Best Prop?

[LaqueRatt]

Looking for a prop for my '77 25 rude. Pretty sure spun the prop. It doesn't want to go except at slow speed and it's not the gears. It still shifts smoothly and stays in gear.

Original prop is 0388088 - 9 ¼ x 11. Boat is a 14' x 63" MirroCraft Deep Fisherman. Usual running weight wet with two humans onboard is approx: 700 lbs.

Looks like I can get:

9 1/4 x11
9x10
9x9

9x9 is the cheapest. Thoughts? Best performing? Would even be able to tell much difference?

 

[airshot]

Best bet is to attach a tach, you really need to know the rpm in order to know which prop is best. Other wise just guessing, and when you guess, it isn't healthy for your motor ! An inch of pitch can be up to a 200 rpm difference and that can make a very noticible difference. Going with less pitch will make the motor rev higher...no speed gain but might get you up on plane a little quicker, but....if you over rev it might cost you an engine.

 

[LaqueRatt]

Wish I could do that, but not having a working prop right now guess I should replace it with a stock type. I was just wondering what to expect if I can't get one. I see very few of them around. Would the 9x10 or the 9x9 perform abysmally for me you think? The 9x9 is $40 cheaper BTW.

 

[LaqueRatt]

Anyone else care to chime in? Does it matter a whole lot which prop I buy? I'm just glad I can even get a prop for this old gem!

 

[kdgrills]

What prop have you been running? Acceptable performance?

As a frame of reference, I have Mirrocraft f3614. I re-powered with a Yamaha F25swhc back in 2017. The stock prop was
11-1/4 pitch, WOT was 24ish MPH @ 5400 RPM. I changed to a 10-1/2 pitch, WOT is 26ish MPH @ 6100 RPM

 

[LaqueRatt]

Is pitch the 2nd no? My original is 9 1/4x11. If so yours is similar right? I never got a chance to really get a feel for how well it was working as it spun the hub within the first 15 mins I had it on the water. Wow you had quite a jump in revs. Kind of surprised. Was the diameter the same?

 

[airshot]

First number is diameter, second number is pitch. When you reduce pitch, rpm goes up, as long as you don't exceed the max rpm recomendation for your motor your good. If to much pitch is used then the motor does not reach max rpm and it is overworked and puts excess strain on your motor. This is why a tach should be used to get the best pitch for your boat/ motor combo.

 

[Rumblejohn]

When you say you "spun" the prop does that mean the prop turns freely when in gear? If so you may have sheared a pin or have a damaged hub

 

[Randaln]

Looking for a prop for my '77 25 rude. Pretty sure spun the prop. It doesn't want to go except at slow speed and it's not the gears. It still shifts smoothly and stays in gear.

Original prop is 0388088 - 9 ¼ x 11. Boat is a 14' x 63" MirroCraft Deep Fisherman. Usual running weight wet with two humans onboard is approx: 700 lbs.

Looks like I can get:

9 1/4 x11
9x10
9x9

9x9 is the cheapest. Thoughts? Best performing? Would even be able to tell much difference?

I’d stay away from the 9x9
You need the bigger diameter
(Blade surface area)
Also there is RAKE to consider..
Try one of your buddies props if you can..
A box fan in your house has almost zero RAKE
RAKE is if you are looking at prop on boat
In the Birds Eye view..
The more rake ..the more the blades are swept/aiming back..
I run a lower rake solas..SS
10 1/4x12
Good whole shot
Good while cornering
Without blowing out..
And it will keep up with the fastest boats during morning take offs..of a pack of 12 boats..

 

[kdgrills]

Is pitch the 2nd no? My original is 9 1/4x11. If so yours is similar right? I never got a chance to really get a feel for how well it was working as it spun the hub within the first 15 mins I had it on the water. Wow you had quite a jump in revs. Kind of surprised. Was the diameter the same?

Yeah, I was surprised by #s as well. I originally went by the conventional wisdom of 200rpm per inch of pitch, & got a 9. That was way too small, I was on the Rev limiter at 1/2 throttle. Yes same diameter, all oem aluminum props.

 

[LaqueRatt]

When you say you "spun" the prop does that mean the prop turns freely when in gear? If so you may have sheared a pin or have a damaged hub

First time on the water, was just playing with motor trying to find the sweet spot. When I did and opened it up within about 15 secs it stopped pulling and would only move at low revs. Pin is good and it never popped out of gear and continued to shift smoothly. After doing a bit of research, pretty sure I just pushed it too hard and 50 year old hub came loose from prop.

