no foam in boat

I bought a 96 cajun 21ft bayboat and there is no foam in the belly of the boat . if it takes on water its going down. Ithrought a boat had to have floation in the boat . Is this the norm ? Should I add some?

Re: no foam in boat

My hull is a sandwich of fiberglass then foam then fiberglass only way to see it is to cut a hole somewhere. How do you know there is no foam built into yours?

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I had some hull damage so i can see that the hull is solid fiberglass.

Re: no foam in boat

It's not mandatory for boats over 20 ft to have flotation foam. Under 20' they must float-over 20' they can sink

Re: no foam in boat

I'd be filling that thing up with 2 part urethane expanding foam if it was mine.

Are you the original owner or did you buy it used? If you bought it used someone else may have pulled the foam out when it got wet and didn't replace it... yes, there are people that foolish.

Even though it may not be required, most fiberglass boats do have a foam core for strength/support and sound deadening.

Re: no foam in boat

also, it doesn't have to be foam, nor does it have to be in the floor. Sealed air pockets can be used, as well as foam floatation in the gunwal area. The only requirement is that the boat doesn't sink.

But in your case, >20 ft, not required.

Re: no foam in boat

see if you can remove something from the inside of the hull on the bulkheads (walls) such as a rod holder or gas tank filler and see if there's foam up in there.

And when a 20' boat with floatation "doesn't sink" all that is sticking up is a few feet of hull. Don't picture yourself sitting in an upright boat, much less a dry one, like the old Whaler ads. Not much to hang on to and in cold water you're dead anyway.

I've seen this myself.

Re: no foam in boat

I agree with everyone else.

Boat of 20 feet and over are USCG Approved to sink!

"Prepare to Dive!"

Re: no foam in boat

My 21 footer has plenty of foam. Actually I have never seen a boat in the 20-24' range w/o foam. This calls for more investigation by the OP.

Re: no foam in boat

Chris1956 said:

My 21 footer has plenty of foam. Actually I have never seen a boat in the 20-24' range w/o foam. This calls for more investigation by the OP.

Click to expand...

Yeah, I suspect a hack job by a PO.

Re: no foam in boat

N00b question here:

What is the foam supposed to do? Keep a sinking boat at the surface of the water (i.e. if it is already sinking it still has enough floatation to keep it surfaced)?

Re: no foam in boat

The main reason boats over 20' and some I/O's (level floatation)don't require foam is the amount of foam that would be required. On larger boats there would be so much foam needed you'd have to pull a barge full of foam along with you to have enough to float a boat with twin big block engines. It takes a cubic foot of foam to float about 60lbs. To get an idea a 5gal can is less than one cubic foot in volume. So think about finding space for enough 5 gallon cans to float 2000lbs in a small boat. Thats of course after you do all the figuring to find out how much all the different materials displace in water. Then to further complicate everything you need level flotation on some boats and now you can't just put the foam anywhere you want to. IMHO if you are putting flotation in a boat after restoring it and you don't put exately the amount that was originally in it from the manufacturer and in the same places you are just wasting money. If your going to add flotation to a boat without any and you don't do all the calculations for the correct amount and placement you are wasting your money. No matter what you use, noodles, air entrapment, expanding polyurethane, blue sheets, pink, etc. You have to calculate how much you need or its gonna sink anyway (if you have a serious problem). Just throwing flotation at a boat and putting however much you can and where ever you can find room don't cut it.

Re: no foam in boat

Georgesalmon said:

The main reason boats over 20' and some I/O's (level floatation)don't require foam is the amount of foam that would be required. On larger boats there would be so much foam needed you'd have to pull a barge full of foam along with you to have enough to float a boat with twin big block engines. It takes a cubic foot of foam to float about 60lbs.

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Lots of boats >20 ft have foam... You are overthinking it, you are calculating keeping the dry weight of the boat out of the water. That isn't the goal of the foam, it is to keep it from going to the bottom. Fiberglass by itself isn't really that dense, somewhere around 1.5g/cm3, which means it isn't that much more than the water itself. (essentially submerged fiberglass weights 25% of what it does on dry land) Any wood on board is less dense, so although that counts in the positive column on land, on water it floats, taking away from boat weight.

In reality what happens is that it becomes EASIER to hide foam in a large boat than a small one!

Re: no foam in boat

I did say to calculate the weight of different materials submerged. Because when the foam comes into play is not until AFTER the boat sinks to the gunwales. And, the cast iron in an engine may displace some water but can not be completely discounted like wood. Wood that is not in the water when the boat is submerged still adds to the weight and must be accounted for. 100 lbs of lead shaped in a block might displace a couple lbs or water and of course sink, but 100lbs of lead shaped like a boat may displace more 100lbs of water and float.

Re: no foam in boat

Wow, great forum! Learn something new everyday.

Re: no foam in boat

Georgesalmon said:

100 lbs of lead shaped in a block might displace a couple lbs or water and of course sink, but 100lbs of lead shaped like a boat may displace more 100lbs of water and float.

Click to expand...

Reference:

http://upload.wikimedia.org/wikipedia/commons/8/81/USS_Nimitz_in_Victoria_Canada_036.jpg

Re: no foam in boat

CHARGER2 said:

N00b question here:

What is the foam supposed to do? Keep a sinking boat at the surface of the water (i.e. if it is already sinking it still has enough floatation to keep it surfaced)?

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It keeps it on the surface, so that it can be spotted, the passengers have something to hang on to until they die of hypothermia, and the hull can be salvaged. But in my experience--too many, thank you--they roll and leave only a small part of slippery pointed hull sticking up.
I've seen them lay flat at the surface upside down, and have the bow standing straight up like a small tower. Few remain upright so you can sit in them like a bath tub. They start that way but it's like sitting on a unicycle: shift two fingers to one side and over it goes. So while it's an important safety feature, if you don't understand its limitations, it's a false safety feature.

If you are ever in the situation you stay with the boat. try to gather all the floating stuff around you (debris field) that you can and keep it together (tied, preferably). You may need it to float and it makes you easier to spot. Tie some lines to the hull to hang on to but don't tie yourself to them, in case the boat decides to sink anyway.

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To the O.P.......

You have a hole in the hull (Bottom) of your boat and you can see the underside of the deck thru the hole! Am i thinking right?