Making of the SNX Hull

[Nate_D]

For the enlarged pump tunnel the plan is to pull a foam mold off of the current tunnel, then sand/cut out the mold. After that's finished, pour foam inside the mold to create a positive mold which will have glass laid over it.

Created an enclosure for the foam.

Tape to secure the plastic.

Foam in. 12oz wasn't quite enough.

Because I didn't use enough foam there wasn't enough pressure to push against the plastic and grab the shape. I had to pull out the plastic, duct tape the tunnel, pour more foam over the duct tape, then place the first foam mold on top, add more foam and place the top back on. While the foam doesn't really stick to the duct tape, there seems to be a higher surface tension (or something) because it was a b*tch to get off this time.

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[McDog]

Holy crap! Don't do it! Not worth the trouble on a oem heavy hull. Good idea for how to do it though.

 

[Nate_D]

Holy crap! Don't do it! Not worth the trouble on a oem heavy hull. Good idea for how to do it though.

Don't pull a mold? Or don't enlarge the pump tunnel?


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[McDog]

Don't enlarge the pump tunnel. Unless your just a glutton for punishment and plan to spend some money on a big pump and motor to push it. That money would be better spent on an aftermarket hull. That intake tunnel is all you need for up to 148.

 

[Nate_D]

Well I already have a 155 and the pump shoe laying around... eh, what's another 10-15 hours anyway? Bring on the punishment!


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[simofx-1]

wow nice progress, im very interested to see how this build continues

 

[Nate_D]

Made some progress on the pump tunnel mold. Because I pulled the mold off of the inside of the hull, and instead of laying glass onto that I am pulling a second mold from the first mold to lay glass over, I effectively gained the thickness of the SMC. Which quite by accident and to my surprise, is almost exactly the right size for a 155 tunnel/shoe. I only had to sand out maybe an eighth of an inch in some areas, if even that. I did widen the middle of the tunnel and transitioned it into the shoe area. That took all of 10 minutes though.

I'm pretty happy with where it is at, but if anyone sees any details that I overlooked or has input on how to improve it further, please do share.


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[swapmeet]

Pretty much sums up my thoughts.

 

[iangdesign]

If he enjoys building then have fun! Might be the next AM hull builder...

 

[Nate_D]

A little more progress tonight.

Rideplate wet sanded and waxed.

PVA down

8oz of cloth down. Mixed up an epoxy/cabosil/milled fiber batch and loaded it into a 10cc syringe with the tip cut off. Filled the chine area on top of the 8oz to help the 1708 form. After that came 4 layers of 1708.

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[Nate_D]

Started work on the nose. The rocker really lifted the first 3" of the nose and while I could have left it, it was just so ugly...

Measured and marked for the cuts

Sawzall and 3" air cut off tool

XPS clamped down and marked. Removed XPS and cut out a section for the hull. Cut a second section and glued it to the first.

Clamped down and glued to the hull.

That's about as far as I got on the nose.

Foam and supplies should be in this Friday. Hoping to have the rear completed, tunnel glassed in, and the new nose area glassed in by Friday night.


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[Dalton]

Well I already have a 155 and the pump shoe laying around... eh, what's another 10-15 hours anyway? Bring on the punishment!


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That's the spirit!

That looks like a very effective way to enlarge a pump tunnel. I think I might do something similar down the road.

Curious to see your plans for the top deck nose. Designing and shaping my top and bottom deck nose was by far the most time consuming stage. Sticking with square-ish lines or going rounded?

 

[Nate_D]

The nose is going to be roundish with the rails at a ~20* downward angle. The top deck will have square lines to it, but will be round looking. That really doesn't make any sense... A top deck cross sectional cut would look like a hexagon cut in half is the only way I can describe the idea. I can't draw worth a damn or I would put it down on paper to work out all the lines. When the time comes, Im just going to dive in and start marking the top deck up until I'm happy and then cut it up.

