a Don Hill and a set of plans for the Honky Dory.

I then stetched my boat to 18' (gunnel) and changed the bottom from 48" to 56".

I am building a modified S&G and Framed. I will be utilizing a couple of the frames

for interior bracing and a subfloor or raised deck.

I plan on changing the interior to look more like one of Jason's boats, but not quite.

I have not only completely changed all of the plans I have, but in the process, I think

I have lost any common sense I "thought" I had.

AND, here is the biggest problem. The only thing I have ever built was the work bench I built

to start this project. At least that turned out well.

I thank all of you for the advice and knowledge that you have shared, and please keep it up.

I will start posting pic's of what I have done so far soon, and in the mean time..

Anyone want a drink?

Sincerely,

Greg

P.S. At least my scarph's are turning out good....

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Permalink Reply by Dave Z on January 16, 2012 at 7:33pm

Greg,

Stick with it. have a drink and ponder it a while. Seriously though, try your hand at some scale models out of posterboard and tape. Will give you a good idea if your plan is working.

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Permalink Reply by Randy Dersham on January 17, 2012 at 9:46pm

Greg, there is no right or wrong to the transom. It could be as thin as a stem or as wide as you want to make it.

I recommend that you choose one of the boat transoms, either the Honky Dory or the Don Hill, and build the boat free form, meaning that you attach the side panels to the stem, c-clamp in the center frame, support that frame and the side panels ( I hang mine from the shop ceiling) so the sides will come around for you to attach the transom. Then when you build the rest of your frames you can fit them and see the shape of the boat develop as you put them in place.

You are right that there is a small difference to the rocker depending on the width of the transom but it is very small for the difference between those two designs.