Floatation choices
 

Hello all,
I'm building a 10' tunnelhull and need to add some floatation (for my own
peace of mind) in the aft section soon. I have a question concerning the
weight and ease of use of Styrofoam blocks vs. a pourable, 2 part type. It's
a
small boat, so, I could easily cut and form blocks of Styro to fit, but I'd
have to find some way of gluing into place, or, would I be better off using
a pourable type? I'm convinced the Styro is much lighter but not as easy to
make fit snuggly into place.
How about using Great Stuff from Dow, spray it in in small layers/quantities
to allow for a complete cure before adding more?

Anyone have suggestions? What's easier? What's more worth it? Any pourable
Mfgr's suggestions?
I'm a newby to boat construction but NOT to woodworking.

Thanks in advance
Don

I would think poured foam could completely fill a space while ill-fitting cut
foam would have unventilted spaces where moisture from condensations could
collect and promote smelly mould and possible rot.

"Donnie Gilliland" ) writes:
Hello all,
I'm building a 10' tunnelhull and need to add some floatation (for my own
peace of mind) in the aft section soon. I have a question concerning the
weight and ease of use of Styrofoam blocks vs. a pourable, 2 part type. It's
a
small boat, so, I could easily cut and form blocks of Styro to fit, but I'd
have to find some way of gluing into place, or, would I be better off using
a pourable type? I'm convinced the Styro is much lighter but not as easy to
make fit snuggly into place.
How about using Great Stuff from Dow, spray it in in small layers/quantities
to allow for a complete cure before adding more?

Anyone have suggestions? What's easier? What's more worth it? Any pourable
Mfgr's suggestions?
I'm a newby to boat construction but NOT to woodworking.

Thanks in advance
Don






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GreatStuff would not be good. When you spray it on an open surface any
thicker than 1/2" it forms large voids. It also does not set up very hard.
2 or 3 lb two part urethane is available from a lot of places and works well
but you have to be careful placing it so that it will not create voids or
blow out a compartment.

You might check out Fomo Handi-foam. It is a two part 2 lb spray in place
foam that comes with a disposable sprayer. It expands to full size in about
10 seconds and hardens in 2 minutes. At about $40 for a 2 cu. ft. kit it
ain't cheap but you have much better control of the placement and it
develops a very solid foam.

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

"Donnie Gilliland" wrote in message
...
Hello all,
I'm building a 10' tunnelhull and need to add some floatation (for my own
peace of mind) in the aft section soon. I have a question concerning the
weight and ease of use of Styrofoam blocks vs. a pourable, 2 part type.
It's
a
small boat, so, I could easily cut and form blocks of Styro to fit, but
I'd
have to find some way of gluing into place, or, would I be better off
using
a pourable type? I'm convinced the Styro is much lighter but not as easy
to
make fit snuggly into place.
How about using Great Stuff from Dow, spray it in in small
layers/quantities
to allow for a complete cure before adding more?

Anyone have suggestions? What's easier? What's more worth it? Any pourable
Mfgr's suggestions?
I'm a newby to boat construction but NOT to woodworking.

Thanks in advance
Don

Depends.

If it's an open compartment, consider extruded foam, like the 2" insulation
sheets at Home Depot. Either pink (OCF) or blue (Dow) will work fine, epoxy
them in place.

If a closed compartment, why would you need to glue the blocks?

And if it is closed, will it be really sealed? Watertight for the life of
the boat? If so, use the lightest stuff you can find; just needs to float
for hours/days in the event of hull failure.

Will it be closed, but with some possibility of moisture infiltration? If
so, consider that poured-in-place foam will create an ideal environment for
rot - even a tiny amount of water will be trapped between the foam and wood.

Personally, I prefer to fill compartments loosely with light foam and/or
plastic seltzer bottles, and leave some kind of drain plug to let out the
water that always seems to accumulate. I think the soda bottles are lighter
than foam, and certainly cheaper, but only fill about 80 or 90% of the
volume.

There's a Coast Guard boatbuilder's site, but they don't have any specific
requirements for flotation materials, except that it has to be
gas/oil-resistant if in the bilge...

