veneer reveals hull flat spot

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obd
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veneer reveals hull flat spot

Post by obd » Wed Jul 18, 2018 8:17 pm

boat.jpg
Not sure if I got picture to come through and my problem is difficult to discern in 2 dimensions, but, I have identified a significant flat spot on my hull that I didn't notice until I had epoxied on the second row of veneer, newbie mistake. I think it is probably due to my plywood butt-block joint. It should be reasonably simple to fair the hull in this area above the second strake, but I have to either remove part of the second strake or try to laminate a second piece of veneer over the original and fair it in. This presents some difficulty due to the challenges of spiling a matching piece. Therefore, I think I am better off attempting to remove the necessary part of the strake and then fairing the hull properly before resuming the veneering process. I am looking for advice and suggestions, particularly thoughts on how to cut part of that strake free. Thanks, Bob

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Milhouse
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Re: veneer reveals hull flat spot

Post by Milhouse » Wed Jul 18, 2018 8:26 pm

If you need to cut something that looks like it can't be easily cut with conventional saws then I recommend the Oscillating Multi tool, it is magic.

I recommend the Feinbut they have one at HFT that is way cheaper and works (just will break faster :))

I am curious how you are doing the veneer, vacuum bag, clamps and cauls?

I can't quite see the flat spot, I recommend greenshot(free tool) for a quick screenshot program and you can easily add arrows and annotations to pics.
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pic.jpg
Jim
16' Ski Boat Restoration
17' Overnighter Sloop

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JimmY
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Re: veneer reveals hull flat spot

Post by JimmY » Thu Jul 19, 2018 9:46 am

At least you'll get to see how good your epoxy job is! :lol: But seriously, Milhouse's idea is probably worth trying.

I had a similar issue at my scarf joints, but is was minor (<1/16") and it took several coats of clear encapsulation epoxy applied around the dip to bring up to fair. I'm not sure how that would look if one plank had a thicker coating than the next one. Maybe you could fair the hull, apply the next plank, sand/blend it flush with the current plank, and then use epoxy to bring that area to fair.

When fairing the rest of the side, use pencil marks and a long board for sanding. When all the pencil marks disappear, it is fair.
-Jim
Nothing says poor craftsmanship like wrinkles in your duct tape!

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Jimbob
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Re: veneer reveals hull flat spot

Post by Jimbob » Thu Jul 19, 2018 10:29 am

Here are my thoughts:
First, will it be really noticeable? But if you are like me, it will drive you nuts if you don't fix it.
If you decide to fix, I would remove a section of the final veneer planking, and then fill in the underlayers with quick fair. Sand until you get rid of the flat spot, and then put on a new veneer section. I would not recommend adding another piece of veneer on top of the flat spot. I think it would look funny where one veneer board blends into the one underneath. (probably more noticeable that the flat spot.) For the removal of the veneer plank, I would suggest a trim router with a straight bit. You can tack on a fence so that you get a nice straight cut on the plank that you leave.

I had to do a fixit on my boat and had to remove a section of the diagonal plank. I used a router with a straight bit for that. See pic of repair below.

Jim
Attachments
The fixed section.
The fixed section.
I set the depth of the router so that it only removed to the depth of the board being removed.
I set the depth of the router so that it only removed to the depth of the board being removed.
Jim Neeley
Building a Barrelback in Sacramento, CA
viewtopic.php?f=15&t=28089#p172969

obd
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Re: veneer reveals hull flat spot

Post by obd » Thu Jul 19, 2018 9:26 pm

IMG_1808.JPG
This picture shows my veneer clamping technique. Milhouse, love the oscillating tool idea. What blade would you recommend?
Jim and Jim, thanks for the advice. I hadn't even considered the trim router idea. That may well be the cleanest way to get that strake off. The flat spot is about 1/8 inch off at its worse. I know the picture doesn't show it well, but when I took the clamps off and viewed the strake, my heart sank. First major screw-up. Thanks again.

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billy c
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Re: veneer reveals hull flat spot

Post by billy c » Fri Jul 20, 2018 7:50 am

Remove the existing butt block in the bad area and replace with a block that has the proper arc? ...don’t mess with the veneer
Billy
Last edited by billy c on Fri Jul 20, 2018 2:12 pm, edited 1 time in total.
Reason: revised butt block sentence
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PeterG
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Re: veneer reveals hull flat spot

Post by PeterG » Fri Jul 20, 2018 10:03 am

From your photo, I see it's pretty likely your clamping method is causing the flat spot problem. Your method uses the chine and sheer as anchor points with the board and clamps pushing on the veneer and therefore pushing on the plywood planking. In between frames you will get a flat spot because there is nothing supporting the plywood on the inside. Once the epoxy cures, the flat spot remains. I suggest using a backer board, on edge is best, cut to meet the shape of the inside of the plywood where you are putting each clamp that is between frames. This will support the plywood while clamping the veneer in place. It means several custom shaped backer boards, one for each clamping spot, but you'll only make one set for one side and re-use them on the other side.
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