Power boat design for economy.

Discussion in 'Boat Design' started by Frosty, Apr 11, 2011.

  1. Frosty

    Frosty Previous Member

    Im a power boat man, I have semi displacement cat, I can cruise 20KTs at 35liters per hour I buy fuel in tons not liters,--1.6 tons

    A 50foot Princess or any of the ubiquitous power boats in this frame uses 3 times what I use, it seems acceptable.

    With fuel going ---where? certainly not down any power boat today needs to have economy firmly in the design yet I don't see it.

    I have never yet seen a Hysucat,--the Semi displacement hydrofoil.

    I still see huge fly bridges with awnings and heavy upper superstructure same old stuff but round eye windows (Azimut) looks nice but still humongous lumpy cumbersome style that is in fashion--at the moment.

    Its as though there is no thought what so ever on aerodynamics, I know 20-25 may not be Concorde but aerodynamics must be a consideration from now on.

    I know its very windy on my bridge at 20KTs and I turn my hat round to keep it on, not to mention the air running through the tunnel. I think it could be improved upon.

    I just don't see anything looking clean and trim with some design.

    If I was to replace my cat I dont see anything that could.

    Plenty of black smoke, hump struggling, tsunami making power boats.
  2. Alik
    Joined: Jul 2003
    Posts: 3,047
    Likes: 327, Points: 93, Legacy Rep: 1306
    Location: Thailand

    Alik Senior Member

    What size of boat are You looking for?
  3. Submarine Tom

    Submarine Tom Previous Member

    I don't believe the words "power boat" and "economy" belong in the same sentence.

  4. Frosty

    Frosty Previous Member

    And there lies the problem, its just accepted and it does'nt need to be.

    Im not looking for one at the moment what can I buy, 44 foot cat 20kts at 35liters.

    Nothing--designers just compete with each other and not the market because it too expensive to build a lemon so we get slightly bigger windows or a different fly bridge. Wally looks to have got some balls when it comes to design but should it be 5 times as much for a different shape.

    All this air going over a boat --cant you get some lift from it? or at least make it stream lined and not look like steam iron.

    I mean look at the aft deck of almost all power boats,--- thats the bit that suck in diesel fumes because of the depression,--the depression that must be holding back.

    Look behind and see the huge stern waves going miles out and still breaking--all that is economy.

    Fuels going to go through the roof --maybe, probably.
  5. viking north
    Joined: Dec 2010
    Posts: 1,868
    Likes: 92, Points: 48, Legacy Rep: 1146
    Location: Newfoundland & Nova Scotia

    viking north VINLAND

    This was the reasoning behind a proper 50/50 min. motor sailer. Typically a 30footer, 14000lb. displacement,controllable pitch prop, 25 to 30hp. diesel motorsailing will easily get you 1/2 imperial gal. an hr. hull speed between 6 and 7 kts. Taking advantage of fair winds say 50% of the time that could translate into 1/4 gal per hr.
  6. Alik
    Joined: Jul 2003
    Posts: 3,047
    Likes: 327, Points: 93, Legacy Rep: 1306
    Location: Thailand

    Alik Senior Member

    Not behind planing boat.

    I just choose smaller boat (but fast enough) for fuel efficiency. One does not want to spend half day to get from Ocean Marina to KoKram.
  7. Frosty

    Frosty Previous Member

    Not behind a planing boat??????????

    Of course you do.

    See how this thread is going economy does'nt matter with power. well it does matter.

    Wake up designers there a big hole here.
  8. Alik
    Joined: Jul 2003
    Posts: 3,047
    Likes: 327, Points: 93, Legacy Rep: 1306
    Location: Thailand

    Alik Senior Member

    Planing boat at speeds over FnV=4.0 has wavemaking component only about 20% of total drag; so wave energy is small and it produces small wave. Maximum wavemaking is at hump mode.
  9. Frosty

    Frosty Previous Member

    Yes im aware of max wave making, I been making waves for 40 years.

    I don't know the maths --your the clever one,-- Im just the owner.

    Im not trying to make waves but I do know as I look back that all that disturbance has cost ME deisel.

