3lb or 4lb foam? That is the question

[kawyjunki]

Well Defoamed my ski, and its time to order my foam I am undecided which way to go 3lb or 4lb? Open to all suggestions? This ski will only ever see flatwater and cruiser wakes so I'm thinking 3 but I would like a little input from those who have experienced the different lbs of foams.

Thanks to all.

 

[Woody]

2lb is fine

 

[Mark44]

I used 3 LB.

Mark44

 

[Crab]

4lb

 

[Big Kahuna]

I took 4 lb and only used half of it, so I got 2 lb.

LOL

 

[Frosty]

screw two part expanding foam that soaks up water... get some blocks of polystyrene from tractor supply. That is some strong azz right there... they use it to block up utility trailers that are shipped to them on flat bed trucks. It's light and comes in 12"x12"x18" blocks.

use a hacksaw blade to cut and shape them to fit and a heat gun to re-coagulate the cut edges. Pack it in as tight as you can and use just a little bit of 2lb to fill the remaining small voides to keep everything super tight.

I did that to my ski last winter and it's about 20lbs lighter than my other RN ski.

:headbang:

 

[kawyjunki]

Frosty, How was your tray supported? Just stack it tight in there and shave it till it was level or what?

I read how MATT had did his with the foam board half way up. Thought about that and then foaming in behind my footholds/and upper half for strength

 

[Frosty]

Frosty, How was your tray supported? Just stack it tight in there and shave it till it was level or what?

I read how MATT had did his with the foam board half way up. Thought about that and then foaming in behind my footholds/and upper half for strength

yup, i cut and shaped several large pieces of the poly foam... took a while... felt like a surf board shaper... LOL

anyway, i crammed those pieces in pretty tight. then cut several smaller pieces to fit in the tighter areas, beneith the tray around all of the cooling/steering lines etc. Then used very little 2lb foam and poured that between all of the voids. Cut and shape whatever is sticking up until the cut out tray piece lays flat on top of the foam.

I would totally do it again bro... it made the ski quite a bit lighter...

around the footholds, do the same thing... cut and shape the upper part of the poly foam until you get a good tight fit when you squeeze your footholds in. Then pour a little 2 lb around them from a small hole in the top of the gunwhales, like in my pictures.

it takes some doing, and a lot of patients but well worth the effort.

 

[kawyjunki]

yup, i cut and shaped several large pieces of the poly foam... took a while... felt like a surf board shaper... LOL

anyway, i crammed those pieces in pretty tight. then cut several smaller pieces to fit in the tighter areas, beneith the tray around all of the cooling/steering lines etc. Then used very little 2lb foam and poured that between all of the voids. Cut and shape whatever is sticking up until the cut out tray piece lays flat on top of the foam.

I would totally do it again bro... it made the ski quite a bit lighter...

around the footholds, do the same thing... cut and shape the upper part of the poly foam until you get a good tight fit when you squeeze your footholds in. Then pour a little 2 lb around them from a small hole in the top of the gunwhales, like in my pictures.

it takes some doing, and a lot of patients but well worth the effort.

Did you have to do any reinforcing to the sides over the bond line or did the foam stiffen everything back up?

 

[Frosty]

Did you have to do any reinforcing to the sides over the bond line or did the foam stiffen everything back up?

I don't think you'd have to, but I did... only because I beat the hell out of my ski. My entire engine bay (side and bottom) are heavily reinforced. I figured while I was refoaming I might as well to the bond line in the back anyway. I used two layers of 8.7 oz biaxle (1 strip about 3" wide and one strip about 10 inches wide). Probably over kill, but like I said, I beat the snot of it.

 

[kawyjunki]

Sounds good. Thanks for everybodies input.

 

[Super Dee]

If I were to do mine again, I would definitely do what Frosty is suggesting.

I used 3lb foam in mine. If I were to do only two part foam again I would probably go with the 4lb foam for the added structural support that it gives. For the extra 2 or 3 lbs overall it seems worth while.

But I'd definitely go Frosty's route and personally I would pour a 3 or 4 lb foam around the rigid foam to fill in the voids.

 

[WildBill69]

screw two part expanding foam that soaks up water... get some blocks of polystyrene from tractor supply. That is some strong azz right there... they use it to block up utility trailers that are shipped to them on flat bed trucks. It's light and comes in 12"x12"x18" blocks.

use a hacksaw blade to cut and shape them to fit and a heat gun to re-coagulate the cut edges. Pack it in as tight as you can and use just a little bit of 2lb to fill the remaining small voides to keep everything super tight.

I did that to my ski last winter and it's about 20lbs lighter than my other RN ski.

:headbang:

i am going to do mine in about three weeks..does tractor supply sell this foam or do you have to dig it out of the trash...:Banane01:

 

[Frosty]

i am going to do mine in about three weeks..does tractor supply sell this foam or do you have to dig it out of the trash...:Banane01:

I saw the blocks sitting behind the fence where they store the trailers outside. I stopped and asked the yard guy what they did with them. He said they throw them into the dumpster. He gave me 8 of them free.

take a bunch so you can practice cutting and shapping... it takes some getting used to. And don't forget to use a heatgun on the cut surfaces after you cut them the way you want. it keeps the little "pellets" of foam from coming off.

 

[WildBill69]

I saw the blocks sitting behind the fence where they store the trailers outside. I stopped and asked the yard guy what they did with them. He said they throw them into the dumpster. He gave me 8 of them free.

take a bunch so you can practice cutting and shapping... it takes some getting used to. And don't forget to use a heatgun on the cut surfaces after you cut them the way you want. it keeps the little "pellets" of foam from coming off.

:bananajump: thanks!!!!! :wave:

 

[kawyjunki]

Since were on the subject, and for the sake of curiosity does anyone know what the actual foam density is on the stock crap that Yamaha use's. It seems to be pretty soft when you would push on it. I mean you can actually push your finger into it with a little work. I would figure they would go with the minimum approval by the coastgaurd which I believe is 2lb.
Any thought on this?

 

[yamaslut]

Since were on the subject, and for the sake of curiosity does anyone know what the actual foam density is on the stock crap that Yamaha use's. It seems to be pretty soft when you would push on it. I mean you can actually push your finger into it with a little work. I would figure they would go with the minimum approval by the coastgaurd which I believe is 2lb.
Any thought on this?

I was under the impression that it was 4lb from the factory...

 

[stanton]

i used 2.5-3lb and i felt it was plenty strong. i reinforced the sides and reglassed my entire tray. it is VERY solid.

 

[THRUST]

screw two part expanding foam that soaks up water... get some blocks of polystyrene from tractor supply. That is some strong azz right there... they use it to block up utility trailers that are shipped to them on flat bed trucks. It's light and comes in 12"x12"x18" blocks.

use a hacksaw blade to cut and shape them to fit and a heat gun to re-coagulate the cut edges. Pack it in as tight as you can and use just a little bit of 2lb to fill the remaining small voides to keep everything super tight.

I did that to my ski last winter and it's about 20lbs lighter than my other RN ski.

:headbang:

i would double check that or test the polystyrene with the 2 part because i have test it in a test bucket and the 2 part actually ate up 50% of the polystyrene.

 

[Frosty]

i actually left it sit for almost a week before putting the tray back together.