246 rebuild live from Delmarva!

[4shore]

Good thing I bought that 7.5 " grinder!

[Callyb]

Good thing I bought that 7.5 " grinder!

An air chisel and a multi-tool really come in handy too. An air chisel especially makes quick work of bulk removal.

Oh. Also, i don't know how relevant it is but the last 3 feet or so of my stringers didn't have any foam either. It was almost like they only get so much per boat... But, then again my boat is a 1966, may not have anything to do with your stringers being empty back there.

[4shore]

Is there any way to put enough foam in the stringers to gain neutral buoyancy or will I have to re pour foam into the hull?

[CLM65]

Is there any way to put enough foam in the stringers to gain neutral buoyancy or will I have to re pour foam into the hull?

You will get about 62 pounds of bouyancy for every cubic foot of foam you have.  If you can determine the weight of your boat and your engine, then divide by 62, that will let you know approximately how much foam you will need.  I'm not sure how much volume there is in your stringers, but my initial guess is that you will also need at least some amount of foam between the stringers to keep the boat from going under.

[kaptainkoz]

Welcome to the site and I look forward to following your build. I Just foamed my 1979 246ccp stringers and I needed 3 1/2 gallons of 2 lb foam to do it. I think 3 gals is just a bit short even taking into consideration the waste I had. I have my build in progress on here as well if it can be of any help to you. I look forward to your progress

[4shore]

I have been watching yours also!
How many cubic ft did you get out of your 2# foam after pouring 3.5 gal?
My thought process is this: 3000 lb for the boat taking into account fuel
500 lb for motor
Another 500 for incidentals. On board water, ice beer food fishing gear.
1000 lb of people (5 guys at 200 lb)

So 5000 lb total which means I will need 80 cu. ft. Of foam at 62 lb of buoyancy.

Do these #'s sound right how feasible is 80 cu ft in this hull?

[Capt. Bob]

how feasible is 80 cu ft in this hull?

How much room do you have?

8' x 5' x 2'= 80 c.f

Start chopping up space below deck. Include the stringers.

Good luck.

[CLM65]

I wouldn't include most of those incidentals:  the water is going to be neutrally bouyant, gas will be slightly bouyant, people can float, etc.  I would only include the things that would sink by themselves and are attached to the boat.  Still going to be a lot of foam, but not as bad as you might think.

[kaptainkoz]

With some wicked math help from captain bob, we were able to figure that the stringer volume on a 246 is about 14 cu ft. Thats 28 sq ft to start. I think 80 is impossible. You may be looking at about 40-50 in total. Its hard to say what kind of expansion you will get per gallon as it affected by temperature, how well it was mixed, an even the angle at which it was poured. I had voids that I had to touch up because they were on the other side of a low spot in the stringer. Also, mixing it 2 quarts at a time (1qt a, 1 qt b) left "hills and valleys" of the foam which affected flow.

As for your math on buoyancy, you have not taken into account the inherent bouyancy of various materials. For example, the plywood in your boat, the cooler, your fishing buddies and even the fiberglass itself have bouyancy. So the foam is adding bouyancy to items that are already bouyant. I hope to never find out if my boat is buoyant when swamped, but in preparation I am foaming the stringers and adding foam (sections, not poured) anywhere I can like in spots under the floor under the coffin box, and the outsides of the stringers.

The immediate importance for the foam job is to get any potentially wet, heavy foam out, and to re-foam the stringers for the rigidity that the foam adds to the stringer. Some guys pull 2-4 hundred pounds of wet foam and wood out of their boats. The old generation foam held water while today's foam is closed celled and will not hold water.

Tearing a boat apart allows you to investigate every inch of it to make sure it is sound or to correct what isn't. The work is Bittersweet as I love it and hate it for different reasons, but the cost savings and the pride factor is what keeps me going. I can't wait to get out there and get asked "who did your work??" I will stand there and smile

[gran398]

I wouldn't include most of those incidentals:  the water is going to be neutrally bouyant, gas will be slightly bouyant, people can float, etc.  I would only include the things that would sink by themselves and are attached to the boat.  Still going to be a lot of foam, but not as bad as you might think.

Good thinking.

Load up the stringers with closed cell foam. Then plan your runs, tubes etc.

 In the areas that are left open....put in foam sheets/blocks. They'll float up under the deck in case of emergency. In the meantime, they sit there, deadening the sound of hull slap. Available in varying thicknesses/configurations. And add the safety you're looking for.

The good news with a floating system....they're not bedded to the bilge per either side, holding water.

