Larry..... probox idea

Hi,

i installed my fins last night as per my other post and came up with an idea. have you thought about having some form of ‘nick’ on the fin boxes in order to make it easy to keep the tows of roving wrapped around??

you know like on a roll of fishing wire there is a nick on the reel for you to hold the end of the line when your not using it.

just think it would make it ultra easy to attach the tows, keeping them tight for when you pop the boxes in.

thanks again for a great product

dog

i’ve never used roving when installing Probox.

i put 2 layers of glass in the bottom of the hole, cut to fit.

and i wrap the box with a long narrow strip of glass long enough

to wrap around at least twice… they go in really easy… i read to do

things this way somewhere here on Sways. if i remember correctly, it

helps prevent epoxy resin from heating up enough to melt the eps.

i’m definitely no pro though.

hi chris,

your glass wrapped round is the same as my rovings and how Larry and the guys recomend on the site. you take legnths of glass and wrap twice round the box its at this point i struggle to get the glass to stay wrapped round the box while i get it in the hole. i end up with some strands getting loose and curling out of the hole.

my suggestion would be to have nicks moulded into the base to enable you to grip the strands as you wrap round.

its not just about the heating up its about having glass as reinforcement wrapped around the box… resin on its own being way weaker than resin and glass together.

dog

once you get the box in and resin flowing you poke the loose strands back in with a small stick

once it gets wet it will stay put

Quote:

Hi,

i installed my fins last night as per my other post and came up with an idea. have you thought about having some form of ‘nick’ on the fin boxes in order to make it easy to keep the tows of roving wrapped around??

you know like on a roll of fishing wire there is a nick on the reel for you to hold the end of the line when your not using it.

just think it would make it ultra easy to attach the tows, keeping them tight for when you pop the boxes in.

thanks again for a great product

dog

Hi dog, If you have some loose strands that bug you, dab a little resin or epoxy on the roven to help it stick to the box sides then install. If alittle of the roving comes up just push it down with a thin stick like Kensurf explains. The little dab will do ya will act the same has the “nick” concept you describe. Go question dog, like that you look at all the angles to make the job easier. Thanks for the input and support. Mahalo,Larry

Quote:

i’ve never used roving when installing Probox.

i put 2 layers of glass in the bottom of the hole, cut to fit.

and i wrap the box with a long narrow strip of glass long enough

to wrap around at least twice… they go in really easy… i read to do

things this way somewhere here on Sways. if i remember correctly, it

helps prevent epoxy resin from heating up enough to melt the eps.

i’m definitely no pro though.

ChrisP, Your way works well also, thanks for your support. Mahalo,Larry

i used a solvent free spray adhesive

sprayed in the hole and then just pressed in some glass and it sticks to the botom and sides in one piece of glass

you can do a couple of layers

i use that adhesive for lots of different layups on small things

like you could use it for carbon rails for instance

last time i installed probox i really struggled with the rovings and had to do a bit of shoving down with a stick as you guys suggest. this time i dabbed some 5min epoxy on the four corners so that as i wrapped it round it could stick. by the time i did the second one my fingers already had bits of glass stuck to the gloves and needed a fresh pair. evntually they were ready to put in the holes but because the glass is tight round the box it catches on the nib of the railside surface of the board (in the centre where theres an indent).

i know its not a massive inconvenience this way but i know how much you guys love feedback, for me it would be an extra added bonus at the bottom of a list of them! if the nicks were in the middle of the indent you would hook your roving under, friction holding it, then wrap round the box twice then resecure under the nick again. ready to pop in the hole. im guessing the boxes are injection moulded which could mean its not doable as its a serious undercut but im sure there’s a way.

thanks again for listening

dog

what is the purpose of putting any glass in the hole? is the box not strong enough on its own?

Greg,

Resin by itself cracks easier than with the cloth. Just like concrete cracks without rebar. You want to strengthen the resin, the box is plenty strong.

Tripper

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i used a solvent free spray adhesive

Does this mean that it wont interfere with the epoxy bonding to the glass and foam? Which one did you use?

Surfingdog,

FWIW, i know we’re talking about different things here but…

now that i’m picturing what you’re doing and remembering what i did the last time i installed some probox’s.

i put the glass in the bottom of the hole and wrapped around the sides of the hole, and then i poured

some resin in the hole, then dropped the box in and topped off the hole. the “coil spring” of the strip of glass

wrapped around the inside of the box kept it pressed against the outside edge of the hole then, the resin

and the boxes dropped in without fuss.

Quote:

what is the purpose of putting any glass in the hole? is the box not strong enough on its own?

