AeroCat power cats, opinions?

Discussion in 'Powerboats' started by Krauthammer, Dec 6, 2011.

  1. Alik
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    Alik Senior Member

    In US, 90% of boat designers do not have any engineering degree. Why are You surprised?

    I believe designing powercats is still much about opinions, preferences and experiences. I was doing seminar with M&M guys two months ago on powercat design and we found that sometimes we have different answers/approaches on same questions.
     
  2. Krauthammer
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    Krauthammer Junior Member

    For the same reason if I were to uncover that 90% of the buildings were designed by carpenters.


    Same with sail multihulls and the last America's Cup gave us a great display of differing approaches.

    Getting back to the single drive multihulls, are we saying that a Tri would be the only acceptable solution?
     
  3. Mr Efficiency
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    Mr Efficiency Senior Member

    Is the Glacier Bay 22 a symmetrical sponson boat ? The only ones of the brand name I have seen weren't, and I did note they were pretty full at the stern. "Disastrous" is probably a bit exaggerated for the description of its handling, reviews are pretty subjective, I would say if the boat in question is being used in large numbers in difficult offshore conditions, there would be no dire vices.
     
  4. Krauthammer
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    Krauthammer Junior Member

    Yes they are, all of them are. See their website on design:

    http://www.glacierbaycats.com/site/design/hull-design/


    You are obviously confusing them with something else.



    Not exaggerated in the least. Magazine reviews in the US are typically "puff" pieces intent on keeping advertisers happy and a critical review like the one on the 22' is very rare and a caution flag. Disastrous, yes when one considers the numerous reports of occupants in the 22' being tossed around at speed and sometimes overboard. It was bad enough for the 22' to be discontinued and eventually the original company to go into receivership.
     
  5. Alik
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    Alik Senior Member

    This is our 6.2m cat... Never heard any problems mentioned with this one, besides I owned one of them (open version) for over 3 years and used it quite intensively as family boat in the Gulf.
    Note amount of spray underway...
     

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  6. Krauthammer
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    Krauthammer Junior Member


    Nice. Is it a single or a twin? Didn't see it in your website.
     
  7. Alik
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    Alik Senior Member

    Twin; on this one I believe they use 2x115HP. My boat had 2x85HP that is more then enough.
     
  8. Krauthammer
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    Krauthammer Junior Member


    Are you categorically saying that a 25' X 8'6" cat can not be designed to work efficiently with a single OB in the 90-140 hp range and to perform flawlessly in open water conditions?
     
  9. Alik
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    Alik Senior Member

    No, I am not saying this. We can do it if we get such design request, but what is speed range?
     
  10. Krauthammer
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    Krauthammer Junior Member


    25 kts cruise, 35 knots max., with usual average loads. The intent is to save the cost of buying and rigging the second outboard and, equally important, to produce much lower mpg at cruise.

    The economics of running such a boat an average of 500 hours/year should yield eye opening savings. Considering that outboard engines require replacement after ~1,500 hours, the savings keep piling up and over a 10+ year useful life of the hull should be stunning.

    It must be a stable platform without rocking at rest (the Glacier Bay 22' was the worst offender here) and capable of trimming and running "through" a healthy chop without slamming and dousing the crew. It must leave a clean wake at trolling speeds and not have noisy hull slap when idling up to fish.

    The design should provide for construction with liner and alternatively with rolled gunnels.
     
  11. Alik
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    Alik Senior Member

    Rocking - this is quite usual for cats, but making cat relatively wider solves the problem. Increased beam reduces the roll amplitude. BUT this contradicts with trailerability requirements.

    In general it is feasible, if we can make it wider the problem with single engine blocking the tunnel will be solved. We can make some tricks on hull and tunnel for efficiency but those I will not share in forum :)
     
  12. Krauthammer
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    Krauthammer Junior Member


    See PM
     
  13. Mr Efficiency
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    Mr Efficiency Senior Member

    No rocking allowed ? This thread is turning silly. Why are there no 25' offshore cats with 25 knot cruise, fitted with just a single 90-140 outboard ? Easy question, it is too difficult, by far, to meet those specs, for a number of reasons.
     

  14. Wavewacker
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    Wavewacker Senior Member

    What happens when you use a single OB on a center mounted "pod" say three feet behind the stern....moving the engine back further in the center?
     
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