I’m interested in everyone’s experience with speed props. I’m not concerned with jumping and running shallow like the boys in Texas.
I have a Tohatsu 60 with a Yamaha black stainless prop. When it’s calm and I’m solo I can see 38mph at 5700 rpms.
What’s realistic? The easy thing would be to take all the extra ■■■■ out of the boat lol.
I’m not against the Tohatsu ECU tune either but that’s a separate thread
I still need to raise my motor but I plan to get a speed prop for my boat as well. Stock prop 11/16 is good gets me to 38 or so with 2 ppl and a light load.
Thats good enough for me but that doesnt mean i don’t “need” more speed
Honestly I think you are probably near the limit of that motors performance. I have a Tohatsu 60 as well, the fastest I ever got on my FS17 was like 38.6mph @5900rpm. That was with the boat unloaded, by myself, and with no tabs installed. It felt somewhat unstable and to fast for a 17ft skiff IMO. 33mph with tabs and another person feels decent, but I’m usually cruising at 27mph.
Do you think the chip tuners could set me up a tune to run a couple hits of nitrous to let me flex on the other hotsu 60’s?
Sometimes boats actually run faster with weight. So it may not be a matter of extra ■■■■ on your boat. It is more wind, resistance that matters. If I tuck behind my console verse stand-up I may gain a mile an hour or two.
I believe chittum runs the Michigan wheel ballistics as a faster prop. They have a thin blade, lightweight with an aggressive design. When I was speaking with George he considered it a one season prop though.
That Chittum is a wide boat and the tahatso does not give much torque. You’re getting 38 that sounds pretty good. I think you would be hard pressed to get over 40 and not take a mile to get on on the plane.
speed would be a lightweight prop so you could go with aluminum. And then you need to find a rake, pitch and design that suits your hull shape.
Technically five blade cleaver props are fast, but that 60 HP is not going to push that
You still have some RPMs to play with since you are between 5500 and 6000 on the Tohatsu 60.
But going up in pitch will gain you better hole shot, not necessarily better speed.
I take it you have a jack plate. How high on the plate do you run? If you raise up the motor and reach 6k, what is the speed and do you maintain water pressure?
Increasing pitch will absolutely give you more speed but only if you had room to run higher RPM. If you’re already at 5700-5800 one inch of pitch on a three blade will get you to 6000 at the same jackplate height and trim angle.
Chittums already run bow down without tabs so you won’t have to tab down and trim out to get top speed like most of us with skiffs that tend to porpoise. I hit 35 last trip with my Foreman three blade XXX cup and 33 with the six blade HPP. With a three blade PowerTech with single cup it will run 38 but I’m not interested in speed. My top speed is always achieved by running jackplate on 3, trimmed just past level and tabs about half down.
No jack plate and no water pressure issues unless I trim and loose grip.
I know a couple guys run that prop on the 115 and I know they have thrown a blade.
Faster top speed can be achieved with:
Less drag - achieved with bow-lift (using a high-rake, cupped, 3-blade bow-lifting propeller and a small amount of motor power trim above flat), less trim tab use (if possible without hopping), and the motor mounted at the correct height on transom.
Prop slip of less than 8%
RPMs nearest to the factory recommended maximum at WOT (without going over the limit), with a light load, 1/2 tank of fuel, one person onboard.
All propeller manufacturers have known issues with throwing blades when there is a factory defect, bubble or tiny crack in the casting. Mercury Trophy Plus, Tempest Plus, and Fury props have thrown blades too when pushed to the limits on high-horsepower motors at maximum RPMs.
I wouldn’t hesitate to try a CAD-designed Michigan Apollo 10-1/8 diameter 15-pitch 3-blade part # 993408, or a Michigan Ballistic 10-1/8 diameter 15-pitch 3-blade part # 933215, on your rig. I’ve used them and I like the performance, geometry, and quality. If you try one of these Michigan props, you’ll need a XHS® (Drop-In Hub) Kit #116, or a XHS II® (Drop-In Hub) Kit #216.
Just my opinions of course. Every boat/motor combination has its own way about it - but following these guidelines from a friend involved in boat racing has been helpful.
@Jason_M how high is your engine mounted? Grab a shot with it trimmed to running height to see where the nose cone is in relation to the bottom on the stern. Since you don’t have a jack plate, you can’t raise it to gain RPMs, which can increase speed. Raising the engine / prop reduced drag in the water, which increases RPMs. But the prop needs some cup to bite the water.
You may be fine with the prop you have, just with a little more engine height. But current height would need to be checked first. @Smackdaddy53 knows those boats and rigging better than anyone IMO.
Thanks for the specifics here.
I’m going to recalculate my slip but I think I was at 10% last time I checked.
This is with the engine all the way down and in the garage obviously.
If I was running on a flat day my approach is to get to WOT and trim the engine until she starts to porpoise a bit then trim down. But we’re talking about slight changes frankly, sometimes I’ll touch the tabs instead of the engine.
Thanks for the pic. I am going defer to @Smackdaddy53 for his expertise. I have an opinion, but Mac knows these boats much better than me.
You’re welcome!
Yep, you’re right at 10% slip which is not bad. Your top speed is pretty good for a stock prop. I have an opinion on motor mount-height like @coconutgroves but I’ll defer to @Smackdaddy53 as well.
FYI, this is my favorite Prop Slip Calculator:
I see opportunity in that picture….. 
Thank you for the prop slip info! I actually confirmed the formula in ChatGPT and made adjustments on the numbers for realtime data results by changing RPM, speed and pitch. Very handy!
It’s not a stock prop. At the time when I bought it Chittum was putting Powertech props on the Tohatsus
What I meant was, it’s a Yamaha OEM prop that hasn’t been modified by a prop shop. Maybe I’m mistaken and it was modified?
Yes it’s an OEM bought from Boats.net but it hasn’t been tuned or modified.