Also makes it easier to dry the bilge in the off season.

Koz...came behind you as posting. More good thinking. And as you say, when you're asked who did the work....give 'em that big smile. As we discussed,  the thrill is in the hunt. The build is the deal

[4shore]

How about filling the void between the inner liner and the outer hull in the freeboard/gunwale area? I am running the new floor all the way out the the outer hull so I could drill holes and pour thru the top. This would also deaden any hull slap, no?

I am also looking for opinions on lamination schedule for the transom if anyone has them.

[kaptainkoz]

I guess you could add pieces between the hull and cap. I dont see how you could pour as there are way too many holes for the foam to come out of on a pour. Im fairly confident that it should float if you fill most of the area under the floor. ALso, not that the foam weighs much, but i dont know if I would want to add weight above the waterline in the gunwales. Im not sure if that would affect steering and roll to some extent. I dont think anyone has gone to the level of adding to that space. Im not an expert, but I do not immediately see why you couldnt. I guess its up to you. Theoretically it would float better if swamped with the bouyancy up high and the dead weight low. As stated before I hope we never have to find out.

I am trying to mindful of overall weight. There have been a few times where I have said to myself that I would like to add glass here and there, however taking out 200 lbs of wet foam and wood and replacing it with 200 lbs of building materials could be counter productive. The boat isnt going to break. Mine hasnt broken in 34 years so it doesnt need me to make her stronger. I am trying to keep it within reason. I have no idea how she is going to run with the changes I am making. Think about the effect your buddies have on the boat when walking around on her while under way. Basically just be mindful of weight and ask yourself if what you are doing is necessary.

[4shore]

I am trying to brainstorm ways of keeping my floatation foam out from under the deck. I don't mind it in the stringers but I really would like the water that may make it below deck to be able to move uninhibited to the bilge.

I like the idea of the foam sheets but wouldn't they bang around in the bilge if not glued to the hull or floor or stringers? What about if when I install the floor I adhere the sheets to the underside of the floor? That would provide floatation and sound deadening properties and still allow water to flow to bilge.

Keep in mind I will be adding below deck storage ( fish boxes) and seating like bondo bills. I could incorporate foam into these builds also to pick up a few cu. ft.

[gran398]

Don't worry about adhering the sheet foam. It just sits in there outboard of the stringers, and doesn't move around much. Even if it did, there is no noise associated. It doesn't float, as (hopefully) there is no water there. The water will be below this area in the bilge.

If you decide to foam the area between the liner and the hull sides, do it in small increments. As we all know, a little goes a long way, sure don't want to push out the liner. Seems like a member a while back was talking about gluing this area Can't remember the thread though.

[dburr]

Floatation and foam..  

The big question is why.  The answer is not always that obvious..  Scotty mentioned noise deadening. Good reason..  Another answer is “because it was there for me to take out so it must have been there for a reason”.. Plausible but not the best, we all know that “it has always been that way ” isn't always the right answer..

If you are interested in foaming the voids to give the deck a big landing area and plan on gluing the deck to the foam that will make it crazy solid and strong and that would in my opinion be the best reason to foam the void.  But with a good glass schedule for the deck that strength for normal sport use is way overkill.  (Not a bad thing mind you)

Strength, that is a good one, the trapezoid stringer is no where near as strong with out some type of core material, putting foam back in there only makes sense. But as far as the rest of the boat?  What do you want to achieve?  If the hull is holed, Scotty’s foam blocking will keep her from completely filling, and as long as there is no water on the deck to slosh around to make you unstable and flip, your ok.  On the other hand if you hit bottom and holed the boat you have other issues and by the way you are on the bottom already so is sinking really an issue...?.  If someone hits you at the speed of heat   the only thing that is gonna save you is luck, PDF’s and quick accessibility to the healthcare system, their insurance (if they have it) will take care of the boat ...

When you replace the deck, you are going to make it water tight (I am sure).  Rigging tubes will keep water out if they go from console (helm station) to stern are glued and terminate above deck level..  Another possible entry is an anchor locker drain, again not likely to get submerged unless the bow is underwater for an extended period of time..

So, worrying about keeping the bait, boys and beer (all movable ballast) afloat when swamped has more to do with the skill of the operator, the scupper size to get rid of the deck load of water, then the amount of foam you have.

Adding foam in between the stringers adds nothing to “floatation” of a sound hull other then add weight to the overall rebuild.  In the event of a catastrophe of a holed hull the foam will keep out the volume of water it displaces…


Just a few thoughts and if I have stated the obvious, my apologies...

Really nice project too!