Full foam between deck and hull ?

Discussion in 'Fiberglass and Composite Boat Building' started by hyboats, Aug 2, 2012.

  1. rwatson
    Joined: Aug 2007
    Posts: 5,852
    Likes: 290, Points: 83, Legacy Rep: 1749
    Location: Tasmania,Australia

    rwatson Senior Member

    Of course, you may have to satisfy insurance companies, customers and the judge (in the case of unhappy customers) that you built/designed a safe vessel with sufficient flotation, of any boat you sell or captain, especially if it comes to grief.
     
  2. tunnels

    tunnels Previous Member

    What Makes You Boat Float ??

    Those places where the foam is in side of glassed chambers ! is all under the floor and up forward !! yes ?? so the front of the hull that will be upside down is the way you want it to float ??
    Clinging to a slippery hull bobbing up and down in the water is ok for you for possibly hours on end in the freezing cold and the dark ??

    Hell i would like to be able to get back inside the boat and have some where to sit and if the gunnels were above water all way round youd even have the option of bailing the boat out and climbing up over the outboard motor and the lightest person bailng the rest out so everyone could get back inside .
    A frind and i looked at all these things and made a automatic inflating tube system the was folder and attached to the sides and across the stern . was enough floatation to have 150mm of the gunwhale out of the water and like i just discribed a person could get back inside and bail the boat out and then others could get back inside .
    THESE ARE VERY SIMPLE QUESTIONS !!
    WHAT MAKES YOUR BOAT FLOAT ??
    IS IT THE FLOATATION HERE AND THERE ???
    WHAT IS ALL THAT FOAM YOU HAVE HIDDEN AWAY ACTUALLY DOING???
    HOW DO YOU MAKE THE BOAT REFLOAT ??
    WHERE IS THE MOST WEIGHT IN THE BOAT ???
    IF THE MOTOR WASNT GOING WHEN IT GOT SWAMPED THERES A VERY GOOD CHANCE WITH SMALLER MOTORS THAT IT COULD FIRE UP AND GO IF ITS UP THE RIGHT WAY AND A TWIN CYLINDER OF EVEN A 3 !.
    So you could get into the boat and bail it out and be in a dry place and a slight chance of your small motor going and you could make you way back to shore .
    People get lost at sea !! boats mostly get washed up on shore so if you are able to stay with your boat theres a much higher chance of EVERYONE being found sooner ! :p
     
  3. hyboats
    Joined: Jun 2010
    Posts: 78
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Sydney

    hyboats Junior Member

    this is my boat, 23.6ft, center console fishing boat.

    look at the picture
     

    Attached Files:

  4. P Flados
    Joined: Oct 2010
    Posts: 601
    Likes: 33, Points: 28, Legacy Rep: 390
    Location: N Carolina

    P Flados Senior Member

    I have read all of this stuff about waterlogged foam and yet there are plenty of outlets selling foam for floating docks with claims of "will not absorb water". These applications are expected to be in the water for years on end and any significant loss of floatation would be a noticed. The big name company, warrants their product as follows:

    Effective with billets manufactured after January 1, 1999, The Dow Chemical Company warrants that for a period of ten (10) years, STYROFOAM™ Brand Extruded Polystyrene Buoyancy Billets, when installed in accordance with application recommendations, will not sink or become waterlogged.

    My bet is that good product lines made specifically for long term floatation use are a good bet if you do not want to take chances with a "multipurpose foam"

    When I have seen well aged foams, the stuff that looks like polyurethane closed cell does not seem to hold up so well. On the other hand, the polystyrene stuff may become mechanically beat up or sun damamged, but material that is less exposed holds up pretty good.

    It would be nice to have real info on the subject instead of what might be "guilt by association" - real problems with some products gets all foams labelled as no good.
     
  5. Ike
    Joined: Apr 2006
    Posts: 2,388
    Likes: 268, Points: 83, Legacy Rep: 1669
    Location: Washington

    Ike Senior Member

    What is the difference between polysytrenes (styrofoam) and polyurethans?

    Boatbuilders primarily use polyurethanes, not because it is closed cell, but because it meets USCG requirements for resistance to gasoline, bilge cleaners, other petroleum products, and chemicals, commonly used on boats. Since foam is often installed in places where bilge water can get to it, and bilge water often has oils and other toxic stuff in it the foam has to be capable of withstanding these. Plus that polyurethane can be applied with foam guns, or by mixing two parts and pouring it in. (that.;;s why it is often refferred to as blown, or pour foam)

    Styrofoam will dissolve if exposed to these. These billets used for docks and floats are usually styrofoam, some times bare foam on freshwater lakes, but often coated with a pvc or other plastic shell to protect them.

    Styrofoam can be used if placed away from places where it will be exposed, or if protected in some way by bagging, epoxy coating, watertight compartments, etc. I have used styrofoam in all three of my boats. It is commonly used in small aluminum boats that have foam boxes under the seats.

    The USCG, ABYC and others do not tell you what kind of foam to use. They only specify how the boat must float, in what attitude. How you achieve that is up to you.

