the truth about noodles

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Boater45

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Re: the truth about noodles

Dead horse:
 

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Bondo

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Re: the truth about noodles

Also, boats like the Boston Whaler line, where the hull is nearly solid foam, get a majority of their strength from the foam.

Remember in the 60's and 70's there were numerous boats that had no stringers at all, just solid foam in a fiberglass hull. They were made by Chrysler and others.

Jeez,...
I'm tryin' to swear off these Foam threads,... My thoughts on Foam are well documented already...:rolleyes:
But,...
For the most part, I gotta Disagree about the degree of Strength gained from the actual Foam factor....

Yes, Foam can be Tough,...
Yes, there are different grades,+ compositions of it...
After having Destroyed enough junk, I've come to see the obvious...
The only Strength gained by foam is it's Compressive strength...

The True Strength of a fiberglass hull is merely the Structual Shapes formed by the fiberglass...
It's basically a Monoqote(sp) frame....
Hulls without wood use the compressive strength of the foam to hold onto their Structual Shape, which is the Strength of it...

I've seen the old Whalers with Rotten foam cores,...
Hitting waves, the boat bottom pounds against the underside of the deck,...
Standing on the deck is "Soft",... You'd swear it'll just collapse bouncin' across the river...
That's because it relies on the Compressive strength of the foam, that went away when soaked with water,+ repeatedly frozen,+ thawed...
If Whaler had wasted some glass on building stringers into 'em,...
You could Drain it,+ it'd last ForEver....

The other brands that did the foam cored stringers are about the smartest format out there,...
If they were build with Enough Glass to manage Flex, they wouldn't need the foam at All,...
It'd just be a lay-up mold...

Your Hardtop project probably relies on foam for Strength more than Most hulls out there...

Everybody knows, There's No such thing as a WaterProof compartment in a Boat,...
Ask anybody on the Titanic...
If folks are so scared of their boat,+ the water,...
Fill it with Foam,... But provide DRAINAGE...
If you're rebuilding your hull,... Build in some Structure,.. That's where Strength comes from...

In My Humble Opinion anyways......;):)

I'll continue to keep the PFDs,+ safety equipment up to date,...
And the hull Drained...

Bill...
 

BigBoatinOkie

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Re: the truth about noodles

I used to spray closed cell urethane foam for a living. Generally we used it as a commercial roofing material. As an example for potential customers, we would spray a large piece of 1/4 inch plywood with 2 or 3 inches of foam, put on a couple of saw horses and my boss would stand in the middle of it without it breaking. I'd say that was a fair amount of tension on that piece of foam. Tensile strengh you might say. Yes it's compressive strength is more substantial, but it also adds a great deal of tensile strength to anything it's applied to as well. The real strength is still in the fiberglass. We used 3 lb. foam by the way.
 

bananaboater

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Re: the truth about noodles

it is for this reason :p, i am thinking about lashing my noodles together in 4 groups(since this is the most # of people on board while fishing) this way when a drug smuggling cigrette boat exits a hidden cove and chops my boat in half :eek:. we can each grab a group of noodles and float to safety ;).

or i could just move out of their way :)

Wait, I can float with one noodle and I am phat. Seems to me if you did not pack them in 4s the opportunity and odds to find one among (after being cut in half) many would be greater right? Increase the odds by a factor of three. Timfives may want to do some math on that to check my calculations. ;)

Albert
 

jspano

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Re: the truth about noodles

bananaboater posted
Wait, I can float with one noodle and I am phat

Sir i know pool noodlers! And you sir are no noodler!!!!
 

oops!

Supreme Mariner
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Re: the truth about noodles

in reguards to the amount of noodles needed...

lets not forget that boats do actually have SOME natural buoyancy.

all parts of a boat displace water.....there for natural buoyancy of some measure.
bear in mind a motor block will have less than a frp plywood deck

the pool noodles will not have to hold up ALL the weight.....but some or most.

carry on.....good thread

cheers
oops
 

saildan

Petty Officer 1st Class
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Re: the truth about noodles

Wait, I can float with one noodle and I am phat.
But you're a human body not a boat.

buoyancy.jpg


The more submerged an object is, the more affected it is by buoyancy. The deeper you are in the water, the "lighter" you are - a human body submerged to waist level will experience only 40%-50% of its weight on land. Standing in chest-deep water reduces weight bearing to 25-30% of body weight and 10% when immersed to the base of the neck.