Sal's Dad

"Donnie Gilliland" wrote in message
...
Hello all,
I'm building a 10' tunnelhull and need to add some floatation (for my own
peace of mind) in the aft section soon. I have a question concerning the
weight and ease of use of Styrofoam blocks vs. a pourable, 2 part type.
It's
a
small boat, so, I could easily cut and form blocks of Styro to fit, but
I'd
have to find some way of gluing into place, or, would I be better off
using
a pourable type? I'm convinced the Styro is much lighter but not as easy
to
make fit snuggly into place.
How about using Great Stuff from Dow, spray it in in small
layers/quantities
to allow for a complete cure before adding more?

Anyone have suggestions? What's easier? What's more worth it? Any pourable
Mfgr's suggestions?
I'm a newby to boat construction but NOT to woodworking.

Thanks in advance
Don

How about using Great Stuff from Dow, spray it in in small
layers/quantities
to allow for a complete cure before adding more?

Anyone have suggestions? What's easier? What's more worth it? Any
pourable
Mfgr's suggestions?
I'm a newby to boat construction but NOT to woodworking.

Thanks in advance
Don


Having just faced something similar (an irregular shape I wanted to have
foam in) I can share some info from Dow:

Great Stuff isn't. It's hygroscopic and open celled; in English that means
it will soon have no floatation in the event of a leak or any air
infiltration which can condense moisture.

I'm using the appropriate product, Froth-Pak, from Dow to fill my very
irregular space. The rest of it I'm epoxying from extruded polystyrene
sheets (just to make it more bulletproof and edge-sealed; it's closed cell
and relatively waterproof as a genre). I'm using it for insulation, but
keeping water out is of major importance to the project.

Froth-Pak comes in 1 cubic foot or much larger sized 2-part containers.
Spray it in similarly to Great stuff, but do some external testing first to
get a feel for how much it expands.

Visit rparts.com's user's forum and look for my threads there; Glenn Ashmore
has also used a two-part poured foam successfully, and I know he's equally
anal about keeping water out.

L8R

Skip


--
Morgan 461 #2
SV Flying Pig
http://tinyurl.com/384p2

"Twenty years from now you will be more disappointed by the things you
didn't do than by the ones you did do. So throw off the bowlines. Sail
away from the safe harbor. Catch the trade winds in your sails. Explore.
Dream. Discover." - Mark Twain

Thanks all, guess I never though that floatation could be so complex. I
think I'll go with Sal's Dad's suggestion of cutting foam sheets and
epoxying into place, seems easy enough.
"Sal's Dad" wrote in message
...
Depends.

If it's an open compartment, consider extruded foam, like the 2"
insulation
sheets at Home Depot. Either pink (OCF) or blue (Dow) will work fine,
epoxy
them in place.

If a closed compartment, why would you need to glue the blocks?

And if it is closed, will it be really sealed? Watertight for the life of
the boat? If so, use the lightest stuff you can find; just needs to float
for hours/days in the event of hull failure.

Will it be closed, but with some possibility of moisture infiltration? If
so, consider that poured-in-place foam will create an ideal environment
for
rot - even a tiny amount of water will be trapped between the foam and
wood.

Personally, I prefer to fill compartments loosely with light foam and/or
plastic seltzer bottles, and leave some kind of drain plug to let out the
water that always seems to accumulate. I think the soda bottles are
lighter
than foam, and certainly cheaper, but only fill about 80 or 90% of the
volume.

There's a Coast Guard boatbuilder's site, but they don't have any specific
requirements for flotation materials, except that it has to be
gas/oil-resistant if in the bilge...

Sal's Dad

"Donnie Gilliland" wrote in message
...
Hello all,
I'm building a 10' tunnelhull and need to add some floatation (for my
own
peace of mind) in the aft section soon. I have a question concerning the
weight and ease of use of Styrofoam blocks vs. a pourable, 2 part type.
It's
a
small boat, so, I could easily cut and form blocks of Styro to fit, but
I'd
have to find some way of gluing into place, or, would I be better off
using
a pourable type? I'm convinced the Styro is much lighter but not as easy
to
make fit snuggly into place.
How about using Great Stuff from Dow, spray it in in small
layers/quantities
to allow for a complete cure before adding more?

