Ok , this is what I would now do . Don't panic . Take off the tape and sand the glassed area . Then as you said fill the recesses . Finely chop some fibreglass. A quarter cup flufffed up . Make a small batch of resin and add the glass fibre fluff until it's as thick as jam . Stuff it into the recesses and poke at it to remove as much air bubbles as possible . I would do it in two stages , no more than 5 mm thick at a time so it doesn't get too hot . Over fill the recesses . Sand the filled recesses area to blend in . Cover the whole fin box area with one more layer of glass . Sand area . Bog . Sand again . Drill the screw holes from the bottom , fin side , out through the top of the board . 7mm drill . Then re rout a smaller , shallower recess than you originally had . That should make it solid . Lightly sand and paint .

jn1 said..
Hi Imax. So what you're implying, is if I fill the front recess with epoxy, it will go into thermal runway and melt my fin box ?

Ok, no worries, I'll do that.

It could go into thermal nuclear meltdown disrupting the space time continuum .
That would be bad .

LOL Ok Imax. I'll follow your guidance exactly as you said above.

Nb/ I looked up the details of the Aparency epoxy I am using. They recommend curing depth of no more than 10mm to avoid heating. The fwd recess is 30x25x10mm.

Regarding the forward recess depth, I based that by getting one of my tuttle long screws with the nylon washer + steel washer and turning it up side down and putting it in to the recess to test it's depth. Then cutting a bit more out of the recess, and retesting it's depth with the fastener. I based the depth that the fastener just sticks out of the recess with the bog on. So when the padding goes on, the bolt is (hopefully) flush with the deck. I don't want my foot touching the bolt. I know it will bug me !. So, I would like to keep the recess approx 10mm deep.

FN: Ok. Thanks. Does the vacuum bag technique improve conformity alone ?, or does it do other stuff as well ?

If anything, this thread is an illustrated 'how not to do it' example . Anyway, it's all learning for me.

jn1 said..
FN: Ok. Thanks. Does the vacuum bag technique improve conformity alone ?, or does it do other stuff as well ?
.

Yeah, it just means that when you do things like the recesses it pulls the glass down into the void and follows the countours of whatever is there. It bonds things more easily as it forces it into contact whereas without it you have to use more resin or use some other method of holding it in place.

It's not perfect and at least for me requires a lot more pre-work, but it generally makes things easier when its setup properly. I have had times when the bag has vacuumed down perfectly and other times where I couldn't find leaks in the bag and the bag would not draw down properly.

Latest update. I was very ill for a week (and I'm still not right), so did nothing in that period. I was able to pick up the tools at the start of the week:

As recommended by Imax, chopped up glass fibre, and mixed with epoxy to make a jammy paste.

I did this is two stages as recommended by Imax. The result.

Bog sand, bog sand, bog sand, bog sand... and if in doubt, bog sand again... really built it up over a period of 5 nights.

Now to drill the holes for the fin screws (going in from the bottom of the fin box).

With fin in and the screws fastened, all looks good. No wonky holes. Pfew !

Next, plane out the wells so that the bolts have a flat land to mate against.

Donesky. The rear well was really hard to see when I was routing it. Not a perfect job I wanted, but oh well.

Although, on the front well, I did manage to route through to the filler again. So, fixing that now. I'll reroute this well out tomorrow. Didn't bother with the jam this time. Just straight epoxy. I only want a seal.

Hilarious thread; mate, I admire your patience, especially when things went TU a couple of times.
You just went at it again. Great stuff.

Hope to hear you happily wanging (that's a technical term for planing) across the water on it sometime soon.

cheers

k.

This morning's effort. The fin bolt wells are wonderful now

New problem. When fin is fastened and bolts done up, the fin is recessed in the box by 1.5 to 1.7 mm. Should I sand off the bog and live with an exposed fin box ?. If I leave it how it is, then this probably does not matter, as this is not a performance board. But it would be nice to have fin flush with board for aesthetics.

PS/ Yes, those bolts are the security type. Stainless 304 in M6 x 100mm. That's all they had at Bunnies. I'll see if I can order some Philips bolts online.

www.bunnings.com.au/pinnacle-m6-x-100mm-stainless-steel-security-bolts-4-pack_p2421016

Ok.

I checked all my fins (noting all my fins fit fine on my other boards- Falcon, Patrik slalom). The only fin that fits ok is my MUF slalom 22 (which is a fin I would not use in this board). But even then, this fin's base is recessed as well. The problem is, if I mod my fins to fit in the Supersport, they will no longer fit into my other boards.

Having a think about it, what I should have done when I was sanding back the box (back on the 10 November), I should have tested the cut depth with a fin to make sure I had cut off 1.5mm (instead of using the 1.5cm estimate). Then, when I glassed over and sanded, it would have been perfect. I therefore did not sand off enough surface.

Ok, no worries. I'll just leave it.

The top is done.

I go into Auto One and ask for "car paint that sticks to anything, dries quick, and doesn't have acid in it... It's for a surf board". Sold:


A quick "shhh, shhh, shhh".

The new pads. I used the old pads as a template.

So, that's the top done.

Ok, I'll flip the board over now and give the bottom a quick spray and we'll call it done.

(I'll be back in 5 min )

You can't really build up a plastic box . Nothing will stick to it . I'd say your job is done . Ride it like you stole it . Job well done

Hi,

just a quick one: Now that you are a pro in modern composites: Just make a g10 spacer for your fin that goes on top, so that the fin sits flush. We have done that for foils in the past and that worked out fine. You can glue it with the same stuff that you glue your footpads, that way it goes off easy when you need the fin for a different board. Or glue it in the box with contact glue. It will probably never come off again :-).

David

jn1 said..
Ok. That's David. Good tip

Hello J, Its your sailing buddy here with the windsurfing tip of the day.
This fin being too low in the board has been a problem for me until I started dropping a rubber band in one end of the taper.
Sometimes 2 rubber bands is needed. It works a treat and a box of them costs almost nothing.

Ok, Thanks H !