pop bottles instead of foam

[dirtyoldman]

I was thinking about it the other day and got to thinking about using pop or water bottles instead of foam under the deck for flotation. They weigh almost nothing and are cheap and won't get waterlogged.

Is there any reason not do do this?

 

[Bondo]

Re: pop bottles instead of foam

Ayuh,...

Search the archives,... "Floatation Foam" should keep you busy for a couple of Months...

That's an Idea I've been talking about for Years,...
And,...
The Whole Foam Vs. Anything Else has been Beaten to Death here...

 

[kandil]

Re: pop bottles instead of foam

In some boats the foam is structural and is needed for the strength of the boat.

 

[slasmith1]

Re: pop bottles instead of foam

In some boats the foam is structural and is needed for the strength of the boat.

Actually in virtually all modern frp boats the foam is structural not for buoyancy. this is typically only used in smaller boats (less than 21 ft) as most mid sized and larger boats have true bulkheads and the fiberglass is thick enough to give the boat enough strength to avoid foam.

 

[salty87]

Re: pop bottles instead of foam

they also don't displace water effectively, lots of air space between them. that means you'll still get a fair amount of water in the boat...how much water does a soda bottle displace? who knows? uncharted territory there

foam doesn't rot boats, water does. allow for drainage and you can still use foam. larger brains than are on this site have worked on designing foam, lots more research than anyone here can afford.

i don't think foam is structural on most modern boats, over 17 feet at least. the hull, stringers, and deck do the work if built properly.

 

[JorgeE]

Re: pop bottles instead of foam

OK guys...
Since I'm at teh initial stages of redoing my Celebrity 224SE, and will be facing this in a few weeks...
I won't leave the foam out - I realize it's there for a worst-case scenario, but I want the safety for my family and friends.
I'm pondering the same thing as I look forward to my project, and I have some questions:
1- How about pop bottles AND foam. The bottles will reduce the amount of foam used, foam protects bottles and there is full flotation since the space between bottles it taken up by foam.

I understand putting in drain holes at center-rear of each compartment, but... some more questions then pop up:
2- When the foam is poured in, won't it effectively plug up these drain holes?
3- These holes will not allow water that may be in the bilge to get into the compartments, since foam is in there, it won't just slosh in and slosh out...

Thanks... this is my first time to replace floor on boat, and to work on stringers, and I've learned MUCH from gus on the forum already - and expect to learn more.

Jorge

 

[salty87]

Re: pop bottles instead of foam

why use the bottles at all? they are the weak link in that chain. the foam will generate a decent amount of heat as it sets. what will the effect be on the plastic bottle? will you be left with voids in the foam from the bottle changing shape? i dunno

poured foam will plug any gap it touches. i lined my hull with plastic when i poured the foam. this made foam blocks that fit the area very precisely. pull the plastic off the foam and the blocks will allow water to move around and under the foam. i probably used 15% less foam than by pouring it into the hull, a fair trade in my mind for drainage.

 

[sschefer]

Re: pop bottles instead of foam

There was a post that I read a while back about using Pool Noodles, (follow this link to see what they are: http://www.poolrafts.com/653.html ).

I wouldn't buy them at that website, I got mine at a local pool supply center for .99 each. I put them under the deck of a 14' Tinny that I had layed aluminum stringers in. Three on each side is all I needed to provide both support and floatation. They work great!

The main reason I decided to use them was because I have had them for the kids that swim in my pool and these things get abused and left in the pool for weeks at a time during the summer. The ones I have are four years old and don't show any signs of deterioation, flaking or water logging.

I'm putting them under the deck of my 18' Tinny too.

 

[Bondo]

Re: pop bottles instead of foam

I understand putting in drain holes at center-rear of each compartment,

Ayuh,...

While it's usually Aft, Center for the Limber Holes,....

The true rule of thumb is;
Aft, at the Lowest point, normally seen....
In a side of center compartment, it could be on either side...

But,... You've got the Right Idea,.... It's the Water,.. Get Rid of it....

