Flotation - some better than none?

[rallyart]

Re: Flotation - some better than none?

aeviaanah, any foam attached will help. If your boat flips and some air gets trapped under the bow that will help float the boat. If you have closed cell foam elsewhere too then more of the boat floats. If your hull weighs 150, the engine 120 and the battery 60 then you need to float 330#. The fuel tank is almost neutral as the fuel is lighter than water and any air in it is much lighter. People are neutral bouyant. Loose gear will fall out or add some more foam to cover what is going to sink fast. If the metal hull fills with water it is handy when you can retrieve it without a Scuba set.

 

[Alwhite00]

Re: Flotation - some better than none?

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

Golly, You would think that would be a no-no when building a new boat - I guess if they pass the original flotation test you can sell as many as you want. (orig mfgs)

LK

 

[oops!]

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.

blue closed cell rigid foam is different than pour in foam. and it is a good product for this purpose. However.....in a fibreglass hull....most of the foam today is used for a structural reinforcment due to the high anti crush strength.

the blue rigid foam will not work in a situation where it must contour the hull and provide structural rigidity. this is where pour in foam really does a great job......but over time, closed cell pour in foam will absorb water.

this is why i suggested to the OP to use the blue rigid foam...... due to excellent long term water resistance and that no structural value is necessary with this craft

 

[oops!]

Re: Flotation - some better than none?

Golly, You would think that would be a no-no when building a new boat - I guess if they pass the original flotation test you can sell as many as you want. (orig mfgs)

LK

that pour in foam is what makes boston whalers so unsinkable........

however...they are a nightmare to fix if the hull is penetrated. once the hull is penetrated, the foam will get wet. once it starts water logging, it takes forever for the water to stop dripping just to get it to the glassing stage.

the real problem with those boats is that the owners rarely know if the boat has a hole in it because they cant see the water !

 

[smokeonthewater]

Re: Flotation - some better than none?

also nothing lasts forever..... It's real crappy that nike made my shoes in a way that they are wearing out and I have to buy new ones real soon

In case it hasn't been said flat out yet..... If your choices are:
1 No foam
2 Some foam
3 Enough foam

then no some foam is NOT better than no foam

 

[cyclops2]

Re: Flotation - some better than none?

" I am just a little pregnant right now. " :facepalm:

 

[V153]

Re: Flotation - some better than none?

this is why i suggested to the OP to use the blue rigid foam...... due to excellent long term water resistance and that no structural value is necessary with this craft

Couldn't agree more. Particularly this application. Fill baby fill!

Anyway. Folks most boat builders put in just a lil more flotation than required by law. Best case scenario your sinking boat will swamp & stay upright. Next case it'll capsize & stay at the surface. Worst case ... well y'know.

Not to start any fights but it is possible to sink a Whaler ...

 

[smokeonthewater]

Re: Flotation - some better than none?

Not to start any fights but it is possible to sink a Whaler ...

Ok now THAT DOES IT! now I'm gonna have to kick your.......... wait, um, what were we talking about?????

LOL

 

[sschefer]

Re: Flotation - some better than none?

http://www.uscgboating.org/regulations/boatbuilder_s_handbook/flotation_part1_g.aspx

This will help you figure out the correct calcs. There is a little known loophole in the rule and that's if the boat is sold without a motor and it has oar locks it is considered a row boat and doesn't need foam. The point being that if you buy a boat that is considered a row boat and you put a motor on it do you also have to add foam...The answer... NO.

Therefore I agree with all the others that said either make it so it will last through an 18 hour swampped condition without sinking or leave it out.

 

[sschefer]

Re: Flotation - some better than none?

Not to start any fights but it is possible to sink a Whaler ...

LOL, yes it is but why would you want to?

 

[fishrdan]

Re: Flotation - some better than none?

Remember that one cubic foot of foam will displace approximately 64 pounds of water.

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.

According to Franks 64#/cuft of foam (sounds right) you'll only need a little more than 5 cuft or foam to float the boat, motor and battery. I didn't include the fuel tank as it will float. To keep everything from sinking, you don't even need 5cuft of foam as water displaces some weight.

My 14' Tracker jon boat had something like 9 cuft of foam, before I hacked most of it out and replaced it with sheet foam. The max capacity of the boat is 628#, 9 cuft of foam = 576. Take away the hull weight displaced by water and it looks like Tracker provides flotation for the max capacity of the boat, so everyone and everything stays floating....

 

[H20Rat]

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.

People are neutrally buoyant... Of course, that means everyone is going to be REALLY wet, if you want to get them out of the water at all, yeah, you need more foam.

 

[smokeonthewater]

Re: Flotation - some better than none?

According to Franks 64#/cuft of foam (sounds right) you'll only need a little more than 5 cuft or foam to float the boat, motor and battery. I didn't include the fuel tank as it will float. To keep everything from sinking, you don't even need 5cuft of foam as water displaces some weight.

My 14' Tracker jon boat had something like 9 cuft of foam, before I hacked most of it out and replaced it with sheet foam. The max capacity of the boat is 628#, 9 cuft of foam = 576. Take away the hull weight displaced by water and it looks like Tracker provides flotation for the max capacity of the boat, so everyone and everything stays floating....

the 5 cubic feet would float the boat under water with it only just touching the surface

I'd consider 1.5 times the amount of foam needed to just float the boat motor and battery to be the bare minimum..... you need enough boat floating above water to be readily seen by another boater..... That just might be an amount that allows a fellow in a bright orange life preserver to climb on top..... another thing to consider is that if it floats high enough to get the transom above water you might actually be able to hang off of the bow while the bilge pump empties the water and get to climb back in.

If you are gonna float it, really FLOAT it

 

[fishrdan]

Re: Flotation - some better than none?

the 5 cubic feet would float the boat under water with it only just touching the surface

Yeah, I guess I didn't state that right as I was just talking about purely "keeping the boat from sinking". Theoretical, how much flotation do you need to keep it from sinking. It didn't come across that way, sorry about that.

I do agree that there should be additional flotation, for gear and occupants. When I replaced the foam in my jon boat I put in more than was there to begin with, better safe than sorry.

 

[cyclops2]

Re: Flotation - some better than none?

Many years ago I read all the stuff on the USCG BOAT BUILDERS sections. They had a formula, simple one, that had a certain % of the hull above water to increase surviveability of passengers in the boat. The section is really about company built boats.............

But there is no difference in standards when we are talking about or designing safety into a boat.

Planes fall.
Boats sink.
Cars stop. And we wait for warm, dry help to arrive.

 

[V153]

Re: Flotation - some better than none?

Ok now THAT DOES IT! now I'm gonna have to kick your.......... wait, um, what were we talking about?????

LOL

Ha! Hey I never said it was easy to sink a Whaler ...? Heh heh heh