Merc 115 prop selection

[MattL]

I have tried some searches on here and elsewhere on the web, and haven't been able to find the answer to my question in regards to max RPM and fine tuning the prop selection for this model. Hopefully some of you guys can help me out.

I have been using a 17p aluminum prop on my 2001 Alumcraft Tournament Pro 175 with 01 Merc 115 HP Four Stroke. I recently damaged the aluminum and decided to upgrade to SS for better durability and better performance.

Previously I was running about 5700-5800 RPM's WOT with the alum. prop but it was a dog out of the hole, top speed decent at about 36-38. I tried a 17p SS and the hole shot was alot better, speed was about 37-39 and it was running about 5900-6000 RPM's. The boat planed much better and rode higher with much better handling around corners. Overall it seemed to be a great fit. My concern is that the RPM's seemed just a little high with the 17p SS. Would I be better suited with a 19p SS or will that ruin the hole shot and bring the RPM's too low?

I should mention that I run the boat with a light load by myself the majority of the time and don't pull skiers or tubers.

I appreciate any advise from those of you with experience with prop selection. If you need any additional information please let me know. Thanks!

[Moose-Hunter]

Figure that added pitch from 17 to 19 will drop your RPM down another 400 or so. That "may" be too low for your engine. And it may kill your holeshot.

I had the same experience as you with my Yamaha 75hp. What worked for me was a polished ss prop, pitched the same as the stocker but with cupped blades. I went from the standard ss (painted) 13x17 to a ss 13x17 cupped blades with just slightly more rake for added lift. No loss of holeshot and greater top end with rpm right where they needed to be.

This is the exact prop that worked for me...

You can see the cupping in the blade. If your engine has a 15 spline shaft and the gear case is the same diameter... Drop me a IM... This one is for sale cheap.

[Esox_Magnum]

If Matt's not interested I would be for my 115 2 stoke...

[delcecchi]

I looked up and your motor should be between 5000 and 6000 at WOT. So it looks like the 17 is a good fit. There is a calculator at the mercury HSOforum, also.

[MattL]

Thanks for the help. I was out again this morning and hit 6200 RPM & 40 mph and backed down(not sure of the accuracy of my tach). The prop doesn't seem to be blowing out at all, where my aluminum would blow out if i trimmed too high. I think i'm going to give a 19p SS a shot as it would theoretically put me at 5600-5800 RPM.

If Matt's not interested I would be for my 115 2 stoke...

Esox, I am not interested in this prop as I will likely return the one I purchased for a different pitch. If you want it go ahead. Thanks.

[Esox_Magnum]

Thanks Matt... Moose pm me your pm box is full....

[Kyhl]

I'm going through the same thing. I have an '04 175 tourney sport with a 115 merc 4s.

Started with a 17 aluminum and hit the rev limiter before I knew what happened, ouch.

Moved up to a 21 but it's a bit much, topping out around 5,500.

I plan to exchange it for a 19 tomorrow.

Between the two of us, 19 sounds like the right pitch.

[Moose-Hunter]

Thanks Matt... Moose pm me your pm box is full....

You got it... PM inbound!

[Northlander]

I have a 17' Lund Explorer SS with a 115 Yamaha 4 stroke and the 19 was a dog out of the hole but good top end. I went with a cupped and thinned 13X17 stainless from Soderblooms and its great. Good hole shot and top end and it holds tight in corners. Call Jay Soderbloom and he can tel ya exactly what he thinks will work best. He really knows his props and does work on them when you happen to ding one up. Prices are great too.

[Kyhl]

Have you had a chance to try the 19 ss?

I got out on a small lake last night to try mine with a 19 and it seemed to work fine. Topped out a 6,000 rpm running solo, trimmed up on glass. Probably around 5,800 at normal trim with another person.

[bigstick56]

Northlander, If you dont mind me asking, could you give me some contact info for Jay Soderbloom? I just bought a new 115 optimax and in need of a good SS prop, sounds like he knows his stuff. You can shoot me a PM if it works for you. Thanks

[Northlander]

You cant get PM's says your over the limit. E-mail me the addy is below.

[Northlander]

Have you had a chance to try the 19 ss?

I got out on a small lake last night to try mine with a 19 and it seemed to work fine. Topped out a 6,000 rpm running solo, trimmed up on glass. Probably around 5,800 at normal trim with another person.

Ya the 19 was a stainless as well. It was ok with just me and a light load but with 2 and a full livewell and gas tank it was slow out of the hole. The 17 pops me right up and I run 43 mph tops with just me and a light load and 40ish with a full load.

[bigstick56]

E-mail sent...

[Kyhl]

Bumping this back up.

MattL, have you found the answer?

I've had a chance to run a 19 on my 175 Tourney recently and I am starting to question if a 17 would be better.

Using the 19 Tues my Tourney ran 5,700rpm at about 35mph with two people in the boat and full gear and gas.

I'm thinking of going with the 17 based on my trials and you first post.

What did you end up with?