Stringer replacement: Should I add foam back in?

[Albin]

I am in the middle of a stringer job on my 85 Sunsport. Everything is going great but I am torn on the foam issue. I have read several rebuilds where people haven't put foam back in so the water can drain more efficiently and I really like this idea. I have also read arguments that you need the foam for the extra rigidity/vibration dampening/quietness/protection if you swamp boat/etc. Then there is also the group of guys who put flotation material in but not pour foam... like pool noodles and shaped foam insulation boards (this method wouldn't provide any rigidity or vibration dampening but would help if you swamped the boat I guess).
I am really leaning towards no foam, but I want to do it right while I have it all torn apart and if it needs foam I will put it in.
What do you guys think, foam or no foam?
I am especially interested in the opinions of someone who did NOT put foam in their rebuild... any regrets?
I would appreciate any insights you guys have.
Thanks!

[TitanTn]

There is someone on this forum who didn't add back foam. I can't remember who. Maybe Okieboarder? Do a search. Whoever it was didn't have any misgivings about not adding the foam.

[Albin]

I will check his build out and and see. I know drize (who posted his stringer rebuild with lots of pictures) didn't put foam in his rebuild either. I don't think it would make that big of a difference but I would hate to put it all back together and regret not having it in there.

[cadunkle]

Whenever mine eventually needs stringers I will not be putting foam in. It'll be plenty of drainage and limber holes and made to drain and breathe. Only want to do it once and technically I don't even want to do it once since I expect to keep this boat as long as I'm around and able to use it. I prefer to avoid any situation where foam may be useful, and if I ever find myself in that situation I'd rather have vests readily accessible and swim for it. Whether it's swamped a few feet below the surface or 40' down makes little difference, insurance will cover it but I'd prefer to avoid that situation for my own safety as well as once a foam boat is swamped it's a floor and foam job now or a stringer job later.

[Albin]

Those are my thoughts exactly. I run in small lakes and can't imagine a situation where I would need to use the foam for buoyancy.
The only reason I would consider putting foam in is for the structure some people insist it adds. I may put in a few extra cross support pieces in but even that may be unnecessary.

[michael hunter]

I am also in the middle of a stringer job . Like you I have been debating about foam. What I have decided to do is use blue 4x8x2'' house foundation sheets and cut them to fit in each compartment between the stringers and supports. It is a closed cell foam so it wont soak up water and by not sealing it to the hull and stringers the water will still be able to get through. There should also be some sound deadening with the foam in place. The stringers I installed are thicker and tighter than the originals so I don't see rigidity issues with them.

[Albin]

Michael, I have been watching your thread with interest. I like the thicker secondaries you did and your overall layout. The insulation foam is an interesting idea, thanks!

[cadunkle]

I run on a tidal river. Just this past weekend while pulling my buddy a tug was coming up river and we were headed down river. We rode over a 4' tug wake (i.e. wall of water) and while the boat may have been out of the water for a moment I was never concerned for the safety of my crew or the boat. My buddy was going to try to hit the tug wake but he said the pull got a little inconsistent with the pylon swaying wildly so he tossed the handle. Snuck up on me, no barge and the wake didn't look that big until I was nearly on it. Sometimes they're rideable other times they're ridiculous. Just another day on the river.

Other times it has been gusty with white caps later in the day and I've run for miles working the throttle as the prop transitions from in the water the to of the water. Other times tug and big ship wakes come when stopped, or I just stop if pulling a rider and the rollers are clearly too big. Cruiser wakes can be nearly as bad and they go by all day. Never been worried about sinking the boat or concerned about the viability of foam. Just be aware to avoid swamping the bow.

Before I'd be concerned with foam I'm worry about sealing all leaks and ensuring 1 good reliable bilge if not two of them. My bilge finally seems to have failed so I'd looking at a 1000+ GPH replacement with larger hose and fitting and adding a second pump. I believe more bilge capacity buys more time and will prevent foam from ever becoming a concern.

[Albin]

That's crazy! I have heard the tugs throw big wakes. The biggest rollers we get around here are from people surfing there wake boats, and I haven't ever had anything come along that I had to worry about.
Good advice on the bilge pumps. I have 2 500 gph pumps that I will be putting in so that should help.

[lively]

I have no foam in my sunsport , I put two bilge pumps 500 gph, and limber holes for drainage . I plan to install floor drains for passengers that jump in and out to help from water always going to the back . The foam ain't cheap . But I like my floor to stay dry and not hold water like it did when I opened it up


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[Albin]

Thanks for the input everyone! I am going to to go with no foam for sure. I am doing the stringers similar to Michael Hunters with the thicker secondaries to help make up any strength lost from the lack of foam. I have the stringers cut and ready to install and hopefully will get them in this week.

[michael hunter]

I run on a tidal river. Just this past weekend while pulling my buddy a tug was coming up river and we were headed down river. We rode over a 4' tug wake (i.e. wall of water) and while the boat may have been out of the water for a moment I was never concerned for the safety of my crew or the boat. My buddy was going to try to hit the tug wake but he said the pull got a little inconsistent with the pylon swaying wildly so he tossed the handle. Snuck up on me, no barge and the wake didn't look that big until I was nearly on it. Sometimes they're rideable other times they're ridiculous. Just another day on the river.

