Help—prop selection

[old dog]

My son is looking to install a SS prop on his tracker 175 TXW bass boat with a 75 hp 4 stroke engine. It presently has a 17 pitch 3 blade aluminum prop. Any suggestion of pitch for a SS 3 or 4 blade prop. I read u should should lower pitch if going to a 4 blade prop. Ie 17- 3 blade to a 15 - 4 blade.
Any suggestions much appreciated

[-JR-]

check out the iboat forum.

[old dog]

No luck there. Thanks

[dodgeboy1979]

if it's a merc engine, go one their website and there is a prop selection tool to use.

[Dean2]

SS prop, less flexible so more efficient. Downside, if you hit anything the prop doesn't bend or break, your lower end does.

So the question is, why the move to SS and then why the move to a four blade. Unless you are pulling skiers with this boat the relative hole shot difference is irrelevant. Unless you are regularly making really long, 30 mile plus, flat out runs the benefits of a four blade will not be apparent. Also, on that low a horsepower motor the four blade will not make much of a difference in real life, you only start to see the changes at 175 HP and up. HP is the limiting factor on how much prop you can turn and four blades have more resistance than three blades of similar design. There is a very good reason why 3 blade props are the norm. Four blades are a specialized piece of equipment designed for very specific purposes.

Next thing, flat out on slightly rippled water, properly trimmed and with a normal load, what is the RPM and speed on the existing prop. If you can just reach redline or within a 100 rpm at wide open throttle, you have the right pitch. If you can't get within a couple of hundred of redline you need a smaller prop anyhow. Be aware that as you decrease the prop pitch you decrease top speed. You however increase hole shot, low speed plane ability, cornering hold and weight carrying capacity.

Now for the question you asked, if you go to a four blade prop despite the info above it usually requires you drop the pitch, exactly how much can only be determined by testing. Make sure wherever you get it allows you to try it and trade at full value for a smaller of larger pitch depending on your testing results.

[TROLLER]

Get a hold of Stu at Propmasters in Airdrie.

He will fix him up with the prop best suited for his boat.

[Walleyedude]

Put your info into this website, and it’ll give you some really good starting points.

https://www.mercurymarine.com/en/ca/propellers/selector/#!/step-four

I get a Laser II or Vengence in a 3 blade SS, and the Spitfire or Spitfire X7 in a 4 blade. I’ve heard really good things about the 4 blade Merc Spitfire props on the 70-115 HP outboards.

All of the SS props run a sacrificial hub which will prevent the damage to your lower unit in all but the worst of impacts, so unless you’re running a really rocky shield lake or a lot of shallow water, I wouldn’t be too concerned.

As far as 3 blade vs 4 blade, I disagree with the post above regarding the use of 4 blade props. They’ve pretty much taken over the outboard market these days, especially for walleye boats, and for good reason. The top speeds are as good or better, and they give you a better hole shot, better cruising fuel economy, and far superior handling in all conditions, but especially in rougher water. I can’t imagine going back to a 3 blade on my boat, the 4 blade is night and day better.

Pitch when going to the SS should be pretty close to what you’re currently running. The advice to nail down exactly where you’re running in your outboard’s RPM range with your current setup and average load is the key to getting as close as possible when you select your next prop. Your boat specs and that info Is all any good prop shop should need to give you a couple really solid recommendations.

The benefits of going to SS won’t be as dramatic as on a higher HP outboard, but it is possible (quite likely) you’ll see significant performance, handling, and fuel economy gains by switching to the correct SS prop and getting your motor height setup properly.

I wish had somewhere I could recommend that would let you buy and test props that didn’t involve shipping, but it’s hard to find locally. I did NOT have a good experience with Prop Masters.

[skykomish sunrise]

Tempest prop best suited but without horsepower you're actually not going to gain a whole bunch and you're better off sticking with the aluminum. Gains with a 75 horse just aren't worth the expense and I guarantee you won't cry nearly as much when you smack a rock if you're only running $100 aluminum

[The jig guys]

My son is looking to install a SS prop on his tracker 175 TXW bass boat with a 75 hp 4 stroke engine. It presently has a 17 pitch 3 blade aluminum prop. Any suggestion of pitch for a SS 3 or 4 blade prop. I read u should should lower pitch if going to a 4 blade prop. Ie 17- 3 blade to a 15 - 4 blade.
Any suggestions much appreciated

Hey my question is why do you want ss. What do you want to gain. I personally delt with this question a little bit on my tracker 175 but with a 115 hp and a good friend of mine with same boat with a 90 hp but both boats with exact same results. So with that our boats where not getting out of the hole very well at all and always wanted more speed. These boats came with the ****ty black max props. I tried a couple props and the only thing i gained was a mile or 2 with a merc tempest plus prop. Never kept it a then tried a merc spit fire prop and loved it. Gained 1 maybe mile and hour and all sorts of hole shot. Let alone the handling. The spit fire prop you go with the pitch that you have on your boat or the pitch that works best. The nice thing to about the spit fire prop is that you can go cheap with aluminium or get it in the x7 alloy. But with the small hp I would just do aluminum unless you got a Lil $ to burn

[old dog]

Thanks guys Will pass on this info to my son. Lots to thinks about and check out for sure