Optimal propeller pitch for 225-H.P. Mercury Offshore outboard?

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Author Topic:   Optimal propeller pitch for 225-H.P. Mercury Offshore outboard?

Frank O posted 02-02-2008 12:17 AM ET (US)
In past threads ( http://continuouswave.com/ubb/Forum4/HTML/005495.html and http://continuouswave.com/ubb/Forum4/HTML/005225.html I've brought up the performance of the 1994 Mercury Offshore 3.0-liter 225-H.P. outboard on my 1995 Outrage 21. The consensus was that I was overpropped with a 19"-pitch Laser II , and I'd do better with something like a 17"-pitch Revolution 4. My goal isn't to goose the greatest speed from the boat, but to get the smoothest ride possible in typical middling conditions hauling my usual load of ~1,200 pounds of divers and gear to dive sites.
Today I discussed this with the owner of the local Merc shop where I'm having annual maintenance done on the boat. He strongly agreed with the overall concept, but said he might go even further and suggest a 16"-pitch Revolution 4 rather than 17".
It isn't easy for me to arrange for loaner propellers (the shop in question can't supply them), and frankly I'd rather go out and dive than conduct a lot of performance tests. I'm up for taking my best guess at the optimal prop and going for it. Any suggestions on making a call on 17" vs. 16"? Thanks much for any ideas. Right now the 19" Laser II tops out at ~4,600 rpm at WOT (whereas the engine is rated for more like 5,800).

Tom W Clark posted 02-02-2008 01:55 AM ET (US)
Frank,
The Laser II is a lousy prop for carrying a load. You should be using a good four blade prop like the Mercury Revolution 4, Offshore/VenSura or PowerTech OFS4.
There is not an optimal pitch for a 225 HP outboard. There may be an optimal pitch for a particular modlel of propeller on a 225 HP outboard on your boat, loaded the way you load it and running in the conditions you run in. It is hard to simplify beyond that.
I know from personal experience that a 21" Laser II turns the same RPM as a 19" Revolution 4 so if using the Rev 4 you will probably need the 15" pitch to get your engine speed up. The Offshore/VenSura will work with 17" of pitch. Not sure about the PowerTech OFS4 but I have a 17" pitch I am selling.
Tom W Clark posted 02-02-2008 02:14 AM ET (US)
I should add that there is no such thing as a 16"Revolution 4 unless it is a 17" or 15" that has had it pitch altered. Rev 4s are made in odd pitches from 15" through 25"
Perry posted 02-02-2008 02:19 AM ET (US)
I have a used 15.25" X 16" Power-Tech OFS 4 blade prop that is in good condition if you are interested.
tmann45 posted 02-02-2008 10:16 AM ET (US)
Frank,
My 1996 Outrage 21 with 1998 2.5 liter Mercury 200 Offshore runs rather well with either 17" Vengance (original) or 18" Enertia even with a heavy load of 2-3 bodies, full fuel tank (114-gal), 35-gallon live well and 40-50 lbs of ice and drinks. With your load I would think an inch less pitch might be appropriate even with your 12.5% more horsepower.
Tom
Frank O posted 02-02-2008 10:21 AM ET (US)
Thanks for the advice. The subject header on my post probably oversimplified the question -- I didn't really mean "what's the best pitch for this engine," but rather, "what pitch should I go with for this situation?"
Now that I look at Mercury's site, it appears as though the Revolution 4 is shown as being available in odd-number pitches for 17" through 23". Is a pitch less than 17" even an option for that propeller?

Tom W Clark posted 02-02-2008 11:02 AM ET (US)
Yes, as I said the Revolution 4 is made in a 15" pitch, part # 48-857022A46, right hand rotation only. It was created when the big Verados came out.
sosmerc posted 02-12-2008 12:27 AM ET (US)
I would strongly agree that you need to get your rpm's up to near 5500 with your normal load on board. I'm a bit surprised that you are currently only getting 4600 rpm.
I'd have your mechanic check things over closely before you spend too much money on props. I would agree though that the Laser II is not the best choice for carrying a load.
If your engine gets a clean bill of health then I'd guess a 15 pitch Mirage-Plus or a 16 Enertia would be the ticket.
rtk posted 02-12-2008 10:41 AM ET (US)
I'm also suprised that you can only turn the 19 pitch LaserII to 4600rpms.
When I first purchased my 1997 21 Outrage it had the same engine as yours and came with a 19 pitch LaserII. Wide open throttle rpms were 5400. My boat has a big hardtop t-top and bottom paint.
You mentioned in your post about the greeen gas that your mechanic made some adjustments to the engine. Perhaps that is the reason that you were only turning the 4600 rpms prior to the repair.
I have tested the Mirage Plus, REV4, LaserII, PowerTec OSF4 and Vensura/Offshore propellers on this boat. My favorite is the Vensura/Offshore. Ride quality in bumpy seas and handling is fantastic with this propeller. Fuel economy is a bit better than the REV4.
I am turning a 19 pitch Vensura/Offshore about 5600 rpms with a full load of fuel with my Mercury 250 EFI. I would think you should be able to turn a 17 pitch Vensura/Offshore to around the same rpms.
The PowerTec was a great prop also but not enough pitch for me at 16. PowerTec says that their 16 pitch runs more like a 17 pitch, so the 16 pitch may work well for you. I also have one I would like to sell, I'd be happy to send it out to you if you want to test it, just pay the shipping if you don't like it.
Rich