    I can go on a great length about why some foam absorbs water and some doesn't. It would probably bore you unless you are a chemist or an engineer. But simply put, correctly made closed cell foam does not absorb water. The key word is correctly made. Pour (or blown) foam is often not correctly made. if you buy pre-made (block or stick) foam it does not absorb water.
     
  6. DCockey
    Joined: Oct 2009
    Posts: 4,673
    Likes: 301, Points: 83, Legacy Rep: 1485
    Location: Midcoast Maine

    DCockey Senior Member

    Ike's response is based in part on US regulations. Elsewhere the requirements may be different.
     
  7. BreezyLake
    Joined: Aug 2012
    Posts: 1
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Minnesota

    BreezyLake New Member

    Flotation in home made boat

    I'm doing research into building a small plywood outboard powerboat and saw this discussion. Could typical PVC plastic dock floats in varying sizes, in strategic locations, supply needed flotation for a boat under 500 lbs.?
     
  8. tunnels

    tunnels Previous Member

    I will ask a couple seemingly silly questions !!
    what makes a boat float ??
    or
    how does it float on the surface of the water ??
    Why does it float ??
    any one ??:confused::eek:
     
  9. idkfa
    Joined: Sep 2005
    Posts: 329
    Likes: 6, Points: 18, Legacy Rep: 79
    Location: Windward islands, Caribbean

    idkfa Senior Member

    Please, how does one go about pouring two part foam so that is does not absorb water, or is it not possible for the diy?
     
  10. Ike
    Joined: Apr 2006
    Posts: 2,388
    Likes: 268, Points: 83, Legacy Rep: 1669
    Location: Washington

    Ike Senior Member

    Follow the manufacturers instructions, to the letter. Two part foam is sensitive to temperature, humidity, mixing ratios, and dirt. So follow the instructions. Do not just pour it in a bucket and mix it up. (which is exactly what most people do.)
     
  11. tunnels

    tunnels Previous Member

    Yes you are right ! So manythings can and do change the way the foam reacts and the end result
    Its possible to use a big funnel lined with paper and a big diamater hose and pour the mix down and into a comartment pushing the hose to the furtherest point so it will espand and push towards the other end and out the holes ,But remember its going to exspand and because its in a enclosed place will generate its own heat and do what it does very quickly and with great force so make sure you have good big holes for the surplus to come out, if not you could end up with bulges in all of the panels !!!!incuding the bottom of the hull if that were its going !!!.
    Not all foams are born equal ,differant manufactures have there own formulations , they are simularto each other but not the exact same exspansion rates so what brand you start with you use all way throught to the end , The speeds at which it exspands can be endless!!
    Pouring foam is quite differant to spray foam .
    I have sprayed foam and done hand poured . the spray foam is instant and some guns mix inside the snap off plattic nozzle outside the gun or can be mixed inside the actual nozzle but very close to the end and at hi pressure !!

    Remember always wear gloves and keep is off you skin . Always wear a mask with a charcoal filter and if you smell the fumes get a better filter !!!.
    It is cancer causeing so protect yourself !! !:eek:
     
  12. SamSam
    Joined: Feb 2005
    Posts: 3,900
    Likes: 196, Points: 63, Legacy Rep: 971
    Location: Coastal Georgia

    SamSam Senior Member

    Bueller?
     
  13. tunnels

    tunnels Previous Member

    And in english means ??:confused:
     
  14. SamSam
    Joined: Feb 2005
    Posts: 3,900
    Likes: 196, Points: 63, Legacy Rep: 971
    Location: Coastal Georgia

    SamSam Senior Member

    Your question made me think of the most excellent movie Ferris Bueller's Day Off. That line "Bueller? Bueller? Bueller?" was in the scene of the teacher taking attendance.
    http://www.youtube.com/watch?v=uhiCFdWeQfA
     

  15. hardcoreducknut
    Joined: Aug 2011
    Posts: 47
    Likes: 1, Points: 0, Legacy Rep: 27
    Location: USA

    hardcoreducknut Junior Member

    Checkout Plascore as an alternative to wood. The honeycomb core traps air in pockets between the layers of glass. Easy to mill, but the first wet out of epoxy should be done with medium to thick viscosity resin. Thinner resin will leak through the veil and to the cells below.
     
Loading...
Similar Threads
  1. fallguy
    Replies:
    22
    Views:
    1,304
  2. WerpKerp
    Replies:
    18
    Views:
    2,587
  3. leaky
    Replies:
    7
    Views:
    1,174
  4. Ctowles
    Replies:
    12
    Views:
    4,070
  5. HighFly_27
    Replies:
    9
    Views:
    2,626
  6. ETSailor
    Replies:
    9
    Views:
    2,194
  7. souljour2000
    Replies:
    19
    Views:
    7,423
  8. Dan H
    Replies:
    5
    Views:
    2,145
  9. jimflorida109
    Replies:
    6
    Views:
    5,620
  10. sbklf
    Replies:
    13
    Views:
    84,461
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.