Props

[Divecoz]

I know we have talked a lot about props a lot , but with No ansswers suited for me as I see it. I want a 4 blade and Moe tried and had a lot of issues $$$$$$ I have now found at http://www.getaprop.com a 4 blade 13.25" x 15 degree pitch I presently run a 14x10 this New Bad Boy is polished stainless and is $367.50 + S&H hummmmmmmm what do you motor guys think and then how about you math wizards??????
I don't need more top end I do need to move more water to improve steering at low speeds ....BTW mine as you see is a 4cyl 4 stroke 50 hp Mercury Big foot

[Hardcrab]

If you are hitting your max mfg suggested RPM wide open throttle range with a 10" pitch prop,
a 15" prop would not be a good choice, IMHO.
I can only go by my experience.

The pitch my boat came with was 14"x13".
As normally loaded, I could only get 46-4800 rpm out of a factory suggested 52-5800 WOT.
The same as to high a gear going uphill in a car and lugging the motor.

I did the math and bought a 14x10".
To much the other way.
I would bounce off the govenor at 60-6200 rpm.
To low of a gear going uphill with screaming rpms.

Took some advice from here and went to a 14x11".
Now WOT comes in at 53-5400 rpm, right in the middle of factory suggestion.
My example shows a big difference with small pitch changes.

I didn't care about the speed differences.
I just wanted the engine to be "geared" right for longest life and best efficency.
Boat engines are always going "up hill", they never get to just coast along.

I don't quite understand your thoughts on moving water at low speeds.

[Hardcrab]

Perhaps I should add I've just started a new experiment with prop pitches.

First of all, for our typical usage, a ten hp would do us fine 99% of the time.
We only motor around the docks to get out to sail.
We don't need the 90hp we have for that.
Several times a year, we'll high speed motor over to Catilina Island.
My 11" prop is the best choice for that usage, and that's whats been on the boat for the last 2.5 years.

Is it best pitch for the normal 99% of our personal usage?
I'm trying to find out.

I've put the 13" pitch back on for normal use to lower the rpms and see if I can get better fuel mileage.
Now, the 13" prop will get me 5 knots (harbor speed limit) at about 12-1300 rpm, down from the 15-1600 rpm for the 11".
I can't imagine the engine as "lugging" at that low rpms.

We only have one trip with this set-up so far, so the jury is still out.

When I know we're going to high speed run to Catalina, I'll take the 5 mins to change back to the 11" before I splash the boat.

[Robert]

Divecoz, I have not posted in a long time. Back in 1999-2000 I tested 9 props on my Mac26X with a Suzuki DF50. I found that the 4 bladed 9 pitch with large surface area was as fast as the 4 bladed 10 pitch. I finally settled on a 3 bladed large surface area 9 pitch stainless prop, but I had it cupped slightly to stop it from sucking air down from the surface. These were all Solas props. The Suzuki 10 pitch 3 blade prop was a decent performer also. The bigger the surface area and lower the pitch as long as you don't exceed RPM limits, gives the least difference in RPMs at wide open throttle when comparing ballasted to un-ballasted. The big area props do not slow down a mac26X being pushed <20 mph since the inefficiency of too great a surface area only matters at higher speeds.
..
If you have only 50hp and you use a 15 pitch prop you will drastically lower your top boat speed, increase fuel consumption and reduce the life of your motor. Of course, if you don't use wide open throttle and want the boat to go faster when the motor is at idle then the 15 pitch would not hurt. The ability to move the boat very slowly at idle is sometimes important around dock and essential for trolling.

[Divecoz]

My greatest concern is with low speed maneuvering. Docking and Retrieving are my greatest concerns. Most recently my embarrassment was while I was trying to dock so as to allow me to wait for the arrival of my truck and trailer. This required docking in heavy cross winds. Greater low speed maneuvering will also benefit my ability to land and depart from my slip with greater safety and less embarrassment .
My thought has been .......... the more water my prop can move at the lowest speed, the better my control will be?
I do manuever with the center board down about 3 to 4 feet and I have tried numerous configurations of rudder...s being up and down . Often to little avail.
Maybe its just a matter of excepting that , to have a stand-up cabin on a trailer sailor your going to have a LOT of Free Board, and there by problems when the wind is blowing from the wrong for you at the moment .... direction.
Hummmm twin 25 's hahaha that might be possible on an X

[Hardcrab]

Well, I would think that "moving" more water will simply equal more thrust, and therefore, speed.
If I understand your thinking, just raise the rpm's of what you have now to "move" more water.
I must be missing something?

The crosswind issue is big.
I use higher speed and reckless abandon ( ) with full dagger and rudders down coming to the docks, and hand walk back onto the trailer.

[Night Sailor]

Definitely go four. A four blade, cupped prop with large blade area will give you a significant improvement in low speed handling. That's what I ended up with for my X after trying three props and six pitches. Although mine is the Merc Classic, with the smaller 13 spline gear case, I have a four blade, 11.8 in. Solas at 8 pitch, and it gives me full RPM at WOT, (and only 1.5 mph less speed at top end that my 12.5 in. 3 blade with 9 pitch). At "no wake" or idle speeds, it's very noticeably able to handle turns, reverses, stops, much better.

