Prop sizing Yamaha F-175

 

Hello Fishwrecked'ers

 

I recently re-powered my Seafarer Victory 6.0 with a new Yamaha F-175 and I'm trying to fine tune the handling and prop selection to compensate for the extra transom weight, Previously it had the original Evinrude Ocean Pro 150 2 stroke. 

I keep hearing that if new 4 strokes arent' propped to be able to reach their max rpms ~6000, it can effect the engines life annd cause damage. . .

The engine currently reaches 5700 rpm, is this good enough? or do I need to go down in Pitch?

 

Thanks! 

 

 

 


Posts: 218

Date Joined: 15/01/10

http://fishwrecked.com/forum/

Sat, 2014-11-01 13:37

http://fishwrecked.com/forum/any-prop-gods-about

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null

Posts: 23

Date Joined: 09/05/11

Nice motor mate, I looked at

Sat, 2014-11-01 15:44

Nice motor mate, I looked at these just recently but ended up going for the Suzuki 175. I would be looking at getting maximum rpm with that motor which is 6000. The dealer who fitted it should have changed props  until he had it spot on. That is what the initial test run is about. I would ask him to do so, it's a lot of money you've spent so you want to get the best performance possible.  

Posts: 5738

Date Joined: 18/01/12

 definitely better to under

Sat, 2014-11-01 16:32

 definitely better to under than over propped.

that allows for a heavy load.

check the engine specs for the parameters

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 Give a man a mask, and he'll show you his true face...

 

 

The older you get the more you realize that no one has a f++king clue what they're doing.

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Posts: 31

Date Joined: 09/10/14

 Cheers guys, I've had it

Sat, 2014-11-01 17:13

 Cheers guys,

 

I've had it back to the dealer who has lifted it to the top mounting hole, but I think it still needs to go higher, I'm reluctant to have the transom re-drilled though! 

 

I was supplied from the dealer a yamaha 3 blade 17 pitch prop. I've tried a 4 blade 15 pitch and that got me from 5600 up to 5700 rpm WOT.  

 

Freoboy I hate to even think it but I wish I had looked at the Suzi a bit more, they seem to be able to swing a bigger prop? 

 

can anyone comment on the "engine life" or damage theory, supposedly they overfuel and carbon up or somesuch if overloaded, Its hard for me to imagine this being the case with a modern injected motor though. . .

 

 

spinksy's picture

Posts: 266

Date Joined: 06/10/10

Freoboy is spot on

Sat, 2014-11-01 17:56

I too went the suzi 175 and when we did the test run he took it to WOT to check propping it went to 6k with a 17 pitch shes a big prop too! My boat is a 6.2 haines and it was a bit bum heavy with the new motor but i have put a drum winch in and that extra weight up front has solved the problem.

Posts: 23

Date Joined: 09/05/11

 My 175 Zuke is spinning a 3

Sat, 2014-11-01 18:20

 My 175 Zuke is spinning a 3 x 16 x 18.5 on a 6.7metre Commodore. 37 knots at 6000 rpm and loving it!

Posts: 315

Date Joined: 07/05/11

U hear that

Sat, 2014-11-01 20:21

 If the motor is working too hard you'll get a carbon build up around the prop exhaust

5700 sounds fine to me. I don't run my four stroke at Max revs as this just doesn't make sense. 

I have been told by suzi and Yamaha dealers that these motors are designed to work at 5600rpm all day but

they're still just a machine. Cruise at 3500 to 42oo rpm and it'll do 3000hrs. Too many ski starts with too bigger prop will do bottom ends 

Im nervous even running new motors at those kinda revs but that's just me

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 Baron Sportsman

Just the depth that Varies

Posts: 812

Date Joined: 09/10/06

Most manufacturers have a

Sat, 2014-11-01 21:09

Most manufacturers have a recommended rpm range and lm sure your in spec .  The question is are you running 5700rpm at a light or heavy load.

Should be propped to turn max rpms at your usual load, ie full fuel, gear and alike.

If 5700 is light once you add all the weight she will drop rpms and work harder.

If your spinning a 4 blade prop they can be run higher on the transom but from the sound of it your on the top bolt holes.

Posts: 5738

Date Joined: 18/01/12

 

Sun, 2014-11-02 10:46

 

____________________________________________________________________________

 Give a man a mask, and he'll show you his true face...

 

 

The older you get the more you realize that no one has a f++king clue what they're doing.

Everyone's just winging it.

 

Posts: 31

Date Joined: 09/10/14

The 5700 rpm was 2ppl and a

Sat, 2014-11-01 22:10

The 5700 rpm was 2ppl and a full fuel tank but no fishing gear tackle etc, so mid to light load i'd say, I'm going to look into both re-drilling the transom and going down in pitch, as Turboz said, when I changed to the 4 blade prop Friday to trial it, there was a sooty carbon deposit on the seal around the prop shaft. . . I've been running a 17 pitch prop and its too much.

 

Thanks for the input I'll keep you posted hoping to get it sorted asap! 

 

 

 

 

 

 

 

 

 

Posts: 1535

Date Joined: 30/12/08

Looking forward to your results

Sun, 2014-11-02 09:17

 as I have a simular issue with my F150 Yammi

Posts: 812

Date Joined: 09/10/06

 Load it up and take it for a

Sun, 2014-11-02 10:44

 Load it up and take it for a run. Then acess where your at. Your props right l recon. Just raise the motor if your not seeing the cav plate when on the plane. You should gain some rpms.

Next would be to try a 15" 3 blade that will turn more rpms than a 15" 4 blade.

I dont think you will have any problems with engine life and lugging the motor,  your not that far off optimum rpms.