Props for 115 Yamaha 4-stroke?

[Deep_Sinker]

I'm looking for suggestions on prop choice for my Yamaha. I wasn't impressed with the over-revving of the stock 17 pitch aluminum prop, so I bought a 19 pitch stainless. The 19 lowered my RPMs by 1100 at WOT but didn't notice any speed gains and have a much slower hole shot. I am hoping to find a prop that doesn't rev out and would still be able to pop a skier out the water. Does such a prop exist? Any other suggestions?

[LMITOUT]

Maybe a 17P 4-blade?

What RPM's were you getting at WOT with these two props?

[marine_man]

What RPM's were you getting at WOT with these two props?

The information LMITOUT asks for above is information that's needed prior to any propping questions can be answered. Also, the RPM at WOT should be when you've got the boat running trimmed up to the optimum running position.

marine_man

[cjac]

It's a tough motor to find the right stainless for. I tried several and gave up, went to the standard Yamaha 19P aluminum.

Northlander has this motor and he has a couple SS props he swaps out pending on what he's looking for.

Try Soderblooms and see what they have in mind for your specific hull.

[Deep_Sinker]

Maybe a 17P 4-blade?

What RPM's were you getting at WOT with these two props?

17P Alum hit the rev limiter at 6000

19P SS gets 4900 at WOT

Both get similar top end (39mph gps).

The SS was bought from Jay. He thought SS would lower RPM to 5600 and increase top end...

Boat is a 1700 Fisherman.

[cjac]

I'd work with Jay and look at a 17P steel, that was what got me closest to the combo of speed and hole shot with decent RPMs.

Another option is the 19P alum, it works for me on almost the same lund hull.

[LMITOUT]

I was thinking raising the motor might help, but then again that will probably mess with your hole-shot. I'd try a 17P 4-blade. That'll get you hole shot and probably less RPM's. That motor should run between 5-6000 RPM's when lightly loaded and right in the middle would probably be ideal.

[marine_man]

17P Alum hit the rev limiter at 6000

Top end on RPM for that motor is 6k... were you going past, or are your sure you were hitting the rev limiter?

Your best best is to go with a 17 stainless 3 blade or the 4 blade as LMITOUT said.

marine_man

[PerchJerker]

Your best best is to go with a 17 stainless 3 blade

I agree. Not surprised your rpms and holeshot dropped so much going from 17 alum to 19 stainless --- you're bringing a lot of variables into play there. A 17 stainless or a 19 alum are probably going to give you better performance than the 19 stainless.

[Northlander]

Deep sinker send me a e-mail and you can come try some of my props out. I have a stainless that Jay cupped, holes and tweeked up a bit and I get 45 with a light load and hole shot and cornering is great. Average with full load and 2 guys is 40mph. Ill be around all weekend and we can test them out if ya like.

[Deep_Sinker]

Top end on RPM for that motor is 6k... were you going past, or are your sure you were hitting the rev limiter?

marine_man

6k is the rev limit. Motor would run up to and cut out.

Northlander, you have mail.

[marine_man]

6K is the top of the RPM spec.. I wonder if there's some variance in your Tach and you were running beyond 6k even though the tach didn't show it.

You should be able to run right up to (but not much over) 6k.

marine_man

[SM1]

I have a similar set up as you deep sinker. 1800 fisherman with Johnson 2 stroke 115. It came with a 17 p 14 dia prop and @ WOT it was 5700 rmp. I did not have a spare so I replaced it with a 17 p 13 1/4 dia hustler aluminum and that gave a WOT @ 5400. I though with a smaller diameter prop I would gain rpm's but this one must be cupped differently. Now I get 39 mph (gps) and a hole shot that should have no prob popping a skier up.

Hope this helps. I know you have a 4 stroke so we may be talking apples and oranges?

[LMITOUT]

The gear ratio is most likely different too.