Lightest Tender/Dinghy/Dink to Carry 6 pax plus luggage?

Discussion in 'Multihulls' started by CatBuilder, Aug 23, 2010.

  1. mydauphin
    Joined: Apr 2007
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    mydauphin Senior Member

    I don't understand why people with catamarans just don't straddle a dingy between the two hulls with some kind of winch arrangement. Of course catamaran would have to be big enough to do it. But the bigger the catamaran the bigger the dingy.
     
  2. CatBuilder

    CatBuilder Previous Member

    Thinking about these sled ideas, I'm all for them. Except... I can't see how you would keep the sled attached and from killing you when you are in extremely large, breaking, following seas.

    Another issue is the outboard/prop on the dinghy. You want your dinghy to plane when you are using it as a dinghy. This means standard power boat outboard gearing and props.

    However... when you are pushing the mothership, you would need a lower gear ratio and a much larger prop. How do you balance those issues?
     
  3. CatBuilder

    CatBuilder Previous Member

    Thanks for the idea and diagrams. I'm not sure could go that route.

    Just some little thoughts:

     
  4. WickedGood

    WickedGood Guest

    3 (qty) 24' boats around with me while I'm sailing? I'm building a high performance catamaran that weighs a little under 12,000lbs. I think the dinghies might come close to outweighing the mothership.

    Yes. Each Dingy would come in at roughly 4,000 pounds and could be independantly operated



    Each Sea Skiff has a little Diesil like a Cummins 5.9 TurboIntercooled which drives a Konard I/O drive. you would then have enough power about 1,500HP to drive the big Mother Cat.

    My cat requires a little over 60HP to reach 14 knots or so. 1500 HP?? Really?




    I think 1,500HP is a bit on the shy side and would really like more. As they say: There no replacement for Displacement. and besides. who are we going to be marketing these boats to? Americans and Americans want and need HORSEPOWER. I guess your Catamarn will just need to get larger. Maybe 2 Staterooms, A Salon , Gally & 2 Heads along with sundeck




    They are used to power the big Cat fly by wire and undock to do double duty as a lifeboat/Crewboat/Tender,Dive Boat, sportfisher, etc

    So you are suggesting also some PLCs and other electronics along with cabling for them between the mother ship and all 3 boats?


    PLCs are good. I have an even better idea if we network it all together with NEMA 2000 and even put radio trandmitter/recievers on each skiff. Rather nice to be able to send the skiff back by itself to the mothership and call it by cellphone when you need it. Never know where youll end up after a hearthy night in port on Liberty?


    Where in the Northeast are you?
    I'm in FL building a boat right now, but I'm from your area. You're South of Portland? So am I.




    Are you the guy who built the Catamarn in a Blue Poly Tarp "Tempory Tent" that has been behind your resturaunt the last 10 years?


    Capt Walt
    http://WickedGooOutdoors.com
     
  5. CatBuilder

    CatBuilder Previous Member

    Ok, a bit more... in a fancy PURPLE color... ha ha

     
  6. cavalier mk2
    Joined: Mar 2010
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    cavalier mk2 Senior Member

    Why do you need the sled/dink to plane? If it is linked correctly it won't matter if there is a large following sea... The idea won't work on my tri but I'd go that route on a cat. I'd have to have a canoe sled with a detachable outrigger. Start sketching ideas and see what develops. And of course if a 1500 HP route is pursued one could always sink the dink for a new mooring.......
     
  7. cavalier mk2
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    cavalier mk2 Senior Member

    Hi Catbuilder, a neat way of managing the solutuion for charter might be to use a variation of the boarding ramp to dock and carry the dinghy/sled. Made out of aluminum it could be strong and light with the ability to rigidly secure the dink to it for your perfect storm conditions. (I like modern fiber lashings.) The lowering end could have attach points to the mothership hulls in different positions to avoid the catapult effect. With the dinghy in use for the guests the ramp can be used to embark/disembark passengers and serve as a swim/dive platform. Of course the engines overhang the ramp a bit. It could be made as strong as you need and also work as a boarding ramp if you dry out.
     
  8. cavalier mk2
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    cavalier mk2 Senior Member

    Most outboards have a shallow water tilt feature that could be set to match the angle when using the ramp-powersled feature.
     
  9. CatBuilder

    CatBuilder Previous Member

    I'm having trouble envisioning this ramp/attachment. I like your idea, in general and would like to explore it.

    I'm still not seeing how anything hanging off the stern of a boat could be considered safe offshore.

    Say you have a breaking wave from astern that washes over the boat and slams the deckhouse, going basically over the roof of the deckhouse...

    What happens to the attachment point when the dinghy rides up on that wave?


    Common practice when offshore is to take your dingy off the davits and get it up on the deck somewhere, where it can't be torn loose or come flying through the door to the deckhouse. When I say "perfect storm" conditions, I mean the real deal. Personally, I don't go to marinas. I anchor out. I live aboard and actively travel, including offshore. While I can imagine this setup working well in a protected harbor and at a mooring or at anchor, how would it work offshore?

    I think I have a lot of conflicting "wants" to work out. I want a dinghy that:

    *carries 6 people and luggage
    *is safely stowed for crossing oceans
    *is a reasonable price
    *planes for entertaining guests and not eating up my entire day ferrying them to/from shore
    *is good on fuel

    Maybe it's not attainable.
     
  10. cavalier mk2
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    cavalier mk2 Senior Member

    The way to make it work is to have the ramp as far forward as you can NOT going past the sterns. The whole ramp/dinghy combo is made strong enough so that when secured it acts like part of the wing deck in breaking wave conditions. Maybe the forward part could be under the cockpit to reduce apparent length? While each component might be a little heavier than stand alone features it surely will be lighter and more economical than main engines/separate dink. How would you move that big dink off davits easily and safely in a running sea ? The planing feature is harder to accommodate without getting gadgety. Inboard dink with hydraulic drive to different props? Retracting prop with jet drives for planing etc.... Think about making it self bailing and provide a hard cover to prevent swamping when docked in storm conditions.
     
  11. CatBuilder

    CatBuilder Previous Member

    Random follow up drag question:

    If I wear a purple dress, do I need to have purple high heel shoes with that or a purple handbag? ;)

    Seriously, here's the question:

    I still need to sail. What would be less drag? Putting a 300lbs tender up on davits and increasing immersion of the main hulls, or towing a 300lbs tender?
     
  12. hoytedow
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    hoytedow Wood Butcher

    I think towing would create more drag, but what do I know? It just seems to make sense because of presenting yet another bow to water friction.
     
  13. cavalier mk2
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    cavalier mk2 Senior Member

    It comes down to what are you towing? Long thin hulls for a cat will have very little drag while a mono dink will have more. Seems sensible to size the sterns for the load if you use davits but too wide creates its own problems in a following sea. How about a light launch/whale boat to store on deck and make the guests row to save weight and gas?
     
  14. Alex.A
    Joined: Feb 2010
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    Alex.A Senior Member

    Have you seen the tender that Boatsmith has on his Tiki30?
     

  15. waikikin
    Joined: Jan 2006
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    waikikin Senior Member

    I vote for the Davits.
     
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