Trailer Cat Design Study

Discussion in 'Multihulls' started by Chris Ostlind, Apr 3, 2007.

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  1. Chris Ostlind

    Chris Ostlind Previous Member

    I've been looking at trailer width, plywood build cruising cats for quite a while now. Even though some of them are pretty darn close to what I wanted, there was still a bit of fluidity to the lines that I was looking for that I could not find in the available designs.

    I did my own version and I'd like to hear any comments from the Boatdesign readers as to what is working for them and what is not after you take-in the new design, the Gato Especial.

    The GE is 21' LOA, has a beam of 8.5' and displaces 2000 lbs. She carries 218 sq. ft. of sail area in a jib and main and is capable of a tidy assy. spinnaker to get things moving off wind.

    There are centerboards in each hull offset to the outer edges of the bottom hull panels. Rudders are flip-up variety mounted in sugar scoop style transoms with boarding steps integrated in the structure. Draft, with the boards up, is a little under one foot.

    The cabin interior accepts a queen-sized bed, has room for a small, two-burner stove something along the lines of a Coleman unit and there's room in one of the hulls for a curtained Porta-Potti setup. Not shown in the renderings is a flip open hatch on the forward cabin slope allowing access to the bow without having to climb up and over the cabin.

    The hull shapes create a full-length spray chine, which also expands the interior volume while keeping the ride drier and more comfortable.

    Engine power is from a 5-8-hp outboard hung from the transom between the hulls with a hoisting mount.

    Cabin access is through a generous companionway hatch with removable boards and hatch lid.

    Straight forward construction in stitch and glue style with marine ply and epoxy glass inside and out allows modestly skilled builders a chance to have a nice cruising boat within their reach.

    The Gato Esp. can be easily towed by a medium sized vehicle without much impact save for visibility to the rear and a hit on the mileage. Launching should be a relatively painless experience with a mast hoisting and rudder attachment, the major chores.

    This boat fits in a similar, small cruising cat, niche as the Jarcat6 and the Waller 670 This is tough company, to be sure, but I feel the design and the layout of the boat meet the competition nicely.

    There is also a ten-foot beam version of the Gato Esp. for those who do not need to trailer their boats. These builders would have local waters, or mast-up storage, where they can leave their boats without the need to hit the road as frequently, if at all. For European builders, the Gato can be reduced in beam to 2.55 meters to meet trailer width limits.

    I'm open to comments/constructive criticisms as part of the design process.

    Attached Files:

  2. waikikin
    Joined: Jan 2006
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    waikikin Senior Member

    Looks nice Chris, the spray rail expansion is a cool idea that I had on a Beach marine cat years ago & worked well, dunno about its use on a boat so narrow, maybe better to leave it off the outboard side & exagerate? it on the inboard side & therefore get maximum centreline beam to the hulls within trailerable limits, although I imagine you've run the numbers on stability to be ok. These trailerable style of cats look to be a terrific boat for coastal cruising without sea sickness, caravan on land & shallow draft for interesting exploration of creeks/rivers ,lakes & conservatively sailed coastal hops, I've heard of Jarcats doing some cool cruising & last year sailed the wangi ragatta, one compeditor had a nice Waller 670? & whilst not screaming around the course on 1 hull like my ride(Egan 950 Tri) was doing some relaxed champagne sailing & I beleive won his division!Regards & all the best with it from Jeff.
  3. Chris Ostlind

    Chris Ostlind Previous Member

    21' Gato Especial Catamaran Project Underway

    Big Bump...

    Hey Guys,

    I've got this pair of guys over in Athens Greece, who are just banging away on the build of my Gato Especial 21' cruising catamaran. They had a short delay when their epoxy order did not arrive as quickly as they had hoped. But, the sticky stuff is on site now and they are moving along with real intent.

    They just sent me the second pile of progress photos of their project and things are looking pretty good. With any luck with the weather and a work ethic like this, they just might be sailing before the summer goes away. The question then... does the summer ever totally go away in the Greek Islands just off the coast of Athens?

    The thought of a cool glass of Greek wine, a nicely grilled, freshly caught local fish and a mound of tasty Dolmades while lounging at anchor just knocks me out. I'm going to have to start saving my cash for an anniversary trip to the Med with my wife.

    You can read the first and second build progress installments on my website.
  4. bill broome
    Joined: Jul 2008
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    bill broome Senior Member

    this is a pretty design. it will sail better than a j6 and have competitive accomodation. but it's too narrow!

    ross turner put a demountable transverse deckhouse on his j7, which was a good idea there. it would be a much better idea on a j6 sized boat, which is a genuine use twice a week size. with the deckhouse off, it shouldn't be to hard to slide the hulls together on rails. this would make a boat wide enough for good sailing, narrow enough for comfortable towing.

    launch/retrieve time about45 minutes, and you need a shoal beach, but there should be a market.

  5. Chris Ostlind

    Chris Ostlind Previous Member

    Small craft design represents a long list of issues which are much less in evidence when doing larger boats. Weight placement, trailering strategies, setup time to launch, stability, propulsion... just the full gamut.

    Each boat will have its strong points and its less strong points and there will not be a "perfect boat" for everyone and their individual interests. The designer, therefore, has to dial-up the best possible combination of possible elements that will fit the original design brief. In the case of the trailer beam Gato Especial, there was a conscious understanding of the sailing beam vs trailered utility possibilities, with one side of the coin being addressed as preferential; The trailer legal launch utility winning out in this design.

    There is a wider beamed version of the Gato Esp. at 10'. It can still be trailered in the US around the clock with a special permit. I'm not sure how difficult it would be to trailer the boat in other countries, though it would be interesting to compile all that info. The ten footer makes for a very spacious platform, has pretty much an optimal balance of stability under sail/handling and, in my opinion, would make for an incredible boat... if the owner understands the extra twiddling they will need to do with the government agency which oversees the road regulations and permits.

    The solution you mention can also be a good one, though it has its own things which the owner must consider as a use process in order to go sailing. Which one is best? That all depends on the guy/gal who is going to put it to use and their personal preferences when it comes to the allowable compromises they wish to engage.

    This is my first cruising oriented, fully cabined cat at this size. I chose to go this way with the design because the challenge appealed to me. I have another 21' cruising cat just about completed with sliding hulls and an open bridgedeck as its solution envelope. In the future, I'll probably find myself looking at a separate, cabin component cat with sliding beam hulls as a design challenge.

    There is a lot of fertile ground to be explored in this category with all sorts of possible solutions to be implemented.
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