And Fluffy guys float real good.
:p
http://www.youtube.com/watch?v=Kw_eYpn7alo


 

erikgreen

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Messages
3,105
Re: the truth about noodles

Wow.. quite the debate going on.

I thought I'd interject a few corrections and some numbers. I'll try to keep this short and simple, although that rarely seems to happen in my posts :)

First, the max buoyancy a cubic foot of anything in water can provide is about 62 lbs. That's if the 1 cf object has no weight of its own and displaces all the water. You can not get more buoyancy than that unless you're floating in something other than water. FYI, sea water is slightly denser than fresh due to dissolved solids, so it provides more buoyancy, but not much.

Pool noodles are usually extruded polyethylene with a density of 1.8 lb per cubic foot or near that. Source: http://www.alibaba.com/product-gs/249714122/White_Extruded_Polyethylene_FOAM_POOL_NOODLE.html

The pink or blue insulation foam from the big box stores (which is polystyrene or polyisocyanurate) has a relatively low density. Density is about 35 kg/cubic meter or 2.1 lbs per cubic foot.

Source: http://www.foamular.com.au/roofing_waterproofing.htm

This puts it at about the same density and buoyancy as standard pourable floatation foam. But due to its chemistry and manufacture it has an extremely low shear and compressive strength, lower than pourable or structural foam.


So, to answer the main question posed by this thread, the pool noodle foam will provide effectively slightly more bang for the buck IF and ONLY IF it's packed in so that no air spaces remain... IE not in pool noodle form.

1 cubic foot of anything provides about 62 pounds of buoyancy by displacing water.. per Archimedes. However, unless you're displacing water with vacuum, the same cubic foot also adds to the total weight that must be floated. You add the weight of the foam or whatever to the weight of the boat or person to be floated.

Since the noodle foam weighs a bit less (.2 lbs) per cubic foot it does a very slightly better job than the pourable foam at providing floatation, but it's not a big difference and you have to pack it in so no air space remains, which is a lot of work.

There may be other reasons to use noodle foam like availability or cost, but I won't touch on those here.

FYI, a cubic foot box made of 24 gauge aluminum and filled with air would provide the same buoyancy for less weight than the pool noodle.

Humans float because they're almost all water. Even a 300 lb guy like me is nearly neutrally buoyant... if I blow all the air out of my lungs and suck in my stomach I can sink - I do this in each scuba class I help teach. This is the case for most people, although some overweight folks can't sink regardless.

So most people don't need much floatation to stay on the surface. One pool noodle will do. Of course, you won't get up out of the water because once your head/arms whatever is out then it's not floating any more and has to be supported by the part still in the water. Try it at the pool.. float on the surface then raise your arms out of the water. You'll start to sink lower.


One more foam point - structural foam. In any density above about 4 lbs/cubic foot polyurethane (or any other rigid) foam can be structural (actually any density can, but it's not really effective below that level).. it can be used to stiffen panels it's poured next to, or as a core in composite panels. It can fill voids with rock hard but still positively buoyant material.

Stringers filled with foam may well need it there. Because "it depends"... not all stringers are made the same. Some have heavy enough glass that the glass alone does the work of stiffening the hull, most of the ones here use a plywood core to provide most of the stiffness and have protective glass over that.

Some very light, strong stringers however are made as long sandwich panels.. the strength comes from the two fiberglass skins being held parallel to each other and not being allowed to move in certain ways. They're stronger and lighter than most other stringer types, and they don't rot. They're also harder to make properly and more expensive.

For these type of stringers, you cannot remove the foam to make them hollow, because they'd become too weak and flexible. Just like you can't not use a plywood core for most of the boats here. Sure, you can layer on glass until it's strong enough then remove the core, but you'll need a lot more glass than you think and probably additional side stringers.

So despite the fact that people seem fond of saying "the core doesn't matter, the glass does the work" around here, be warned that the core may well matter in your boat :)


Erik
 

erikgreen

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Re: the truth about noodles

I used to spray closed cell urethane foam for a living. Generally we used it as a commercial roofing material. As an example for potential customers, we would spray a large piece of 1/4 inch plywood with 2 or 3 inches of foam, put on a couple of saw horses and my boss would stand in the middle of it without it breaking. I'd say that was a fair amount of tension on that piece of foam. Tensile strengh you might say. Yes it's compressive strength is more substantial, but it also adds a great deal of tensile strength to anything it's applied to as well. The real strength is still in the fiberglass. We used 3 lb. foam by the way.

