Catamaran tender to replace rib?

Discussion in 'Multihulls' started by DennisRB, Jul 4, 2014.

  1. DennisRB
    Joined: Sep 2004
    Posts: 1,265
    Likes: 24, Points: 38, Legacy Rep: 228
    Location: Brisbane

    DennisRB Senior Member

    Does anyone have any suggestions for a DIY small catamaran dinghy design to replace a rib? The emphasis is on very light weight and stability. My current 10' wood floor Achilles weighs in at around 35kg.

    My idea was to have a small electric outboard for going to shore and back 95% of the time, and it would then be able to take a tohatsu 8-9.8hp 2 stroke for fast long range performance when used for exploration etc.
     
  2. Corley
    Joined: Oct 2009
    Posts: 3,740
    Likes: 173, Points: 63, Legacy Rep: 826
    Location: Melbourne, Australia

    Corley epoxy coated

    1 person likes this.
  3. Manfred.pech
    Joined: Apr 2010
    Posts: 588
    Likes: 74, Points: 28, Legacy Rep: 319
    Location: EU

    Manfred.pech Senior Member

  4. DennisRB
    Joined: Sep 2004
    Posts: 1,265
    Likes: 24, Points: 38, Legacy Rep: 228
    Location: Brisbane

    DennisRB Senior Member

    This looks pretty awesome. But at $3.5K for the kit it seems a bit expensive.
     
  5. DennisRB
    Joined: Sep 2004
    Posts: 1,265
    Likes: 24, Points: 38, Legacy Rep: 228
    Location: Brisbane

    DennisRB Senior Member

  6. Charlyipad
    Joined: May 2014
    Posts: 218
    Likes: 7, Points: 18, Legacy Rep: 57
    Location: St Simons is ga

    Charlyipad Senior Member

    Hi Dennis, Have you considered a nester? I am building Dave Gerrs version and so far has been simple and cheap. Though not a catamaran would be easier to build. I am keeping mine whole for the time being to save weight. Also I skinnied down a bit on the bulkheads and used two inch foam sandwich for the seats. she,s pretty light, though I haven't finished and weighed her yet

    http://www.boatdesign.net/forums/boat-building/kurt-hughes-daycharter-36-a-31846-22.html#post690593

    There are plenty of other photos around if you google Dave Gerrs nester
     
    1 person likes this.
  7. brian eiland
    Joined: Jun 2002
    Posts: 4,788
    Likes: 157, Points: 73, Legacy Rep: 1903
    Location: St Augustine Fl, Thailand

    brian eiland Senior Member

    Zap cat tender

    from over on another forum....

    Now I remember what it was called ....a Zap Cat
    Images

    https://www.youtube.com/watch?v=Dazy3BpV_Cs


    https://www.youtube.com/watch?v=qKBtUf3hw7Q

    ...or how about this Takacat

    http://takacat.com/3.html
     
    1 person likes this.
  8. groper
    Joined: Jun 2011
    Posts: 2,467
    Likes: 121, Points: 73, Legacy Rep: 693
    Location: australia

    groper Senior Member

    Why pay for a design for such a small boat? Why not just DIY it and bend up some foam sheet material and glass it? Add some rub rails around it to prevent damage to the mother ship and voila? And you get the satisfaction of creating it entirely yourself...
     
  9. JSL
    Joined: Nov 2012
    Posts: 746
    Likes: 37, Points: 28, Legacy Rep: 41
    Location: Delta BC

    JSL Senior Member

    Check out Livingston. Don't know if they are made anymore but they are a good tender - rowing or outboard
     
    1 person likes this.
  10. Mr Efficiency
    Joined: Oct 2010
    Posts: 7,765
    Likes: 273, Points: 83, Legacy Rep: 702
    Location: Australia

    Mr Efficiency Senior Member

    A small, light catamaran is not a suitable choice for a tender, imo. The inflatable would be as good as anything. And thinking you can motor around exploring at some kind of speed with a 10hp outboard in a weigh-nothing little cat, you will just have a flighty menace with it's nose pointing to the sky.
     
  11. Richard Woods
    Joined: Jun 2006
    Posts: 2,179
    Likes: 145, Points: 63, Legacy Rep: 1244
    Location: UK, USA and Canada

    Richard Woods Woods Designs

    I would agree, if you want a tender to carry a load then don't use a catamaran. It won't have the load carrying, nor the storage space in the hulls. You are better off with a barge for a yacht tender. However if you want to go fast then it would make more sense. Even then you won't necessarily be lighter

    I have just built a 10ft row/sail/motor dinghy using 2 sheets of 4mm ply, so it weighs 22kgs including the d'box, mast step. outboard bracket etc. As a plain rowboat it is lighter still

    My 8ft Crayfish dinghy can safely carry three people plus their gear, and is made from 2 1/2sheets of 4mm ply (I actually built a light one once from 2.5mm ply)

    In comparison a 14ft catamaran uses 6 sheets of ply yet sensibly only carries 2 people when motoring

    The Livingston dinghy is very heavy. I always say the best tender is an aluminium rib with the tubes filled with helium

    Richard Woods of Woods Designs

    www.sailingcatamarans.com
     
  12. brian eiland
    Joined: Jun 2002
    Posts: 4,788
    Likes: 157, Points: 73, Legacy Rep: 1903
    Location: St Augustine Fl, Thailand

    brian eiland Senior Member

    Lets see, I didn't see the OP asking to carry BIG loads :confused:

    So I think the cat form can certainly give him the stability that many tender owners find important. Even that little Zap cat can give good stability.
    :p

    Now imagine the 'floor/hull' of the tender is nothing more than a flat plate,...pretty easy to fabricate from say a flat panel of nidacore with a suitable skin on either side.

    Then why put somewhat complicated and expensive 'inflatable tubes' at either side?? Why not solid foam tubes similar to the foam collar material utilized on the 'SAFE boats'?

    Then couldn't those foam tubes be provided with milled channels that would slide over the special configured ends of the flat panel floor board. Designed properly you might not even have to glue the foam tubes on, but rather secure them in place with 'commercial grade velcro' (interlocking mushrooms).

    The size and cross-section of the foam tubes would determine buoyancy ...and load carrying.

    If light enough, and inexpensive enough, you might even want to carry 2 such tenders
     
  13. Mr Efficiency
    Joined: Oct 2010
    Posts: 7,765
    Likes: 273, Points: 83, Legacy Rep: 702
    Location: Australia

    Mr Efficiency Senior Member

    It gets down to whether you want something you have a level or near-level footing in, if you do, a tiny cat is a dud.
     
  14. Mr Efficiency
    Joined: Oct 2010
    Posts: 7,765
    Likes: 273, Points: 83, Legacy Rep: 702
    Location: Australia

    Mr Efficiency Senior Member

    Key is where is the tunnel roof in relation to the water, if there is quite a bit of clearance, you will have a little boat that is somewhat sensitive to fore and aft weight shifts, if it is kissing the water, or lower, you have a boat that will slap like all heck. You can't win, so don't bother !
     

  15. Alex.A
    Joined: Feb 2010
    Posts: 348
    Likes: 9, Points: 0, Legacy Rep: 108
    Location: South Africa

    Alex.A Senior Member

    How about an outrigger?
    Gary Dierking -http://homepages.paradise.net.nz/garyd
    Or a design yourself - like Glenn Tiemans in the pic.
     

    Attached Files:

Loading...
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.