Small power catamaran

[bsmit24]

I am interested in building a small power catamaran. I have not been able to find many plans. There are a few such as Glen L but the tunnel is very low. What are the design issues that I should look at. With of hulls or ratio, with of total vessal or ratio, hieght of tunnel, width of tunnel, shape of hulls, etc. and how these differ depending on whether it is a displacement craft or planning hull? any insight or interesting websites or books would be helpful.

Thanks

[nero]

What do you plan to do with your power cat? Live on it, cruise it, race it. Where are you going to keep it? How big are you and your guests? How much time do you have to build it?

Kurt hughes and John Shuttleworth have designs.

[bsmit24]

It would be to cruise and fish. My main objective is to get a smooth ride with little power and a relatively small boat (14' to 18'). Nothing to fancy, just a project that I want to do and a new challenge.

[yokebutt]

Bsmit,

How about an old hobie 16 with an outboard? You could always replace the trampoline with a rigid platform.

Yoke.

[nero]

How about a proa?

http://www.harryproa.com. Rob Denney

Kurt Hughes has several small designs. Rapid building technique also. Plan prices are affordable.

[marshmat]

Proas are intriguing as sailing craft, yes. I'm not sure if the concept is that good an idea for power craft though. In displacement mode you'd be restricted to hull speed on the ama- not a problem on a sailboat that rarely approaches that speed, but a concern on a power craft. A symmetrical cat would probably be more efficient.

For the 14-18' range: I do like Yoke's idea of a hopped-up power-Hobie. If I were building this as a little back-lake cruiser I might actually design the beast myself, be creative....

Now a few rough guess answers to bsmit's questions: Compared to a monohull, a cat's hulls tend to be very slender. For planing, you typically keep the outer hullsides parallel while narrowing the tunnel significantly (the air in the tunnel then helps lift). Hull bottoms can be V or half-V, and are often asymmetrical (it's a complex art...). For displacement hulls, it's usually more like two separate boats bolted together- each slim and sleek. Hullforms- near infinite variety. The stability comes from the wide spacing between the hulls. Tunnel height is determined mostly by the waves you'll run in and the tunnel should be high enough that the waves don't slap it too much.

The art of hull design is as complex or simple as you want it to be. If you're fishing little back lakes, this could be a fun one to experiment with. If you're a big-water type it might be better to look at stock designs.

[JEM]

Take a look at http://www.davesflatcat.com/ . I think Dave is a member on this board. Last I heard, he's willing to share the plans.


Matt - JEM Watercraft

[bsmit24]

Thanks guys. I have a 40hp yamaha so I would like to try a planing hull first. I did find one that I liked on http://www.constellationyachts.com/skiff.htm . The davesflatcat is interesting but the tunnel is very low and the hulls have flat bottoms. I currently have a bateau so I would be more interested in something that would take a little rougher water. I also like the twin vee 17 but I really want to build the boat. There just does not seem to be much out there.

[Tim B]

If you tell me what you're after (E-mail me - Tim@MarineDesign.tk ) I'll draw up some ideas/plans for you at reasonable cost. I can't easily post you drawings, but we can work in electronic form, no problem at all. Then you can either print the plans full-size, or just take measurements off them. I will supply full measurements for each part.

All the best,

Tim Brocklehurst.

[Jimboat]

Check out my website for tunnel hull designs and methods...

[Aksan]

I do not know all your intents but , here is another thing you can look at

Full catamaran centerconsole 13 ft long , 30 - 50 HP range.

You can get one and rig your own engine to it:

Aksano Catamarans www.aksano.com

The boats do 25-45 MPH and are amazinlgy stable and eye catching..

[kengrome]

It would be to cruise and fish. My main objective is to get a smooth ride with little power and a relatively small boat (14' to 18'). Nothing to fancy, just a project that I want to do and a new challenge.

I have a new design that should slice through and skim over the water and run *very* smoothly in nearly all conditions. When lightly loaded I expect it to hit semi-displacement speeds of 15+ mph on a cheap 6.5 HP industrial inboard gas engine (think Honda GX200).

It is a 17 foot powered trimaran (sorry, not a catamaran) inspired by the traditional Philippine banca boat with further inspiration from the Atkin tunnel-stern Seabright skiffs. It is designed with a deep vee forward that transitions to an inverted vee aft, thus it will function well in both displacement and semi-displacement modes:




Yes it can hold four people as shown, but would be a better boat with only 1-2 people.

My goal was to improve and "modernize" the inexpensive but less than steller performing traditional Philippine power banca (or 'pumpboat') by making it into a lighter, faster, more fuel efficient, and much safer boat for offshore fishing. It drafts about 9 inches so shallow water use is practical, but its primary goal is good seakeeping qualities in the open ocean -- while retaining the economy and fuel efficiency of its predecessor.

This boat is designed to be CHEAP and easy build using plywood and epoxy, with epoxy/glass sheathing of the outer hull as an option. The akas and amas can be unlashed and removed for storage and transport inside the main hull if the seats are built to be removable, so the whole boat should store in minimal space hanging from the ceiling in your garage.

[Aksan]

Hmm..

There are alot of desigs out there that will effectively slice throught the water and use very few HP. But the key point in Design is,that is light years away from actual fishermans visuals..

I mean that want the efficiency in numbersn but they want it to look cool.
You also have to fin means of building this thing so that is simple to fabricate.

If you can design something that is COOOOL to look at , plus it is efficient, then you have a CHANCE in the US boat market.

Now if you are doing this for your sake just to buil one off, then it is great, I would give myself more space to move about and less seats, bench seat would be just fine in this kind of set up...

Oz.

[Squidly-Diddly]

http://www.livingstonboats.com/boats_185.asp

They seem to be the standard 'small power cat'.

Anyone ever put one through its paces?

[Aksan]

Well I build the Aksano cats but I think the reason they did not catch up a lot was they were too plain, too simple lacking style and speed.

I know a few of people who bought ours product www.aksano.com after owning a Livingston, things I heard was;

Lower grade appeareance, engine cavitation, cracks / heirline fractures appearing in areas gunnel was bonked to the dock


Comparable F3 to a 13 ft livingston goes faster despite the fact that it weighs more smoothness of the ride is equivalent, the quality is comparing apples to oranges, we are lightyears ahead of that concept.

Dave livingston very nice guy, was the one who started the company, very smart men, ge is getting a litlle old now his sons now run Martini boats. The company livingston is now located in western shoreline of Washington, veyr slow in business.