How would you sink a box in stringerless 2# EPS?

General Discussion
1

I had thought about an extra “page” or two of 4 oz draped into the slot, lapping out maybe 2 inches on either side…?

Hoping for some guidance on if it’s possible and how best. I’m working with a fin location that would be about 1.75" thick, maybe even 2", not sure, but relatively thick good 2#, and I think I’d be running a Bonzer fin or something similar on profile and flex, nothing too extreme…

medium glass

Other option was to quad it with LokBoxes. Just want to know about whether the possibility exists for a single in a stringerless, with reasonable certainty of not rooting it out in the first year

thanks!

2

Hi Janklow,

Just try to make a good connection from top to bottom in the board.

It greatly improves stiffness in the fin too.

Try a glass connection or even carbon…

Soul

3

Using a ‘‘glass-over’’ box that’s somehow tied to the deck is going to be strongest.

Figuring out how to do this is the problem. Somebody may have experience with this,

we haven’t done any single boxes at Coil.

A high density insert could be a solution.

Or you could glass the deck first, then score through to the deck from the bottom of the route

hole, a la FCS’ H-pattern, before you glass bottom and install box?

I’l try to ask Kirk and Eric what they’d advise, they are really good problem-solvers. But we’re

kinda busy ----hey!, I should be at work now!

Mike

4

Hi,

This is the simplest way when the board is already glassed.

Blue is the outside glass, black is the box, green the new glass.

Router out the hole for the box plus a bit room for glass.

Then cut through to the deck two thin cuts.

Cut a bit under the bottom glass for a good connection to it.

Clean the inside of the deck glass,put resin in the hole and push the glass with a thin long thing against the deck.

Then put in the box and cut the glass at the bottom when it starts to gel.

Best to glass over the box after this.

Seems strong enough to me, bit like the FCS system.

Soul

5

I would think that the simplest thing would be to install the box with a couple of layers of glass in the hole, sand/grind it down as normal and then put a patch of glass over the box after that.(tape over the boxes slot) When the resin is gelled, but not hard, you cut around the tape line and pull out the glass over the slot. Tape over again when gloss coating.

I have done it a few times myself, in 2# EPS(with stringer) and a repair on a friends Harbor. The Harbor had it done that way in the original install, and it had withstood a fin impact very well. The box had chunks torn out, but the board and glass around it had only some almost invisible hairline cracks.

Realatively simple and quite strong, with the box connected to the glass and the hole reinforced with glass.

6
Quote:
I would think that the simplest thing would be to install the box with a couple of layers of glass in the hole, sand/grind it down as normal and then put a patch of glass over the box after that.(tape over the boxes slot) When the resin is gelled, but not hard, you cut around the tape line and pull out the glass over the slot. Tape over again when gloss coating.

Bingo. No reason to tie it to the deck or overthink anything. glass under, glass over. Works fine, even with 10" + longboard fins in the boxes…

7

Here’s what we do. BEFORE YOU SHAPE route out and install HD foam, we use H80 Dcell through the deck. No worries from there on, shape as regular, glass, install box etc., and sand as you normally would.

8

Drew can you post a picture of how you are doing this. Thats the idea I had but id like to see the way it should be done.

9

No sweat, we have to do a H.P.P.S.L.B. right now. I’ll try to remember to take pics and dig this post back up, but PM me in a week if I forget and I’ll snap some for you. It’s pretty easy. We made a jig for the right size hole to fit onto the LokBox uber-jig (I’ve said before we use that thing for routing almost everything). We use the pencil router bit (this is the only application I have for that p.o.s.). Cut all the way through the deck, kind of a sick pleasure in it’s own. Put back in some d-cell using gorilla glue or whatever flips your skirt glue. On that note, anybody else notice they pulled the Elmer’s ultimate in order to re-formulate??? Use some tape to hold the dcell in place and that’s pretty much it. Cut it level with a pull saw and shape away. Hope that helps somebody.

edits: you could just as easily do this with a jig-saw just drawing your outline onto the blank, not necessarily needing a jig and router deal…I haven’t tried it, but I’m sure you could use some pour foam in place of the dcell, or whatever material really, some balsa wood look kool. I think the important thing is going through the deck so both the bottom and deck lam provide extra strength. Some might call it a breaking point, but in my case I think the perimeter stringers make up for any foam inconsistency in that spot. Maybe something to consider for others??

10

The double stringered blank or mini-stringer inserts offer good side support for a longbox…

11
Quote:
The double stringered blank or mini-stringer inserts offer good side support for a longbox...

I’d so something similar…

But make the wood strips a little thicker (3/16" or 1/4")

And orient them along the major stress axis ie: they should run perpendicular to the box…the maximum width of the overlap with the glass is a major determinant of strength and stiffness.

Place one about where the leading edge of the fin will go, and a second one about 3 inches behind that.

Route the box hole out through the wood inserts…

Glue box in hole…

Grind the outer lip down…

Glassover half of the lip…

Surf.

12

This would be my suggestion, but John beat me to it! I built a board for a friend of mine and installed the fin box with a similar setup that flew off the roof, landed fin down on the freeway and blew the bottom of the box through the deck but the box sides and bottom of board were fine.

13

Thanks guys–the more I think about it, the more I like the deck connection or the flange solutions…

but

Johan, was the glass like a page(s) tucked down into the hole and lapped out onto the lam on the sides of the hole like I said? (or whatever layer) – can you describe it ?

the box had chunks broken out?

thanks

greg

14

When you put glass in the slot, some will stick up when you install the box. I basically hold up the box with a piece of glass wrapped around it with one hand and then trim of the glass at around the top of the lip. I’ve found it easier to put the resin in the hole and then the box with the glass wrapped around it.

When it’s all cured you grind the whole things; box lip and extra glass down and after that a patch gets put down over the box.

When the glass patch has gelled you cut out the slot. Hotcoat, sand and polish.

Here is what the box looked like before the repair. Ripped out fin completely, and as I said, there were just some fine hairline cracks in the glass around the front of the box. Strong!