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Transatlantic in a 32m planing hull motor yacht?

Discussion in 'General Yachting Discussion' started by Pascal, Apr 23, 2024.

  1. Pascal, Apr 23, 2024
    #1
    Pascal

    Pascal Senior Member

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    That post on the new Ocean Alexander 32L having transatlantic “capabilities” had me cringe a bit… 4000 USCG fuel, longest leg is Bermuda - Azores or about 1800nm…. Non displacement hull… at 10kts that’s about 180 hours or 7 days…

    besides the obvious weather and seaworthiness considerations, fuel seems to be real tight… I m not sure what 1900 hp Mans burn at 10 kts in that boat but I d guess about 20 gph… (we burn about 22gph with 16V2000 at 10kts)

    that leaves zero reserve once you add 3gph for the 40kw gen.

    more marketing hype?
    Capt Ralph likes this.
  2. YachtForums, Apr 23, 2024
    #2
    YachtForums

    YachtForums Administrator

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    When I was proofing the news piece, found myself questioning that transatlantic number too. Builders have some liability with performance figures and generally don’t overstate but still… seems optimistic.
  3. jsschieff, Apr 23, 2024
    #3
    jsschieff

    jsschieff Senior Member

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    I wondered about the guest to crew ratio. It can hold 10 guests and just four crew. Would that overwork a crew?
  4. Capt J, Apr 24, 2024
    #4
    Capt J

    Capt J Senior Member

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    There are always drums and fuel bladders.
  5. K1W1, Apr 25, 2024
    #5
    K1W1

    K1W1 Senior Member

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    I read a review online and saw this: "Drop the speed back to 10 knots, and the 32L has transoceanic range of 3,496 nautical miles." There was no indication of the fuel capacity or burn rate.
  6. Pascal, Apr 25, 2024
    #6
    Pascal

    Pascal Senior Member

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    Same press release it seems… I looked at the website and the specs show 4000 USG fuel tanks… no way that boat can do Bermuda - Azores on 4000 gallons. Maybe down to 8.5 to 9 kts but still…
  7. K1W1, Apr 25, 2024
    #7
    K1W1

    K1W1 Senior Member

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    If they allowed a 5% reserve it would give 3800 USG. That allows 380 USG a day for 10 days or 15.83 USG an hour for two main engines and a genset. I know MAN were pushing a 175mm Bore engine a few years ago with a pretty stunning 180gm/kwh - Not sure if that's what this is running but pretty sure that figure is at optimum performance and if not the propellor curve would increase the burn to over 200. If it were to run for 349 hrs the numbers seem even more out of kilter with reality
    Last edited: Apr 25, 2024
  8. Pizzazz7, May 8, 2024
    #8
    Pizzazz7

    Pizzazz7 New Member

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    Any powerboat can do 2,000 or 3,000 miles if you drop the speed enough. If you are making 0.5 nmpg at 10 knots, you would be making 1.0 nmpg at 7 knots. With a boat this large, this is the preferable way to go as shipping the boat will be more expensive. It will take time and may be uncomfortable but totally doable.

    The more interesting question is how many boats can do it at planing speed. For my boat, I have calculated between 0.7 nmpg and 1.0 nmpg at 20 knots, depending on weight of the fuel. Assume minimum planing speed is 16 knots and you will vary speed according to conditions, most likely matching the wave speed. So, for 2,000 nm, one needs 2,500 gallons of fuel. That is 2,500 x 7 lb = 17,500 lb of fuel on a dry weight of 30,000 lb. In other words ~35% fuel to displacement ratio. This is nearly impossible on a 50 ft boat. It could be done as a record attempt, i.e. fixing large bladders on the bow and stern, picking a nice weather window and going for it but it is not practical (or insurable) for any reasonable cruising. Still, thinking that rockets can get to 95% fuel to weight ratios...