Yammy Jet Drive, any experience?

[mvining]

We are considering the purchase of a 80 HP, 4 stroke, Yamaha Jet Drive outboard. I understand that this engine is the same 1741cc/106ci power head as the 115HP 4 stroke which I think is pretty reliable from lurking at this web site. Does any body have any experience with this lower unit configuration from Yamaha? <br /><br />The boat is a new 19 foot RIB (Rigid Inflatable Boat) that would normally be used with a traditional 115HP outboard. We frequently use the boat as a regatta safety boat and also to set and retrieve racing marks, so top end speed is a consideration. The idea of an outboard without a prop is very appealing in both situations<br /><br />Price considerations are not as much of an issue as performance and safety. Any comments?

 

[Forktail]

Re: Yammy Jet Drive, any experience?

The F115 is a fantasitic outboard, fuel injected and proven. It is especially unique in that it comes in a tiller version...which can also be outfitted with a jet unit. You've got the right outboard.<br /><br />But you lose 35 hp by putting the jet unit on it (that's why they call it an 80 hp). Jets are specifically designed for shallow water. And there are draw-backs to that. <br /><br />Expect very poor holeshots, poor top end speed, more noise, fussy mounting adjustments, cavitation on small waves, and additional clean out and maintenance upkeep. You won't be able to tow or pull much either, and the boat will perform much worse with a load.<br /><br />Your RIB probably has a "V" or semi-V bottom, which generally aren't adequate for jets. In fact some flat bottom boats have special bottoms to help make jet outboards perform. And some V bottoms simply don't work.<br /><br />Go prop if you can.

 

[rodbolt]

Re: Yammy Jet Drive, any experience?

hello<br /> yep what forktail said plus in my area milfoil kills them by causing cavitation. and if you idle in shollow water it sucks itself full of trash. good luck and keep posting

 

[backdraft]

Re: Yammy Jet Drive, any experience?

Commadore, as above plus they are notoriously bad for close in control of the boat as you have to blip the throttle constantly for turning it. nevjb

 

[Forktail]

Re: Yammy Jet Drive, any experience?

Jeepers, I almost forgot about reverse control....there isn't much.<br /><br />They do work fantastic in shallow water running though.

 

[mvining]

Re: Yammy Jet Drive, any experience?

Wow, we don't really care about shallow water performance. We are always in water that sailboats are in, so we are in plenty of water. <br /><br />The drawbacks sound pretty big. The RIB is a deep V, and maneuverability is a big issue. Sounds like we should just go the traditional route.<br /><br />Thanks for your comments.