Frank O posted 03-09-2008 10:21 AM ET (US)
Just an update on this topic -- I ended up putting a 15"-pitch Revolution 4 propeller on the outboard. Yesterday was the first time we've been able to get it out of the harbor, and we ran it for a couple of hours. There was swell of 4 to 5 feet that was middling to short period, so we couldn't open it up all the way. In a couple of flatter spots we did get it up to 35 mph, though. This was with four divers and gear, plus a newly filled 100-gallon tank. Overall I'd say the speed transitions seemed smoother than with the 19" Laser II, but I need more time in the water under different conditions to understand better how it's different. I also want to develop more experience in trimming it (I gather the idea is, once at speed, to bring the engine up until just before it cavitates, which we would see by the water pressure gauge dropping?).
I did notice that steering with my manual linkage seemed harder than I remember it being. This made more obvious some play in the wheel and some clicking I heard from under the wheel when changing direction. Can harder steering be a side effect in going to a shorter-pitch, four-blade prop, or is this probably from other causes?
Swellmonster posted 03-19-2008 08:01 PM ET (US)
1998 20 outrage, 225 efi.
I have 2 props, 15 and 17 rev 4
15 runs like a 10 speed bike in 2nd gear, loaded boat any speed, any load, you rock and haul azz but hit the rev limiter, still not bad, the 17 hits 5400 but room to trim alot and full of power at all speeds....
Both props keep the vessel high on the water, barelly need tabs with all the lift....
Reelnauti posted 12-01-2008 04:45 AM ET (US)
[This dormant thread was revived after nine months.]
I have re-powered to a Honda 225. I think the Powertech 4 blade SS 15 1/4 X 16 OFS propeller is the one for me.
gss036 posted 12-01-2008 10:37 PM ET (US)
I think you will like the prop. That is what I have on my 225 Honda, and it performs really well. I just put a Northstar fuel flow meter on it, and I am now waiting to get out and work with it to see if I can get better fuel consumption. Winter is here now so it will be at least February before I get out again.
jimh posted 12-03-2008 10:30 PM ET (US)
How do the PowerTech propellers accommodate so many different engine designs? Do they use an interchangeable hub system?

