Is it possible - water jet drive with 5 hp engine?

Hey Jobterrier, hey everyone else. I'm new here so this is my fist post; and this is the topic giving me grey hair currently, so~ Please let me know how this project turns out.

Next month I'll be starting my first boat build ever. I've been schooling myself on this for about a year but that's no substitute for ever having done anything. This first boat is just going to be a simple, cheap toy - so I won't be upset at all the things that can and will go wrong.

The hull is going to be low, thin and flat, based on some very low profile shoal water designs I've seen, constructed of 1/4" ply + glass. Deck will be one flat piece, no glass, just good paint. About 8x5. I have a real good grasp on what needs to get done before I own this hull.

Cheap but acceptable propulsion has been running away from me though. I don't need to fly but I don't want to troll either. I've entertained wavemakers (pond/aquarium stuff, interestingly, they look exactly like tiny water jet set-ups) that can move up to 6000 GPM, and bilge pumps that can move 9000 GPM, but after seeing a YouTube of some pump driven boats I decided, well, that those just aren't up to snuff. I looked at 24v motors with batteries and solar recharge, and while I really like that, the initial expense is just not in my budget right now. Currently I'm entertaining the 212cc gas engine (7hp), but I would want to inboard and jet it if I went that way. Still, if pumps can be used successfully it will greatly simplify my project to use a 212cc pump instead of manufacturing a whole prop-jet set up. Good thing I've not yet committed to ordering that part.

Ok. Thanks all, and I look forward to browsing everyone's know-how all over this place.



PS; Have you looked at "Longtails" and "Mud Buddys". Those are made for shallows.
PPS; Mogai is not a Mokai typo, it is a class of Romulan warbird.

 

That is what Hamilton jet thought when developing their units. One of their farm workers pointed out that to make a jet work better you should discharge the intake water out into the air which is much less dense. So who invented an efficient jet unit.? They did first try using a centrifugal pump but...

 

Just find an old standup jetski and use its engine and jet, a beatup hull with running motor can often by found very cheap.

 

Gonzo has the right idea: consider a prop/tunnel. I don't think there is a water jet on the market that would work on as little as 5 hp.

 

x2. And if it must use a 5hp motor, hook up that motor to the jetski pump. Might need a jackshaft for alignment and gear reduction. Should be a lot more efficient than an ag pump.