TOPIC: Foam

I know a lot of you (especially you Bob) are thinking, "Will I ever be as cool as Nautilus?" Well frankly, no. However, you may, with practice, master the Nautilus highly technical system of installing foam into fiberglass runabouts. To that end, I will enlighten you with the following treatise:

I buy my foam from US Composites: www.uscomposites.com/foam.html You'll need three 16 lb kits of the 2 lb foam (FOAM 0216) for a 17'-18' inboard boat or an 80 lb. kit (FOAM 0280) for an eggbeater. The 80 lb kit is a better choice in either case because if you haven't used it before, you'll screw it up and use too much. You don't like the price? Tough titty! You need it.



Observe the "slight" protrusions above the framework. Now is when my hi-tech state-of-the-art foam removal tool (in which NASA has expressed great interest) comes into play. It will allow you to remove many of the giant globs that have expanded way above the framework because you didn't know what the hell you were doing and you poured too much.



I also use a Sawzall with a 10" blade to cut away any foam that it can reach. After that, I attack with a really mean-looking sanding disc on my angle grinder to remove large portions fast.



Any low spots and voids can be filled with small pours and finally, a palm sander with 60 grit will easily smooth it all down to frame level.



By now, you are, understandably, overwhelmed by my genius (and who wouldn't be?) and many of you are wishing you were me but don't let envy distract you. If you have followed my flawless directions carefully, the result will be a bilge filled solid with marine foam that forms a hard flat base which will help support your decking and make your vessel unsinkable.

After the decking has been installed, it must be completely fiberglassed-in to prevent any water intrusion. This foam "resists" water but can be saturated over time. Once the foam has become water-logged, your boat could gain several hundred pounds in weight and performance would seem like you filled all the seats with fat chicks. Ride high and dry.

With Sincerity and Humility, I Remain Your Idol,

Nautilus

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Nice! I really like the high tech tool.......which will remove more than just foam if you're not careful!

Bob

Thanks for the awesome tutorial. I do have a couple questions.

1 How much is that high-tec tool and where can I get one? (you should post a link to where you can get one)

2 Did you over pour your foam to show us how to cut it back because you know we dont know what we are doing and you want to show how to fix it when we pour too much?

LOL your awesome man. keep the topics coming.

The high tech tool is a piece of a broken 1" wide band saw blade with 3 teeth per inch. For a handle, I used two small slabs of wood (mahogany of course) and wrapped them with white duct tape. The handle goes on the end that allows you to cut when pulling, not pushing.

The foam sets up fast...really fast. Once you mix it, it needs to be poured immediately, no longer than about a minute lag time before it starts to turn to mush in the container. Over-pours are unavoidable. It's all guesswork. The first time you pour, you'll think you didn't use enough...then you'll watch a giant mushroom form WAY higher than you wanted. At the speed it needs to be poured, it's best to opt for more, not less, to be sure that area is filled, hence the fat blobs here and there.

You should also order about 10 pre-measured 2 quart mixing containers from US composites. They can't be reused so they're a one shot deal. Mix each batch very thoroughly and very fast...then pour fast. The foam needs to set up at least an hour before cutting.

I did see a video of a guy pouring foam and once he dumped the foam he immediately cleaned the container with a paper towel and then with some acetone and wiped it out again. I know they are cheap but it appeared with a cleaning before it starts to set up you can reuse without much waste of cleaning supplies. He did state if you don't do that then they are useless.

And you know I was pulling your leg a bit asking them questions right? LOL But i have to know does it have to be mahogany, i have some birds eye maple, and can I use black tape or maybe blue?

Keep the info coming... without a retainer!

If you don't use mahogany and white duct tape, it will just be a cheap knock-off, not a true Nautilus hi-tech tool. The rest of the classic boating world will laugh at you.

Thats why i want the link to order an original "Nautilus Tool" I dont want people laughing at me!

It will take more than a tool to stop them!

Jan,
When you state,..."After the decking has been installed, it must be completely fiber-glassed in to prevent any water intrusion. This foam "resists" water but can be saturated over time. Once the foam has become water-logged,"
Is this your experience with what is referred to as "closed cell foam"?
doc

Secret hidden camera of Jan before his patented pouring technique.

Doc: Yes...the manufacturer states, "will resist the absorbtion of water." So, it's not at all like a sponge but enclosed with water, it will eventually become saturated. It's been my experience that anything "resistant," i.e. stain resistant, wrinkle resistant, etc., will eventually stain or wrinkle.

