Negative Bows ?

Discussion in 'Boat Design' started by Canada Bob, Apr 25, 2009.

  1. Guest625101138

    Guest625101138 Previous Member

    The boat in the attached clip goes through waves but has a wave deflector aft of the real bow to keep pilot from getting drenched. I guess its bow is the extreme of reverse sloping bows.

    Rick W
     

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  2. martinworswick
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    martinworswick Junior Member

  3. Ad Hoc
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    Ad Hoc Naval Architect

    Rick

    Interesting appendage. It certainly increases the waterline length, but the fact it has almost zero buoyancy doesn't really increase its added mass to the inertia for pitch damping. It only pierces the waves by merit of the fact that it has no choice, owing to the direction of the main hull. Whether a large or small wave is encountered by the extension does not alter the motion of that fwd part, or any other part...however, once the wave come into contact with the main hull, then that is a totally different situation. Hence, it really just adds waterline length.
     
  4. capt vimes
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    capt vimes Senior Member

    it seems to me that more and more ships go wavepiercing...
    on a cat or tri it looks like the way to go if speed is on your mind... quite reasonably i think.

    the powerboat on the first image is 'earthrace' which broke the existing record for a circumnavigation just last year... must look absolutly crazy to see her in a good seaway.. :eek:
    http://www.earthrace.net/
     

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  5. Guest625101138

    Guest625101138 Previous Member

    A fine point but it broke the "powerboat circumnavigation" time. Solo yachtsmen circumnavigate faster than this. I think the current multi crew sailing record is 50 days.

    Rick W
     
  6. Time
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    Time Junior Member

    solo sailers dont have to go through the equatorial canals...so the distance to travel is much greater to start with!!!! so the efforts are not comparable at all.
     
  7. Guest625101138

    Guest625101138 Previous Member

    Yes I know this. Makes the sailing records even more impressive by comparison. Considerably higher average speed in the sailing vessels. Just shows how good modern sailing boats are.

    Rick W
     
  8. capt vimes
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    capt vimes Senior Member

    57 days or so about to my knowledge for multi crew on a tri (or was it med2?)...
    nevertheless - earthrace did not cross the roaring 40s to the south but went via the panama- and the suez-canal which is the route for powerboats obvisously. (oh - was mentioned already.... ;-) )
    they are just not build for the servere conditions you may encounter around the antarctic.... ;-)

    btt: wavepiercing boats tend to have a raked bow although earthrace actually has a very steep one but still with a positive angle.
     

  9. Milan
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    Milan Senior Member

    There was a period in the naval strategy, (1860’s – 1880’s), when it seemed that ramming would become most important tactic once again.

    That was a time of rapid development of naval technology. Steam engines made ships more manoeuvreable and armour protected them from contemporary artillery for a while. It was logical at that level of technological development to try to use a ship as a projectile. Soon enough, further development of the artillery and torpedoes made ramming obsolete. Still, rams continued to be built on the naval ships for another couple of decades.

    (The best example of successful use of ramming was naval battle in the Adriatic Sea, nearby island Vis, between Austro-Hungarian and Italian navies in 1866).
     
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