trans-Atlantic motorsailer

Discussion in 'Boat Design' started by Mupwi, Aug 4, 2021.

  1. Mupwi
    Joined: Apr 2007
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    Location: durban south africa

    Mupwi Junior Member

    I grew up sailing big crusing and racing monohulls off the east coast of south africa and recently got into sailing small beach cats like the hobie 14.

    im now in the process of imigrating to the uk and thinking of what type of boat would be sutable for me when get there.

    I as I have many friends in Norway, Ireland, new York and new Hampshire and with the distances being much cloaser than from ssouth africa i thaught it would be doable to sail to them rather than having to fly the european ones seam easy in most boats but now my thinking turns to crossing the atlantic.

    imnot a fan of long slow cruises ive got too many other things to do but would the 3000nm tripbe posible in say one week 7 days reliably the records are down to half of that but obviousely in verry spicific weather conditions and on hume multi million$ yachts.

    im wondering with a bit of motorsailing or just motoring where nesesary it 7 days would be posible on say a 30ft cat with a crew of 2-3 not expecting any sort of comfort just basic bunks for 2 and space for provisions for the trip. Are there any desighns that could do this or any i just dreaming I was thinking basicaly a scaled up hobie with say a 15hp outboard.
     
  2. bajansailor
    Joined: Oct 2007
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    bajansailor Marine Surveyor

    In a nutshell, NO.
    Do the math.
    3,000 miles in 7 days is approx 430 miles / day, or an average speed of 18 knots!

    Ummm yes - but they are likely to be the large (80'+) racing trimarans that are professionally crewed, with weather routing supplied, trying to set records.
    You would be lucky to average 150 miles per day at the most on a 30' cat, especially as she will be well laden with provisions - and she would definitely not be an oversized Hobie!
    As someone once said, 'nothing goes to windward better than a comfortable aeroplane'.
     
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  3. Mupwi
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    Mupwi Junior Member

    I think you are being overly pessimistic its already been done single handed on a 75ft tri under sail alone so it must be easier if you can power through the less windy sections you make it sound like 18 knots is undoable while even a tornado at only 2/3 of the size i sugested is capable of thoes speedsare you saying a boat with a 50% longer waterline and similar shape would not be able to? as for not being an oversized hobie thats basicaly what all thoes record seting boats are they definately arent beamy crusing boats. Whoever came up with that quote may have been right unfortunately ive never found a comfortable aeroplane to test the theory.
     
  4. Mupwi
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    Mupwi Junior Member

    this one did prety close and with all the comforts of home.
     
  5. Rumars
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    Rumars Senior Member

    If you have never flown on a comfortable aeroplane, you don't have the money for a boat that can do 18kn average speed to New York, sail or motor.
    Just in theory yes, it's possible, but not on a 30ft boat, that's to small, you need at least double the lenght just to be able to carry enough fuel.
     
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  6. bajansailor
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    bajansailor Marine Surveyor

    Ummm Mupwi, the cat in your link fell far short of averaging 400+ miles a day on her transatlantic - and at 55' length, she is considerably bigger than the 30' cat you mentioned earlier.

    I am not being pessimistic re the thoughts in my previous post, just realistic.
    It is quite possible that you can design a 30' cat that can sail at 18 knots - but it will not have the cargo capacity for all the stores required for you and your crew to undertake a long passage.
    The invention of freeze dried food helped a lot to reduce the weight of stores on ocean racers, and water makers are pretty efficient and reliable nowadays, but you would still need an emergency water supply if your water maker breaks down, and nobody has yet managed to invent freeze dried water yet....... :)
     
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  7. Mupwi
    Joined: Apr 2007
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    Mupwi Junior Member

    maybe i wasent clear in my original post im not saying it has to be 30ft or 7 days but in that ballpark so maybe 40 ft and 10 days. we have a data point of a 55ft boat doing it in 11 days and with all the comforts of home and in a crusing type boat so i can onlyasume a more striped out finer hull boat would do better as for provisions i dont see that beeing exesive in weight i figure 0.5kg per person per day in food and 2l of water so 2,5kg if we alow for a 10 day passage thats 25kg per person 2 crew thats only 50kg total around 150l of fuel should give about 3 days under motor so total crew and cargo weight arounf 400kg dosent sound to exream for a 30-40ft boat im my thinking ive had300kg of crew on m 14ft beachcat ad that still sailed ok.
    Ive been looking around ia bit more and it seems somthing like the dna f4 would probably be capable
     
  8. bajansailor
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    bajansailor Marine Surveyor

    OK Mupwi, you are obviously the expert here, so all I can suggest is that you go and buy yourself a DNA F4 - link below - and set off across the Atlantic in it.
    F4 Foiling Catamaran - Foiling Multihull | DNA Performance Sailing https://dnaperformancesailing.com/our-boats/f4-foiling-catamaran/

    Take 0.5 kg of food and 2 litres of water per person per day, and see how long that will last you.
    Good luck!

    Just be aware that it will be a lot quicker, more comfortable, much cheaper, and much more safer if you simply buy first class plane tickets for yourself and your crew and hop on an aeroplane to go and visit your friends across the pond. And then go sailing on their boats over there. Or hire one when you get there.
     
