Standup Zone Forum
General => The Shape Shack => Topic started by: stoneaxe on April 07, 2013, 05:38:02 PM
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I want to start doing my own repairs. I need to fix the fin box on my 9er and I figure this will be a good time to start. I've done some glassing on dings and small stuff but this will be the first bigger fix. I've got a router and such. I assume the the router templates for each fin type you work with are necessary. What else do I need?
This box was fixed before. Unfortunately it was originally just set in the EPS, no divinycell, and the repair was done just by using filler and epoxy. When I took out the box and cleaned out all the loose crap it left a pretty good gap. I think I should probably glue in some divinycell or is the expandable foam good enough....would definitely be easier.
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http://www.swaylocks.com/forums/glass-under-fin-box (http://www.swaylocks.com/forums/glass-under-fin-box)
Good info in this thread.
I use Chinook finboxes. Chinook boxes are designed for windsurfing and are much tougher than surf boxes. Dimensions are identical except for one, box depth. Windsurf boxes are 1/8" deeper. For surf use, you just grind 1/8" off the top of the box. Either before glassing, if doing glass over install, or after, if not.
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This is for the front side. Here's what it looks like. I'm getting the water out of it right now.
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Don't use expandable foam!
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I fell really hard on one of my futures fins last week and decided to go in and call it a day.
I hit it hard with my forearm as I was instinctively using my arms for protection. My first thought was that I had a huge gash going on but was lucky and wasn't cut up. I did get a massive bruise. When I got in I checked the fins and boxes and got lucky again as I didn't see any damage there. I always use some glass under the boxes and set them in some stronger foam blocks and me thinks that is what kept them fully intact.
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That looks pretty bad, being so close to the rail. I'd definitely cut out a larger area and use some rigid foam reinforcement. Probably add a layer of s-glass or better along the rail too.
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Don't use expanding foam, it's good for a lot of things but fin boxes isn't one of them. Divinycell.
the big problem you're going to have is getting the alignment of the fins right after you get the reinforcement in. That box is super close to the rail, it's going to be a bitch. If you don't have a good guy near you to do that, then take your time, make a good template, and do it right. Here's a design for a futures fin template. http://www.fiberglasssupply.com/pdf/surfcomponents/futurefinjig.pdf. (http://www.fiberglasssupply.com/pdf/surfcomponents/futurefinjig.pdf.) You can buy templates for specific boxes, though some of the ones I've seen are kind of wimpy. I made a base out of lexan and the guides out of plywood for the template I made. I can't find the damned thing. Time to clean the garage.
With that fin so close to the rail I'd probably glass over the divinycell and under the fin box for one layer and lap the rail a little with that layer. You'll need to put a fin in the box while that layer sets up so you can keep the fin perpendicular.
Then do a standard box install. this is for a windsurfing powerbox, but it's clear about what to do. I suspect Eve wouldn't glass under the box, but I would.
http://www.boardlady.com/jppowerbox.htm (http://www.boardlady.com/jppowerbox.htm)
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Wasn't there a way to repair something like this with a beer can.
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I thought of that beercan post when I started this... ;D
Yeah....my biggest concern is how close to the rail it is. Good suggestion to lap it over. Anybody got a chunk of divinycell to sell? Looking online I can only find sheets and they are mucho pricy.
I'll make a template in some very dense wood I have...should be fine.
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You can use 3/8 sheet to build a box, either formed arond the new finbox or as a built-up solid block. If you form it around the finbox you'll need to make a template the size of the reinforcement block and do you alignment on it. That means your template will be a one shot. You can use blue construction foam if you glass under the box. Not as strong, but glassed under it will be a strong or stronger than a PVC install.
I'd consider removing the finbox on the other side as well, filling both holes with blue foam, glassing over the holes and then installing probox or FCS plugs. Probably easier in the long run and Probox or FCS fins are nice.
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Funny you should say that. I was starting to think the same way. The board is a 5 fin setup. I've broken the fin boxes in it 3 times before. I'm thinking of pulling them all and reinforcing.
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Yeah...I looked at Eva's site. When I heard she was retiring I saved the whole site as a PDF just in case it ever disappeared. I knew I would be needing it someday. Glad it's still up...she even added a little.
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Take the time to make a template if you want, they do help. But over the years, I've been replacing all different kinds of boxes (different sizes), on different kinds of boards, mine mostly.
So if you want to save some time, just router it out freehand, draw lines first, of course, but if you are slow and steady, you can do it freehand no prob.
Foam and glass doesn't bounce around the router like wood can.
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Good point....I have pretty good freehand router skills too. Even in wood...some of the carving I've done I start with a plunge router.
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FCS plugs are pretty simple, and Probox has nice templates for cheap.
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Sometimes I do some freehand routing at approximately half the depth then take some files/sandpaper to it to straighten things up and clean up the perimeter. Then drop it down to full depth and use the smooth shaft of the upper part of a 1/4" bit against the cleaned up perimeter and finish it up to the proper depth.