    =20 % ? that high!!!! thats a huge drag why dont you try to make it 0%

    Planing boats make waves, Im not talking 1000llb speed boat with an 85 yamaha, I mean 50 foot, 23 tons, twin cummins 800HP 20knots. Thats big waves and a 150 liters an hour too.

    This is the point its not good enough and its all you get, even Alik is defending the situation.
  10. Alik
    Joined: Jul 2003
    Posts: 3,047
    Likes: 327, Points: 93, Legacy Rep: 1306
    Location: Thailand

    Alik Senior Member

    This is FnV=2.0, FnL=0.85 - far from being planing boat; planing starts at FnV=3.0 (some researchers say 2.5, some 4.0).
  11. BYDE
    Joined: Mar 2011
    Posts: 54
    Likes: 3, Points: 0, Legacy Rep: 66
    Location: Italy-China

    BYDE Junior Member

    designers and boatyards produce what they think that the market asks, so the customers are those who mainly drive the new developments.
    even if I agree with your points Frosty, and your boating philosophy, I'm afraid that's not the same for the great part of the market, especially the mid-big size powerboat segment.
    if owners ask for cool-looking planing villas to show off with friends and business partners then the designer will squeeze his brain to reach that target, and he'll sacrifice, say, fuel consumption since the owner doesn't really mind about it (because they can afford it and because they use the boat 4-5 weeks in a year).

    however you surely noticed great changes in the last years, mainly towards more environment friendly designs. you see less powerful models, more research into lowering resistance, hybrid or fully electrical propulsions on series boats, etc etc...
    give it another few years to develop fully and gain consensus among customers. it just needs some time, but that's most likely the way we go.
  12. Perm Stress
    Joined: Sep 2009
    Posts: 554
    Likes: 24, Points: 0, Legacy Rep: 323
    Location: Lithuania

    Perm Stress Senior Member

    Power boat design for economy....

    If for economy of moving it -same amount of stuff on much longer hull, and speed so selected to avoid hump mode. Not much boats built to this philosophy today...

    If for economy of staying at marina -minimum possible length for the amount of stuff. Exactly the design space boundary of most today's powerboats.

    For now, having elegant and swift hull count almost for nothing in the eyes of customer, as compared against two-stored bridgedeck, and maximum ratio interior/LOA.
  13. Frosty

    Frosty Previous Member

    Sounds like you designers don't know what to do and with all these new materials on the market.

    A aerodynamically designed catamaran, solid fibre glass not balsa or composite, ribs of some kind acceptable 44 feet weight max 8 tons dry. ( no such thing as foam resin yet?)
    Low speed planing hulls 15 knots planing, max 30knts. 50 liters per hour max

    Interior, light weight aircraft type plastic mouldings like a modern Airbus, all removable and replaceable --no wood what so ever, alluminium mouldings not angle and polycarbonate sheet or similar adapted with imagination. Seating free standing but securable in places of choice.

    Bathrooms as pods but removable, tanks removable, light weight carpets throughout removable washable and replacable.

    Toilets stainless steel not heavy pot, lightest plastics or carbon fibre or poly carbonate.

    No windows in the lounge (its too hot here to care about whats happening outside) very thin upper super structure for weigh considerations. No bridge.

    Galley, light weight wipe clean style white plastic and mouldings.

    Air to air cooling for air con.

    Twin deisels with surface drives with long hydraulics that can remove the shaft completely from the water meaning only fibre glass remains in the sea.

    Dry main engine exhaust with air to air engine cooling. (I hate sea water).

    Dipping rudders.

    No fly bridge just a step up outside of aft of the lounge locating one dry steering station for all nav aids making a sleek low down look.

    400,000 US
    2 people like this.
  14. yipster
    Joined: Oct 2002
    Posts: 3,486
    Likes: 96, Points: 58, Legacy Rep: 1148
    Location: netherlands

    yipster designer

    ah, now your talking :cool:

  15. ekamarine
    Joined: Nov 2008
    Posts: 43
    Likes: 1, Points: 0, Legacy Rep: 36
    Location: Turkey

    ekamarine Junior Member

    %100 agree on this )))
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.