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  9. Rumars
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    Rumars Senior Member

    There is a big difference between 11kn and 18kn average, and the price reflects this. A TS3 TS3 Catamaran https://ts3catamaran.com/ is 300 000€ new all in, while the DNA F4 is 1 390 000 USD used.
    You can always buy some older raceboat for the price of new rigging and sails, just search for IMOCA 60, Volvo Open 70 and so on.

    0.5kg of food and 2l of water per day is to low.
     
  10. bajansailor
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    bajansailor Marine Surveyor

  11. container
    Joined: May 2019
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    Location: new zealand

    container Junior Member

    Mupwi have you ever done an offshore passage? have you ever sailed on a 30-40ft multihull and experienced what it takes to average 18kts boat speed for prolonged periods, let alone offshore and at night? I have sailed on a french ultimate 40 trimaran - 40ft long, 40ft wide- which was designed for a 2 handed trans atlantic race, the thing is an absolute weapon and it would be simply terrifying trying to sit on 18kts through a dark atlantic night while sailing effectively single handed (which is why you only see the french doing it, they are fcking mad)

    look at what it has taken for other boats to achieve those average speeds on such a long passage, you will notice, without exception, they are all over 100 feet long and all fully crewed by seasoned professional sailors. that is what it takes.
     
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  12. Skyak
    Joined: Jul 2012
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    Skyak Senior Member

    Not to pile on but you are arguing about whether a sailboat can go between two points in a very short period and overlooking that you would likely need to wait a decade for the weather conditions that would make it possible, and only if you launch in a very tight window. Motoring is just not relevant to the problem -it is too heavy to carry a motor and fuel to propel a boat that size over 10kn -and you couldn't make the time up with speed with the extra weight. There are more problems than shortage of wind. Look at the winds it takes to push a 30-40ft boat 18kn and you will find they mostly occur in proximity to wind and/or waves that can destroy a light sailboat.
     
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  13. KeithO
    Joined: Jul 2019
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    Location: Michigan

    KeithO Senior Member

    If one had a near bare hull 60 footer, hull speed calculates out to approximately 10.4kt. Perhaps more under ideal conditions if light and surfing comes into play. If one built a sharpie displacement motorboat or converted a sailing hull and then fitted a single engine propulsion system and substituted fuel weight for ballast (lose most of the keel). Such a voyage could probably be done fairly economically. GA to South Africa would be nearly 7k nm. One way, 24/7 would take 673 hours which is surely overly optimistic since one would have to check the oil at least once a day etc. So 28 days or call it a month. Its long enough that you will get to know the passengers very well. Of course it would be a helluva adventure too. On the basis of 250 nm days, it really wouldn't be a huge issue circumnavigating the globe, but one would still have to make sensible decisions on weather windows and overall strategy for the trip to be comfortable. There are already luxury yachts in this class (Dashews) doing this, but out of reach of all but the most well heeled. But still orders of magnitude slower than what you are suggesting.

    Now I have been thinking about this problem and the solution may be a large Ekranoplan. Basically a hull with a wing and a tail that flies in ground effect (or sea effect in this case). A powerboat that doesnt touch the surface.... Yet I wonder about its range ? It would have to be awful big to make an Atlantic crossing given the amount of fuel it would have to carry. Officially they are not planes since they cant climb out of ground effect. So no pilots license needed (theoretically). The russians have done the most work on this concept, they were looking to transport troops and weapons from Russia across the ocean to the US in the event of war and their goal was high subsonic speeds. Cant be detected on radar since flying just a few feet above the waters surface. Fuel consumption better than regular aircraft and surface vessels while at higher speed.

    But that's not a small boatbuilding project and several major players have already spent millions trying to develop them for the taxi market. Part of the problem is probably the lack of suitable engines, unless one steps up to massively expensive turbines, in which case there are lots of options but with a much greater fuel burn and purchase price.... What the island nations need is something fueled by diesel, which is generally not available in the market...
     
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  14. KeithO
    Joined: Jul 2019
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    Location: Michigan

    KeithO Senior Member

    [​IMG]
    Max speed 300kt, cruise speed 240kt. Wouldn't take that long to cross the Atlantic, but range was only 1000nm. If one shed some of the 302 000lb payload to take more fuel, the range should be acceptable...

    General characteristics


    • Crew: 15 (6 officers, 9 enlisted)
    • Capacity: 137 t (302,000 lb)
    • Length: 73.8 m (242 ft 2 in)
    • Wingspan: 44 m (144 ft 4 in)
    • Height: 19.2 m (63 ft 0 in)
    • Wing area: 550 m2 (5,900 sq ft)
    • Empty weight: 286,000 kg (630,522 lb)
    • Max takeoff weight: 380,000 kg (837,757 lb)
    • Powerplant: 8 × Kuznetsov NK-87 turbofans, 127.4 kN (28,600 lbf) thrust each
    Performance

    • Maximum speed: 550 km/h (340 mph, 300 kn)
    • Cruise speed: 450 km/h (280 mph, 240 kn) at 2.5 m (8 ft)
    • Range: 2,000 km (1,200 mi, 1,100 nmi)
    • Service ceiling: 5 m (16 ft) in ground effect
    Armament

     

  15. Skyak
    Joined: Jul 2012
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    Location: United States

    Skyak Senior Member

    [QUOTE

    [/QUOTE]

    Shed payload and add more fuel tanks??? With twin 23mm cannons and six missile launchers couldn't you just find a tanker full of aviation fuel that would prefer being a few tons light to being a mushroom cloud of flame? BE REALISTIC!!
    ;)
     
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