Foam - defoam - refoam.... why?

[Ericfox]

OK.... so I am a bit confused...

Stock skis are not water tight, so people defoam/refoam their skis when they get some water in there.

People say that you can drill little holes in the back and all the water will eventually drain out and the foam will be dry.

After refoaming people try to seal up the hull, but I can not see that you could ever completely seal it up.... so eventually the new foam will get waterlogged as well.

Why not just drill the little holes in the back/ put in some sort of mini drain plugs and just take the plugs out after each ride to allow any water that got in while riding to drain out....not sure how long it would take to drain out, but this kind of makes sense.

maybe even put some small pressure fitting somewhere so you could hook it up to an air compressor on a very low pressure to help "push" the water out?

 

[steve0we]

good points, good questions! I look forward to the answers and as a new ski owner Id like to know too.

 

[Mark44]

I did install drains and a channel system for water to escape and not sit in the foam I have done my ski like this and Katies ski. I also sealed the bond line inside and over the years still get water inside.

Mark44

 

[Frosty]

I think Mark44 installed brass fittings into the lowest part of the chines in the transom of his ski. He can unscrew them to drain water out.

However, the foam that is used in a superjet will hold water. If only a little water is leaked in, toward the bottom, then yeah i guess it could drain out... but if you get a lot of water in there over time i don't think it will help, IMO.

The pressure fitting idea sounds kinda cool and might be worth trying.

For me, i plan to NOT use the typical two part expanding foam but instead use polystyrene foam - like what is in the SXR's. I cut my tray completely out, and plan to shape polystyrene blocks to fit. They are quite strong, and considerably lighter than the two part foam, and will not absorb water.

I'll post more on that in my build up thread as I beging the process.


LOL - must have been typing at the same time Mark...

 

[Ericfox]

So is it just a fact of life that every few years a superjet owner must defoam and refoam?

I am tempted to drill the holes and install little fittings. Will they do any good without a channel system?

Mark, do you think a low pressure force put into that area would help push out water?

I already have a little water in my foam and I have a 2007 superjet with only about 30-40 hours or so on it.

NOT looking forward to refoaming someday... I may think about doing what you said Frosty. However, I might have heard that people dont use that type of foam because of structural reasons??? --> I have no idea if there is any truth to that...

Frosty... would you install drains then if/when you install the poly foam? Will that foam DEFINATELY not absorb water over a period of years? If not, then you may have a follower as long as there are no structural concerns....

 

[superjet0587]

I set a few waterlogged pieces of foam on the shelf in my garage to see how long it would take for the water dry out, it took a bout a week in the heated garage, i imagine in the ski with just drain holes it would take quite a while for all that water to drain out.

 

[Ericfox]

I set a few waterlogged pieces of foam on the shelf in my garage to see how long it would take for the water dry out, it took a bout a week in the heated garage, i imagine in the ski with just drain holes it would take quite a while for all that water to drain out.

Sounds like we need some engineering here... we need a foam dryer!!!

1)drill a bunch of holes in a pipe with a solid end

2)drill a hole on each side of the back of the ski (1/2" or so) very deep almost to the firewall

3)insert pipe and hook pipe up to a shop vac for a few hours/ or maybe days-(buy cheap azz shop vac in that case just for this)....

4)insert drain plug to make it easy to repeat the procedure...

that is my best idea off the top of my head.....rather than maybe just doing what frosty said about the poly foam....

 

[Ericfox]

perhaps I might make a box with some foam in it... wet it... and experiment on it... keep posting ideas....

So far I like Frosty's idea the best as long as there are no structural concerns and that poly foam truly does not absorb water over time....

 

[Mark44]

I used Dow foam on the bottom of the hull leaving channels for the water to drain back to the drain plugs and used two part foam on top of the Dow foam. The back of the ski is not thick enough to accepts threads or is the glass dense enough I used a piece of 5/8” 101 nylon formed to match the contour of the ski under the scupper valve and exhaust to accepts the ¼” NPT threads for the drain plugs. I attached the nylon with West Systems epoxy.

I have even pressurized the tray area with compressed air to check for leaks and found a pin hole in the top of the tray and around the exhaust. I can take an air gun and blow in one of the drain plugs and force water out the other but usually just pull the plugs and tilt the front of the trailer up and let the tray drip dry.

