Tiny waterjet from Mokai in renewed tri-design

Hi all, need you thoughts on the following:

What if one would use the small waterjet propulsion from the Mokai (http://www.mokai.com/the-mokai.html) but plant it in a wavepiercing small trimaran design ? Would that make it more efficient and therefor higher top speed then the 15 mph advertised, keeping the weight limit almost equal ?
From the first looks (I am not a naval architect) it mees that the Mokai design is made to be low profile, flattenend underwater body, so not optimised for speed... am I correct ?

I like the whole idea of such a small propulsion in combination with the reliable Honda engine.

 

I have done some consulting for Mokai, mostly involving legal matters related to their design, and in the process I was able to try out the Mokai here in the ICW here in Florida. It is a very unique boat that has a wide range of uses. It is a planing boat, and it is meant for speeds faster than human propulsion by paddling. It is not necessarily meant for super fast running. I have talked with Mokai about more power for faster speed--to do so would require a bigger engine and pump, and that would make it much more difficult to transport. The beauty of the Mokai as it is now is that all the components can quickly disassemble--it is easy and quick to get the Mokai into and out of the water.

Mokai is aware of the need for continuing improvements of their design, so I, for one, am staying aware of their future developments.

It's a neat boat.

Eric

 

Thanks Eric, so that convinces me of the proof of concept and that is is a good product. I also liked the simplicity of the engine and the easy of construction. But, would it be suitable for a small personal craft like a wavepiercer trimaran (maybe like http://www.amorousmarine.com/portfolio.php?boatId=15) and would it then potentially give higher speeds ? Even an electric propelled version with LiPo batteries might be interesting. www.seabob.com has got that part already figured out !

 

The Amorousmarine boat appears to be considerably bigger, therefore heavier, than the Mokai. And everything relates to power-to-weight ratio. So I would imagine that the Mokai's Honda engine is not going to be powerfull enough for a larger boat. You are not going to go faster with that engine and pump in the larger, heavier boat. You would need a bigger engine. The pump unit in the Mokai, as you are probably aware, is separate unit, and as I recall, they developed it for their own use, but don't quote me on that. I think there are bigger units available from Honda.

I also had a client in England a few years ago that wanted to develop a battery powered jet surfboard that was very similar to the PowerSki.

http://www.powerski.com/

The Powerski is a single propulsion unit, fossil fuels, I think, whereas my client's version was a twin-pump unit to be powered by rechargeable Lithium batteries. The project fizzled in the end and after developing the hullform for them, and they building a prototype, I never heard anything more. But the point of this that certainly the technology is available and workable.

I have also been in touch with a fellow who has been connected with Powerski in the past, and he would like to set the world record for water-borne jumps, kind of like Evel Kneivel but on the water using a jet powered surfboard. The record jump is recorded for posterity in one of the Roger Moore James Bond films where the boat in the chase scene goes flying through the arie; it was about 83 feet, I think. My contact's target is 100'+. Financing is always the problem, and that is where that project is at the moment--to find the financing for building a really light, strong, carbon fiber jet powered surfboard.

If you want more power, have you considered the Mercury jet pump? They make 200 HP and 250 HP jet drives. These are basically an outboard powerhead mounted on top of the jet unit.

http://www.mercurymarine.com/engines/jetdrives/optimax-jet-drives.php

My original design for the Cherubini Classic 20 speedboat was centered on the 200 HP Mercury jet drive. You can still get the CC20 with a jet, and it is also offered in a Bravo I I/O drive with gas or diesel engines. The link: http://www.cherubiniyachts.com/20.html

Eric

 

Thanks for your reply again Eric. Most be more people with the same idea running around. On this forum there is a guy who made a LiPo electric powered jetski who will send me some pics. I am more fond of tri-marans, and the amorousmarine one was about 80 kg, so not far off from the 63 kg (I believe) of the Mokai. One could also design a lighter version of a trimaran, the Amourous one seems a little bulky to me. I would mix the amourous sailing tri (without the foils) with the motor tri. So the goal would be, little powered , light powertri, preferable with jet (no ugly outboard) with the simplicity of the Mokai, if possible electric...... what a goals.

 

In case anyone is interested, Mokai has a new engine now, and speed is about 35% better, according to their website: http://www.mokai.com/.

Also, I added a story on my website about the patent infringement case that I assisted Mokai Manufacturing with. Mokai was sued by a patent holder for infringing on his patent for a jet powered kayak. Central to the case was, "What is a kayak?" I wrote the expert report to answer that question, and a summary of the case can be seen here: http://www.sponbergyachtdesign.com/Forensic.htm. Scroll down to "What is a kayak?"

Eric

 

Very interesting stuff Eric.

FYI I found a typo in the last sentence of the first paragraph under the second photo in your article on your website.

-Tom

 

Found it, thanks!