Pro-Guide v-175 w/Merc 115 Prop Question

[DogWalker]

I have a 2015 Tracker Pro-Guide V-175 boat with a 115HP Mercury four stroke. I’m replacing the 17 pitch 3 blade stock propeller. We use the boat mostly for fishing but also tow the kids around the lake.


According to the Mercury Prop Selector site, one of the options is a SpitFire 4 blade, 13”, 17 pitch prop. With my estimates, the total weight is 2600 lbs, the calculated engine RPM is 5,750 and the calculated speed is 36mph, which is pretty close to the speed I see. It’s much slower with the kids onboard.


My question is I’d like to get more top speed but don’t know the ramifications of going against the Mercury recommendations. I’ve seen some postings on the net by guys who went with a 19 pitch prop or even 21 pitch and they have been happy with it. If I understand correctly, you’d sacrifice hole shot but would get higher top speed. With my current prop, hole shot is pretty slow but I’m not all that concerned with hole shot.


I’d appreciate any thoughts or experiences y’all had.

[Extremeboating]

You need to categorize the selection on their website by Fish and Ski with the overall performance targeted towards top speed, after that you need to calculate the pitch by performance, not by weight.

4 blade props rarely achieve the same top speeds as a three blade propeller. Ideally you want to be right in the middle of your RPM operating range. So if you are between 5500-6000 range you would want to be around 5800 or so. Mine operates 5500-6000 as well but my operating range is between 5900-6000 normally. No issues here. If you want to clean up that holeshot some and potentially even gain some top end, a hydrofoil would assist you further in doing so. These Tracker boats like them for some reason.

The issue with your setup is that the overall boat is heavy even more so once you load it down with people and that will slow you down considerably.

17 pitch sounds a bit on the low end for a 115, but I also don't know what your current RPM is either.

[DogWalker]

Good info, thanks. I agree the 17 seems low and given they put a 17 on originally tells me they went with a standard option, probably cheaper. My RPMs are 5500-5600, but probably don't get higher given that we are at 3000ft+ above sea level with the lakes we're going to.

One of the guys on the Mercury 4 stroke forum has a marine shop, hope he has some insight.

Thanks for responding!

[Extremeboating]

Good info, thanks. I agree the 17 seems low and given they put a 17 on originally tells me they went with a standard option, probably cheaper. My RPMs are 5500-5600, but probably don't get higher given that we are at 3000ft+ above sea level with the lakes we're going to.

One of the guys on the Mercury 4 stroke forum has a marine shop, hope he has some insight.

Thanks for responding!

A 17 pitch prop should ideally keep that 115 revving nice and high. If you go with a 18-21 pitch it is going to reduce your RPM further and potentially take you out if that powerband sweet spot that gives you the most speed.

Now I don't know if you own a ProXS or what, but those 115 ProXS's have a RPM operational range of 5200-6000 RPM. I'm going to assume that is the one you own. Given your altitude, current RPM and propeller pitch you are using I would say you are topped out on speed. The only other thing you can do is convert to stainless propeller and do a hydrofoil. The propeller should definitely give you some extra speed and a hydrofoil may or may not help you with speed but would definitely help you with holeshot and speed required to maintain a plane.

To be honest, I wouldn't change the pitch of the propeller at this point, but you definitely have some room to play around with differing materials/ add ons still.

[Dharr]

That 4 blade spitfire is going to help raise more of the boat out of the water and will give you more speed as well as going to stainless should gain some. I was getting 42 stock now consistent around 50 with the x7.

[DogWalker]

Good info all, I appreciate it. I'm gonna go with the 17 pitch 4 blade, hope they're not backordered.

[DogWalker]

Quick update. Prop arrived and I took the boat out and easily hit 40mph @ 5800 RPM with 3 people onboard! Hole shot is significantly improved, and handling at speed is much better. Dharr, you were right, that prop pushes the boat much higher out of the water, pad is further back. Much appreciated, I just with Merc had included this prop originally!