 

[Bsquared]

Re: pop bottles instead of foam

"how much water does a soda bottle displace?"

Uh, this should be pretty easy to figure out, given that liquid capacity is written on 'em OK, you have to subtract the weight of the bottle, but that's an easy thing to check.

I wouldn't be too worried about degradation out of sunlight, but another reason to avoid gas in the bilges...

Sailors use plastic bottles and inflatable bags all the time as a lightweight solution. I've got an early 80's Laser with a factory-installed plastic bottle that just slides around in there.

If the boat was using foam for structural reasons, you don't want bottles.

 

[arks]

Re: pop bottles instead of foam

This thread reminds me of a Mythbusters episode. They wanted to know if ping pong balls could be used to raise a sunkern boat. Pretty interesting stuff, and they were actually able to do it!
Their biggest challange was figuring out how to physically get them into a submerged hull. As I recall, it took something like 20,000 balls to get their test boat to neutral bouyancy.
That's a LOT of balls....

 

[Mark42]

Re: pop bottles instead of foam

Luckilly for us if you want floatation, there is a convenient product already developed that works really well. Its called "floatation foam", a bit pricy, but it works really well.

BTW, does anyone know if Walmart TCW3 oil is as good as the brand name TCW3 oil? Or which oil is the best?

And while we're at it, is it best to solder or crimp electric connections?

Does poly stick to epoxy?

Do you have to use marine grade plywood in a rebuild?

 

[sturdavj]

Re: pop bottles instead of foam

OK Mark42, I am prompted to respond to one of your baits, I?ll leave the rest for someone else to bite on?

If you don?t mind chasing down intermittent electrical problems then use crimp connections. If you want to spend your time fishing/boating than solder your connections, using rosin core solder only. Providing one knows the difference between a cold joint and a quality solder job.

In either case be sure to tug test your connections before leave them.

 

[sschefer]

Re: pop bottles instead of foam

OK Mark42, I am prompted to respond to one of your baits, I?ll leave the rest for someone else to bite on?

If you don?t mind chasing down intermittent electrical problems then use crimp connections. If you want to spend your time fishing/boating than solder your connections, using rosin core solder only. Providing one knows the difference between a cold joint and a quality solder job.

In either case be sure to tug test your connections before leave them.

Don't forget the Scotch Kote...

 

[sschefer]

Re: pop bottles instead of foam

Mark you forgot my favorite... Will a 350gph bilge pump feed a 2.5gpm washdown pump.

 

[AguaSki]

Re: pop bottles instead of foam

Does poly stick to epoxy?

Does epoxy stick to poly?

 

[slasmith1]

Re: pop bottles instead of foam

Mark you forgot my favorite... Will a 350gph bilge pump feed a 2.5gpm washdown pump.

and like can I use that same pump to get gas down the dock from my pinto 'cause gas costs too much at the marina?

 

[sschefer]

Re: pop bottles instead of foam

Nah, just fill you pinto up at the Marina and give it some resale value.

 

[sschefer]

Re: pop bottles instead of foam

Does epoxy stick to poly?

Yeah, good question. How do you suppose the get teflon to stick if nothing sticks to it.

 

[sschefer]

Re: pop bottles instead of foam

I was thinking about it the other day and got to thinking about using pop or water bottles instead of foam under the deck for flotation. They weigh almost nothing and are cheap and won't get waterlogged.

Is there any reason not do do this?

Apparently others here don't feel it's a good idea. Structurally they won't do much because air is easily compressed. You could fill them with water and they would be structural since water is not compressible but that wouldn't be very logical.

For floatation you would immediately restrict yourself to elevations that are equal to or near the elevation that you were at when you capped the bottles. At higher altitudes they will expand and possibly burst or even lift your deck and at lower altitudes they will contract and do little or no good.

Acoutstically, I'm not sure what it would sound like when you slapped a wave and it resonates through all of those air chamber amplifiers.

So, my vote is no. I think you need something a little more stable like foam or the noodles that I've tried and found to work.