Jet powered catamaran

Correct.

Well, what is your criteria, is it cat's or waterjets in very shallow water?

The hull type makes little difference to the working of the waterjet, whether deep or in shallow water. Those links I posted show this very well. Either the jets they use are only good in monohulls for some reason or they are not.

In the absence of any criteria posted, other than a cat and waterjet.....what do you think?

 

AD Hoc. The criteria for us is a catamaran powered by water jets.(original post)
Hull design does make a difference when using this type of propulsion system opposed to conventional drive system in a Catamaran, any hull configuration in fact.

The main issue with water jets is cavitation, therefore hull design in way of the intake should be free of any hull protrusions strakes, chines, to reduce aerated water flow into the intake grate.
Our design incorporates asymmetrical hulls we feel this reduces turbulence on the inboard side of the hull form and makes for a much cleaner water flow, early model testing would suggest this.

There is no perfect design for any boat be it water jet or other drive system catamaran or mono hull.
Development of hull /boat design will continue and evolve in the marine industry.

 

Not really a cat,but perhaps a modified picklefork may do the trick? But at 18' I don't think so...

I was a passenger in a 1300 hp blown Chrysler 426 powered pickle fork once...never again.

 

There have been numerous deaths and serious injuries involving NZ jet boat tourist operations over the years, quite inevitable really when you push things to the edge on a daily basis. But they need the tourist $$$ and so it goes on. I think those kiwis were the loons who invented bungee jumping too !

 

SPJ, I doubt you will find any asymmetrical cats in use by maritime rescue bodies in Australia, it seems to me a tall order to create a boat that will excel in shallow water, debris laden floodwaters, and offshore, and not have it lacking in some way.

 

You're missing the point.

The point is, all the issues you raise, and more, have be successfully mitigated by the like of Hamilton jets, for example. Those boats i posted are very good example of this issue being overcome.

Thus there is your only issue, your hull.

Since those monos shall have a much lesser deadrise angle at the stern than your asymmetric cat. Thus if you want a cat with jets in shallow water, you shall have to alter your lines to accommodate the jets, so the jets work. Because the evidence is that the jets do work in shallow water, thus, the objective is ensuring the lines of you hull accommodate the requirements for the propulsion system.

If you feel you have the holy grail of hull design with your asymmetric shape, than that is a square you shall have to circle yourself!

 

Needless to say, a catamaran/tunnel configuration is going to draw more water than a typical monohull jetboat at "sensible" speeds (unless you want to run aground at 80 km'hr and turn the occupants into unguided missiles), simply by reason of the narrower effective beam, an extra 6 inches could make a lot of difference in shallow water.And I suspect that would be the minimum extra depth you'd need.

 

Mr E. I sure there are no asymmetrical catamarans used by rescue organizations here in Australia, according to prior research.
We don't plan to reinvent the wheel and of course this boat will not be suitable for every application.
If this boat will save lives it will be all worth the effort.

 

Good luck with it, I guess it doesn't matter that a cat is handicapped in shallow water, it still leaves you with the flood and offshore options. I can't really see why asymmerical is the way to go, though, I think 80km/hr would be the most you would ever be able to safely use, and tunnels are just speed machines really. Doesn't matter if the symmetricals throw heaps of aerated water into the tunnel, your jet intakes aren't in there.