Stringer/ Floor Replacement Lessons Learned

I would like to chime in about the FOAM, NO FAOM Issue.
my understanding of the correct way to foam under a floor is after the floor is re-installed.
say what ? yes, I was taught be the guy that was a former owner of the American Skier brand. he walked me through the floor replacement of my 85 AM skier.
what he explained, is if you install the foam first, then cut it off at the floor level, you are opening up the closed cell foam by cutting it off. maybe you are sealing if again if you glass directly over it as was originally done at the factory. I am not an expert on that.
how to install foam after the floor ? the hardest part is jacking up the front of the boat, maybe 6 to 8 feet of so. this can be done by putting blocks under the trailer axel, then raising the front of the trailer. I had access to a fork lift,
prior to this, you drill 2" holes every 16" or so, between the Hull and the secondary stringers, this enables you to pour in the pre mixed foam into the holes, starting in the back of the boat until the foam comes out the hole, then moving forward to the next hole and so on.
when complete, lower the boat. once the foam has set up. cut it off at the floor, and batch with cloth and resin.
   

I would agree with your overall description of how to foam the floor. Just be careful not to explode the "chamber" you intend to fill. The foam creates a large amount of force if it has no place to go...

Agreed,

my explanation was pretty abbreviated. the foam needs to be poured in slowly, making sure not to pour in to quickly, or to excessively. .

interesting, thanks for your comments.
I used the Part A-B foam method, poured in.
so with this Handi Foam, with smaller holes, is it harder to not blow out the floor by injecting too much ?
my floor was plywood on my AM skier, now I am doing my sisters 83 SN, I am planning on using 1/2" foam board except under the seats, here I will use 2 layers of Cossa board.
will the handi foam work ?

Kjerchinger wrote: I am doing my sisters 83 SN, I am planning on using 1/2" foam board except under the seats, here I will use 2 layers of Cossa board. will the handi foam work ?

Keith,
There is a learning curve determining how much foam to inject. If you do use the method, start with small amounts. If you do overfill, there is some pressure so I would not recommend the foam board. The Coosa or ply is a good idea. The kits come with extra nozzles so you can stop, let the foam kick and then go to the next cavity with another nozzle. They supply tho types of nozzles. One is for spraying and the other for injecting. The injection nozzle tip is made so you can add 1/4" ID poly tubing as an extension. I've gone up to a 3' extension without a problem. You can then get way back into a deep cavity.

Looks Solid, nice job Rob

Foam comes in different sizes sized by board feet. Calculate what you need and go shopping.

dgray007 wrote: Food for thought after doing a stringer and floor replacement on my 89 Nautique 2001. There are 2 types of fiberglass shops. One's that have burnt down and one's that will... Do your research on the resin that you buy. Some boats were made out of SMC fiberglass and standard resins do not stick to them. Cheaper is not better. The cheaper variations, available at most box stores and marina's, have a filler comparable to limestone mixed into the resin. This makes wetting your fiberglass mat very difficult compared to the higher quality resin. I used about 6 gallons of resin and an entire roll of mat. 3.5ft wide by 50 ft long? or longer... You will burn through a lot of material and a lot of rubber gloves. I went through 2000 pairs of rubber gloves by the time I was completed... Paper Dixie cups are great for mixing and they are cheap. Don't use plastic... They tend to melt. Fiberglass creates heat as the chemical reaction occurs. The combination of warm ambient air temperatures, atomized solvents in the air and high reaction temperatures can make a recipe for disaster. Be careful, Make sure you have enough ventilation and if you can afford them sparkless tools, and heaters. Ye old torpedo furnace isnt recommended. Your boat will have open cell foam used in its construction. Replace it with closed cell expanding foam. 2lb foam is fine. Your boat will be much stronger and will n ever sink.... Some basic protective equipment makes you look like a huge dork but will make your job a little more tolerable. Throwaway jumpsuit, tape the legs and arms closed if you have to, comfortable respirator and goggles to keep the fumes out of your eyes. It gets pretty thick in the bottom of the hull after glassing the floor together. Cardboard templates are a lifesaver before cutting into that $60 sheet of marine grade plywood. Use bondo or similar filler to round inside corners or anything else to help the fiberglass lay down. Fiberglass mat does not like sharp angles. This will ultimately make the repair stronger and more reliable. After applying filler to the inside corners take the glossy surface back off before applying fiberglass. The resin won't stick to a glossy surface. Same goes for the old fiberglass. If the surface is glossy or dirty the new stuff will not stick and you are wasting your time. Do your prep work! Seriously consider hanging your boat during this process. If your boat is on the trailer the hull will deform as you remove structural components. Hanging the boat with the hooks designe by Correct Craft will allow the hull to relax. Lastly. Get creative and make your boating life easier. Move that battery compartment out from underneath the bow. Put a cup holder in the floor by the drivers seat. Yes they fit. trust me on this one. Congrats. you are now qualified to replace stringers... p.s. 3m 80 grit 8 inch grinding disks fit on your high speed buffer with a cheap adapter.