Hey Greg,

It’s my understanding wrapping the ProBox with heavy glass roving increases the strength of the installation in 2 ways:

  1. Resin reinforcement (as tooltripper states)

  2. Fills the gap between the box and foam which aids in handling torque loads transferred through the fin.

The box itself is plenty stong. The integrated system of box, resin, and foam is simply stronger when adding glass reinforcement.

~Brian

www.greenlightsurfsupply.com

Latley I’ve been using a dab of epoxy ding repair putty to secure the roving to the box before installing.

Works great and doesn’t interfere with epoxy resin bonding.

No need to push stray strands back into the hole with a stick.

~Brian

www.greenlightsurfsupply.com

Brian, thx. I think I disagree, tho. I don’t see how reinforcement around the box which only press against the foam helps strengthen the install. If not anchored to either the deck (FCS) or the bottom skin via a flange, the box will move with the bending moment. Seems to me added reinforcement is just extra weight. Your thoughts?

The glass takes the place of some of the resin, so weight doesn’t really come into it?

The rovings are only really essential (maybe not even) when using poly

Epoxy sets so damn hard, i’m yet to see it crack - I use milled fibre in it.

The box and whole chunk of resin seems to rip out of the board, before the epoxy will crack.

Even with the super strong compsand installs.

Although i’ve only seen one fin busted out on a compsand so far - the guys head came off worse :slight_smile:

It’s useful to keep the exotherm down though, not that i’ve had that problem

Edit: oh yeah, the contact cement is only very lightly dusted on, it doesn’t take much at all. Boat builders love the stuff, and the bonding seems to be fine

Quote:

Brian, thx. I think I disagree, tho. I don’t see how reinforcement around the box which only press against the foam helps strengthen the install. If not anchored to either the deck (FCS) or the bottom skin via a flange, the box will move with the bending moment. Seems to me added reinforcement is just extra weight. Your thoughts?

Hi Greg Tate, I think you are missing a important factor here, Brian at Greenlight is talking about a ProBox and not a FCS plug. The shape of the Probox is designed to hold loads with in a cavity on it’s own, unlike a FCS plug which has a small shallow footing not able to hold any lateral loads on it’s own. The extra glass inside the cavity is to displace resin which has no impact strenght or if in epoxy to displace heat up. The fiber glass wall gives backing support against the foam wall and anchoring to the bottom lamination completely sealing the box cavity away from the ProBox,giving the ProBox support from pushing in the foam and rocking loose. There is very little resin in a proper ProBox install. Hope this helps you understand the difference between a ProBox and FCS install.

As you can see below ProBox is install with straight glass and resin or epoxy. NO MILLED FIBERS IN A RESIN PASTE WHICH HAS NO STRUCTUAL STRENGHT is used in a ProBox install.

Mahalo,Larry

www.ProBoxfinsystems.com

Quote:

Latley I’ve been using a dab of epoxy ding repair putty to secure the roving to the box before installing.

Works great and doesn’t interfere with epoxy resin bonding.

No need to push stray strands back into the hole with a stick.

~Brian

www.greenlightsurfsupply.com

Great idea Brian, mahalo,Larry

Quote:

i used a solvent free spray adhesive

sprayed in the hole and then just pressed in some glass and it sticks to the botom and sides in one piece of glass

you can do a couple of layers

i use that adhesive for lots of different layups on small things

like you could use it for carbon rails for instance

Pretty interesting process Paul, Love the ideas you guys come up with. Keep the stoke my friend. Mahalo,Larry

Thanks, Larry, I use and understand FCS installs. ( I use your system too)

I’m just pointing out that adding glass to the box hole will just have that glass bearing against more weak foam. Forget FCS for a moment. As I see it, the anchoring of the Futures, OFishl and ProBox depends on connecting to the bottom lam. Adding glass and anymore resin than needed to cement the box to the foam seems to me to be just added weight. There are other ways to reduce exotherm such as mixing with microspheres.

The only way I can see glass in the hole being of any help would be if it connected to the bottom lam. Just bearing against foam is no help.

The only thing I do in the hole is mix micro spheres and cabosil in the resin to lighten it up. This also provides the needed adhesive for the box to the foam and for a small area around the hole, saturates the foam with resin thereby strengthening (albeit only a little) that foam. (too much resin will just drain to the deck) But I make really sure the flange of the box is well connected to the bottom lam. Sometimes I borrow a little from the FCS method and make two small holes down to the deck to connect there if I know it will be in a tough use situation.

What am I missing?

All the best.