HDPE bottom plate instead of FG / Anti-fouling paint?

Discussion in 'Materials' started by Jeff in Boston, Sep 11, 2020.

  1. Jeff in Boston
    Joined: Sep 2020
    Posts: 10
    Likes: 0, Points: 1
    Location: Boston

    Jeff in Boston Junior Member

    Hi all!

    I'm working on a boat design, and have some (many!) questions.

    Background: I want to build a displacement power catamaran or trimaran of about 20 to 22 feet. It will be in the ocean and if I finally get a #$%$% mooring it will be moored.

    While I love the idea of an HDPE boat, and find the videos of plastic welding fascinating, I know it is really heavy, and my attempt at welding with a small welder wasn't encouraging.

    I'm interested in it's ability to shrug off abrasion and no need for anti fouling painting. I'm wondering if it would work well to put a 1/4" skin of HDPE on the bottom of a flat bottomed plywood boat. Is there any reason it wouldn't work? I'd like to minimized my use of fiberglass and make it easier to maintain. I figure if the bottom of the hull doesn't need anti-fouling then I can just scrape and paint the sides below the waterline as needed.

    I know about the thermal expansion problem and think I can work around it. I'm wondering if having stationary water between the HDPE and ply would accelerate rot? I wouldn't think so?

    Thanks!

    -Jeff
     
  2. Mr Efficiency
    Joined: Oct 2010
    Posts: 8,804
    Likes: 570, Points: 113, Legacy Rep: 702
    Location: Australia

    Mr Efficiency Senior Member

    How are you proposing to attach it ?
     
  3. upchurchmr
    Joined: Feb 2011
    Posts: 3,050
    Likes: 149, Points: 63, Legacy Rep: 579
    Location: Ft. Worth, Tx, USA

    upchurchmr Senior Member

    Great fantasy.
    Let us know how it goes.
    But if you want to avoid antifouling, why not plate the sides also.
    What are you going to do to protect the plywood, if not glass epoxy?
    You did say it will be moored in the ocean. Right?
     
  4. Saqa
    Joined: Oct 2013
    Posts: 489
    Likes: 9, Points: 18, Legacy Rep: 75
    Location: Hervey Bay

    Saqa Senior Member

    I am in the middle of a HDPE 20' cat build. The hulls are ready, working on bridgedeck structure now. Dont be too discouraged, HDPE has its advantages. Even in my small HDPE cathedral hull I can run all over Hervey Bay on days where other boats cringe on getting on the plane. Cant wait to launch the big one.
     
  5. Mr Efficiency
    Joined: Oct 2010
    Posts: 8,804
    Likes: 570, Points: 113, Legacy Rep: 702
    Location: Australia

    Mr Efficiency Senior Member

    What is your boat's make saqa, the cathedral hull I mean ?
     
  6. Saqa
    Joined: Oct 2013
    Posts: 489
    Likes: 9, Points: 18, Legacy Rep: 75
    Location: Hervey Bay

    Saqa Senior Member

    Smartwave 3500
     
  7. Mr Efficiency
    Joined: Oct 2010
    Posts: 8,804
    Likes: 570, Points: 113, Legacy Rep: 702
    Location: Australia

    Mr Efficiency Senior Member

    You have given it a good review, I will have a look.
     
  8. Saqa
    Joined: Oct 2013
    Posts: 489
    Likes: 9, Points: 18, Legacy Rep: 75
    Location: Hervey Bay

    Saqa Senior Member

    Have a look on FB groups, Smartwave owners. I think its a wierd combinatio of why HDPE is so hated here that somehow come together to actually make it the ideal material for a lazy boater who works the boat hard. Yup 10+ marks as my review
     
  9. Mr Efficiency
    Joined: Oct 2010
    Posts: 8,804
    Likes: 570, Points: 113, Legacy Rep: 702
    Location: Australia

    Mr Efficiency Senior Member

    I guess it is also a relatively quiet boat ? Plate alloy, moreso than pressed alloy, is like listening to marbles rolling around in a can, when drifting. I think a major demerit, and I wonder whether in shallow water, it doesn't spook some kinds of fish.
     
  10. Saqa
    Joined: Oct 2013
    Posts: 489
    Likes: 9, Points: 18, Legacy Rep: 75
    Location: Hervey Bay

    Saqa Senior Member

    It is very quiet, and the wave smash is very dampened underway. Very comfy
     
  11. Mr Efficiency
    Joined: Oct 2010
    Posts: 8,804
    Likes: 570, Points: 113, Legacy Rep: 702
    Location: Australia

    Mr Efficiency Senior Member

    Clever people those kiwis.
     
  12. bajansailor
    Joined: Oct 2007
    Posts: 1,162
    Likes: 307, Points: 83, Legacy Rep: 37
    Location: Barbados

    bajansailor Marine Surveyor

  13. Saqa
    Joined: Oct 2013
    Posts: 489
    Likes: 9, Points: 18, Legacy Rep: 75
    Location: Hervey Bay

    Saqa Senior Member

    Smartwave and Mac Boats are the two brands from Advantage Plastics. Also apparantly Macca's playground equipment. Google Smartwave or Mac Boats. The new Mac 700 is a beast and very well suited for some of my comercial aspirations
     
  14. Saqa
    Joined: Oct 2013
    Posts: 489
    Likes: 9, Points: 18, Legacy Rep: 75
    Location: Hervey Bay

    Saqa Senior Member

    Anyway, sorry for the thread hijack. I think its time anyone who wants to open their mouth to downtalk HDPE as a valid boat building material should take a pause and field study the production designs in existance or be thougth a fool downunder where thousands of these vessels are actually as a matter of hard real fact are running around happy

    I would love to see these experts offer a 3.5m design in "regular boat building materials" that is MORE robust, cheaper and easier to maintain, more sea worthy, that I can beach up under power on pebble stone or rock, that doesnt need any paint or finish, that is repairable in a single pass, will not be affected by UV or chemicals, that will not break if dropped, where a tinkerer can keep drilling holes to fit things and keep changing mind and repairing the hole in a single pass and drilling another, get some air off wakes and waves and land without shock (my fav :) ) while being cheaper to buy or build and own over time then my Smartwave 3500........then open mouth and go for the rubbishing of HDPE

    https://macboats.co.nz/

    Home - SmartWave Boats https://www.smartwaveboats.co.nz/
     

  15. bajansailor
    Joined: Oct 2007
    Posts: 1,162
    Likes: 307, Points: 83, Legacy Rep: 37
    Location: Barbados

    bajansailor Marine Surveyor

    Saqa, I don't think that anyone on here has criticised HDPE as a boat building material?

    Thank for 're-doing' the link to Smart Wave - I don't know why my link went straight to Advantage Plastics.

    Would you like to post some photos of the 20' cat that you are building, or maybe start a new thread about it?
     
Loading...
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.