Kraken 25 trimaran rebuild and question re: boarding step for off the beach tri

Discussion in 'Multihulls' started by Corley, Jul 11, 2010.

  1. Corley
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    Corley epoxy coated

    Hi,
    I'm progressing quite well with my rebuild of a mk2 kraken 25 trimaran the main hull is setup on its strongback 50% of the moulding battens and stem lamination are in place next step is to fit the transom and daggerboard case in place which I'm building now. I also have a question I'm wondering if I should integrate some sort of folding boarding step into the transom or crossbeam the freeboard is quite low but it will still be a little tricky getting onboard from waste deep in the water at the beach particularly when walking out past sandbars etc. Has anyone built a step like this for their otb tri or cat and is there anything available off the shelf?
     
  2. rayaldridge
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    rayaldridge Senior Member

    Here's what I did:

    [​IMG]

    The end of the ladder has a Dyneema lanyard that goes to a shackle on the bridle and back to a cleat on the tabernacle. When sailing, the ladder comes up until it's parallel with the water. It makes a step for getting around the front of the mast, since Slider has no forenet.

    It's not deep enough for deep water and weak people, as I discovered when I needed to get aboard from chest deep water when I was sick as a dog. I made it this length so it wouldn't bang on the bottom in shallow anchorages. The solution was a loop of line that hangs down enough to give you a foothold in deep water, but which flips up onto the ladder when sailing.

    The ladder is made from 1/4" ply, reinforced with 3/4" strips of solid timber.
     
  3. aussiebushman
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    aussiebushman Innovator

    I have a similar problem with the Trinardo style tri I'm building, because I'm a diver and will need to get out of the water with a tank, weight belt etc.

    The picture above is fine for a cat, but I can't see how it would work on a tri. The solution seems to be either a "swim deck" extension to provide a lowered platform beyond the actual transom, or a folding ladder. I favour the latter like the custom ladder I made for my cat out of sections of a conventional folding aluminium ladder - see drawing. This was much stronger than the rubbish available from the chandlers and if the extra weight is a problem on a small tri - you could always scale back the dimensions.

    What is important is to have the ladder long enough when lowered that it goes deep into the water so a foot can be placed easily on the bottom rung with little or no effort. When folded up, it can be secured to serve as a stern safety rail

    Cheers

    Alan
     

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  4. rayaldridge
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    rayaldridge Senior Member

    Alan, that's a clever solution. The only quibble I'd have is that your boarding ladder should be available at all times, and not stowed away when sailing, because if someone goes in, you need a good way to retrieve them easily and quickly. Slider's ladder is secured up with a lanyard that cleats to the base of the mast, which a swimmer in the water can reach without difficulty-- mainly because the boat is so small.

    Slider's solution really only works if you have no bow netting. Slider doesn't, because with a 16 foot cat, no one is going to be using the netting while sailing, and you can reach the jibstay from either foredeck. If I had a larger boat with bow netting, I'd have hinged it off the back of the aft crossbeam. I guess I could have done that anyway, but the mast gives someone climbing out of the water something to hang on to, and a ladder that doesn't have an extension above the deck line is awkward to use, because by the time your feet have reached the top rung, you either have nothing to hang on to, or you're bent double at the waist.

    I think the idea could be adapted to a tri if it didn't have full wing decks. If it did, you could articulate the ladder so it lies flat on the wing deck when not in use, but pivots up, back and into the water when needed.
     
  5. aussiebushman
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    aussiebushman Innovator

    Good points Ray, but actually, on the cat, the ladder could be lowered from the water by simply undoing the securing line from a small cleat on the ladder itself. Because if its location, the pushpit rails on both sides of the swimdeck were used to pull oneself up the ladder. See picture

    My comment about the ladder forming part of the stern rail was only a thought about how to make it doubly useful. I'll still consider this when the new tri hull is finished

    Cheers

    Alan
     

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  6. rayaldridge
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    rayaldridge Senior Member

    I understand-- great looking boat, with a lot of well-thought-out ideas visible in that pic. It looks like your ladder idea also solves one of the more irritating problems with boarding ladders-- the tendency to swing forward under the cross arm when someone tries to climb it.
     
  7. catsketcher
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    catsketcher Senior Member

    Use the rudder or a swim step

    For something as elegant as the Kraken I would advocate an unobtrusive addition. On my cat I have a small flat portion on the back of the rudder. It is like fence but only on the back. You can use it to get a leg up when the rudder is down.

    Alternatively you could extend the hull strip planks about 200mm and then use this as a transom step. It will need a vee cut out. For the Kraken you really need to keep it all nice and streamlined.

    cheers

    Phil
     
  8. aussiebushman
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    aussiebushman Innovator

    Can someone please post a picture of the Kraken 25. Can't find one on the Internet

    Thanks

    Alan
     
  9. Corley
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    Corley epoxy coated

    some photos of the boat in her sailing days, rebuild in progress need to get a decent digital camera for some current photos but the main hull is getting there and looking good.
     

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  10. aussiebushman
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    aussiebushman Innovator

    Thanks Corley - yes, a lovely design. Re boarding ladder, maybe consider mounting a fold-down s/s version on the side of the main hull just aft of the rear beam. Though not as rugged as the one on the cat described earlier, a standard lightweight model available from most chandlers would do the job. These come in many different configurations, one of which would be fairly unobtrusive when raised. By adding a couple of small "stops" glassed to the side of the hull below the ladder it would prevent it from swinging under the boat when in use - a major hassle as mention above by Ray. If you 'fair" the shape of these stops, they will create minimal drag

    Hope this helps

    Alan
     
  11. captainsideburn
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    captainsideburn Junior Member

    I would think for a boat as small and light as this you wouldn't want anything like a heavy wooden ladder, maybe a rope loop that you can drop over the side just long enough to get your waist up to deck level?
    BTW you might recognise in that first photo my catamaran, an Attunga
     

  12. aussiebushman
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    aussiebushman Innovator

    Who said anything about a heavy wooden ladder? The one I recommended in my last post is light gauge stainless steel tube at a guess, 10 Kg at most. You would hardly know it was there
     

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