Besides the PVA pissing me off, I am really happy with how the plate mold came out and the way I am anticipating the plate looking based on how it laid up. Hopefully it releases correctly tomorrow. After seeing how well the plate mold came out and adding up the costs, there will definitely be a mold pulled for the hull.


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[Nate_D]

@McDog Does Waternut still come on this forum? I have a couple of questions on his layup schedule. Actually you might be able to answer them since you were laying up the bottom deck with him... Do you recall what his schedule was?


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[Nate_D]

Plate came out pretty good. I'm happy with it for a first part.

Total thickness came out to be 3/16". Target was 1/4", so it was slightly off. Another layer of 1708 would have been perfect.

There is a pretty big gap between the plate and the recessed area. I have a plan to remedy that tomorrow. It involves sand paper, metallic duct tape, release wax, bondo, and the new ride plate...

 

[Dalton]

A thick coating of PVA is sufficient to release bondo, spray foam, or really anything for that matter. If you're planning on doing it how I think you are PVA would be a good substitute for the metalic duct tape.

 

[Nate_D]

Probably so. The glass on the inside of the plate is rough, so I don't know if just PVA would release. The duct tape was/is going on the ride plate to create a smoother surface. I could probably sand the inside of the plate and then shoot the PVA on it... Basically the hull is getting sanded to an acceptable level and then the inside of the plate is going to be prepped for a clean release, then bondo applied liberally to the recess and the plate pressed down to the correct height. Hopefully this leaves me with a smooth bondo finish in the form of the plate that I can prep for primer/paint


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[Dalton]

I tried duct tape once and hated it because of the texture and lines it left on the mold surface. Even on the rough surface PVA will release given its not too porous. I would sand the rideplate first then apply PVA. I've had PVA release from surfaces sanded with 40 grit no problem.

Edit: The way you can test to make sure is coat an area of the plate with pva and try peeling it off after it dries. In my experience doing this saves tons of time repairing the surface impressions from the duct tape.

 

[Nate_D]

When I first started this project I had wondered why hardly anyone did a full width ride plate, now I know. It's a lot of work... Easily more work than all of the other commonly done mods combined. Especially if you want to do it right. Between the mold, foam molds, the cutting, the glass work, sanding, pulling parts... 60+ hours and I still have another 8 hours or so of sanding/prep.

Cut around the outside of where the new glass is with the air cut off. Thanks to SMCs terrible bonding characteristics, a flat head and a hammer was able to easily remove all the excess.

Dremel with a 60 grit sanding drum to clean up the hull side mating surface. 60 grit sanding block for the ride plate side. And 3 hours of sanding, matching the plate up, sanding a little more, lining the plate up again, sanding..

There's a very slight angle/rocker designed into the plate recess area. About 8 degrees. I will be able to adjust the ride plate angle from level to ~8* rocker (not really a rocker, more of a straight angle I guess). So the hull can go from -1 in the rear to -7.5 and have an adjustable plate angle from 0 to ~8 degrees.

Next I wrapped the ride plate in foil duct tape. I debated sanding the inside of the plate smooth to avoid the surface impressions on the body filler. Would it be easier to sand fiberglass and have a clean bondo surface (probably still need to sand it) or just sand the body filler... Probably just sand the body filler. So I went with the foil tape. If I was laying glass against it, I would have sanded the plate and avoided the tape lines.

The tape received a healthy coating of wax and was shot with PVA.

Mixed up the body filler and applied to the hull. Pressed the ride plate down on top.

This is after the first round.

And after two more rounds of body filler (each time I had to re shoot the plate with PVA).

I still have a little more body filler and sanding to go, but it's getting there.




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[Nate_D]

Little more sanding done. Some more to go tonight. Picked up a 3" drill mounted sanding drum. Helped out some.

Really looking forward to being finished with the bottom deck. So much sanding done and so much left to do. Feels like I've been working on this ride plate area and shortening the ski for forever and a day. I am hoping that I can finish it by Friday and be working on the pump tunnel on Sunday.


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