How important is foam density?

[Roseand]

Getting a new hull and deciding between open bulkhead with pool noodles and new style versiplugs with debri strainers vs closed bulkhead with not sure type of foam yet. It's my understanding that displacing air is the most important part, but how much of an impact does foam density have for flotation?
One main "pro" to the open bulkhead is I can leave a channel above each chine and have all incoming water go straight to the rear insted of get flung around by the coupler.

 

[WFO Speedracer]

In a nut shell the higher the density of the foam is the less it will expand and absorb water and the higher the structural value is, I don't even bother with the two lb and three lb stuff .

 

[yamanube]

IMO a sealed or semi sealed cavity is better regardless of what kind of foam it is. The open tray, pool noodle stuffed situation really leaves a lot of room for water to fill and negate the buoyancy of the small amount of foam you fit in there.
Foam density really will only be a significant factor if the hull structure is not up for the task of supporting the impacts.

 

[Sparkplug]

My Evo and xfr are both foamed. Both have sunk but bobbed just under the surface with me helping. I was able to get them to shore. My buddies xfs without a bulkhead. Sunk like a straight up rock.

Google about pool noodles. Gimmick and a half. Better than nothing I guess. But why not just stuff life jackets in your hull if your looking to pinch pennies or be ghetto?

 

[Roseand]

My Evo and xfr are both foamed. Both have sunk but bobbed just under the surface with me helping. I was able to get them to shore. My buddies xfs without a bulkhead. Sunk like a straight up rock.

Google about pool noodles. Gimmick and a half. Better than nothing I guess. But why not just stuff life jackets in your hull if your looking to pinch pennies or be ghetto?

This is the first time I've heard of an am hull floating when sunk! Not many people speak from experience. Do you know what kind of foam was used?

 

[Sparkplug]

This is the first time I've heard of an am hull floating when sunk! Not many people speak from experience. Do you know what kind of foam was used?

It didn't float. It bobbed under the surface. And I had to help it. Potentially losing 15-35k will make a guy try really hard. I also ride river where the shore is not more than 150ft away.

It's the factory foam that rickters come with when you ask for it. Not sure.

 

[Quinc]

I wouldn't use pool noodles under the tray. They deterioate after a while and hold water. Under the hood is fine as you can replace them as needed. Cutting the foam to shape out of an old couch would work too.

Another option would be these foam balls:

Spex Lite EPP beads for refoaming

I'm in the process of cutting up my tray to re-foam and I've been reading through all the threads looking for options. EPP sounds like the ticket and I found a company selling EPP beads. Spex Lite 5524B EPP beads. Has anyone tried these yet? Think they'd work? Price is $125 for 56 liters...

www.x-h2o.com

 

[Roseand]

It didn't float. It bobbed under the surface. And I had to help it. Potentially losing 15-35k will make a guy try really hard. I also ride river where the shore is not more than 150ft away.

It's the factory foam that rickters come with when you ask for it. Not sure.

I'd still consider that a win for being able to hold onto it. What method do you use for water removal? Bilge pump, scupper etc

 

[WFO Speedracer]

I used the stock Kawasaki foam out of a TS on one of the skis I am redoing, it fit perfectly on the inside of the ski with no trimming needed . On the Superjet I did I used chunks of Blue Dow foam and stuffed them in wherever they would go then I poured 4LB foam in all the cracks and crevices to hold it all together.

 

[Sparkplug]

I'd still consider that a win for being able to hold onto it. What method do you use for water removal? Bilge pump, scupper etc

Both my skis have scuppers. I solely ran those for the past 2 or 3 seasons. I recently went to a rule 350 in my Evo for surf. And I got a seaflo 750 automatic for my xfr but idk how that's gonna do since it goes inverted quite a bit.

