roto-molding motor yachts

Discussion in 'Boat Design' started by capt_jack, Jul 1, 2010.

  1. capt_jack
    Joined: Jun 2010
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    Location: Houston

    capt_jack Junior Member

    I saw an interesting article about Triumph's line of solar powered "party pontoons" which are much more affordable than usual due to the yard using roto-molding to construct the hull.


    The designer claims the build process offers the following benefits:
    1. Very affordable
    2. 5 time stronger than fiberglass
    3. The marine-grade polyethylene is buoyant and will float even if the hull is "sawed in half".
    4. The HDPE can be welded and repaired with a propane torch
    5. No paint required, color is embedded through the entire hull

    Granted the start-up cost for a yard would be more expensive than for a fiberglass or wood based system but mass production costs would be lower.

    It's not something backyard builders can do beyond a certain size of boat but I'm curious if it would make a motor yacht above 50 foot in length more affordable? From what I've read a great deal of the superstructure could be built in one step and the various elements would be very sturdy being molded together rather than joined.

    If it lives up to the hype I hope it means large motor yachts might be much more affordable in the near future.
  2. daiquiri
    Joined: May 2004
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    Location: Italy (Garda Lake) and Croatia (Istria)

    daiquiri Engineering and Design

    I know very little about roto-molding process, so I have nothing else to offer but this little consideration:

    [​IMG] [​IMG]

    Sorry for the off-topic comment, but I've got some excess negative energy today (it's a too hot and damp day here)... :eek:
  3. Chris Ostlind

    Chris Ostlind Previous Member

    Close, Dude...

    I think the design evolution had distinct connections to cross marketing and that the rotomolders were looking for subliminal imagery for the connection.

    I give you the Adidas Star Wars high top and the Lego take on the Star War's Jabba Party Barge.


    Attached Files:

  4. apex1

    apex1 Guest


    "party pontoon" why not

    "5 times stronger than fiberglass" premature dream or just a lie

    "motor yacht above 50 foot" is such a complex system, the few pennies saved on a rotomould hull wouldn´t be worth talking. (if there would be a saving, due to the high tooling investment)

    It is not easy to connect bulkheads or engine beds on HDPE, to name just two out of many.

    All in all, this idea pops up here every other month but that makes it not a good idea.

  5. Chris Ostlind

    Chris Ostlind Previous Member

    I generally agree with your comments, Richard, but there have been exceptions and they do indicate potential if some of the tougher technical obstacles can be overcome.

    Triumph boats have been making rotomolded power craft for some time now. Their biggest boat is 23' 8" x 8' 10".

    The possibilities of a RM boat at 50' LOA are mind boggling.

    As for toughness... I'm not all that surprised about the 5 times stronger claim, but it would depend on how they define strong. It's pretty hard to kill a RM boat. They hold up to the most severe poundings and tend to jump back to their original shape, neither of which are hallmarks of composite products. Because of that, repairs are seriously reduced. As a recreational product material, it's pretty hard to beat RM HDPE, if you can accomodate the inherent weight of the stuff and you are prepared to pop for a hefty up front tooling cost to get into the game.

    It is possible to build prototypes in high temp epoxies and produce numbers of parts that will allow the product to be explored. This cuts the costs for the hard core, production level aluminum tool enormously and lets the manufacturer find out what will need to be done for the final part.

    50 feet, though... I'm thinking it has to be built from several pieces that have molded fittings and are bolted with embedded structural components.
  6. WickedGood

    WickedGood Guest

    Das Boot?

    Im sure they will be Popular in certain limited regions.


    We are waiting to see how it turns out.

  7. dskira

    dskira Previous Member

    What do you mean?
  8. WickedGood

    WickedGood Guest

    What You Mean by What do you mean?

    A Shoe Boat?

    Do you really think you could posibly market that in New England, never mind Maine

    A Shoe Boat?

  9. Chris Ostlind

    Chris Ostlind Previous Member

    You can market anything anywhere. Making it a successful marketing effort is another thing entirely.

    Perhaps the Pet Rock stirs up a memory, or two, for you?
  10. WickedGood

    WickedGood Guest

    Well I supose.

    However, Do you have any idea how long it took to get Maine Lobstermen to use Plastic Pegs insted of wooden ones? Nevermind those new fangled Rubba Bands


    I recall when Logic Boats (Now Truimp) first came out. They offered to Give me one free boat for every 5 boats that I bought.

    Maybe if they do that kind of deal again I might think about it, Maybe?

    Does anyone want to build me a boat that I can set up a tent on to use as a hunting blind?

    Now thats an idea I could Sell.

  11. apex1

    apex1 Guest

    Well Chris,

    I don´t see any advantage for HDPE on a 50ft. motoryacht.

    You named one of the major disadvantages already, weight! And when we focus on the avarage use of the average 50ft. boat (which is not battering the reefs of the pacific ocean) we are already there. The industry is well aware of that material and does NOT use in in substantial quantities.

    For the rest I like to point to this thread:

  12. Chris Ostlind

    Chris Ostlind Previous Member

    Well, Richard,

    The boat that was shown isn't exactly a motor yacht as most folks would know one. It is, very much, a recreational platform for purposes of fun on protected waters. In this application, weight is one of the smallest considerations with which to deal.

    I wouldn't be surprised at all if the advantages of a RM boat of this type were to be especially powerful. For example, right here in Utah, we have a very big body of water called Lake Powell. During the summer months, the place is filled with PWC's, wakeboarders, houseboats of all shapes and sizes, fishermen, kayakers, etc. Not much sailing there due to fickle winds and narrow canyons with unpredictable breezes.

    The lake also has a serious potential for messing with one's day in the form of underwater obstacles made from the same sandstone that surrounds the lake as beautiful cliffs. The people who use their houseboats in this fashion like to beach their boats to provide shore access to the occupants. Since most of the houseboats are in service as rental vessels, utilized by the actual owners intermittently, you can get a very wide range of driving skills. This leads to some serious accidental abuse.

    A plastic hulled boat could be a lot less expensive to buy than an aluminum version of same, require less maintenance and would potentially be a much more carefree investment for the families that would use such a boat.

    The material may not be currently used in substantial quantities, but I remember hearing that same argument from the glass kayak makers when plastic boats first hit the market. Look where that reality has gone over the last ten years.
  13. apex1

    apex1 Guest

    Well, Chris,

    I would not have noticed that, thanks!:p

    But the OP said clearly:
    Got it?:D
  14. jonr
    Joined: Sep 2008
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    Location: Great Lakes

    jonr Senior Member

    Rotomolded boats definitely have some advantages for some uses and smaller boats. Hobie switched from fiberglass to rotomolded for the less expensive catamarans used for rentals for good reasons - and they aren't bad boats, maybe 10% heavier. Hybrids can also make sense: rotomolded hdpe, aluminum, fiberglass, inflatable, etc.

  15. Landlubber
    Joined: Jun 2007
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    Location: Brisbane

    Landlubber Senior Member

    ...i used to do Rotomoulding of tanks for a Chandlery wholesaler here, i made the moulds, not too difficult, but the ovens are limited in size, so i seriously doubt ANYONE has an oven big enough for a 50 footer, even if someone was silly enough to make the moulds for it...Heating the mould could be done externally of course, but it then becomes a trial and error situation to cook the pellets correctly....trial and error on a 50 foot job would prove economically fatal.
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