Glass under fin box?

[swerfle]

@$1

Just stop hitting rocks and problem solved. Or get a fin made out of gummy bears.

 

see I’m a contributing genius.

I thought of the gummy bears idea- sortof a ratrod take on a greenough flex fin, but see a fair amount of seals where I surf, and I was worried they’d constantly be nibbling at my fin…

[McDing]

White gelcote or white pigmented resin with 4 oz. in the slot in alot of the better quality glass shopps on the West Coast USA.  Also often seen;  A tail patch over the box from rail to rail.  if you tape it off you could easily use the black pigment and some 4 oz.  Lots of production shops just sink the box in Q-cell or  milled fiber with pigment added.  I like white boxes, but it is said that they yellow(UV).  

[LeeD]

  They used to sell a soft flexy fin just for that purpose, one that you could actually surf smaller waves with, and would give a bit when hitting organic substances.  The ones I used were green or yellow, had a small stiff fiberglass center core, and some soft rubbery plastic that made up for about 70 % of the fin.

[johnmellor]

Hi LeeD -

They still make them.  The 'Superflex' style can be pretty functional in the right waves.  They also make some that are more rigid...

http://www.surfcohawaii.com/Super-Flex-Pro-Teck-Fins-s/62.htm

[swerfle]

@$1

 if you tape it off you could easily use the black pigment and some 4 oz.

just came in from the garage. Wish I would have read this first:  I went with 4 oz and black pigment… forgot to tape it off… looks like its going to be a huge mess to clean up. I’ll post pics in a couple of days.

[LeeD]

Wrong again.
Look at windsurf boards for the strongest box.
Post thru to the deck! Increase the surface area of the box.

[Wood_Ogre]

I used to work with the Chinook guys . They were the inventor of the Chinook boxes because surfboard fin boxes were two piece  and would split from the stresses of windsurfing. Chinooks are one piece and yes they  have the lugs that go through to the decks. But they make other molded things too. And yes you put the wood stringers on each side of the box. Blew out a lot of surfboard fin boxes before the Chinook came along . Never ever blew out a Chinook !!!

[haavard]

@$1

This is the standard procedure on most surftech, hawaiian island and other pop-out style (and even some standard style) epoxy boards. Typically it’s done when the board is made of an extremely light foam (think 1lb EPS which usually requires a veneer on the deck to keep it from denting and dinging). The reason you line the box with glass is for extra strength since the foam itself isn’t really strong enough to hold the box in place with just the resin/q-cell mix. The torquing and flexing of the fin over time would create a cavity around the box and weaken it without the glass present. 

I don’t understand the point of the glass inside the cavity. Ok, so you have made the resin around the box stronger then q-cell, but the foam is still weak. Doesn’t the glass reinforced resin around the box still push on the same weak foam as a q-cell filled resin would? The weak link is still the foam. The only advantage I can see is that the resin doesn’t crack so easily, but wouldn’t that be achived by adding chopped glass in the resin? I know fin boxes are often installed with just q-cell, but that leaves the resin prone to cracking.

The only way I can see that glass will improve a box install is if you put down a layer of cloth over hole and cut the glass down the center of the hole and into the corners and wrap that glass into the hole, then line the hole with glass and laminate it in before (or when) you install the fin box. Hard to do without getting bubbles around the edge of the hole, but pretty strong.

[nj_surfer]

@$1

…put down a layer of cloth over hole and cut the glass down the center of the hole and into the corners and wrap that glass into the hole, then line the hole with glass and laminate it in before (or when) you install the fin box…

Brilliant… 

I’ve always done a tight fit with a cloth “sock” around the box… relief cuts at the corners so the side panels of cloth fold up perfectly. Then an over-box patch, which makes the most sense from a conventional install perspective. But you’re idea is well worth a try next time, and I’ll do it in addition to the bigger patch and sock.