Other times it has been gusty with white caps later in the day and I've run for miles working the throttle as the prop transitions from in the water the to of the water. Other times tug and big ship wakes come when stopped, or I just stop if pulling a rider and the rollers are clearly too big. Cruiser wakes can be nearly as bad and they go by all day. Never been worried about sinking the boat or concerned about the viability of foam. Just be aware to avoid swamping the bow.

Before I'd be concerned with foam I'm worry about sealing all leaks and ensuring 1 good reliable bilge if not two of them. My bilge finally seems to have failed so I'd looking at a 1000+ GPH replacement with larger hose and fitting and adding a second pump. I believe more bilge capacity buys more time and will prevent foam from ever becoming a concern.

Back in the 80s when we got our first boat [A 73 18' Invader trihull 115 Evenrude] we were on the Cal sag canal when we came across a tug . The wake didn't look big until it was too late . Do to my lack of experience we launched over the wake like a humpback whale in a feeding frenzy and then came crashing down it hit so hard it cracked the upper hull if 3 different locations and dialoged the center windshield. It was deffenetly one of those WTF moments. That boat taught us a lot of lessons 1- never buy an outboard 2- Never go on rivers 3- Never buy a Trihull. To name a few

[jasun]

I am a little late to the party, but I also did not put foam back in. I have had no regrets about it either. Especially when I took the boat out of the water for this year, I had a small leak in the swim platform and one exhaust pipe. Had I had foam in then it would have been exposed all summer long to this water.

For sure do limber holes though. I regret how I did mine. Mine are too small and get clogged with tiny bits of carpet that may have gotten in the back. I left the area under the gas tank unfloored. That is also something I have greatly enjoyed when I has come time to look at my rudder and anything else back there.

I would recommend doing as big of limber holes as you can. If you haven't already done it.


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[Albin]

Grea ideas jasun. i have some limber holes, but they are pretty small, i think i will enlarge them a bit to help prevent clogs. I also like the the idea of no floor under the gas tank and will do it that way.

[codemonkey82]

This brings up a question regarding my 89 comp. It's only 19' and I believe anything around 19' or less requires foam. Anyone have any input on this? I have heard the foam isn't enough to keep if from visiting Davey Jones in the event of hull failure anyway. I think I would much rather put in a couple of high flow bilge pumps if possible...

[jasun]

I always heard anything less than 20 feet required foam. But let's face it, unless it sinks and they salvage it how are they ever going to know?


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[cadunkle]

This brings up a question regarding my 89 comp. It's only 19' and I believe anything around 19' or less requires foam. Anyone have any input on this? I have heard the foam isn't enough to keep if from visiting Davey Jones in the event of hull failure anyway. I think I would much rather put in a couple of high flow bilge pumps if possible...



Not sure if foam or air pockets are keeping this afloat, but...

http://ixcr.com/supraupsidedown.jpg

[codemonkey82]

Talk about a bad day!

[chris young]

Wow! That's going to be expensive! Do you know what the story is?

[Jetlink]

Wow! That's going to be expensive! Do you know what the story is?

That was/is a forum members Conbrio I think. Took a wave over the bow hard and submarined the whole thing. The boat "turtled" and had to be towed to shore. They did manage to get it upright and back on the trailer though.

[Jetlink]

Here's the thread regarding this specific incident.

https://forum.supraboats.com/showthread.php?11638-Sunk-Conbrio&p=80521#post80521

The owner stated what happened on page 2 I think. Haven't heard much from his camp since he started rebuilding his boat. Would be nice for an update.

[TitanTn]

And yeah, technically it's 20' and less that require foam. Not sure that everyone would catch it, but a savvy insurance company might deny the claim on a 19' sunken boat without foam.

[Salty87]

no idea what an insurance company would decide but the USCG boat building regs obligate commercial manufacturers...
"The posted information is for manufacturers of recreational boats who must comply with the applicable regulations. Depending upon boat type, engine, length, usage, etc., a regulation (and corresponding guide) may, or may not, be applicable.

While we encourage recreational boat owners to use the information for their benefit, compliance with the regulations is the responsibility of the boat manufacturers."


regardless, foam isn't the problem as much is the application of pouring it. i went with a modified pour that resulted in somewhere around 15% less foam being used than a traditional pour method. line the area with plastic before pouring. foam doesn't stick to the plastic well so remove it and the foam is molded nicely for whatever space. has to be done before the floor goes in though. the molded blocks allow drainage around/under.

once you've got the engine running, wind blowing, tunes...you won't hear any noise difference if you don't put any foam in. and, i don't think foam adds any rigidity unless so much is poured the floors almost blow out.

[Okie Boarder]

I did not add foam back in and I actually put in more cross supports (ribs) using 2x lumber. I got plenty of rigidity and the boat is solid. When you are sitting parked and little waves are kinda lapping at the boat, you notice the sound more. Sometimes just driving you'll notice more noise. Other than that, it's great. I'm glad I did it that way.

[TitanTn]

Salty AND Okie!! Welcome back ole chaps!

[Okie Boarder]

Thanks. Yeah, it's been a while...haven't been real active on this forum for a while.