Ian's TNT Build

[Forge]

Hello all,
I just started on my TNT Build, I figured now that we are stuck at home most of the time due to coronavirus, this is the perfect time to take on a boat build.

I started a post earlier in the introductions board titled ' I plan to build the lightest TNT ever' where I discussed my goals for this boat. To reiterate here are the top key design aspects I am focusing on:
1. Lightweight: must be able to be easily carried by two people and stored under the cabin for winter.
2. Safe and sturdy: ideal for the nephews to drive themselves and withstand occasionally hitting the dock and being beached.
2. Most speed and range possible while using a 10hp motor: this is because I plan to use the boat in the summers in Canada, and a 10hp will not require the boat to be registered. Speed is important since we plan to cruise up the lake on long all day trips and less than 20mph would make the trip too long (30mi one way)

So far I have cut out my frame peices from mahogany, and the gussets, knees, stem and breasthook from okoume plywood.
I have stenciled out the project board on a rough cut of the 3/4" that will become the transom when I finish the frames.
I ordered epoxy and some silica filler to thicken it up. I am planning on laminating the stem and breasthook first. This should be a good learning piece before doing the frames.

If anyone has some suggestions for bonding/laminating the frames I would appreciate any tips before I pull the regular noobie mistakes on my own...

I will post some pictures soon of my first pieces etc.
I am already very excited about this boat, the size and shape are perfect for a summer cabin runabout that will be easy to pull out and go cruising for years to come.
-Ian

[Forge]

First pieces are now together! Just laminated the stem today, we will see if I got the epoxy mix right, I am going to check the mix cup to make sure it fully hardened...

After reading a lot of posts on methods for assembling the frames I used the following approach:
I predrilled for the nails and then drove two of them in just until they barely stuck into the second piece, then pulled them apart. When I coated the two pieces with epoxy and then stuck them back together the two nail points held the pieces in alignment so they didn't slide around when I clamped them and drove the rest of the nails. Went pretty smoothly I think, granted the epoxy cures properly

But making progress!

[JimmY]

Hi Ian,

Sounds like you're off to a good start. Most epoxies are somewhat tolerant of mix ratios, just stay vigilant with your mixing. It is easier and faster to make sure you measured correctly and mixed thoroughly, than to scrape off uncured epoxy.

[Forge]

Thanks Jim, I bought a big bag of mixing cups and popsicle sticks off Amazon that have graduated measurements on the side which helped a lot. I checked the mixing cup this morning and the leftovers were solid, and I used a thumbtack to test the hardness of a few bubbles of squeeze out down the stem and it was cured pretty hard so I seem to have got a good mix on this first round.
I will be sure to stay vigilant on the mixing.

I am planning to laminate the two breasthook pieces and then fit them to the top of the stem all in one batch of epoxy.

Does anyone know if it's better to wait to fit the breasthook to the stem when it's on the building form? And I need to double-check if there are any fasteners used as well. It seems the pieces are designed to fit up independently, and then be mounted to the building form as one unit.

[Forge]

Laminating the Stem

Here are some of the first assembly pictures, the stem is together, the breasthook is on in the next one. And now I am prepping to gusset the 1st Frame

Stem w Breasthook attached

This is an example of how I am driving the nails just to the point where they stick into the predrilled holes on the second piece and then pulling them apart. This way when I apply epoxy and then go to drive the nails, the pieces are already pinned in place when I set the gusset down onto the frame.

Frame 1 gusset prepped and ready for epoxy

[JimmY]

Looks like you've got a good system going. I recommend assembling as much as possible before attaching it to the form, including the transom knee to the transom. It is a lot easier in my opinion to get these pieces aligned and clamped together on your workbench than when they are hanging in mid air.

[Forge]

I now have all my frames and transom together (except for the deck beam at frame 3...
I can really see how it is going to be in full size and it's pretty exciting. It's time to order some longitudinal lumber and set up the building form.
Here are the frames all layed out and ready to go:

Also, since I am focused on keeping the weight down, I am going to share the weight of components as I go, if anyone has any records of what their weights were with different materials I would be curious to compare.
Frame3: 3.4lb, Frame2: 3.2lb, Frame1: 3.0lb, Stem&breasthook: 3.4lb, Transom: 16.6lb
For a total of 29.6lb in frames...

[denbrlr]

Looks good. It would be a good time to encapsulate those parts now. The TNT is a great boat. I built one in 2010/2011 and still use it a lot. In fact, I just went for a boat ride in it about 30 minutes ago

Lee

[mrintense]

Some of that weight will be lost after the fairing so the pieces will end up lighter

[Forge]

Thanks Mrintense, I am looking forward to the fairing process, but I will try not to get too carried away trimming weight.

Not much progress for the next two weeks. Went to visit my brother in Portland and we are restoring an airstream trailer he bought this spring.

[Evan]

Nice work, be interesting to see what it weighs at the end.

[Roberta]

I miss riveting and playing with clecoes.

Roberta

[Forge]

Yea it was actually pretty fun, he definitely needed two sets of hands for some of the pieces of sheet metal that wrap around under the frame.

I got home this past weekend and went to home depot for some 2x4s for the building form. I have the form built up and notched for the frames. I set the frames on it to get an idea of how it's going to come together. It is starting to show the real shape of the boat now if I just imagine the keel and chines.

I need to find a shop to mill the longitudinals for me since I do not have the space or tools to cut and plane the lumber down to size

[Forge]

Just found my first goof!
I didn't cut out the notch for the chines in the transom frame peices before laminating them to the transom. I was going to wait to make all the notches in the frames until I had the chines and sheers ready to go in hand, which is okay for the frames, but in the case of the transom it's going to cause me some extra work since I don't want to saw clean through the transom...

I will probably cut them out with the router adapter on the hand-held dremel tool I have. It's just going to be annoying to keep them square and not get too messy...

[JimmY]

Borrow a router with a straight bit, you'll be done in no time.