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Custom jet project

499 Views 1 Reply 1 Participant Last post by  curtis73
I'm looking to speed up my learning curve a bit. I'm doing a custom project. I'm not new to modifying and building boats, I've just never done a jet. Long story short, I have an 8' glass tri-hull dinghy that currently has a 3.5hp outboard. I use it for fishing, but the shallows make having a prop, umm... a frustrating and sometimes expensive choice. The whole point of my getting this little thing was because of shallow draft, so I'm going to cut and paste a PWC drive in the hull.

Where I lack knowledge is in which drive to choose. This is not a "let's see how fast we can go" project. This is something that I want to be able to plane and go quickly, but it's primarily a river fishing boat. I'd be happy with 15mph. If I happen to splurge a little and I can do bursts of 30mph, I won't complain.

The name of the game is getting adequate power without displacing all the capacity of the hull. I'm not afraid of throwing some reeds, timing, and lean out carb jets to make a lighter/smaller engine output more like the next size up, so for instance if I can take a 300cc drive and make it perform like a stock 400cc and save 20 lbs, I'll do it. I've been considering using one of the 15hp OMC powerheads I have sitting around, but until I find a pump and make all the adaptations I would have a crazy amount of work into it when I could likely find an existing drive that's light enough.

What skis would you suggest I consider that have a relatively light drive with good aftermarket support, better reliability, good output per displacement, respond well to mods, etc? I'm likely looking in the smaller range unless you all know of a 550 or 650 that is particularly light. The boat in question is 8' long, 4' wide, and 14" freeboard at the oarlocks. Dry weight I estimate 100-120 lbs.

So what's out there? HP/lb with an emphasis on the lb part.

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Even if some of you have an idea of what a drive felt like when you lifted it? Just trying to narrow it down from the wide range of options. Should I just Rotax it from a Sea Doo and be done?
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