Has anyone ever played with different pitches on props? Is this good for the motor? What gains are there? I know they say that if you put on a stainless prop you gain 3 or 4 MPH, but is it good for the motor? Any suggestions appreciated.
As long as you do not exceed the recommend top RPM’s… you’re fine. Actually its better for the engines to be running closer to red-line than for the engine to be lugging around a heavy load at lower RPM’s.
For every decrease (move from 21 pitch to 20 pitch for example) in pitch you’ll pick up 200 rpms (generally…. ballpark). You typically lose 200 peak rpm’s as you move to the next sized higher pitch prop.
Yes, the last 3 boats I have owned I played with different props to find the right one. What are you currently running for motor, RPM’s, Prop size and pitch.
Going to stainless…. A 3-4 mph gain in top end is generous, but possible on high HP motors. Most of the time you will have better hole shot, better bow lift, and will stay “hooked up ” to the water on sharp turns on plain. The extra bow lift may allow you to pick up some speed.
Most boat dealers have a demo prop program. Give several a try and buy the one that works best.
J.
I am running a 125 Mercury. Right now I have a 19 pitch and run at about 5100 RPM. I have not been able to go over 45MPH yet. I would like to go over with a full load. 
Ok, your motor is rated at 4750-5250 max rpm’s. You will want to be as close to 5250 as possible. You have to check out the Merc prop claculator site. Link here:
I ran your motor makeing a few assumptions about your boat and came up with some numbers that don’t jive. They all suggest going to a 23-25 pitch prop. But do indicate a top speed of 46.5. I’m thinking you may need to raise your motor at lest one hole. (Raising your motor one hole will increase your RPM’s approx. 200 rpm) That combined with a 23 pitch prop and an increase in RPM’s may get you that 1.5 mph…???
Hit the above site and run your own numbers. Let me know what you come up with.
J.
If you like to run in and fish shallow water back waters & then run out of those same shallow backwaters, your going to need a good hole shot, which means lowering the pitch of your prop. If your boat porpoises while at top end then your probably trimming your motor down abit. If in case of the later I would body pudy a wedge on the bottom last two inches of the boat. Or add trim tabs. I don’t think a stainless steel will go any faster than an alluminum prop, but it sure will take alot of wood abuse. If your really serious, a manual jack plate “about $350” could be a good investment to reduce engine drag, and add a water preasure gadge for engine safety. Talk to your bass fishing friends, for some of them, their boat performance is more important than their fishen rods! 
{John }
I went through this excersize last year with my Mariner 50. The boat came (used) with a 14 pitch prop, which worked fine with only two people in the boat. When we stepped it up to three, it took forever to get on plane, and when trimming down in rough water (ahhhh, Coralville in the summertime), I had it overheat on me. The R’s with three people in that boat could barely top 5150, with a top speed of about 35mph (gps).
The recommended range for the motor is 53-5800, so I swapped into a 12 pitch. I have been very pleased. I lost about 3 miles per hour on the top, but with the boat fully loaded, it will come on plane reasonably. The tach now reads about 5500 wot, and I have not had any problems with it overheating since.
A lower pitch may not cause loss of top-end, since the motor is able to rev into a range where it is making more power. Two strokes don’t have a tuned HP range like cammed(sp?) four stroke engines do, so it will continue going up with RPM’s until either the carbs or the exhaust start to choke it.
Just got a new Lund 1675 explorer with a Merc 60 4 stroke EFI Tiller. Still has the stock alum. prop and the dealer set the motor all the way down on the transom. Question #1- Should I be setting the motor up one or two holes so the prop shaft is closer to the bottom of the hull? Question #2- What size stainless prop would you recommend? Most of the time I’m by myself but there will be times I’ll have company. I haven’t gone into the site Jon J posted yet so I’m just looking for someone with a rig like mine to compare with.
Before anyone gets confused, I AM talking about the prop shaft and not the cavitation or anti-ventilation plate.
I thought that the anti-ventilation plate was supposed to line up with the bottom of the hull. I don’t have the owner’s manual handy, but it makes sense to me.
Some of the hard-core bass-boat guys use mechanical (hydraulic) jack plates to give the motor a setback and the ability to raise it while on plane, which should get you higher top-end speed. I would worry about ventilating during the holeshot if it were permanently mounted that way.
A lot of the new boat hulls, including Ranger, Tracker, and Triton, have a built-in setback on the transom. Does that just reduce hull drag, or does it provide some leverege when getting up on plane?
Thanks Jon J. According to the site, with a 125 Merc two stroke, a 18 foot aluminum boat I should have a pitch of 24 if I want top speed. Thanks for the link.
Yes, but if you simply go from a 19 to a 24, your RPM’s will drop way too low. You wil need to go up a hole or two to compensate.
It’s a pain in the butt, but when you get it all set up right, it will be time well spent.
J.
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