Years back. When footholds were cool. I did some and used that expanding foam from us composites. 4 lb I wanna say. When cured it was very similar to superjet foam, but people said it would not be able to absorb water. Whatever it was. Floated very well

 

[kevbo]

Two part urethane foam wont melt when gasoline gets on it. Pour it in thin layers, this will keep it from bulging the hull and help decrease water absorption. Anything behind the bulkhead should never get wet since you can seal the compartment. You can make a small bilge area in the bottom of the sealed area and use a drain. Put some plastic wrap inside the hull in dead spots and make some removable castings. There is absolutely no reason for a ski to ever sink unless it has a careless owner!

 

[Pro-pulsion]

I used Styrofoam Highload 100 for my tray refoaming because it has the highest compressive strength of their line at 100 psi. After doing a lot of research on it, this ended up being the best option for the purpose. It's also used as a sublayer under the tarmac at airports. I have been through one full season plus what time I've logged this year with no issues

https://www.dupont.com/content/dam/dupont/amer/us/en/performance-building-solutions/public/documents/en/styrofoam-brand-highload-40-60-and-100-pis-43-D100079-enNA.pdf

 

[Sparkplug]

Two part urethane foam wont melt when gasoline gets on it. Pour it in thin layers, this will keep it from bulging the hull and help decrease water absorption. Anything behind the bulkhead should never get wet since you can seal the compartment. You can make a small bilge area in the bottom of the sealed area and use a drain. Put some plastic wrap inside the hull in dead spots and make some removable castings. There is absolutely no reason for a ski to ever sink unless it has a careless owner!

Idk man. I can jump and turn sub a superjet or a fr2, and sink it in 1 shot. Goes down. And never comes back up. Careless? Maybe? Fun as hell? You bet your ass

 

[kevbo]

I was referring to the care and maintenance of the machine. None of that is in a riders DNA.

 

[Sparkplug]

I was referring to the care and maintenance of the machine. None of that is in a riders DNA.

I think the op is referring to catastrophic failures that sink skis.

Mine have been exhaust couplers coming off. Hood latches popping open. And a cooling line that came off the bulkhead. Killed the motor. And before I could get to shore. Sunk it with the scupper


I've learned. As soon as the ski dies. and doesn't immediately restart. You get that nose in your hand and swim as hard as you can towards shore. I've sunk skis probably 20 times or so. Enough that I don't even worry once it gets to shore.

 

[Pro-pulsion]

This build thread shows how I setup siphon bilges in the tray area because I'm fairly confident that eventually water is going to start getting in there again. I've had my share of drain plugs and ball valves, water always eventually found its way in around them. A fully sealed tray area with some water removal contingency planning was to me, the best backup plan if the water ever started getting in there again...

Super Jet - 1996 Round Nose SuperJet Project

I'm resurrecting my old thread. I can't believe I have had this ski for 8 years now :oops: But, I am back into the tray hauling it all apart again. My reason is that the bottom deck of my tray section has broken open leaving a rather substantial breach on both sides. My thoughts are this...

www.x-h2o.com

 

[Sanoman]

But does an short a/m hull have room to hold enough foam to keep it from sinking? Let’s say, a Rip, Circus, or Bun size

 

[Sparkplug]

Doubtful. When riding a high hp short hull am hull with expensive drive train. Or if you like riding. Keep in mind poop can fail at any time. Usually the worst. Always have a way out. Dont be far enough away from shore or a friend you can't bail out. If you do. That's your fault.

 

[Sanoman]

The two circus freaks l built had so little room under the tray, it wasn’t worth foaming them.

 

[Jr.]

Funny how foam density no longer seems to matter. Back before aftermarket hulls were introduced.
when the Sq and roundy hull was a surf riders go to weapon of choice. Making the SMC or Metton hulls withstand the pounding of hard core surf was the critical mods. Everyone defoameed the hulls, internally reinforced them, and then refoamed. The foam was a structural part of the hull. We used 4 lb density on the lower half, and lighter 2 lb density in the upper gunwals. Everyone who rode surf, lauhed at the idea of ping pong balls, pool noodles, or pink foam insulation. Those hulls when introduced to surf, were the first ones down in Davey Jones Locker,!!
oh how times have changed……….

P