Now I'm debating what to do if can't get the proper prop. Does anyone know where can get a hub for it? As scarce as props are I'll bet hubs are even scarcer.

 

[Randaln]

Hubs are not Scarce look up HMS hubs
Or take it to your local prop shop
You cannot put it in yourself
Without an insertion funnel and a hyd press

 

[LaqueRatt]

Funny, but prop shops seem to be a thing of the past. We once had a couple in town, but one is no more and the other, a marina, does not seem interested. They do have the tools though and told me once before they'd press a hub for me. Non gratis I think, but could be wrong.

Thanks for the tip on HMS hubs, I stumbled across them yesterday and it looks like they have the right hub. Since the prop is in pretty good shape, guess that makes the most sense.

This may go on the back burner for a few days though, because it looks like I'm getting a new boat.

 

[thill]

The biggest question is, how did it perform with the 11 pitch...
1. When the boat is empty and you are alone?
2. When carrying a normal load of people and gear?
3. When you are at max load?

Are you happy with the performance?

I have found that with small motors, it doesn't hurt to have several props. With my 35 Evinrude, I ran a 13 pitch when alone or with 1 other person, and an 11 pitch for when I had more people on the boat. I switched them often, and could do it in less than a minute.

An off-brand tiny-tach worked well for me. The first one I got was good, the second one was defective, and they sent a replacement, so the quality control of those things is not very good, but they work well enough to get a motor figured out.

 

[DaleH]

Ideal Prop Pitch: This used to be a 'sticky post' in the Motors Forum, but they all got lost once Jim sold off the Site ... but go here and enter in ALL of the specifics for YOUR hull, motor and gear:

https://turningpointpropellers.com/PROPWIZARD/index.html?tan=

 

[Still Afloat]

Ideal Prop Pitch: This used to be a 'sticky post' in the Motors Forum, but they all got lost once Jim sold off the Site ... but go here and enter in ALL of the specifics for YOUR hull, motor and gear:

https://turningpointpropellers.com/PROPWIZARD/index.html?tan=

Interesting. I tried the prop wizard a few times times.
- Loaded (120 lbs of rigging and gear) Lowe 1448M, one person and a 20hp DF20A
- Empty Lowe 1448M with one person and the DF20A
- Empty Lowe 1448M with one person and a 9.9hp DF9.9B

It provided the same prop recommendation for each configuration. A three blade 9x9. Maybe it’s more accurate for larger boats but, it doesn’t seem that useful for my little tin boat.

 

[LaqueRatt]

Thanks for all the input. I didn't buy that boat I was wanting to get. Was getting bad vibes from it and couldn't get the motor to turn over. It's a 16' Starcraft. For a tinny the thing seemed to weigh a ton. The roller trailer alone prob weighs what my Mirro AND trailer weigh. Don't know if I really want such a massive boat.

Anyhow I'm back to solving the prop issue. I really appreciate everyone's thoughts, but keep in mind I haven't tested ANY prop on this boat so I don't have a baseline. The very first time out on the lake she spun on me....BUT I was not impressed with the performance to that point. If it was any quicker than the 18 I took off of it, it wasn't much. I do suspect though the prop was maybe beginning to let go.

 

[Still Afloat]

I just bought a 9-1/4 x 11” for the 1448M just to try it out. It might be too much prop but, if I don’t try it I won’t know.

 

[LaqueRatt]

9 1/4 x11 is stock size for my 25 that's going on a deep V 14'. Just going to go with this size again unless have the old one rehubbed.

Michigan Wheel has the prop and the hub, but don't sell direct to public. Guess I'll see if my local marina can order one. Prop Wizard doesn't seem to work right for me. Asks me only about the motor and then says no props available.

 

[Still Afloat]

It was probably good to pass on the boat if you just were not feeling it.

I have separate thread going on my prop testing for Suzuki DF9.9/20 On the 1448M. To share the highlights, I got the new prop and headed for lake but the 11” pitch prop they sent was for a Honda and it didn’t fit. The 9.25 x 9” pitch prop was on rev limiter at less than 3/4 throttle. These small props seem to run about $60 to 70 so it probably won’t cost you much more to replace the spun prop than getting it fixed.