Anyone have suggestions? What's easier? What's more worth it? Any
pourable
Mfgr's suggestions?
I'm a newby to boat construction but NOT to woodworking.

Thanks in advance
Don

It really isn't complex. You just want to have enough trapped air to
offset the heavier-than-water components of the boat. Make sure you've
got enough in the stern to float your motor, with the powerhead out of the
water!

Another thing I've used for flotation is spare plastic fuel tanks, strapped
to the bottom. Keep one or two extra tanks with half a gallon of gas
sloshing in the bottom, and you'll always get home. Not to mention lots of
extra range, for occasional long trips.

Sal's Dad

"Donnie Gilliland" wrote in message
...
Thanks all, guess I never though that floatation could be so complex. I
think I'll go with Sal's Dad's suggestion of cutting foam sheets and
epoxying into place, seems easy enough.
"Sal's Dad" wrote in message
...
Depends.

If it's an open compartment, consider extruded foam, like the 2"
insulation
sheets at Home Depot. Either pink (OCF) or blue (Dow) will work fine,
epoxy
them in place.

If a closed compartment, why would you need to glue the blocks?

And if it is closed, will it be really sealed? Watertight for the life
of
the boat? If so, use the lightest stuff you can find; just needs to
float
for hours/days in the event of hull failure.

Will it be closed, but with some possibility of moisture infiltration?
If
so, consider that poured-in-place foam will create an ideal environment
for
rot - even a tiny amount of water will be trapped between the foam and
wood.

Personally, I prefer to fill compartments loosely with light foam and/or
plastic seltzer bottles, and leave some kind of drain plug to let out the
water that always seems to accumulate. I think the soda bottles are
lighter
than foam, and certainly cheaper, but only fill about 80 or 90% of the
volume.

There's a Coast Guard boatbuilder's site, but they don't have any
specific
requirements for flotation materials, except that it has to be
gas/oil-resistant if in the bilge...

Sal's Dad

"Donnie Gilliland" wrote in message
...
Hello all,
I'm building a 10' tunnelhull and need to add some floatation (for my
own
peace of mind) in the aft section soon. I have a question concerning
the
weight and ease of use of Styrofoam blocks vs. a pourable, 2 part type.
It's
a
small boat, so, I could easily cut and form blocks of Styro to fit, but
I'd
have to find some way of gluing into place, or, would I be better off
using
a pourable type? I'm convinced the Styro is much lighter but not as
easy
to
make fit snuggly into place.
How about using Great Stuff from Dow, spray it in in small
layers/quantities
to allow for a complete cure before adding more?

Anyone have suggestions? What's easier? What's more worth it? Any
pourable
Mfgr's suggestions?
I'm a newby to boat construction but NOT to woodworking.

Thanks in advance
Don

Use both. You can save a few bucks and be regulation too. In larger
boats you can save a lot of $ by using chunks of dock billet or other
foam. Use it as a filler with the USCG regulation two part and surround
all the chunks and fill voids with a layer of the two part foam and you
have also solved the issure of sticking it in place...

I have never been able to find info on CG approval/endorsement/preference
for any particular flotation.

snip
the USCG regulation two part and
snip

Can you cite some kind of reference for this?

The only relevant thing I have seen is at
http://www.uscg.mil/d8/mso/louisvill...bp16761_3b.pdf
page 39. Wish I could cut and paste the text here, but the gist is that
there are many appropriate materials and techniques, some better than
others. The only restrictions seem to be that fuel-resistant foam must be
used near the engine and in bilges, and the hull can not be used as part of
an air chamber. (So I fill the chambers with soda bottles).

Sal's Dad

Sal's Dad says:

I have never been able to find info on CG approval/endorsement/preference
for any particular flotation.

They won't recommend, as it would:
a - restrict freedom of choice.
b - would favour one manufacturer over another ( since most cores are a
patented chemical brew made by only one company) Note the word "most"...
c - THey would have to re-write the regs every time some new process/chemical
appeared on the market.

It is up to you to find a core that meets the requirements, and is in your
opinion the one you want.

Steve