ski prop for 1994

Stingrayaxe, thanks for your feedback.
From my post #10: May be a couple wks before I have an opportunity to run the boat to provide the RPM data.

Remain surprised that apparently mfr's don't provide prop recommendations for boats they manufacture.
ie:
For the 1994 180BR I/O 5.0L (190HP) Alpha One 1.65:1 ratio with standard 14X19 prop and 4,600RPM max, the recommended prop to maximize ski/holeshot performance is _________.
Would seem a mfr could evaluate this when testing their new boats, and include optional prop sizes in the owners manual.
Instead, apparently owners have to experiment and use RPM/pitch change relationships/etc. to guess which prop to try.
Doesn't make sense to me, but maybe I'm missing something.
 
surfinagin said:
Would seem a mfr could evaluate this when testing their new boats, and include optional prop sizes in the owners manual.
Instead, apparently owners have to experiment and use RPM/pitch change relationships/etc. to guess which prop to try.
Doesn't make sense to me, but maybe I'm missing something.
Click to expand...
Boat manufacturer's do test their boats -- to provide the best, all around prop for most customers. There are just way too many variables to expect them to test every single boat they have with multiple props and conditions to offer alternatives. Switching props is, and always has been, the responsibility of the owner. And, quite honestly, that's how it should be - if someone wants to change their prop to something different than what's recommended, that's on them.

Besides, I can't imagine it being a good idea for a manufacturer to recommend a prop that could cause the engine to over rev. Expecting them to do that and open themselves up to all kinds of problems is unreasonable. If you want to use a lower pitch prop, that's 100% your call and I've done that, too. But the responsibility is yours to keep the engine from over-revving.
 
Lazy Daze said:
Switching props is, and always has been, the responsibility of the owner. And, quite honestly, that's how it should be - if someone wants to change their prop to something different than what's recommended, that's on them.

If you want to use a lower pitch prop, that's 100% your call and I've done that, too. But the responsibility is yours to keep the engine from over-revving.
Click to expand...
Lazy Daze, thanks for the education.
If that's the way it is, then fine -I understand it's 100% my responsibility.
Still, I remain surprised that mfr's don't provide an optional "ski" prop recommendation since owners commonly need one. I'm sure you gave the right reasons, but regardless the legal risk by identifying an optional "ski" prop seems minimal if the mfr recommendation is conservative (does not "push the envelope"). But so be it.
Stuck until an opportunity to run my boat and gather the RPM data, then make best guess at an optimum 4-blade prop size/pitch to maximize skiing performance within max RPM -then hope it works!
 
Actually, by far, most people never change props. The number of people doing that gets skewed because of forums or possibly because of the "group" that someone might hangout with. But I work in the industry and I can definitely tell you that the percentage of people that change props is much smaller than you might think.

Manufacturers can not recommend a prop that would exceed the max RPM. Dropping even one inch in pitch will raise the RPM higher than allowed. In many cases, even the standard prop can still be run hard enough to exceed the RPM's. That's why it is still completely and fully up to the owner.

Another thing to keep in mind... your boat is over a quarter century old. I doubt 4-blade props where even a "thing" back then!

Going on forums and talking with other people and "experimenting" is how we all do it. However, you might want to check with a "prop shop" such Prop Gods. I have never personally used them, but I hear good things about them.

But remember, if you drop pitch, you will NOT be within your max RPM range for sure. So you will have to use the throttle and trim accordingly. The only way to "have your cake and eat it, too" is to install the Smart Tabs.
 
Thanks Lazy Daze-
Other than to get a skier out of the water, my boat almost never sees WOT -don't know how much that may help minimize potential issues exceeding max RPM.

Yes, I did get the impression that changing props is fairly common, with so many general recommendations (ie: drop pitch by 1 when going from 3 blades to 4").
Guess that's why I assumed going from 14X19 OEM 3-blade to a 14X18 4-blade was probably a safe bet to try for a better hole shot.

I'm kind of anal -the thought of drilling holes in my hull for Smart Tabs triggers that;). I take very good care of my boat and it looks almost new though "over a quarter-century old"! May still come around and get that drill out.
 
A 14x18 is certainly a "safe" try and will net you some improvements. The question of whether it's "what you're looking for", though, can't be answered by us as it's a highly subjective question. But keep in mind that ANY prop can be "safe" since you are in control of the throttle.

Holes: Yeah, if you haven't done this kind of thing I can understand why it seems like a daunting task. This again, though, is subjective. For example, I wouldn't hesitate to drill those holes and install the Smart Tabs. I couldn't tell you how many of those I've done - along with true, hydraulic trim tabs... and countless other holes under the waterline. Done properly, it's completely safe. But again, it's all relative to a certain person's comfort level.

Just an FYI, for someone experienced in this type of work, the labor to install them is only about 1 to 2 hours. It might be worth paying someone to do it.
 
Thanks for your perspective on the 14X18 4-blade being "safe" -I'm leaning toward ordering one to have a new prop ready to install when I next run the boat, vs running the chipped prop for RPM data.
Spent some time googling "14X18 4-blade aluminum prop" with no luck -apparently an odd size?

