Ian's TNT Build

Outboard designs up to 14'

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Forge
Posts: 27
Joined: Fri Sep 20, 2019 11:15 am

Re: Ian's TNT Build

Post by Forge »

Got it with the router bit on the Dremel tool, worked pretty well and cleaned up with some sandpaper. I will adjust it as necessary when I get the chines ready.

This was after my first pass, I adjusted the bit deeper and made additional passes until it was all the way down to the plywood.
20200911_163617.jpg
Aerospace Engineer, Pilot, Sailor, Tinkerer and Surf Bum

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vupilot
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Re: Ian's TNT Build

Post by vupilot »

I can tell you from experience you definitively arent the first one to make that mistake, wont be the last either.

Forge
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Re: Ian's TNT Build

Post by Forge »

So I ended up using the skil saw to mill my keel and battens. I went to Austin hardwoods in Irvine and they had a lot of pieces of phillipine mahogany already cut to 3/4 thickness. I thought they only sold bigger lumber, but was happy to find they have a lot more to offer mostly milled. So I opted to just do it myself at home.
I don't have a table saw anymore so I used the straightest edge from one of the pieces as a guide and ran the skil saw along the guide. It pulled a bit but not too bad. The keel came out straight but the battens will need a bit of sanding and planing on the sides to even out a jog or two. I am not too worried about it thought since the sides of the battens don't touch anything that would really need a straight edge.
20200912_110708.jpg
Also, the peices I picked out happened to be a bit narrower at one end so I ended up with slightly tapered battens from 3 in at one end to 2.5 in at the other. This should work out well since they are supposed to be tapered from frame 2 forward.
Anyways... long story short :arrow: I might get the frames mounted and Keel laminated this weekend :D
20200912_120953.jpg
Unfortunately I could not easily find a place that stocked Sitka Spruce, so my dreams of super lightweight wood is taking a back seat to practicality. Although I don't think it's too much of a compromise compared to the phillipine mahog. The okoume plywood was much more bang for the buck.
Aerospace Engineer, Pilot, Sailor, Tinkerer and Surf Bum

Forge
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Joined: Fri Sep 20, 2019 11:15 am

Re: Ian's TNT Build

Post by Forge »

It's starting to look more like a boat! I have been leveling the building form while the keel laminate dries. It's a bit tricky adjusting for the unevenness of the 2x4s, but this 8ft level is well worth the $100 at home depot. I was able to measure with calipers to get my notches within 0.010"
Leveling the building form
Leveling the building form
I used some folded post it notes for shim stock to adjust my notches
High quality 3M brand shim stock
High quality 3M brand shim stock
And finally I have the frames mounted and am ready to cut the keel ends to length. It's very straight from frame 2 back and I don't see any gaps between the keel and the underside of the level. :P
Straight edge and keel lined up to be measured and cut to length
Straight edge and keel lined up to be measured and cut to length
Any thoughts or recommendations before I cut the keel and start drilling holes etc :?:
Aerospace Engineer, Pilot, Sailor, Tinkerer and Surf Bum

Forge
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Re: Ian's TNT Build

Post by Forge »

I just have to say I am shocked by how effective a small hand plane can be :o
When I cut my battens and keel with my skil saw the blade pulled to one side and it was especially bad on two of the battens. There was a very pronounced s curve pattern down one side. See here:
Wavy S curve down side of batten
Wavy S curve down side of batten
After a few minutes of planing the side I was able to get a nice straight edge along the whole side. I marked where the high spots were and tried to make sure to focus on those spots the most. But I noticed the plane would grab naturally on the high spots and let go at the low spots.
I think I could have just blindly ran the plane along and it would have taken care of the high spots all on its own. I wish I had discovered this amazing tool sooner.
Here is my end result:
Straight edges after hand planing
Straight edges after hand planing
Also, I rescued the hand plane from a junk drawer. It was all rusty and dull and it only took 30 minutes with some sand paper to clean off the rust, flatten the bottom and sides and sharpen the blade. What a great salvage, I can't imagine how much sanding I would have had to do without it.
Aerospace Engineer, Pilot, Sailor, Tinkerer and Surf Bum

Forge
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Re: Ian's TNT Build

Post by Forge »

I just cut the joint for keel to the transom using a Japanese pull saw I bought from Amazon. I was surprised how accurate it is. The cut comes out super clean.
20200914_103911.jpg
The angle was easy to cut to and it all fits up really well
20200914_104243.jpg
Here is everything dry fit together.
I also am planning on adding a small cutout at the end of the keel and battens to let water drain from one side to the other and allow the transom to drain fully without all the little corners trapping 3/4 inch deep puddles of water. I think this should be okay without causing any issues, there is plenty of strength and material from the transom surrounding the area.
20200914_105819.jpg
Aerospace Engineer, Pilot, Sailor, Tinkerer and Surf Bum

Forge
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Re: Ian's TNT Build

Post by Forge »

I am curious how to handle the flex in the keel that happens after bolting it down to the stem. The section between frames 1 and 2 seems to bow up in reaction to the forward section being bent downward.
The plans highlight the need to keep the keel straight from the transom to frame 2, but the upward bowing seems problematic. It will create some unwanted rocker in the middle of the hill. I would prefer not to have to fair it all out by hsnd. It could be as much as 1/8 of an inch at the highest spot.
20200920_173853.jpg
This view shows it from the transom looking forward. The gap between the keel and the level can be seen from the high spot back towards the transom:
20200920_173026.jpg
I think the best approach is to fair Frame 2 under the keel to drop it a bit towards the curve to the stem. This would reduce the height of the bump between frame 1 and 2. And then the curve would gradually start and flow into the stem.
Is this what is supposed to be done? Or is there another approach? Has anybody had this same issue when laying up the keel?
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JimmY
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Re: Ian's TNT Build

Post by JimmY »

I had the same issue with my Squirt. I epoxied and bolted the keel to the stem, and then readjusted the transom angle to get the keel flat on rear of the bottom (only 2 frames). At least on the Squirt, the hump is supposed to be there. If you are sure the notch in the stem and frame 3 are correct, then probably adjusting frame 2 is your best bet. I would suggest that you lower or fair the entire frame, otherwise you will have the same problem with the battens, since they are supposed to be flat as well.
-Jim
Nothing says poor craftsmanship like wrinkles in your duct tape!

Forge
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Re: Ian's TNT Build

Post by Forge »

Thanks Jimmy, I went ahead and faired under the keel at frame 3 and it seems to have made it much better. There is a bit of rebound still causing the keel to rise between frame 1 and 2, but now that it sits a bit lower on frame 2 the rise is a nice smooth barely noticeable curve that brings the keel up into a nice flat transition toward the back. I also lowered/raised the transom like you mentioned, to see how that contributed. It definitely helps to have that adjusted properly as well since it causes the keel to bow up or down depending which way you adjust it.
20200921_130244.jpg
You are right about the battens, I will have to do the same to bring all four of them down a bit to match.
I am going to spend a good amount of time trying to get them all set just right at all the frames.
The guy at the lumber shop said the boards were about a 1/16" over 3/4, so I will have to make up for that as well to match the corners where the chines are supposed to be.
Any recommendations for fairing tools? I was thinking of using a nice flat peice of lumber with sandpaper glued onto one end.
Aerospace Engineer, Pilot, Sailor, Tinkerer and Surf Bum

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