[Rhodes22-list] ...on spray foam and other musings....

[R22RumRunner at aol.com]

Bob,
I'm just curious, why would you want to insulate the interior hull of a  
R22?
 
Rummy
 
 
In a message dated 2/14/2012 8:32:59 A.M. Eastern Standard Time,  
spreadgoodnews at gmail.com writes:

Thanks  Rob.  I am building out a 43' steel sailboat hull.  I am finishing  
the final interior epoxy coats now then i will spray closed cell 
polyurethane  foam all over the interior hull over the stringers and ribs.  Then i 
have  read i should spray a fire retardant elastomeric paint over the foam to 
resist  ignition in case of an interior fire. This foam will insulate as well 
as  contribute to the oxygen barrier of the epoxy.
what kind of foam did boston  whaler use in their hull construction?  My 
friend has a bw dinghy hull  that weighs about 300 pounds! Thats like 20 
gallons of absorbed water!   My understanding of closed cell foam is that if it 
is cut after spraying it  will absorb some, but i am not sure how much.  I 
think the Rhodes has the  good stuff in there like the foam that floats 
docks.(closed cell  polyurethane?)
Also is a pool noodle polyethelene foam? You can get that  stuff in sheets 
and it would be nice to insulate the rhodes interior hull  with.  It wont 
absorb water either.
Thanks,
Bob



On  Feb 13, 2012, at 9:58 PM, Rob Granger <rgranger at sbc.edu>  wrote:

> Okay I didn't want to seem heavy handed when I stated  before that I was
> "almost certain" that Great Stuff is closed cell  because there is a lot 
of
> controversy on this topic and to be fair,  not all spray foams are the
> same... but I'm a chemist and I felt it  was necessary that we get this
> straitened out since many of us are DIY  boaters...  so on the topic of
> spray foam
> 
> Some  spray foams are latex and therefore open celled (DO NOT USE LATEX
>  SPRAY FOAM ON YOUR BOAT) but Great Stuff expanding spray foam is a
>  polyurethane-based foam and not a latex foam.  So unlike the latex  spray
> foams it is *closed cell*.   And you should not be  afraid of it absorbing
> water.  It will (however) stick to the  hull like ... well a polyurethane
> glue (think Gorilla glue).  So  the bag idea is the way to go if you ever
> want to get it out again...  or line the area with visqueen before you
> spray.  I've used both  approaches and they both work fine...  I can post
> pictures if  anyone wants to see the results of the bag or visqueen
>  approach.
> 
> So to clarify, polyurethane foam (Great  Stuff)  is *closed cell*... so it
> is fine to use on your boat,  even in low spots.
> 
> The pink and blue foam boards at Lowes and  HomeDepo are also great to use
> for floatation foam.  They are  *extruded* polystyrene and so they will 
not
> fall apart into tiny  little balls that make a mess everywhere... (Iike
> cheap styrofoam  will).  I have about six 3" boards cut up and crammed 
into
> my  MacGregor 22'.  And all of the little left over pieces are in a  bag,
> crammed into a tight spot and filled with spray foam (along with  some
> packing peanuts I got in Christmas boxes this year).
>  
> A note on packing peanuts.  They're now two kinds.  The  old-school kind 
are
> made of styrofoam.  Those are fine to use on  a boat.  The other type are 
"*
> green*" and made of  cellulose.  The cellulose peanuts will dissolve in
> water.   Obviously you do not want to use those.  It is easy to tell which
>  type you have.  Drop one in a glass of water and wait a bit.  Or you  can
> bite one  :-)
> 
> If you are skeptical about the  closed cell nature of Great Stuff 
expanding
> foam...(and it is not a  bad thing to be skeptical) you can read about it 
on
> the Dow Chemical  site... you wont hurt my feelings if you do... I promise
> :-)
>  
> Here is the link to the Dow Chemical site
> 
>  http://building.dow.com/na/en/products/sealants/windowdoor.htm
>  
> 
> my 2 cents.
> 
> ... the other Rob
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