Flotation - some better than none?

[aeviaanah]

Just gettin to the point where I am going to add flotation to the boat. I have done the math and I need a ton of foam to meet required flotation. My question: is some flotation better than none? I keep telling myself its a dumb question but I need to ask.

 

[5150abf]

Re: Flotation - some better than none?

The purpose of the foam is to keep the boat from sinking so if you don't put enough in the boat will still sink it will just take longer to get to the bottom.

I pulled the foam from my boat and never replaced it BUT, I river fish and am never more than 60' from shore and I trailer my boat so if its on the water I am in and I have an alarm on my bilge so if I take on water the alarm sounds well short of having a problem.

Logic would dictate you use enough or none because not enough won't work.

 

[jigngrub]

Re: Flotation - some better than none?

Meh, safe boating is overrated eh?!

I have too much time and money invested in my boat to even think for a second about scrimping on floatation... but it doesn't seem to bother other people... it's prolly just my OCD.

 

[tpenfield]

Re: Flotation - some better than none?

Just gettin to the point where I am going to add flotation to the boat. I have done the math and I need a ton of foam to meet required flotation. My question: is some flotation better than none? I keep telling myself its a dumb question but I need to ask.

I did the foam flotation thing on my Catalina 22 sailboat a while back. The amount of flotation depends on how high you want the boat to sit in the water. Think of it as a 'yes or no' kind of answer. It has to have enough to float, or what's the point; it will sink anyway.

Keep in mind, that the boat's weight will displace water when submerged. You could factor that into your calculations to reduce the amount of flotation needed. It won't be all that much, but it could make a difference. If your preference is to float higher in the water (once you are swamped), then go for a full compliment of foam, i.e. enough for the boat's total weight.

 

[Maclin]

Re: Flotation - some better than none?

What size and type of boat are we talking about?

 

[jacoboregon]

Re: Flotation - some better than none?

If it's worth doing... It's worth doing right.

 

[cyclops2]

Re: Flotation - some better than none?

At last check of foam requirements it had to be AT LEAST this good. See....USCG safety site..... look up the... construction section....foam flotation.
It has been years since I visited it. VERY good information site for a D I Y project. Not sure if Foam Companies can put on their foam product that it is USCG Approved.

 

[cyclops2]

Re: Flotation - some better than none?

Lots of USCG approved companies selling Polyurethane 2 part foam. A web search of.... USCG approved foam flotation will get you what you need.

Seems only the ...60 pounds of flotation per EXPANDED cubic foot is approved. The stuff can start foaming in 45 seconds !! So read ALL the instructions & do small batches at a time.

 

[Frank Acampora]

Re: Flotation - some better than none?

What is a "ton" of foam?

Remember that one cubic foot of foam will displace approximately 64 pounds of water. SO: if your rig weighs 1000 pounds (considering all loads), you will need 15.6 cubic feet of foam to remain neutrally buoyant. This would be a block 2.5 feet on all sides in size. Not really a lot considering you would spread it through the hull. --And---actually it would take a bit less if you consider the water displaced by the hull and interior.

 

[zopperman]

Re: Flotation - some better than none?

I used sheet foam. It works well and I met the USCG foam req's.
You can see it in my thread in my sig...

 

[aeviaanah]

Re: Flotation - some better than none?

Its a 12' aluminum boat with a 15 hp 4 stroke.

Boat weighs about 150lbs empty
Motor weighs 120lbs
Fuel tank and battery are another 100lbs


I figured about 10.5 cubic feet of foam.

 

[cyclops2]

Re: Flotation - some better than none?

Do not forget to add more foam for the maximum # of people the boat can carry. Assume adults. They are your friends.

My boat is rated for 8 people. I have life vests everywhere in a 18 1/2' boat.

 

[cyclops2]

Re: Flotation - some better than none?

For that sized boat . Just buy a Blue Foam floating dock piece. They are very good. Cut the 2'x3'x 6',8' or 10' length up as you need pieces. under seats. You can use G E RTV Silicone Rubber to hold the foam chunks in place. Works very well in our racing boats. Put enough lines of RTV to really get some grippage area. The Blue Foam resists sun & UV rays.

 

[oops!]

Re: Flotation - some better than none?

we are just talking about an alunminium row boat here......go to home depot.....and get some rigid blue foam insulation.....its cheap and they come in 2 inch thick sheets.

cut it up and put it under your bench seats. stand it on edge so it wont flop around you can always wrap some tape around it if it flops.

i would not use the pour in expandable foam in this situatiuon

 

[Alwhite00]

Re: Flotation - some better than none?

I have a question - It seems as if the "water logged foam" issue is always comming up, Especially on older boats. Why the hell did they use foam that absorbs water (or does all foam do that?) and obvously if you have any ammount of water in your foam it is not going to work - Just seems like a bad design right from the start.

LK

 

[cyclops2]

Re: Flotation - some better than none?

There is open cell, semi-open cell & fully closed cell types to pick from.
Only use the CLOSED CELL type.

 

[oops!]

Re: Flotation - some better than none?

I have a question - It seems as if the "water logged foam" issue is always comming up, Especially on older boats. Why the hell did they use foam that absorbs water (or does all foam do that?) and obvously if you have any ammount of water in your foam it is not going to work - Just seems like a bad design right from the start.

LK

after a few years of being around water .....pour in closed cell foam will start to break down.....thats when the water logging starts

 

[cyclops2]

Re: Flotation - some better than none?

I have never seen the Blue Foam ( closed cell by DOW foam ) ever soak up water. It will slowly crumble away after 15 to 20 ?? years under wood floating docks. NEVER soaked up water.

 

[H20Rat]

Re: Flotation - some better than none?

What is a "ton" of foam?

Remember that one cubic foot of foam will displace approximately 64 pounds of water. SO: if your rig weighs 1000 pounds (considering all loads), you will need 15.6 cubic feet of foam to remain neutrally buoyant. This would be a block 2.5 feet on all sides in size. Not really a lot considering you would spread it through the hull. --And---actually it would take a bit less if you consider the water displaced by the hull and interior.

Also need to take into account the density of the hull material... That can make a HUGE difference. If you have a 100% wood boat, you don't need nearly as much foam (or any) to keep it afloat, compared to the identical metal hull.

 

[cyclops2]

Re: Flotation - some better than none?

Smokey

Most of todays new & old woodies have been Epoxied to death to seal them. HEAVY now. Might not even float at all.

Got it !

Fill the woodie with water. If it refuses to sink. You are OK ??