Hull Foam....why>?

[Georgesalmon]

Re: Hull Foam....why>?

Welllll,,,,That's a bit simplistic, a man nearly floats in the water cause he's already mostly water and doesn't need much extra help. If I tied a 220lb piece of concrete to that PFD it would not float even a little bit. Every material has a different density and size and needs to displace enough water to float or needs help from some foam displacing water for the rest of the weight. Think steel ship that floats but if you rolled up all that steel into a tight ball down she goes.

 

[Grandad]

Re: Hull Foam....why>?

Welllll,,,,That's a bit simplistic, a man nearly floats in the water cause he's already mostly water and doesn't need much extra help. If I tied a 220lb piece of concrete to that PFD it would not float even a little bit. Every material has a different density and size and needs to displace enough water to float or needs help from some foam displacing water for the rest of the weight. Think steel ship that floats but if you rolled up all that steel into a tight ball down she goes.

Ya George. Point taken. I calculated the amount of foam I needed in my boat based on the engine's weight and specific gravity in water, plus the aluminum hull in water, plus, plus plus... However, the original poster didn't seem to understand the basics. As he said "I'm not an engineer", so I dumbed it down to KISS. - Grandad

 

[bigheaded5]

Re: Hull Foam....why>?

Im sorry Granddad but your KISS math....like George first points out, a MAN is already boyant and has foam in his PDF yes, and he may weigh 220 pounds....but your math.... a 2200 pound boat 10x the foam if its boyant, but NOTHING on the boat floats on its own.... I can see at best the foam makign the boat slightly lighter after it sinks.... Im still not convinced its a must do for MY situation. Im in the bay...average depth 5'. I trailer it and never leave it overnight. I have a Bilge pump, 2 battery's and a manual pump if all else fails.

But again....thanks to you all

 

[jigngrub]

Re: Hull Foam....why>?

As for how little foam you think is in your boat remember that everything in the boat when submerged displaces water, for ex: a 50 pound battery might weigh only 25 pounds under water because it would displace 25 pounds of water.

I calculated the amount of foam I needed in my boat based on the engine's weight and specific gravity in water, plus the aluminum hull in water, plus, plus plus...

Too bad your boat has to sink before this law of physics goes into effect.

I'd rather calculate the foam for the total dry weight of everything, that way you don't hardly have to get your feet wet.

Like in this video:
Lund Boat Floatation Video - YouTube

How comfortable do you think you'd be in the boat pictured below in 40*F water compared to the Lund?

^^^^^^^The floatation foam in this boat was calculated for everything submerged and then just a little extra.^^^^^^^

 

[Stumpalump]

Re: Hull Foam....why>?

The foam will only become water logged if you use the wrong kind. So long as it is closed cell (not white styrofoam) it will be fine. You can even use the pink/blue insulation foam board from Lowes/HD in a pinch. As the others have stated, modern vessels are required to have a certain minimum amount of flotation such that 1"-2" of the boat will remain above the water line even if it becomes completely submerged (aka "swamped"). There are also several forms of structural foam that are used alone, or in conjunction with various epoxy and vinyl ester resins to add integrity to the hull. While antique vessels are often exempt, many of us (myself included) find ways to add extra foam/flotation for good measure.

So what is good foam to use? If bought at a home store is the pink or blue stuff going to hold water and disolve with gasoline? I had a Glaston from the 60's that had a fuel tank split. It split wide open and dumped 12 gallons of gas in the bilge. The factory foam was dissolved.

 

[Grandad]

Re: Hull Foam....why>?

Im still not convinced its a must do for MY situation. Im in the bay...average depth 5'.

I suppose that depends upon how tall you are. - Grandad

 

[GaJeff]

Re: Hull Foam....why>?

How comfortable do you think you'd be in the boat pictured below in 40*F water compared to the Lund?

^^^^^^^The floatation foam in this boat was calculated for everything submerged and then just a little extra.^^^^^^^[/QUOTE]

At least it didn't sink completely... just recover and restore all over again!

 

[jbcurt00]

Re: Hull Foam....why>?

I can see at best the foam makign the boat slightly lighter after it sinks.... Im still not convinced its a must do for MY situation. Im in the bay...average depth 5'. I trailer it and never leave it overnight. I have a Bilge pump, 2 battery's and a manual pump if all else fails.

But again....thanks to you all

When you're done using this boat, do you plan to cut it up & dispose of the hull at the local landfill. Removing the flotation foam may make sense to you & how you plan to use the boat, but what about the next guy that owns it.