Nautilus,

Not to question your superiority over us mere mortals, but on the subject of foam...I see the obvious benefit (boat won't sink, deck has more rigidity) but obviously there is a debate about foam. In particular, that water will always find a way into a bilge. Kinda like rust never sleeps, you know? I'm debating if my Glasspar Seafair should get foamed or be left like they built it, with the addition of a bilge pump. I'm not thrilled with the idea of foam slowly absorbing water over years until the boat has more ballast than all the cobblestones on Nantucket. Thoughts?
Thanks,
Eric

The closed cell foam really is pretty resistant to water absorbtion but sealing all edges with fiberglass is close to a guarantee that the foam will not be exposed to water at all. Yes, you could argue that water will always find a way in somehow but how much water and how long would absorbtion take? My suggestion: Take your best guess as to how long that would take, if it happens at all, and then weigh that against how long you think you'll live. The chances are very good that any water absorbtion will be someone elses problem!

All kidding sorta aside. Foam....yes over 50 years it'll soak up, turn brittle, find its way to the drain hole and plug it up. After 30 years you'll find yourself tipping the boat back so far on the trailer it would slide off it it wasn't strapped on. The wood floor will rot away and you will be too old to G.A.S.
Foam was meant for floatation in case you run a stump through your hull at excessive speed. Hull strength is an advantage, noise reduction and rigidity are a plus. Fact is that foam has it's +/-. Some manufacturers put a minimal blob under the floor and load the underside of the gunwales. By the time all this happens the transom you replaced will be rotted again. Bottom line....it's YOUR boat do with it what you think is best. Get advice like Jan is giving and make an informed decision.

"Get advice like Jan is giving and make an informed decision."

That's exactly what I am attempting to do.

Jan, if say I did foam the entire underside of the deck on my Seafair, wouldn't that negate the drain for the bilge altogether? I can't see any reason to leave a drain hole (which can let water in if not prepped or plugged correctly) for a bilge that is totally filled with closed cell foam.

I have other questions I'd like to ask you (Jan) outside the realm of foam just to get a good plan in place, but I don't want to stray too far off topic here, unless you think that's okay...I'm just a newbie trying to suck up as much information as I can from those who know a helluva lot more than I. Then hopefully one day I can be the elder sage who can share advice when I have some grey in my beard.

I would create a "well" around the drain hole. Box-in an area about 1' square and completely fiberglass it...bottom and sides all the way up and over the flooring...totally watertight. (I've done this before) That should give you all you need to drain rain and wash water and maybe occasional bladder overloads.

I can't remember who it was right now but I know one or two folks have run PVC down both sides of the keel to let the water get back to the drain hole. I think they had holes drilled in the side toward the side away from the keel, not to big for foam to get in once poured. No holes in the bottom so it channels the water back to the drain. There were pics of it and I think it was in this main forum but it was a few years back I think.

Bob

I'd like to see that. It all sounds sketchy to me. From my experience, that foam will squeeze into everywhere...the smallest holes and cracks. The foam wouldn't have to get "into" the holes, just cover them. My guess would be that once poured, the foam would fill or cover every hole in the PVC and you'd never know it, making the whole thing useless. I give that idea two thumbs down.

Okay, Jan, I get the drift but since that box is sealed the drain is then only to allow water that lands on deck from rain, spray, bladders, etc...a place to escape. I already have that, but at deck level. I have 3 in fact.
1-bilge (lowest)
2-deck (mid)
3-splashwell (1959 only style)
Now this boat will be destined for a marina slip one day, so it won't be trailered out all the time. wouldn't it be better in that case to omit the lowest drain therefore sealing the hull, and just keep the deck drain which is above water line open for the inevitable rains and such to escape? As is the weight of the engine should provide a rake toward the stern to keep water draining.

On another level, let's just say I'm German and want things done to last....What is my best course of action for rebuilding? Floor, stingers and transom are all shot. In my mind, using nice DRY pressure treated lumber for the stringers, then foam the bilge. Floor, Coosa all glassed in and transom Coosa too? Then I have read Coosa in a transom isn't as stiff as marine plywood and motor torque will flex it. If you were building with frequent exposure to elements and longevity in mind, (this ain't no trailer queen) how would you approach it?
Thanks,
Eric

Since you asked...I would have ONE "catch basin" in the rear with a drain plug and get rid of any others. Put your bilge pump in there and have a 110V trickle charger maintain the battery. Have a good cover made for the cockpit to shed most, if not all, of the rain.

I'm old...and old school. I deal in wood. I know nothing about Coosa. It sounds like some kind of bug to me. The transom needs to go in first. I would build it using two layers of 3/4" marine plywood, sandwiched together with waterproof glue. (I forget the name. It's comes in a plastic bottle. They have blue, red and green labels. Buy the green.) Next, clamp it in place with a complete layer of 3M 5200...solid coverage, not some modern art design with spaghetti nerdles. The edges of plywood are it's Achille's heel. That's where moisture will get in. I always coat the edges with 5200 as well. Once in and the 5200 has cured, coat the new transom with CPES and then fiberglass in.