A lot of interesting ideas/thoughts, especially about hanging the hull and using bondo.

Anyone seen this system? They don't address rotten wood, but if they come up with a way to inject epoxy into rotten wood after the boat is dried out, stringer replacement may not be necessary.
http://www.dryboat.com/

So is fiberglass to an extent... Bondo use should be kept to a minimum and only used as a filler to round inside or sharp corners so the fiberglass lays down and wets out properly. If you get air mixed into the mat or mesh you pretty well just wasted your time. The Bondo, in its most basic form, is cotton fibers mixed with fiberglass resin. Bonding properties between your fiberglass resin and the bondo is really a really good mechanical bond. If you are using the epoxy type setup to repair your boat you should do some more research as to compatibility between your filler and your epoxy resins.

If you are using the epoxy type setup to repair your boat you should do some more research as to compatibility between your filler and your epoxy resins.

There may be, but I cannot speak to them.

Well I'm on my 2nd shop the 1st really messed everything up, now the 2nd guy has to find out how bad and go from there.
Gonna get a update Friday afternoon I hope.
JT

3m does make a good product and I have used that exact gallon on other projects I can't get terribly technical here because I'm by no means an expert but that product is designed for small repairs. Think 1 sq foot and smaller. When you are trying to wet out a large area there are advantages to having a resin that is designed for that situation. The off the shelf 3m home depot resin is cut with calcite, or basically limestone. wet out time, work time, overall strength is fine for general small repairs. Structural repairs in large areas of a boat really call for a high-quality resin that has not been cut or filled with calcite. The biggest advantage is the speed in which the mat or mesh "wets" with the high-quality resin. With the home depot stuff, you would have to work in a 1x1 area, The industrial quality stuff will wet a 4x8 sheet of plywood with mesh with plenty of work time before the resin kicks. This gives you a chemical bond across the entire sheet creating a single panel that is chemically bonded vs multiple chemically bonded areas that are mechanically bonded together to form the same 4x8 panel. I should probably define a mechanical bond as well. A mechanical bond occurs between old cured fiberglass and the new glass and resin that you put down over the top. The chemical bond is the hardening process that happens when you mix resin and hardener. Can you use the home depot resin? sure. Will it fall apart? Probably not. Will it make your life more difficult? yep...

Hope that helps a little. Again, I'm not an expert. below is a site that explains a little better than I can. I have purchased from them and have not had any issues.

https://www.carbonfiberglass.com/Resin-Systems/Polyester-Resins/6736-Premium-Polyester-Layup-Resin-Quart.html

Just got done with new stringers in my 65 coda I used the west system epoxy and slow hardener worked excellent! Used Douglas fur straight grain @ 200 bucks each! Well worth it. Used silica filler to seat the new stringers to the floor then 4" fiberglass then 6" fiberglass and up and over the stringers. Its unbelievable how much strength in the bottom of the hull with new stringers. Lots of work to get to this point all I can say is take your time this job cannot be done in one day. Good luck I'll try and post some pics soon.

One last thing. I would remove windshield if had to do another one.

Not that it is in the way. But just in case. I did not cover mine and had finger prints all over it.

Getting ready to replace the floor and stringers in my 84SN, with 2480 hr on it.... its a great boat.