Two different inserts failed on one of my boards. The board lady adds divinycell to the sides of the inserts; I am guessing this is to make it harder for water to get into the board in case there is a little bit of delam over the insert (less chance of failure?). But my question is: do people use her tip or not? Overkill? I might be overthinking this but I don't want more water inside the board...

I have used the method described by the boardlady and it works fine. I think part of the problem is that the epoxy does not stick well to the engineered plastic of the inserts,yet the epoxy paste and divinycell sticks well to the side profile of the insert. The divinycell then gives more surface area for the fibreglass to stick to on the surface of the board.

As the foam is quite weak, I can't see the divinycell providing a benefit other than giving this extra surface area to bond to. More surface area to stick to the insert, and then more surface area for the divinycell to then stick to the top skin of the board.

I have used 9mm divinycell all around, because that's what I have available.

When you see some of the construction of the boards when you pull them apart you will see the standard is not so good sometimes. One board had the inserts separate from the top skin and each hole was bubbling water. I believe that the extra surface area avoids this problem.

Agree with both the above.

I use offcuts of 5mm corecell as the advantage is a 1" wide strip will do both sides, then the bottom is same width now you've added 10mm to it so that same 1" wide strip s exact fit for the bottom.

Its thus very quick to snap it off to length, butter it, and slap it around the insert. 5mins to do all of them.

A split insert no longer means water in the board.

Thank you, all for your reply. Do you guys know if Komatex (foamed pvc) would work? A plastic store near my house sells it and it is three times cheaper than divinycell (plus, I don't need to pay 25 dollars for shipping). Komatex is used for outdoor signs, I think. If no one had used it before I will go with divinycell. now, there are several densities for divinycell; would H80 be hard enough?

I recognise that shed......

I ran some numbers and Sintra/Komatex is about 31#/ft2 or 6 times the density of H80.
It seems to possibly be easier to find and maybe even cheaper.
Probably not great for increasing the surface area of inserts but it could be an interesting material for reinforcing certain areas on board builds.

Apparently its popular for building large scale models and costumes.

My reference to pour foam, was misguided, by me. Without knowing about Komatex, it's a sheet not liquid before it hardens, as is pour foam.
h80 is 5lb
the property of Komatex, Grant , where did you not come from?
if this is a good substitute for divinycell or the other structor materials , how come it's not been brought up before ? And in use then
Does it make friendly with epoxy and stick to,other materials ?


.

Most of that foamed PVC board is 300 - 500kg/m3 its overkill.

WillyWind I can post u some corecell for nothing if you want, a4 size is offcuts

WillyWind said..

Mark _australia said..
Most of that foamed PVC board is 300 - 500kg/m3 its overkill.

WillyWind I can post u some corecell for nothing if you want, a4 size is offcuts

Thank you, Mark, for the offer! Another sailor from the area has some extra Divinycell and I might pick it up today. so this is a formula board that I am using for windfoiling so I will replace the 2 hole inserts for 5 hole inserts to have more range (I noticed that when I sail without foot straps my front foot is three or four cm further back than the furthest back insert for the front strap). I will take some measurements and report back.

While you are hacking at the board, you may want to see if you need to move the mast track a bit. It's not uncommon for early vintage formula boards to have a track too far forward. You want to be able to put the mast base from 100-115 cm or so from the front tuttle screw hole. That you are moving the foot strap screws suggest that you are needing to move things back. You can also raise the boom if you haven't already.

Paducah said..

WillyWind said..

Mark _australia said..
Most of that foamed PVC board is 300 - 500kg/m3 its overkill.

WillyWind I can post u some corecell for nothing if you want, a4 size is offcuts

Thank you, Mark, for the offer! Another sailor from the area has some extra Divinycell and I might pick it up today. so this is a formula board that I am using for windfoiling so I will replace the 2 hole inserts for 5 hole inserts to have more range (I noticed that when I sail without foot straps my front foot is three or four cm further back than the furthest back insert for the front strap). I will take some measurements and report back.

While you are hacking at the board, you may want to see if you need to move the mast track a bit. It's not uncommon for early vintage formula boards to have a track too far forward. You want to be able to put the mast base from 100-115 cm or so from the front tuttle screw hole. That you are moving the foot strap screws suggest that you are needing to move things back. You can also raise the boom if you haven't already.

You are correct, Paducah. Although this is a newish formula shape, when I compared it with an exocet rf 91, I noticed that the mast track of my board is shorter so I cannot set the sail as further back as in the Exocet. I will buy the 10 inch mast track and that will give me the right amount of range, I think.

I use key hole surgery . It leaves all the original laminate for strength and neatness and is easy .
Rout through the laminate the size of the new bigger plug .
With a srewdriver gouge out the eps foam core 1 cm deeper and wider than the plug . Don't need to be neat .
With a bent nail or coat hanger scrape foam from under the laminate also 1 cm ish.
Fill with 80 kg expanding foam . No need for glueing or glassing in block . ( you could use expand foam in a can , Bunnings $8 ) .
Re rout hole plug size .
Glue in plug . If you want you could glass line the hole , I don't .
A couple small glass patch layers over the top .
This way it's a smaller fix area that the pad will probably cover .
Done , super dooper easy .
Same can be done with mast track and fin boxes .

Grantmac said..
It's more available because sign shops use it but the density is about the same as plywood. Overkill for most of our purposes.

It might be an interesting material for making a sandwich construction board without internal glass layers? Just glue directly to the blank then glass over. Supposedly it heat molds well.

Define glue

forceten said..

Define glue

Easy, stuff that fixes things together

Could probably use polyurethane if you wanted. Although a laminating epoxy and vacuum bag would be more typical.
Might need something more flexible for the rails. Cork seems like an interesting option posted recently.
Could be a fun experiment.

WillyWind said..

forceten said..
My reference to pour foam, was misguided, by me. Without knowing about Komatex, it's a sheet not liquid before it hardens, as is pour foam.
h80 is 5lb
the property of Komatex, Grant , where did you not come from?
if this is a good substitute for divinycell or the other structor materials , how come it's not been brought up before ? And in use then
Does it make friendly with epoxy and stick to,other materials ?


.

I just found this:
www.tapplastics.com/image/pdf/Working_with_KomaTex.pdf
under laminating it says that resin based adhesive can be used.
my bad about pricing. Komatex has the same price as divinycell (at least in the two places near my house). The big difference is that I can buy Komatex in any size whereas the the minimum amount of divinycell I can buy is a quarter sheet.

I read this, it says you can use an adhesive for riding PVC.

again ,if this is a option ,why is it not in use?

I wonder how many sailors have been spared the pain of a broken metatarsal when the footstrap insert broke loose?