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Author	Topic: Optimal propeller pitch for 225-H.P. Mercury Offshore outboard?
Frank O	posted 02-02-2008 12:17 AM ET (US) In past threads ( http://continuouswave.com/ubb/Forum4/HTML/005495.html and http://continuouswave.com/ubb/Forum4/HTML/005225.html I've brought up the performance of the 1994 Mercury Offshore 3.0-liter 225-H.P. outboard on my 1995 Outrage 21. The consensus was that I was overpropped with a 19"-pitch Laser II , and I'd do better with something like a 17"-pitch Revolution 4. My goal isn't to goose the greatest speed from the boat, but to get the smoothest ride possible in typical middling conditions hauling my usual load of ~1,200 pounds of divers and gear to dive sites. Today I discussed this with the owner of the local Merc shop where I'm having annual maintenance done on the boat. He strongly agreed with the overall concept, but said he might go even further and suggest a 16"-pitch Revolution 4 rather than 17". It isn't easy for me to arrange for loaner propellers (the shop in question can't supply them), and frankly I'd rather go out and dive than conduct a lot of performance tests. I'm up for taking my best guess at the optimal prop and going for it. Any suggestions on making a call on 17" vs. 16"? Thanks much for any ideas. Right now the 19" Laser II tops out at ~4,600 rpm at WOT (whereas the engine is rated for more like 5,800).
Tom W Clark	posted 02-02-2008 01:55 AM ET (US) Frank, The Laser II is a lousy prop for carrying a load. You should be using a good four blade prop like the Mercury Revolution 4, Offshore/VenSura or PowerTech OFS4. There is not an optimal pitch for a 225 HP outboard. There may be an optimal pitch for a particular modlel of propeller on a 225 HP outboard on your boat, loaded the way you load it and running in the conditions you run in. It is hard to simplify beyond that. I know from personal experience that a 21" Laser II turns the same RPM as a 19" Revolution 4 so if using the Rev 4 you will probably need the 15" pitch to get your engine speed up. The Offshore/VenSura will work with 17" of pitch. Not sure about the PowerTech OFS4 but I have a 17" pitch I am selling.
Tom W Clark	posted 02-02-2008 02:14 AM ET (US) I should add that there is no such thing as a 16"Revolution 4 unless it is a 17" or 15" that has had it pitch altered. Rev 4s are made in odd pitches from 15" through 25"
Perry	posted 02-02-2008 02:19 AM ET (US) I have a used 15.25" X 16" Power-Tech OFS 4 blade prop that is in good condition if you are interested.
tmann45	posted 02-02-2008 10:16 AM ET (US) Frank, My 1996 Outrage 21 with 1998 2.5 liter Mercury 200 Offshore runs rather well with either 17" Vengance (original) or 18" Enertia even with a heavy load of 2-3 bodies, full fuel tank (114-gal), 35-gallon live well and 40-50 lbs of ice and drinks. With your load I would think an inch less pitch might be appropriate even with your 12.5% more horsepower. Tom
Frank O	posted 02-02-2008 10:21 AM ET (US) Thanks for the advice. The subject header on my post probably oversimplified the question -- I didn't really mean "what's the best pitch for this engine," but rather, "what pitch should I go with for this situation?" Now that I look at Mercury's site, it appears as though the Revolution 4 is shown as being available in odd-number pitches for 17" through 23". Is a pitch less than 17" even an option for that propeller?
Tom W Clark	posted 02-02-2008 11:02 AM ET (US) Yes, as I said the Revolution 4 is made in a 15" pitch, part # 48-857022A46, right hand rotation only. It was created when the big Verados came out.
sosmerc	posted 02-12-2008 12:27 AM ET (US) I would strongly agree that you need to get your rpm's up to near 5500 with your normal load on board. I'm a bit surprised that you are currently only getting 4600 rpm. I'd have your mechanic check things over closely before you spend too much money on props. I would agree though that the Laser II is not the best choice for carrying a load. If your engine gets a clean bill of health then I'd guess a 15 pitch Mirage-Plus or a 16 Enertia would be the ticket.
rtk	posted 02-12-2008 10:41 AM ET (US) I'm also suprised that you can only turn the 19 pitch LaserII to 4600rpms. When I first purchased my 1997 21 Outrage it had the same engine as yours and came with a 19 pitch LaserII. Wide open throttle rpms were 5400. My boat has a big hardtop t-top and bottom paint. You mentioned in your post about the greeen gas that your mechanic made some adjustments to the engine. Perhaps that is the reason that you were only turning the 4600 rpms prior to the repair. I have tested the Mirage Plus, REV4, LaserII, PowerTec OSF4 and Vensura/Offshore propellers on this boat. My favorite is the Vensura/Offshore. Ride quality in bumpy seas and handling is fantastic with this propeller. Fuel economy is a bit better than the REV4. I am turning a 19 pitch Vensura/Offshore about 5600 rpms with a full load of fuel with my Mercury 250 EFI. I would think you should be able to turn a 17 pitch Vensura/Offshore to around the same rpms. The PowerTec was a great prop also but not enough pitch for me at 16. PowerTec says that their 16 pitch runs more like a 17 pitch, so the 16 pitch may work well for you. I also have one I would like to sell, I'd be happy to send it out to you if you want to test it, just pay the shipping if you don't like it. Rich
Frank O	posted 03-09-2008 10:21 AM ET (US) Just an update on this topic -- I ended up putting a 15"-pitch Revolution 4 propeller on the outboard. Yesterday was the first time we've been able to get it out of the harbor, and we ran it for a couple of hours. There was swell of 4 to 5 feet that was middling to short period, so we couldn't open it up all the way. In a couple of flatter spots we did get it up to 35 mph, though. This was with four divers and gear, plus a newly filled 100-gallon tank. Overall I'd say the speed transitions seemed smoother than with the 19" Laser II, but I need more time in the water under different conditions to understand better how it's different. I also want to develop more experience in trimming it (I gather the idea is, once at speed, to bring the engine up until just before it cavitates, which we would see by the water pressure gauge dropping?). I did notice that steering with my manual linkage seemed harder than I remember it being. This made more obvious some play in the wheel and some clicking I heard from under the wheel when changing direction. Can harder steering be a side effect in going to a shorter-pitch, four-blade prop, or is this probably from other causes?
Swellmonster	posted 03-19-2008 08:01 PM ET (US) 1998 20 outrage, 225 efi. I have 2 props, 15 and 17 rev 4 15 runs like a 10 speed bike in 2nd gear, loaded boat any speed, any load, you rock and haul azz but hit the rev limiter, still not bad, the 17 hits 5400 but room to trim alot and full of power at all speeds.... Both props keep the vessel high on the water, barelly need tabs with all the lift....
Reelnauti	posted 12-01-2008 04:45 AM ET (US) [This dormant thread was revived after nine months.] I have re-powered to a Honda 225. I think the Powertech 4 blade SS 15 1/4 X 16 OFS propeller is the one for me.
gss036	posted 12-01-2008 10:37 PM ET (US) I think you will like the prop. That is what I have on my 225 Honda, and it performs really well. I just put a Northstar fuel flow meter on it, and I am now waiting to get out and work with it to see if I can get better fuel consumption. Winter is here now so it will be at least February before I get out again.
jimh	posted 12-03-2008 10:30 PM ET (US) How do the PowerTech propellers accommodate so many different engine designs? Do they use an interchangeable hub system?