Depending on which side he stood on, he was either exercising the compressive or tensile strength of the wood. If you had put a second piece of wood on the other side and let it cure, you would have had a cored sandwich panel, which would have been several times stronger and stiffer than the single board sprayed with foam. Probably you could have dropped the wood down to 3/16" ply and gotten the same strength as the 1/4 with foam if you'd used a second piece of wood.

At a higher cost, of course.

The wood panel, by the way, would have been strong enough to be used as part of a boat hull with some waterproofing... no glass required. The reason we usually use glass though is to save weight and get even more strength.. the tensile strength of glass is very high. It's also lighter and smaller than a wood sandwich. To work though it needs a core that holds it in place. The 3 lb foam can do this with or without the wood, although not as well as 4 or 8 lb. Keeping the wood in place would make the sandwich stiffer than without, but also heavier. Most of the stiffness gain would come from the fact that the two skins are held farther apart than without the wood, not from stiffness of the wood.

Combine wood's weight, cost, susceptibility to rot, etc and you get an idea why we just use fiberglass over foam or wood cores rather than using wood skins.

Erik
 

avimgod

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erikgreen

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Re: the truth about noodles

Depends on where you get pour-in. From US Composites, their[SIZE=-1][SIZE=-1] FOAM-0280[/SIZE][/SIZE] kit, which is 2 lb density foam, costs $244 plus shipping and will fill 40 cubic feet.

Erik
 

avimgod

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Re: the truth about noodles

Depends on where you get pour-in. From US Composites, their[SIZE=-1][SIZE=-1] FOAM-0280[/SIZE][/SIZE] kit, which is 2 lb density foam, costs $244 plus shipping and will fill 40 cubic feet.

Erik

Their 2part is what I have been looking at, but got intrigued by the , conect hose, turn on tank, spray approach of the Versifoam... it comes with all consumable items needed for the price...
 

erikgreen

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Re: the truth about noodles

I guess if you'd like to spray it, sure :)

I'm ok with mixing it up and pouring in the limited places I use the stuff.

Erik
 

avimgod

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Re: the truth about noodles

I guess if you'd like to spray it, sure :)

I'm ok with mixing it up and pouring in the limited places I use the stuff.

Erik

I have been reading the pool noodle threads, and not really digging the idea..

The pre-formed foam sheets are intruiging idea, but again,not real enamored with the idea.. pour in has been leading the way for me as my boat is a family boat used in big fast moving river, and I would like to add as much buoyancy for flotation in the event I should ever swamp her.

I will definitely be using foam, and either the spray in or pour in will be my route..

I will be replacing all the foam in my floor, to the outboard sides of the stringers, from bow to stern... all new wood, all new foam, all new boat for the new boating season..

On a side note, Pool Noodles, Arent they flamable?
 

erikgreen

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Re: the truth about noodles

Most foams are. I believe that includes the PU boat foams. Cover 'em up and keep away from open flame :)
 

coostv

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Re: the truth about noodles

This does not pertain to noodles, but I figured why start a thread for this question.

Why not do both pour in and the pink or blue glued to the hull to save some money on the pour? I suppose this would pertain more to a fiberglass boat than a tinny.
 

erikgreen

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Re: the truth about noodles

Well, I dunno what the noodles cost, but for me the pour-in stuff isn't THAT much more expensive. Why monkey around with experimental solutions if you're not going to save at least half the cost?

My usual method of savings is to not install foam at all... I haven't built or modified a boat yet that it was a good idea to fill the bilges with stuff that won't drain properly.

Erik
 

ezmobee

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Re: the truth about noodles

I don't think anyone has yet recommended anyone with a glass boat use noodles for floatation. For aluminum boats, where the pour in foam provides no needed structure and has proved to cause issues I feel noodles are a viable alternative. This is what was OEM in my boat:

DSCF2225.jpg


A pile of white, water absorbing, foam strips. Noodles have to be at least as good as that.
 

timfives

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Re: the truth about noodles

Wait, I can float with one noodle and I am phat. Seems to me if you did not pack them in 4s the opportunity and odds to find one among (after being cut in half) many would be greater right? Increase the odds by a factor of three. Timfives may want to do some math on that to check my calculations. ;)

Albert

Albert,

You are correct, however as stated before, the noodle doesn't have to float your entire weight, as the human body has its own buoyancy.
T
 

Bob_VT

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Re: the truth about noodles

So how many cadaver's would it take to float the boat :eek:
 
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