And So it Begins . . . Knottybuoyz' New Project

[knottybuoyz]

"Give me a lever long enough and a fulcrum on which to place it, and I shall move the world." - Archimedes, Greek Mathematician, 287 - 212 BC

"Give me enough clamps and ratchet straps which to place on it, and I shall stop the world from moving." - Rick Laporte, Amateur Boat Builder, 1960 -

One of the more interesting challenges to this project is laminating two sheets of 1/2" marine plywood together to form the curved transom. That's the reason for the funky transom mold I showed you earlier.



I tried a few different approaches to getting one sheet to conform to the mold. There's a tremendous amount of energy stored up in a sheet of plywood when you try to torture it into a shape it doesn't want to go into! I found that out when I tried to release the ratchet straps after the first trial! Yikes!

Anyhow, I quickly realized (in my dream last night, yeah exciting I know) that I need more grip to wrangle this part into shape. Adding some cleats in the right places are the ticket.



This gave me the advantage I was looking for. Places to put plenty of clamps.



As you can see the plywood now follows the mold pretty well. A few minor adjustments and it'll be perfect.



Some of the guys on the designers forums suggested adding kerfs to the sheets to allow them to bend easier. I never thought of that but it's a good idea, and probably safer too. I'll explore that later.

That's it for now. Off to clean up the old boat. Got a prospective buyer coming to look at it today.

[DeepFrz]

Good luck in selling your boat.

[Blue Stocking]

Does that mold become part of the boats transom area construction?
If not, how much extra curvature was designed in to allow for the straightening forces of the ply.
Once did a transom consisting of 3 thicknesses of 3/8" mahogany ply.
Cut the curvature out ot 10Ft lengths of 2 x 12 pitch pine. Bolted the concaved section to the bench, pulled the curve down with the matching convex form, with threaded rod through the forms projected ends.
Using the formula that is used for deck beam curvature, built in 6% extra, graduated across the full width.
The completed transom, at rest, came back very close to drawn shape.

[delmarrey]

Just get the ply wet and set it between two saw-horses at it's edges. Murphy will bend it for you.

[knottybuoyz]

Originally Posted by Blue Stocking

Does that mold become part of the boats transom area construction?

No. It's not part of the boat.

Originally Posted by Blue Stocking

If not, how much extra curvature was designed in to allow for the straightening forces of the ply.

I don't know. I would assume the designer took some springback into account.

I might try Del's suggestion on some scrap pieces to see how it works. I've only got one shot at this part.

I am able to get both sheets to bend into shape with brute force.



It's tricky but it'll work. Having conversed with a few other builders this is the way they did it.

It's way too hot (40C, 105F) in the shed today so I'm gonna think on this one.

[knottybuoyz]

Originally Posted by DeepFrz

Good luck in selling your boat.

Never showed.

Boat's nice and clean now though!

[hummingway]

Easing the back with kerfs does allow ply to bend much easier but unless you put a lot of kerfs it isn't a very fair curve; you get a bend where each kerf is (in my experience). Starting with thinner plys and laminating them works wonderfully in a messy whole lot of glue and clamps sort of way! You will have decking and hull to help the ply hold it's curve so, by way of speaking famous last words, I thnk you'll be alright.

[Capt Phil]

Thanks for the continuing saga of your build, Knottybuoyz... every time my enthusiasm lags in the rebuild of my old 1955 Chris Craft Continental, your efforts give me new encouragement to keep at it... cheers, Capt Phil

[knottybuoyz]

Thnx Capt Phil, appreciate you looking in. I have a great admiration for anyone considering the resto of a classic wooden boat. Really.

Anyhow, I popped the clamps and straps off.



It sprung back about 3/4" on each side. Dunno if that's good or bad.



Just seems like a whole lot of screwin' around for one part. Onto the next challenge, stitching the cabin roof together.

[Blue Stocking]

Theres your 6%. In all fairness, the number of veneers and the wood in the ply can make a considerable difference on the "return", . Nothing that some extra re-inforcing won't heal.
Looks great all the way

[marshmat]

Not bad, Rick. Not bad at all

I've tried kerfing plywood a few times for models. I don't bother anymore- it'll bend tight but it just won't bend fair, and it completely destroys the structural value of the outer (i.e. most critical) layer of the plywood. More, thinner plys and more brute force seems to be the way to go.

Enjoying the reports so far... keep 'em coming

[knottybuoyz]

Thnx fella's. It was a bit of a strain on my poor ole' tired noodle but I figured it out with a lil' help from my friends and the Internet.

Lori, my neighbor Robert and I moved the cabin roof panels in on the long table.



Better picture I think.



It's 16' 4" long by 8' wide. Sorta brings a whole new perspective to the size of this beast we're bringing to life and the boat is another 2 feet wider than the roof top! I know a 31' boat doesn't sound like much but when you're building it in your 36' long back yard in a shed that's only 32' long everthing seems supersized for some reason! I'm sorry, I had 'nuther "WTF have I gotten us into now" moments tonight!

[hummingway]

Boats do look big when you get them out of the water. Someday you'll be drinking a Guiness from the deck of the thing and won't even be able to remember wondering if it was a bad idea.

[Blue Stocking]

Originally Posted by hummingway

Boats do look big when you get them out of the water. Someday you'll be drinking a Guiness from the deck of the thing and won't even be able to remember wondering if it was a bad idea.

Amen to that, brother

[knottybuoyz]

Reminds me of this picture.



This fella built his TW28 about 6 years ago with his boys. I can only dream of the satisfaction he must have been feeling at that time. I hope he's still getting as much enjoyment out of the boat now as he was then.