Mark44

 

[Tuttle]

Fl-Cracker took all the foam out of his ski and added 1/4" drain holes with plugs in the rear. His ski still floats, well kinda floats. :naughty:

 

[Frosty]

Frosty... would you install drains then if/when you install the poly foam? Will that foam DEFINATELY not absorb water over a period of years? If not, then you may have a follower as long as there are no structural concerns....

yes i will do just that. and AFAIK that foam does not absorb water at all. As for structual strength goes, it will have to be cut to fit fairly tight under the tray area. The foam I am using is used to ship small trailers via flatbed semi truck. They stack the foam blocks between the trailers and stack the trailers 4-6 high. These blocks DO NOT crush under load while in transport, and in fact the weight of the trailers do not even leave any marks on the foam. Beyond that, the foam is way lighter. The equivalent sq inches of polystyrene, as compared to the two part foam, is significantly lighter.

 

[Ericfox]

Do you need to have foam around the footholds for support?

If you use the poly foam would you not put it around the footholds?

The holds seems like the area that would be the hardest to put the foam around... I am guessing that is why mark44 used the 2 part foam on top and the other foam on the bottom.... Although I guess I could rip out my footholds and put poly in behind and carve it out.... BUT I JUST INSTALLED THEM!!! lol

I already installed my footholds... but I have not glassed or turfed the tray yet...How long have you guys found your turf to last? Should I save refoaming and doing all the above till I have to returf again? I don't want to become psyco about my foam being dry, but I don't want a big weight in the back of my ski when I am trying to learn new tricks....

I have my ski torn up pretty good now, so that is why I am torn on just doing something like MARK44 and Frosty are talking about now, or maybe waiting until next time I tear things up.... --- prob. a few years whenever my turf starts looking crappy...

I'm a newbie to the superjet, but this foam thing seems crazy... why would they make a design that would do this in what most people have told me in a short amount of time....

 

[Mark44]

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Well you have a big decision to make, if it was me and I had my ski apart already I would cut open the tray and install a scupper trim tube and a drainage system while I had it apart but that my friend is a decision you will have to make do it now and never do it again or do it in a few years.

How long do you plan on owning this ski?

Mark44

 

[Frosty]

I am doing it because the project RN i just picked up had about 20lbs of water in the foam.

I plan to cut and shape each piece of foam for a perfect strategically placed fit to provide maximum structural support without worrying about the foam shifting. Under the tray is the most import part... where the riders weight is focused. I will be reinforcing the sides too while i have the entire tray cut out and exposed.

 

[Ericfox]

Well you have a big decision to make, if it was me and I had my ski apart already I would cut open the tray and install a scupper trim tube and a drainage system while I had it apart but that my friend is a decision you will have to make do it now and never do it again or do it in a few years.

How long do you plan on owning this ski?

Mark44

Prob. a few years... depends on my money situation... in another few years I may want to get an aftermarket hull, but I might have kids at that point and want to hang onto this one.

Mark, can you describe how you made the drainage system in your foam on the bottom? Did you just buy the big sheets of foam they sell at like Lowes in the 1" or 2" 4x8 sheets and cut it to fit?

 

[Mark44]

i

I am doing it because the project RN i just picked up had about 20lbs of water in the foam.

I plan to cut and shape each piece of foam for a perfect strategically placed fit to provide maximum structural support without worrying about the foam shifting. Under the tray is the most import part... where the riders weight is focused. I will be reinforcing the sides too while i have the entire tray cut out and exposed.

HOLY CRUD......... man did you cut the tray out.mfg:

Mark44

 

[Ericfox]

I am doing it because the project RN i just picked up had about 20lbs of water in the foam.

I plan to cut and shape each piece of foam for a perfect strategically placed fit to provide maximum structural support without worrying about the foam shifting. Under the tray is the most import part... where the riders weight is focused. I will be reinforcing the sides too while i have the entire tray cut out and exposed.

Wow... thats awesome... I have never seen one cut open that much. Is it easy to reinforce it back to original strength or better?

 

[Mark44]

Yes that is the foam 2” I installed on the bottom of the tray held in tight in places with a dab of two part foam, I cut pieces and placed them on the bottom of the hull leaving a few channels about a ½” wide cut in the bottom of the foam with a knife going from right to left I also laid the foam on top of the v shape contour of the hull going back to the drains leaving a channel on both sides the entire length of the ski this channel intersects with the channels that go across the bottom. Then on top of that foam I poured two part foam, you need expanding foam under and around your holds. IMO

Mark44

 

[Mark44]

This is what I cut out of Katie's to refoam.

Mark44

 

[Mark44]

This is what I cut out of Ketsair square nose to refoam and install one way valve.

Mark44