To foam or not to foam

[voodoolord]

I just got done scraping the old foam out of my hull and Im still getting some water seeping from the stern side of the stringers. It looks like it might take a while for the water to drain. The stringers are glassed in and very strong so I figured I would hold off on cutting into them. Should I replace the foam or install the deck without it? A local boat repair shop recommended I just leave the foam out. He said that the foam will probably get wet again and doesn't really do anything for the boat. The only thing I thought the foam might do is keep water from sloshing back and forth if it gets wet in there again. What do you guys think? Also Im wondering if anyone has ever added a small drain on each side of the bilge through the stringers that you could unplug every once in a while and let any water in there drain out. That doesnt sound too bad to me as long as the plug or cap stays water tight. Any thoughts? Thanks.

 

[oops!]

Re: To foam or not to foam

hi....welcome to iboats.

the foam in some boats are structural. some are just for safety.

it depends on the year of the boat and the make.

if you leave the foam out of a boat that needs it......chances are you will crack the glass in the hull.

from reading your post, i gather you are kinda new at this......no worries.....we were at one time too,

in the 70's the USCG passed a law that all pleasure craft boat's had to have foam. this was so that if the boat sunk....at least it would keep afloat and give the suvivors something to hang on to untill help arrived.

the builders found out that pour in foam had fantastic anti crush benefits.......boston whaler even made a whole boat from it !
the builders found.....that because of the anti crush stregnth of the foam.....they could cut production costs by using less fiberglass and resin. so......if you have one of these boats.....(bayliner is a prime example) you would need to add a few more layers of fiberglass to the hull before you could get away with no foam.

as far as limber holes in the stringers to allow water to drain to the bilge.....yes...put them in, and make sure the exposed hole in the wood is carefully encapsulated so water cannot start to rot away the stringer.

 

[oops!]

Re: To foam or not to foam

hi....welcome to iboats.

the foam in some boats are structural. some are just for safety.

it depends on the year of the boat and the make.

if you leave the foam out of a boat that needs it......chances are you will crack the glass in the hull.

from reading your post, i gather you are kinda new at this......no worries.....we were at one time too,

in the 70's the USCG passed a law that all pleasure craft boat's had to have foam. this was so that if the boat sunk....at least it would keep afloat and give the suvivors something to hang on to untill help arrived.

the builders found out that pour in foam had fantastic anti crush benefits.......boston whaler even made a whole boat from it !
the builders found.....that because of the anti crush stregnth of the foam.....they could cut production costs by using less fiberglass and resin. so......if you have one of these boats.....(bayliner is a prime example) you would need to add a few more layers of fiberglass to the hull before you could get away with no foam.

as far as limber holes in the stringers to allow water to drain to the bilge.....yes...put them in, and make sure the exposed hole in the wood is carefully encapsulated so water cannot start to rot away the stringer.

 

[voodoolord]

Re: To foam or not to foam

Thanks oops, At least I had one idea right. The reason i brought up the foam thing is it didnt look structural at all and there didnt look like there was enough there to actually keep the boat afloat if it filled up. I will say that it also didnt seem like it was really waterlogged as both trash bags full weigh maybe three pounds. I removed it to find out where the water was coming from.
So their called Limber holes huh? Ill do some research on them. I was envisioning a pipe thread type drain in the stringers that I could cap off and just pull the caps but is it better to just have them open all the time? Also what is a good way to seal around the inside of the holes through the stringers? Kind of funny if they prevent water from building up on the sides of the boat why the manufacturer didnt put them in in the first place but oh well. Thanks for your help.

 

[rickryder]

Re: To foam or not to foam

Hi Voodooo,

Welcome! Post up some pics of what your working with so we can help you along

If you have water seeping from your stringers it may have gotten to the wood core and it's rotting the stringers... since your in there it would be best to start core sampling the stringers,bulkheads and transom.... You didn't say what boat you have so I can only assume at this point.

Core samples are done with a 5/16" drill bit wrap tape on the bit about 3/4" at a depth gauge. Drill into any wood that looks dark behind the glass...if the chips come out white and dry...fill the hole with 3m5200 marine sealant (you can get it at Home Depot in the paint dept) and move on to more test holes....start low and work up since boats mostly rot from the bottom up...

