What and where to foam

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Fuzz
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What and where to foam

Post by Fuzz » Wed May 16, 2018 6:24 pm

There is a lot of debate going on now and in the past so I thought I would start this thread to get folks input.

Lots of folks foam in the whole bottom. Some want no foam below the water line and limber holes for draining. Both have their good and bad points. So what are you guys doing and why?



fallguy1000
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Re: What and where to foam

Post by fallguy1000 » Thu May 17, 2018 12:40 am

Okay, my rig is foam and gets no buoyancy foam and I am no expert.

However, my Lund aluminum fishing boat jas foam.

The foam in it is well placed and it allows for drainage and it will not hold water in it.

That said; it takes a couple of days for the boat to dry out after a soaking rain. Not sure if the plywood floor is the culprit or the foam or a combo, but the boat is slower for sure.

Personally, I would try to foam those places where the boat can drain and I would avoid trapping water in the bilge.
My boat build is here -------->

viewtopic.php?f=12&t=62495

OneWayTraffic
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Re: What and where to foam

Post by OneWayTraffic » Thu May 17, 2018 4:22 am

My experience from my build has me swearing to never foam a compartment with any penetrations, sealed or otherwise. I would foam under the sole, and then route all wiring etc under gunwales.

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BarraMan
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Re: What and where to foam

Post by BarraMan » Thu May 17, 2018 6:04 pm

Everything under the sole of my boat is foamed except for the spaces that contain the fuel tanks - which drain into the bilge. I used blocks of high density closed-cell foam to fill the spaces then filled the gaps with 2-pack polyurethane foam. Given the way that the 2-pack foam sticks to everything and pieces that I have tested do not absorb water (closed cells shouldn’t) I have no reason to think that water can penetrate my foamed compartments.

Time will tell, I guess!

Fuzz
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Re: What and where to foam

Post by Fuzz » Thu May 17, 2018 6:23 pm

I really like how the foam stiffens things up and fully foamed the bottom of my dory. But I keep thinking what would happen if you swamped the boat. Almost all the floatation is in the bottom and I think it would turn turtle. So I wonder about building the next one with no foam and a drain set up in the bottom and the foam along the gunwales. Just wondering if having floatation higher up would that keep in from rolling over if swamped? Would building this way prevent the sort of problems some of the guys have had? Too much time on my hands :doh:

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OrangeQuest
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Re: What and where to foam

Post by OrangeQuest » Thu May 17, 2018 6:37 pm

Fuzz wrote:
Thu May 17, 2018 6:23 pm
I really like how the foam stiffens things up and fully foamed the bottom of my dory. But I keep thinking what would happen if you swamped the boat. Almost all the floatation is in the bottom and I think it would turn turtle. So I wonder about building the next one with no foam and a drain set up in the bottom and the foam along the gunwales. Just wondering if having floatation higher up would that keep in from rolling over if swamped? Would building this way prevent the sort of problems some of the guys have had? Too much time on my hands :doh:
Sounds like you should swamp your dory and see what will happen!! Question is: Is there enough foam in it to keep the sides from going under? If it will keep the sides up then you may can rock enough water out of it to float it enough to get in it. Make sure someone is taking pictures!! :D :D

I have rescued a few swamped canoes and what little floatation they have is under the seats (most of them). But they all have stayed right at the surface right side up. I have to flip them over as I pull them upside down on my boat to drain all the water out, do the same method on sit inside kayaks but once across my boat have to rock them a little to get most the water out. Tee rescue style. Sit on top kayaks are almost always upside down when people fall out of them, easiest to flip back over and get people back in.

OneWayTraffic
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Re: What and where to foam

Post by OneWayTraffic » Thu May 17, 2018 8:24 pm

No foam under sole: Hole in boat and it sinks. If there is foam higher up, then it sinks to the level of the flotation.

Foam under sole: Unless it is perfectly sealed water will eventually get in there. A few freeze thaw cycles (in some climates) and it begins to do damage.

We have had people on this forum who have had water get in under the sole. We also had at least one guy who put a hole in his boat and lived to tell the tale, partly due to the foam. We have had water make its way between sealed compartments under the sole as it is difficult to ensure a 100% seal at the top of stringers and frames when you put the sole down.

I would foam in your case and install large side chambers/seats for stability when swamped. The water is cold up there.

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Re: What and where to foam

Post by TomW1 » Sat May 19, 2018 4:20 pm

Fuzz wrote:
Thu May 17, 2018 6:23 pm
I really like how the foam stiffens things up and fully foamed the bottom of my dory. But I keep thinking what would happen if you swamped the boat. Almost all the floatation is in the bottom and I think it would turn turtle. So I wonder about building the next one with no foam and a drain set up in the bottom and the foam along the gunwales. Just wondering if having floatation higher up would that keep in from rolling over if swamped? Would building this way prevent the sort of problems some of the guys have had? Too much time on my hands :doh:
Fuzz, foam under the gunwales is never a bad idea and yes it will keep you from turning turtle. With the wide gunnels of the dory a 4" deep layer of foam from transom to bow would be enough to keep it upright. Although the OD18 is pretty stable as built. Jacques actually recommends that it be done on some boats.

Tom
Restored Mirror Dinghy, Bought OD18 built by CL, Westlawn School of Yacht Design courses.

Fuzz
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Re: What and where to foam

Post by Fuzz » Sat May 19, 2018 6:57 pm

My reason for starting this thread was thinking about what would really happen if you swamped the boat. I believe the Coast Guard calls for upright floatation in boats under 20 foot. I believe the boats built here that are foamed below deck will stay floating but I also believe most of them would turn turtle. Keeping the boat floating and upright would enhance the chances of survival. Keeping most of your body out of the water and visible would go a long way to make that happen. Thus my thoughts on placing a higher percentage of the foam higher up.

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Re: What and where to foam

Post by Jaysen » Sat May 19, 2018 8:05 pm

If that's a USCG req, then we have to ask "how do you define boat"? I say this as kayaks, canoes, many many small sailboats, and a lot of > 20' john boats won't sit right side up unless they are filled from the inside (equal distribution of incoming water). Once that water comes in over the side... well hope you can swim.

Maybe my experience is abnormal though.

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