Haven't drilled a hull, but comfortable with power tools and installing Smart Tabs appears EZ.
My problem is simply putting holes in my hull!
 
Definitely - if the current prop is damaged, it's of no use for data logging. It doesn't take much to screw things up.

I'm about 99% positive I had bought an 18" 4-blade Black Max (Mercruiser) prop for my 180BR. But that was a while ago. I do know, for sure, that it was a Merc brand prop. I'm not sure what the diameter was, but focus more on the blades and pitch.

Try a local Mercruiser (or Sea Ray) shop.

Edit... just to be clear... I am POSITIVE that it was a 18" 4-blade from Mercruiser - the 99% was about the name of the prop.
 
Last edited:
Closest match to a 14X18 that I've found so far:
Michigan Wheel Vortex 992203 14-1/2" X 18" 4-Blade RH Propeller. No idea if the extra 1/2" diameter is a problem(?)
Not ready to give up, but the 14X18 is apparently an "odd size".
 
Only a problem if it hits the cavitation plate. More surface area will reduce top RPM a little.
 
Thanks Stingrayaxe-
Regarding prop/cavitation plate clearance-
Is there a minimum clearance, or OK as long as the prop clears the cavitation plate?

Can't ck the measurement since boat not nearby, but an additional 1/4" (by raising prop diameter 1/2") should clear the cavitation plate.
I like the benefit of added diameter would help counter the higher RPM's with less pitch.
 
Disclaimer: I'm not a pro...just been a boater for 30+ years. I've never heard of a minimum clearance. It just needs to clear the plate. I can tell you for my current set-up with the 5.0 TKS that I went from a 21" pitch 3 blade to a 19" four blade. It resulted in my RPMs getting closer to max. Better low speed handling. Lower speed to maintain plane. I lost about 4 MPH from the top end (Was 51ish with the 3 blade). It's now a stump puller. I have to really take it easy with the throttle when I am pulling a skier/wakeboarder or I'll pull their arms off!

That said every boat is different and your results may differ. It really is an experiment like Lazy Daze said. You just go with the best guess using all the data that you have. Based solely on what he has said many times on this forum, smart tabs are on my short list for the next upgrade. I just need to get over drilling holes in perfectly good boat!
 
Thanks -
You successfully dropped 2" on pitch while maintaining your OEM prop diameter?
That makes it tempting to go from my 14X19 to 14X17, which appears to be a more common size than 14X18.
Realize "results may vary" but that may still be a reasonably conservative option for Experiment Step 1.

With you on the Smart Tabs -prefer not drilling into my hull!
 
It will really help when we know your current baseline results. You will know how much top end RPM you have to play with. Since your current prop is already a 4 blade 20" pitch, dropping 3 inches seems like a lot. However, if you're at the low end of the max RPM range you might have room to do it. If you are in the middle then a drop to 19 might be best.
 
FYI... it's an "anti-ventilation" plate, not a cavitation plate. Cavitation is something completely different. :)

But, I'm not aware of any minimum clearance between the prop and the AV plate, either.

Have you checked with a Merc dealer about the 14x18? I am 100% positive that I had a 18" 4-blade by Merc... but that was quite a while ago and maybe things have changed.

Holes... nah, what's a few more holes?! There's already a huge one in the transom! ;)
 
Stingrayaxe said:
It will really help when we know your current baseline results. You will know how much top end RPM you have to play with. Since your current prop is already a 4 blade 20" pitch, dropping 3 inches seems like a lot. However, if you're at the low end of the max RPM range you might have room to do it. If you are in the middle then a drop to 19 might be best.
Click to expand...

OEM prop = 3-blade 14X19.
Based on my limited understanding, going to a 4-blade should drop pitch by 1 (14X18).
Again, based on limited understanding, assume that the less-than-expected holeshot improvement by the installed 4-blade is due to the pitch was raised (14X20) vs lowered from the 14X19 OEM.
 
Lazy Daze said:
Have you checked with a Merc dealer about the 14x18? I am 100% positive that I had a 18" 4-blade by Merc... but that was quite a while ago and maybe things have changed.
Click to expand...
Google could be lying, but extensive search did not find an aluminum 4-blade 14X18 prop.
Would expect Google to find one, if they still exist(?)
 
surfinagin said:
Google could be lying, but extensive search did not find an aluminum 4-blade 14X18 prop.
Would expect Google to find one, if they still exist(?)
Click to expand...
Might be best to call your local Merc dealer. Often time a 5 minute phone call is more productive (whether yay or nay if it is still available) than Googling and extensive typing on a forum.......
 
Conclusion for anyone seeking info from this thread:
Marina recommended Quicksilver Nemesis 14X19, which they let me try out.
Definitely an improved holeshot and less bow rise vs the Michigan Vortex 14X20.
Hit 4,600RPM at 42MPH (just shy of WOT). Lost approx 5MPH, which is no concern.

Bought the prop. Maybe experimenting would identify an even better prop, but I'm satisfied!
Thanks
 
You must log in or register to reply here.

Forum statistics

Threads
113,241
Messages
1,429,127
Members
61,123
Latest member
Tim Duncan
Back
Top