I"d suggest trying the 8 pitch for your larger prop, and if not satisfactory for rpm achievement, have the pitch adjusted up or down by 1.

[Rick Westlake]

Has anyone tried one of the Scandinavian "ProPulse" adjustable-pitch props? I was thinking of one for Bossa Nova ... the idea is that (1) you can change the prop's pitch to fit your motor & hull, and (2) if you break a blade you can replace it rather than replace the whole prop.

[irayone]

PIRAHNA PROPS IN SAN LUIS OBISPO CA. HAS PROPS THAT YOU CAN CHANGE BLADES 3 DIFFERENT PROP SET UP FOR APROX 300.00 THE BLADES ARE ONLY 20.00 EACH SO THEY ARE EASY TO REPLACE OR CHANGE OUT. I HAVE A YAMAHA F60TLRD WITH A 11 5/8 X 11 WHICH IS WHAT THE MANUFACTURE SAYS I SHOULD HAVE...HOWEVER WITH MY LOAD I AM ONLY AT 4900 RPMS ?????? WHAT DO I NEED A 10X10 ??

[Boblee]

We use two different props for different uses, if we are lightly loaded and want top speed will use the 13.75 x 13 which works great but when loaded for 2-3 weeks on the water and carrying gear to use as a caravan on land we change to the 13 7/8 x 11 HYDRUS which will get the revs up but is much slower.
We only use the aluminium props as we get into some awkward spots with rocks and trees (also the ladder) and would rather damage a prop instead of the gearbox.
Both props are going to be reset and have some nicks removed as are both of the dinghy props.

[1st Sail]

For what it's worth. '06 26M, Etec 50, 2 batteries, 2 anchors, cooler, 3 adults, 24 gal fuel. 13.75 x 13 etec factory prop, 5200rpm w/ balast, 5300rpm no ballast. 14 x 11 etec factory prop 5700 rpm, w/ballast 14-15mph, no ballast 5800+rpm, 16-17+mph. I've followed the prop issue on and off over the past years. Seems there are a lot of 50hp with 14 x 11 if you have an OB (merc, etec) that can swing the 14. I use the 13.75 x 13 for extended crusing under 10mph and keep the 14 x11 for those afternoon run off the wind and motor back by sunset. The factory props are relatively inexpensive and the performance is good. I'm sure a tweaked stainless would improve the numbers some. Target RPM for the Etec 50 is 5500-6000. Thanks to all those who took the time to post their specs. Because of your efforts I have satisfactory performance out of a stock prop at a reasonable cost.

[3Kioni]

I've used a 4 blade Pro-Pulse prop on my 18' welded aluminum boat (60 hp Johnson 2 stroke), and would use one on my 26X, except that Pro-Pulse doesn't seem to have a hub available for my 2001 50 hp Nissan TLDI.
The advantage of 4 blades at high power/low speed, such as while towing another vessel, was obvious. Although there was no gain on high speed performance with the Pro-Pulse prop (over a stock OMC aluminum prop), there are a couple of advantages. First, if you damage a single prop blade, you can remove it and the opposite blade, giving you a balanced two blade prop to get you home. Replacement blades are about US$25 from West Marine, and are probably a little cheaper elsewhere. Another advantage of the Pro-Pulse "system" is that you can vary the pitch by up to 4", just by releasing the hub clamp, rotating the four blades, and reclamping the hub. The theory here is that rather than carrying two differently pitched props to allow a change from "cruising mode" to "towing toys" mode, you can adjust the pitch of the one prop on your motor. (There's also no possibility of the thrust washer, retaining nut or cotter pin disappearing into 2' of bottom mud while you're changing a prop...)
The Pro-Pulse blades are a composite material, and do flex under load. However, that flex may well prevent a broken blade - but then again, maybe not. It depends upon what you hit. (In the waters of British Columbia, the Canadian Coast Guard Auxiliary has to contend with what is referred to as hard kelp, which can even destroy stainless props.) Anyway, "hole shot" performance isn't a strong point of the Pro-Pulse props, but then MacGregor owners tend not to be the 'go quickly' type of mariners. (Some blue hulled owners may think otherwise, but we white-hulled folks know better...)
In summary, if I could get a Pro-Pulse prop for my 26X, I would. The vessel is a pig to manoeuvre under power at slow speed at the best of times; a 4 blade prop would at least change the handling characteristics to that of a piglet.

[Kelly Hanson East]

Dive - I think you may be over-emphasising, or maybe over-anticipating, how much the 'right prop' will help you handle at low speeds. With my Merc 50 BF, with the engine attached to the steering linkage, I am able to dock pretty decently after 7 seasons, and even back-and-fill the boat in windy conditions.

Part of this is I realise I can recognise a bad approach much earlier now, and wave off before it gets ugly.

I ran a 14x10 per Art when I bought the boat, and switched to a 14x11 for lower rpms at low speed. This is slightly overpropped, the 14x10 is the right prop for this combo.