Dry treated lumber will work fine for the stringers and other framing members but coat all thoroughly with CPES. Cut/sand the foam to the level of the framing. I use 3/8" (9mm) marine ocoume, meranti or sapele plywood: www.worldpanel.com/marine-plywoods (None of it is cheap!) Coat with CPES and then fiberglass in completely.

Try to find somebody you can pull a Tom Sawyer on. Show him how much "fun" you're having tearing all that crapola out of the boat and then allow him to talk you into helping. Give him all the shit jobs while you go "check on a few things." Go have a beer. Word!

Finally, remember that free advice is worth twice what you pay for it.

I believe you mean Tite Bond I, II, and III.

Sounds like a good plan, although the drain in the splashwell will remain as it is always open to the elements, even with a cover on the cockpit.

So you are saying your advice is worthless? Hardly. Thank you.

My Seafair was a stern drive. I didn't realize that yours is an outboard in which case, I would go the with the drain well/ bilge pump/drain plug scenario in addition to the splashwell drain. It doesn't have to be very big...just enough to accomodate your bilge pump. That will take care of any/all rainwater.

I'm going to think outside the box here... for me ? I'm thinking beer bottle science here.
If you take a cold brew out of the fridge and put it on the counter and don't open it, what happens ?
You get droplets of water forming outside the bottle, or condensation. Even though the bottle is still sealed, condensation still happens because of the temperature differential. So I'm thinking the same thing happens with boats ?
If the air is hot, and the hull is colder because of the lake temp is colder, wouldn't condensation occur under the floor no matter how sealed the floor to hull is ? If foam fills the entire hull from the floor down, where does the condensation go ? I'm guessing into the foam ? And over the years, you're screwed !
This may be a dumb idea ? But if there was an thin air space between the hull and foam ? the condensation can occur naturally, but still drain to the bilge without soaking the foam over time ? So putting in a sheet of plastic with short nubs, kind of like the pizza box 3 prong things to keep the lid from sticking to the pizza. between the hull and foam, will allow condensation or rain to get to the bilge pump without getting trapped in the foam ? Just my two cents ? If some one here invents this ? I want credit too ! Ha-Ha-Ha !

Chuck:

Using your beer bottle analogy, given that the foam is completely encapsulated with fiberglass, wouldn't it hold true then that the condensation would be on the OUTSIDE, i.e. the flooring?

Sure condensation could happen but like Nautilus states you are looking at it wrong. so take an empty water bottle and seal it up. This will be more likely the scenario of under a sealed floor. Now if the bottle stays sealed the little bit of moisture that is in the air inside the bottle isnt enough to soak or rot anything. People are really overthinking this whole thing. It has already been brought up before in different ways and the fact still remains that it will take many years of a poorly taken care of boat for the closed cell foam to become waterlogged. If your boat is so abused and neglected, and the floor is not properly sealed and or you just like to drill holes in your new floor to allow drainage into your foam, that you have to worry about foam being waterlogged, I believe your floor would rot first and need replaced then you can just rip out your waterlogged foam and start over anyway. The point is if you seal up your floor properly, take proper care of your boat, your floor and your foam will most likely outlive you.

Agree, disagree, what ever. It seems that Nautilus may have way more experience than most on this subject, just accept the fact that the earth is not flat and move on, or you can just fill under your floor with ping pong balls for floatation purpose only. I dont think they will become waterlogged.

Mars is flat.

Here is my take.....

Closed cell foam will eventually absorb water is left submerged indefinitely. I also believe the amount of absorption will vary with its condition.
By that I mean a nice block of freshly expanded foam that has never been pounded & twisted inside a hull will absorb little.
Foam that has been beaten inside a hull will have cell damage allowing more water absorption. This is my belief without any documented tests.

I also agree that properly cared for, it will be many years before it becomes a problem.
Keep boat covered & remove the plug. Better yet, keep it indoors when not in use.

And the beat goes on.....
I'll add another scenario to this brain storming session. Flex... choppy conditions will pound and flex the hull, wood, glass, alum, makes no difference. Some boats I've rebuilt had the glass separating from the hull under the drivers seat area because of the weight concentrated in that area, pound it a few years and it will come apart. Others that were "sealed" had small air tubes inserted in the bow area to allow the encapsulated air to breath so when the boat flexed or pounded the air would not compress and blow the seams. Look long term, Nothing lasts forever, Put the thing together the way you want and enjoy it. 30 years from now let someone else worry about it.