I use 1" pvc pipe cut into small pieces...enough to go thru whatever I want a limber hole in....and glue it in with 5200 and seal well around both sides....

Pics are in my resto thread below... Lets see what ya got!

 

[Georgesalmon]

Re: To foam or not to foam

Some, but most foam is not structural. Where it is used for floation as required by the CG it is ususally about 2 lb density per cubic foot. At that density you can poke you finger in it. Structural foam needs to be much more dense than that. At the densities of 2lb/cuft it is very friable and won't support much of anything but itself. Structural densities are pretty expensive to the point of costing more than fiberglass and resin. Why most boat builders don't use foam for that. Boston Whaler is an exception but their boats are not cheap. Good, but not cheap.

I would replace your foam with an equal amount for safety reasons. For sure if you will be taking your family boating. It is there for basic floatation on an older boat and level floatation on a newer one if the boat is swamped. You can use inexpensive styrofoam from your local building supply. Only remember that styrofoam can not stand fuel and will melt if it comes in contact.

 

[voodoolord]

Re: To foam or not to foam

Heres some pics. The light colored area is where the foam was, theres still foam under the hammer in the first pic. Also the stringers where the water is coming out. It seems like the glass has broken down a bit at the seam between the stringer and the hull in a couple of places. Can I dry this out until it stops leaking and glass it over? The thing is its really strong so Im hoping I can avoid cutting into the stringers. Ill never get out of this boat what Ive put into it so far and dont want to go into it much deeper.

 

[Georgesalmon]

Re: To foam or not to foam

It does not look to me that the foam was structural. You'll be waiting a longgggggggg time for it to dry out. If you need to repair that (probably should) best to cut it out and dry whats left. I don't care what the label says, in my experience nothing bonds well or for very long when applied to wet surfaces. If there is water coming out under the stringers it is not a good situation period. Need to drill a small hole (1/4")in the side of the stringers and see how saturated with water the core under the glass is. If the fiberglass "hat" sections are as you say, nice and strong the core material might not be so important except where the engine mounts are. That's IMPORTANT and in one of the pictures looks pretty bad! Needs to be addressed.

 

[rickryder]

Re: To foam or not to foam

I would start drilling and see what you find.... Check the engine mounts like George suggested....thats very important! Then again so is everything else

 

[voodoolord]

Re: To foam or not to foam

Thanks for the reply George. I put a high power shop vac in the corner of each side of the stringers for about 15 min and believe it or not it really made alot of difference. Theres just a little moisture now. Ill keep hitting it with the vac off and on today and see how well it does. Speaking of the mounts, you can see where I ripped the glass off of the side of the mounts. Can I rough up the glass on the mount and reglass down the side to the stringer? What is the black coating on the mount? It was layed down all around the engine compartment and in the bilge. I was guessing some kind of sealant.

 

[rickryder]

Re: To foam or not to foam

Most likely bilge coat or paint.... If you can rip the glass off it's bond is bad.... you really need to do core samples to find out if there is rot in the mounts and stringers....

can you just throw glass on it....YES....will it stick or be correct NO!

This is a big safety issue and needs to be addressed properly

 

[Georgesalmon]

Re: To foam or not to foam

what he said

 

[Georgesalmon]

Re: To foam or not to foam

I wish I had thought of the shop vac trick. Sounds like a great idea. The black looks like bilge paint as mentioned by rick. That's just gel coat with some fumed silica and surfacing agent (wax) mixed in so it will cure hard on the top. Its used to make things pretty but also helps keep water out of the fiberglass. It doesn't have any strength and would be a resin rich layer between it and any glassing you would put over the top of it. You must grind it all off before re-glassing your motor mounts so the interlaminar strength is not compromised. If those motor mounts are wet they do need to be replaced. The lag bolts need something good to hold the motor down, lots of torque there. Hint; a piece of an old broken pallet (often made of oak) works really well for that and can be found behind thousands of business establishments across the country. You can often get them for free.

I had an engine come loose once in a 26' starcraft AL boat. The wood inside the AL motor mount was rotten and lags came out. Not fun! In that case I had to pull the engine, drill out the rivets, pull the mounts, put new wood inside them, and rivet back to the hull. In your case you should address this now, it would be a real mess later on after you are finished.

I know thats not what you want to hear.