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Old 04-20-2017, 12:31 PM   #1
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Default Flotation material necessary ?

I have a 15' aluminum boat. The styrofoam is melting where gas deteriorated it. The loose foam can clog my bilge pump. I was going to replace with HDPE (High Density Polyethylene) Sheet from amazon. I would need $472 worth leaving unaffected styrofoam.
Benefits are the boat won't sink,noise reduction and I'll be legal.
But I stay in bays mostly. Have life preserver and insurance for boat.
My boat is a welded aluminum dory with center console and 50 Yamaha.
Thanks
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Old 04-20-2017, 03:06 PM   #2
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The Coast Guard regulations requiring level flotation for boats 16 feet and under only applies to manufacturers, what you do to your boat after purchase is your business...
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Old 04-20-2017, 08:05 PM   #3
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Quote:
Originally Posted by commuter boats View Post
The Coast Guard regulations requiring level flotation for boats 16 feet and under only applies to manufacturers, what you do to your boat after purchase is your business...
Good to know. I feel I should for peace of mind but they want so much for the material.
Guess I should of asked if there are benefits on not having it that might convince me not to bother.
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Old 04-20-2017, 10:19 PM   #4
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There are cheaper ways to go, you could replace the styrofoam or you could put in polyurethane for a fraction of that money .
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Old 04-21-2017, 05:06 AM   #5
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Do you know a source of polyetelene that is affordable. I found it expensive. At amazon they have HDPE (High Density Polyethylene) Sheet, Opaque Off-White, Standard Tolerance, ASTM D4976-245, 1.000" Thickness

It is 1" thick ( my old foam was 1 7/8") and two feet long. Each piece is about $40 and I need 12. I am leaving half of old foam in there to save cost.
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Old 04-21-2017, 07:14 AM   #6
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I found the polyurethane sheets at Grainger.
Thanks Commuter Boats
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Old 04-21-2017, 07:49 AM   #7
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Quote:
Originally Posted by saltwater1 View Post
I found the polyurethane sheets at Grainger.
Thanks Commuter Boats
It's readily available in two parts liquid to be poured in place, somewhere around $50 a gallon. You could turn your boat over and pour foam into your seat cavities.
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Old 04-22-2017, 05:11 AM   #8
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Foam insulation sheets are used in construction. Softer, but work fine. "Great stuff" expanding foam works also.
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Old 04-22-2017, 03:20 PM   #9
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hpde sheet at 970kg/m3 wont float a lot of boat.
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Old 04-23-2017, 06:09 AM   #10
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A cubic foot will float about 60 pounds, roughly. A watertight compartment can act as a float.
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Old 04-23-2017, 09:37 AM   #11
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Quote:
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A cubic foot will float about 60 pounds, roughly. A watertight compartment can act as a float.
Depends on what material you are using. That HDPE sheet that puppy mentioned has a density of about 60 lb/ft^3. With water at around 62 lb/ft^3, that's only 2 lbs of buoyancy per cubic foot of HDPE (hence puppy's statement).
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Old 04-23-2017, 10:44 AM   #12
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Quote:
Originally Posted by CLM65 View Post
Depends on what material you are using. That HDPE sheet that puppy mentioned has a density of about 60 lb/ft^3. With water at around 62 lb/ft^3, that's only 2 lbs of buoyancy per cubic foot of HDPE (hence puppy's statement).
I missed that when I give my recommendation, there are polyethylene foams used in seat cushions and such and I thought that was what he was referring to but the foams are not referred to as HDPE but URTH instead. With just a touch of investigation I also find that most of the polyethylene foams are open cell...
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Old 04-23-2017, 02:21 PM   #13
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I used Dow closed cell styrofoam sheets in my 16 ft lowe aluminum boat.Cut to fit.
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Old 04-23-2017, 08:49 PM   #14
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Quote:
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closed cell styrofoam
is an oxymoron.

There is no such thing as "closed-cell" - just different degrees of open-cell. And styrofoam is considered to be "open cell"[

More info at http://boatbw.blogspot.com/2015/11/t...t-to-foam.html
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Old 04-23-2017, 09:14 PM   #15
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Quote:
Originally Posted by MoPoxy View Post
is an oxymoron.

There is no such thing as "closed-cell" - just different degrees of open-cell. And styrofoam is considered to be "open cell"[

More info at http://boatbw.blogspot.com/2015/11/t...t-to-foam.html
That discussion on foam is not entirely accurate, in fact without reading very much of it I found several statements I believe to be false.
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Old 05-02-2017, 08:43 AM   #16
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Quote:
Originally Posted by CLM65 View Post
Depends on what material you are using. That HDPE sheet that puppy mentioned has a density of about 60 lb/ft^3. With water at around 62 lb/ft^3, that's only 2 lbs of buoyancy per cubic foot of HDPE (hence puppy's statement).
True, but it is hardly "foam", and certainly not flotation material.
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Old 05-02-2017, 09:33 AM   #17
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HDPE is not a foam it is a hard plastic. You would want a LDPE. Common densities would be from 1.2-2.2#/ft³, and can run up to 9#/ft³. The lower densities are the same material that pool noodles are made of and are sold in plank form.
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Old 05-07-2017, 04:36 PM   #18
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I have a 14 foot rowboat, a bit smaller than your boat. I have lashed two fenders under the foredeck, two under the main thwart, and one large one under the stern thwart. Each fender is (as normal) an air filled "tube", costs around $20 locally (less on special or at boat shows), so say around $100 installed for the lot. No chemicals or adhesives involved, and a pretty simple and seamanlike looking result.

Tony.
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