Ocean crossing with motor-yacht

Discussion in 'Powerboats' started by phatzih, Jul 7, 2005.

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    Location: The Netherlands

    D'ARTOIS Senior Member

    A Transatlantic crossing? From Gib to the Acores and than futher to the Carib Isles - quite possible if you can take the required fuel with you.
    Hence my remarks: (I know fast power and sail) with a boat of small size and doing 15 knots in force 6 - 7 is unwise if impossible. I believe that we have had this discussion much earlier. I believe 7 to 8 knots is a more realistic speed for a small craft.

    Then I agree with Fast Fred / with your kind of calculations you will end up in big trouble.

    Those boats you mention are not made for ocean crossings, nor will you find any insurance co that will cover your trip.
    A 40 hp outboard consumes about 10/15 litres per hour at that speed of 7/8 knots so you will need for your trip to the Acores about 2400 litres with some reserve, so I believe that with this extra weight your attempt is unlikely tpo succeed. If you use a twin engine configuration, the figures are even worse.

    And then the seakeeping aspects of the boats you mention, is of course another discussion. With all this extra weight the boat has to carry you have to be just once unlucky and you are done with.......
  2. yacht371
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    Location: North Vancouver BC Canada

    yacht371 Yacht Designer

    The actual boat we will be using is not outboard powered but has a single Volvo D3 diesel, and uses much less fuel than the outboard version. I don't like outboards because they can "drown".

    As far as speed goes, the range calculations are based on a 15 knot speed, but the mileage is much better at 7-8 knots and we certainly can slow down if conditions are rough. On the other hand by careful use of weather forecasts which are now quite accurate for the 4-5 days we need for each leg, we hope to avoid Force 6 and above.

    Before we set off we will run a comprehensive set of instrumented fuel economy tests in various loading conditions. However my fuel calculations, based on early sea trials and found at www.aviadesign.com indicate 1000 liters will be more than enough at 15 knots. In practice speed will vary depending on conditions.The boat can maintain 15 knots in quite rough seas due to narrow wave piercing hulls(14:1 B/L ratio) and V shaped central pod. However heavily loaded at the beginning we will probably run at 12 knots or less then speed up as fuel burns down.

    We are not heading to the Caribbean but to St. John's Newfoundland which is quite a bit closer to the Azores, only 1200 NM. Then up the St. Lawrence and Great Lakes for trucking to the West Coast.

    Safety equipment is detailed on the website. Crew are all experienced small boat ocean crossers. The boat is unsinkable, but of course could be capsized.
    However, I have never found a single recorded instance of a power cat capsizing. Of course someone has to be first...
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    D'ARTOIS Senior Member

    Not a single boat in the world is unsinkable. The first leg to São Sebastão is about 674 NM linea recta; from there to St. Johns is a good 1250 NM, also measured over the ground.
    The first leg requires 1260 ltrs + 15% reserve (bare minimum); the 2nd leg, the roughest and most risky requires 2345 ltrs calculated at a general speed of 8 knots. This 3D engine is rated at 150 hp and that consumes at the bare minimum 160 grs/h so calculate yourself. You are going agains the wind; starting at the 2nd leg you will have the prevailing winds between 10.00 and 11.00 hrs; that will not only slow you down considerably but will make your ride very uncomfortable, specifically in a twin hulled vessel. That's why you see so many cats on the North Atlantic.

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    Location: Conn in summers , Ortona FL in winter , with big d

    FAST FRED Senior Member

    "one of those crazy Parisian drivers"

    After the welfare set riots folks from Paris are no longer called "Parisian".

    New description is PARISITES!

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