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Gear ratio vs. pitch

E

Eluder

Member
two questions that I need son advise on--
85 eluder with a 200 Mercury Black Max
Old lower unit had 1.87 to 1 ratio with a 21 pitch mercury stainless prop
I got a NOS lower but it has 2 to 1 ratio and the RPM is over 6K
Lower MPH along with GPH way up their!
Should I get 23 pitch prop or install the old gears into NOS unit?
Gears are good but old lower bearings wore out and it was a
84 pre-load unit!

Thanks, Eluder.
 
I think you should go farther than a 23. I have run a 25 on a 175 with the 1.87 gears, same prop is currently on a 150 with the 2.0 gears. I would think you might be in the 27 range with a 200 with a 2.0 gearcase.

Personally, I'd leave a factory set-up gearcase alone and change the prop, plus the prop change should be cheaper as you can always sell the old prop.
 
Prop the right one

I just wish I had the set uP tools, have everything else!
Reading on the forums it leads it self to a 24 to now a 27 pitch-
What to do, i guess only trial an error but it might be cheaper to swap
Gears. Labor and a bearing?
Tanks, eluder
 
I will say this, the math says you need a 22.5 pitch prop to wind up in the same place you are now. Have you ever tried a higher pitch prop in the past?
 
Hi, I've got an exciter with a 175 efi, it's the same boat but closed bow. I'm running a spare 2:1 case while my 1.87 is rebuilt. You can mostly figure it out with math. I've confirmed that the equation translates to real world results with my lower unit change. If you're happy with the performance of the 1.87:1 and 21p prop. you are at 21"/1.87 = 11.23" theoretical travel per revolution of your drive shaft. To match that with a 2:1 lower unit you'll want x"/2 = 11.23 or x= 22.46" (23p). That should give you very close to the same top speed, hole shot, and rpm as you had with the 1.87:1 case and a 21p prop. I agree with the previous poster though, with that hull and a 200hp id try something like a 25p laser ii.
I also agree that a prop change would be easier than messing with the gears in the lower unit.
 
To back up jumbofordman's suggestion; I have tried a 27p laser ii on this set up with a 2:1 case and I got the same top speed as with a 25p but at lower rpm. I only got about 5350 rpm with plenty of trim at 63.5 mph. My boat is a little lighter, and it's set up with a 5.5" of set back and the engine up a little bit. If you're set up similarly with a 200, and your main goal is top speed, id bet you're 25 extra hp would let you make good use of a 27p laser ii. Otherwise a 25 is prob your best bet
 
Prop Size

I was going to do the prop calculations but we're at the Jersey Shore--
Ortley Beach Moose Lodge#399. Hello to any Moose Members!!
Just my luck had an offer to I think a free 23 SS.

I will investigate the new pitch size---BTY anyone want to part with
One?? Lol

Thanks everyone!!
 
Prop Size

I was going to do the prop calculations but we're at the Jersey Shore--
Ortley Beach Moose Lodge#399. Hello to any Moose Members!!
Just my luck had an offer to I think a free 23 SS.

I will investigate the new pitch size---BTY anyone want to part with
One?? Lol

Thanks everyone!!
 
25, 26 or 27 pitch

SaskExciter said:
To back up jumbofordman's suggestion; I have tried a 27p laser ii on this set up with a 2:1 case and I got the same top speed as with a 25p but at lower rpm. I only got about 5350 rpm with plenty of trim at 63.5 mph. My boat is a little lighter, and it's set up with a 5.5" of set back and the engine up a little bit. If you're set up similarly with a 200, and your main goal is top speed, id bet you're 25 extra hp would let you make good use of a 27p laser ii. Otherwise a 25 is prob your best bet
Click to expand...

I would like a the lower RPM and the 25 more HP! So a 27P,
What about a 26P?? Also most important what make prop should I be
Looking for?? I want the option of either a 26 or 27 if one come up
On the make someone has experience with.
NOS power head with only 70 Hrs on, NOS lower unit maybe 5 hrs on her!

Thanks, Eluder.
 
To give you a more informed opinion/suggestion I need more info on your set up. Do you have a jack plate? If so how much set back from the transom? Are you cool with having one all out top speed prop and another for water sports and carrying a bunch of people in the boat? You could get a speed prop and keep the 21p for sports/full boats.
As to what type of prop I have good luck with merc laser ii props for manners and top speed. You may find you need more bow list than the laser for carrying people in the open bow, but that prop would get my vote.
 
Prop

I do not have jack plate and have 5" of set back.
I guess I really want something a little better then what I had.
Max number two to three adults and was happy with original
Lower unit ratio-but since I need a different pitch for the 2 to 1
Ratio I wanted to field some feedback.
The Bay gets really choppy with the south wind so I hug the
Shore line skimming over the Sand Bars. I just don't like the 6K +
With the 21P and the Fuel it SUCKS Down at WOT.

Thanks again!!
 
Hi, thanks for the info. I guess I should also have asked what kind of speed you got with each lower. all things considered I'm thinking you'd be happy with a 27 or 25p laser II or similar. With the 25 and 2:1 lower unit you should be around 5800 rpm at 61-63 mph (gps) and have a good all around performance. The 27 would give you more speed, especially with a jack plate but it would hurt all other areas of performance. At least that's what my experimentation has shown, but it's so true that every set up responds a little differently. so can't really "know" until you try.
Please let me know what you try and how it works
 
25P

Thanks! My last set up I got about 60-65 from the Pitot speedo-when
It worked, so what everyone is telling me a 25P fits the application.
ONE Important question what other Prop make is worth it? I like the Lazer
11 but looking for a used one and price is right-Just a thought.
I do not need it like tomorrow, so I can wait for the recommended
One. BTY what should I expect to pay for one??
Thanks for your sharing your knowledge and time!
Give her full Bore the next time out! Eluder...
 
I was running a 26 pitch Trophy Plus on my Predictor with a 2.0L XR2 with a 2:1 gear ratio and was spinning 6000 RMs and running in the low 70's.... 6 inches of set back. if you search my posts there are plenty of pictures and descriptions with video. with a 200 on a bigger boat you should be able to spin a 26 Trophy easily.. the 2:1 gears will snap you out of the hole easily..

I am now running a 2.4 Mod VP with the 2:1 gears on a 21 Action and am seeing 77 with a BBlades 29 pitch i have 18 inches of set back and am at or just above the pad..

it all depend upon what you want the boat to do for you, etc...
 
Sounds like your predictor was dialed in nicely! I love the way they predictors look flying! Still haven't seen one in person though... Someday!

I paid 225.00 for a used laser II a few years ago. I feel like it was a fair price but I usually have to pay a little extra for things living in the Styx.
 
Eluder, I just got some useful info on another post. A 26p laser is a smaller hub with larger ears and apparently performs really well. I have no experience with it but keeping that in mind along with you trying to decide between a 25 and a 27..... It might be your perfect prop.
 
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