It'll look good, it'll work, but do you have the new owner sign a waiver that stipulates that he's been informed that there is no flotation foam aboard? What about anyone that boards your boat? Will a waiver cover them? Or the next guy's family?

There is ample evidence that flotation foam SHOULD be used, if you choose not to, for whatever the reason, I'd consider it a mistake.

I never dumped a motorbike, but always wore a helmet... Apparently I didn't 'NEED' it

I've never swamped a boat, or been aboard a sinking vessel, but always wore a PFD. I didn't 'NEED" to as I am an excellent swimmer.

Every boat I've ever been aboard had all the necessary safety gear for fire & life safety (both PFD & throwables) but never used them either, fortunately. I didn't 'NEED' them either.

Have you ever dragged someone out of below 40F rapidly moving water? I have. He was in the water probably 30-45seconds, he was a weird blue/gray color and he could hardly raise his arms over his shoulders enough for us to grab him at our bow & struggle to get him over the stern of our boat. My wife never boated w/ me & my friends again. We didn't even know the guy, he just fell in up river of us. So although WE weren't doing anything unsafe (stupid really) trying to drag this stupid SOB outta the water, we endangered ourselves. Although we were properly prepared & able to render aid, would anyone down river of us have been as prepared to drag 1 of us out?

Hope for the best, plan for the worst........ Pray you never have to find out if you or those around you are properly prepared.

BTW: Despite the cute Sandy Bullock~Harry Connick, Jr movie: HOPE DON'T FLOAT.

 

[WIMUSKY]

Re: Hull Foam....why>?

Not sure the reason for this thread. The members have given overwhelming reasons why a boat needs foam yet the OP poo poos those recommendations and is going to do what he wants, regardless..... Maybe he was bored.....

 

[kfa4303]

Re: Hull Foam....why>?

Well, you know the old saying; "There are old sailors and there are bold sailors, but there are no old, bold sailors."
You can lead a horse to water, but you can't make him install flotation foam, I suppose :/

 

[Landof9000lakes]

Re: Hull Foam....why>?

see me at the bottom...oh stop lol

Ed

Depends on where you are from.

Watch for them and you will see stories throughout the fishing season of guys on the great lakes with fishing boats that were swamped. And the ONLY thing keeping them from drowning or taking a long swim/float was the floatation in their boat.

 

[Landof9000lakes]

Re: Hull Foam....why>?

some boats are so cheaply made today that the foam plays a part in holding them together. In some high end boats such as some Boston Whaler's the foam "is" the core structure, sandwiched between 2 shells of fiberglass.

Boats now are constructed MUCH better than older boats. Pull apart any older sea nymph or starcraft like in so many threads here and compare that to pictures of new hulls from the various builders.

Glass boats (especially bass boats) are much the same. MUCH better construction.


That is why I'm adding the foam to my boat. To make it much more solid feeling in rougher water. Sound deadening and structural benefits far outweigh the issues that it does have.

The boats that are waterlogged have been outside and exposed to water for a LONG time.

 

[Landof9000lakes]

Re: Hull Foam....why>?

Jigngrub that Lund would look similar if it were completely swamped.

Thing is it would suck to be in that boat in cold water.....But having something to hang on to (that boat) vs floating in the lake with nothing but a life jacket could mean the difference between life and death.

 

[bear_69cuda]

Re: Hull Foam....why>?

My Key West floats like a bobber even cut in half! I wouldn't dream of owning or restoring a boat w/o foam...

 

[tpenfield]

Re: Hull Foam....why>?

My Key West floats like a bobber even cut in half! I wouldn't dream of owning or restoring a boat w/o foam...

View attachment 220080

I will say, Bear . . . you did one fine job gluing that thing back together. :thumb:

 

[jimmy wise]

Re: Hull Foam....why>?

I think its that the foam is expensive.....imagine the difference in ride feel. a boat properly foamed verses open space. as for foam being structural its used in autos all the time to stiffen structures . ive seen cardboard tubes 2 inch filled with foam take 10000 psi in a press. I am going back in forth between pour in and pink or blue coated with epoxy. I have heard all theory from plastic bottles, acid bottles, pool noodles, plastic balls and I hear there are sealed plastic flotation bags. the safe bet is pour in because of the calcs on the product. how do you get uniform flotation on non uniform products. I like the pink foam you can make drain channels in it. its a big argument on here

 

[kfa4303]

Re: Hull Foam....why>?

That's the age old debate. The 2 part foam is great for getting into nooks and crannys, holding fuel tanks in place and it offers a bit of structural support, but it's a major PITA to get our of the way should you, or anyone else, ever need to make repairs in the future, whereas the foam board can be removed. Either way, some foam is better than no foam.