[ICHTHYDEMON]

If you had a boat capable of running either a jet or prop,would say a 80hp motor give the same performance with either? Or will the prop motor of the same size outperform a jet by a wide margin?

 

[BrionLutz]

Icthydemon,

Prop is way more efficient.

Rule of thumb is about 30% more efficient.

Brion

 

[trap50]

I think the newer jets are rated at the pump like the props. But older oned yes I agree with Brion. I still think if your not chasing shallow water a prop is far more efficient.

 

[big john]

slow-speed steering/manouvering may be easier with a prop. and when you shift a jet pump into neutral you don't necessarily get neutral. on my pump i still get enough forward movement that i can troll slowly (which i have done many times). a friend's jet also moves forward while shifted into neutral but not nearly as much as mine.

keep in mind that a pump is direct drive, and the impellor is always sucking water. the only forward/neutral/backward control you have is changing the direction of the thrust.

the dynamics of a pump are very different compared with a prop. the force of the impellor sucking water upward pulls the transom downward. and the water pickup adds some degree of drag resistance. you DEFINITELY need more horsepower with a pump than with a prop.

my boat hull has a 10 degree vee all the way to the transom, and after much use my opinion is that a pump is better suited for a flat-bottom transom area than a vee shape.

 

[ICHTHYDEMON]

I ask because I was going to get a pump on my new boat. After having thought about it for a a couple weeks,I've decided that fishing in the saltwater is more important to me than fishing the rivers. I'm getting a 19' Super Vee,and am thinking about a 90hp Yamaha prop for the back.

 

[BillK]

Just bought a 19 foot North River after debating the same questions. My only suggestion is to go with the 115 Yahama if your budgets allows. That little bit of extra horse power will come in handy in the ocean for running those long distances to where the salmon and halibut are. Plus it came in handy when I decided to make a quick turn around at Newport on Sunday.

BillK

 

[TundraIII]

With the SportJet setup on my Motion Marine the 30% rule does not apply, its actually more like 6% from what I understand. The 30% rule would still apply to a standard outboard configuration I believe.

Anyone out there with better info?

 

[Pickles]

Lets see do the math, My 175 sj which is rated at the impeller has a merc 200 hp powerhead. That would mean the jet causes a 12.5 percent drop in efficiency compared to a 200 hp prop. Though according to mercury the 175 sj actually puts out 183 hp at the impeller meaning only a 8.5 percent drop in efficiency compared to a Mercury 200 hp outboard prop.

 

[BrionLutz]

fish-addict,

It doesn't have anything to do with horserpower ratings. It has to do with the physics of the jets vs. the props.

I think if you talk to anyone who has an outboard with a prop and jet attachment, the prop will show the rule of thumb 30% more efficient numbers in speed and fuel efficiency.

I have a jet but I don't kid myself that it is anywhere near as efficient as prop.

Advantage for jet is shallow water operation, not speed or fuel efficiency.

Brion

 

[Reel Fun Fish'n]

The 30% rule applies only to the older style pumps with aluminum impellers. if your running a stainless steel impellar upgrade you can add about 17% back on a 200hp.
All of the newer pumps bulit, say the in last 2 years come with the stainless steel impeller and the liners are configured differently also makeing the pump flow more water and at a higher pressure.
My old boat was a 21ft super pro-vee I just took delivery of my new 23ft super pro-vee with the new 200hp and new pump. No comparison as far a performance betweet the old and new, even with the new boat being 10 inches wider

 

[big fishy]

Have had a Hewescraft 210 River Runner with a inboard Sport Jet for years. It will get me places that a prop won't.(sometimes not a good idea).Outboard jets are are about 30% less efficient.Inboards are a lot better on efficiecy. Trolling with a jet does not work very good, been there done that, you will need a kicker. Also if there in a lot junk in the water there will be times when it becomes blocked.I live where there are a lot of rocks and Mr. Rock is not our friend. There are a lot of pros and cons about owning a jet. If you not need to go shallow our have a lot of rocks i would stick with a prop.