Help me choose a prop!

[Pkoerner]

Good afternoon-

With spring in the air, I am really getting the itch to lauch the boat. After fixing up a project boat it is now time to find the ideal prop for my rig. Since this is my first time swapping out a prop, I would like to have some help choosing the right one.

I have a Force 125 hp motor hanging off the back of my 1983 17' Norris Craft 1700 Super Pro Medalist. It is model number x1254x7a. The operating range of the motor is 4500-5500 RPM. It has a 3 blade stainless prop on it currently, but I am unsure of the make/model. I have it mounted on a Minn Kota Power Up tilt. I have never seen this model of tilt before, but it was on there when I bought it, and seems to work just fine. I am unsure of the weight of the boat, but it carries 18 gallons of fuel, 2 fishermen (about 370 lbs) and about 100 lbs of gear max.

Right now (well really last summer while I ran it), it was a little slow out of the hole, but at the same time it was not where it should be at top end either. I did not have gps on it, but the speedo on the boat registered 35 at its highest reading running at 6200 rpm.

I would like to find a good all-around prop for my rig, with a slight emphasis on the top-end. However, at the same time, I would like to know both a solid hole-shot prop, and the best numbers for a top-end high speed prop.

I really appreciate all the help, and will try to provide any additional information that you will need. Thanks!!!

[Nichor02]

Hang in there Pkoerner. We have a prop man on here, and he knows his stuff. He will hook you up as soon as he sees this.

[Pkoerner]

Thanks Nic. I'm in no rush over here. Still gotta wait a little bit for the water to warm up just a touch. Also have to get a few exams out of the way.

[Jay Martin]

What year is the Force? If it's older than 1994-95 then you might be stuck with what you have. Prop builders stopped building propellers for the older Force engines.

[Pkoerner]

It is a 1987 model with a 15 tooth 4" through hub exhaust. I thought this was a pretty common size for a prop, and most of the marinas in my area said they could find me something that would fit.

Regardless, I'd still like to know what diameter and pitch I would be ideal incase I did happen to come across something after my search went unanswered.

Thanks

[Jay Martin]

When Mercury bought out Force, Mercury made some changes, the lower unit was one of those changes. Mercury props will fit the newer case. I know that Turbo no longer offers props for the older style case you have. I can make a call monday to see what I can come up with.

By the way, are you wanting a performance style prop?....Also stainless or aluminum??

[Pkoerner]

Yeah I'm not surprised the props aren't made any more. I'd like to know a good size for an all around performance prop or one with a little more emphasis on the top end. Also I'd like ot know a good size for all-out top end performance. Stainless would be nice, but I'm also interested in aluminum too.

I guess the bottom line is that I'm looking for options hahaha! :D Thanks for the help

[Jay Martin]

Yeah I'm not surprised the props aren't made any more. I'd like to know a good size for an all around performance prop or one with a little more emphasis on the top end. Also I'd like ot know a good size for all-out top end performance. Stainless would be nice, but I'm also interested in aluminum too.

I guess the bottom line is that I'm looking for options hahaha! :D Thanks for the help

You can foreget the top end performance if your going with aluminum, the price will be the only good thing about it.
Since the engine is older there are things to consider, how much HP is the mota really turning out?
I really need to know the numbers off the prop you have, this is the only info we have to make prop suggestions. My guess will be a 13.5 x 21p.

[Jay Martin]

Heres something that might help on your search...Type in under google search, "propeller for 1987 125 hp force" it pulls up alot of good info.

[Darth VMAX]

What about those "Ballistic" props? They are very easy to spin and IMO would benefit an old motor that perhaps isn't making the HP it once did.

I had one on my 1995 130/268 Stratos until I got a Renegade. I could spin a 21' 3 blade to 6250 (ended up getting the Gade in a 25" pitch)

[Jay Martin]

This is a tuff one. All I know is there is something different about the older Force that required a prop made for that gear case, I could be wrong, this was before my time, I started working props back in 1995.

[Jay Martin]

O.K.!! Powertech does not offer a prop for your engine either. I did find out that Mercury and Michigan wheel has something that will work.
I was told that you need a prop that has very little rake because of the power curve of this engine. You will need a prop that is loose on holeshot. Past that I'm not a Mercury dealer so that means I can't buy Mercury props.
Hope this helps, keep us posted on the progress.

[Darth VMAX]

Laser prop from Merc? I know those props work very well on the I4 115/125's (about the only motor they work really good on). The 150 Force is a Inline 5 cyl so maybe it would work for those too.

[Jay Martin]

The Laser II would be my first choice but it is a high rake prop.

[ffixt26]

I have a 1998 TR-20 single console. I just replaced my outboard with a 2011, Mercury Optimax Pro XS, 200 3.0 L. I have a 6" hydraulic jack plate and hydraulic steering. I tried a Fury, 3 blades, 25 pitch and after the break-in period, I could not get past 5200 <?xml:namespace prefix = st1 ns = "urn:schemas-microsoft-com:office:smarttags" /><st1:stockticker w:st="on">RPM</st1:stockticker>. The boat would start to violently chime walking. That’s something I’m not wishing to live with or learn how to overcome. <?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" /><o:p></o:p>
<o:p> </o:p>
I replace the Fury with a Tempest plus, 3 blades, 23 pitch prop. On a full tank (56gal) of gas, two persons in the boat and equipment I was able to get up to about 5000 <st1:stockticker w:st="on">RPM</st1:stockticker>, 60<st1:stockticker w:st="on">MPH</st1:stockticker> and steady. However, at about 5400-5500 <st1:stockticker w:st="on">RPM</st1:stockticker>, 65<st1:stockticker w:st="on">MPH</st1:stockticker> the boat would begin to once again violently chime walk and had to back off. <o:p></o:p>
<o:p> </o:p>
Any advise on how I can run at the WOT 5800<st1:stockticker w:st="on">RPM</st1:stockticker> or between 5600 5750 <st1:stockticker w:st="on">RPM</st1:stockticker> and keep the boat from entering into a violent chime walk. I was thinking of going to a 21 or 23 pitch Trophy 4 blade. <o:p></o:p>
<o:p> </o:p>

[Jay Martin]

Please start a new thread about your boat, lets not enter-mix these two subjects. I will be happy to answer your question...:D:D...

[Darth VMAX]

http://www.propline.com/Select-Boat-Props-By-Brand/Michigan-Wheel/Ballistic-High-Performance-Stainless-Steel-Michigan-Wheel-Propellers/Chrysler_Force_U_S_Marine_Outboards/90_150_Dual_Exhaust.htm

[Pkoerner]

Well I finally got some school work out of the way and had some time to take some measurements. The prop is a 13" diameter and 21 P. It is sitting 6 inches below the pad (measured from bottom of pad to center of nose cone). The markings on the prop read: FC125RED 21P.

I have a feeling I'm running too deep. Could that be the problem here? I am at the upper end of the rpm range, but wouldn't raising the motor cause the rpms to go even higher?

Thanks

[Jay Martin]

Raising the engine will increase RPM's but it does sound like the boat is set up as good as it's gonna get, Heres why, the Force does not have the low end punch to get itself out of the hole so a lower pitch is needed to do so, the motor is ran deep to keep the rpm's in order on top end so unless you can add a planning aid like a whale tail theres not much more you can do except having the prop worked for more holeshot and increase the pitch by 1 to help lower thr rpm's on the top end, this will allow you to raise the motor.

[clm6741]

I may be mistaken but a Norris Craft is a lightweight hull that should run pretty fast if setup right. I know that force is not the most powerful but I would think you could get it setup right and get that motor cleaned up some and haul butt in it.