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Author Topic:   Mercury Prop on Honda

galtsfan posted 01-21-2007 05:18 PM ET (US)
I'm repowering my 17' Outrage with a Honda BF150. The Optimax I'm replacing has a a nice 4 blade Mercury Marine OffShore Series Prop the Part number is 45-525900-19. My question is will this prop fit on the Honda. Is a hub kit all that's required? It measures about 14 1/2 dia. and I assume the -19 means it has a 19" pitch.
Tom W Clark posted 01-21-2007 05:30 PM ET (US)
Yes, your Offshore will fit the BF150 without any additional parts. Same hub kit.
I think you actually have #48-825900-19 which is a 14" diameter x 19" pitch Offshore propeller, and an excellent one at that.
Be aware that the gear ratio of the BF150 (2.14:1) is not the same as the 150 OptiMax (1.87:1) and that the WOT ranges of these motors are not the same. The Honda relines at 6000 RPM while the OptiMax redlines at 5750 RPM.
In reality, the higher redline of the Honda may partially compensate for the gear ratio difference, but ceteris paribus, you will need more pitch with the Honda *if* it is as powerful as the OptiMax.
All this assumes the OptiMax was a 150...
galtsfan posted 01-21-2007 07:37 PM ET (US)
Actually, the The optimax was a 135.
Thanks for the insight Tom
Perry posted 01-21-2007 07:41 PM ET (US)
Tom, since he has a 135 Optimax for sale in the Market place forum, I assume he had this motor on his 17 Outrage. The 135 Optimax has a 2.0 gear ratio which is closer to the BF150's.
The 19 pitch Mercury Offshore prop should be a good starting point although some here might think a 4 blade prop is overkill on a 17 foot Whaler.
Tom W Clark posted 01-22-2007 01:33 AM ET (US)
The OptiMax 135 has a 2:1 gear ratio and only a 5600 redline. This will net out closer to the Honda except for the Honda's extra power.
Try the 19" and see, but I suspect you will need to move up to a 21" to accommodate the Honda.
Tom W Clark posted 01-23-2007 09:40 AM ET (US)
If the Offshore proves to be not enough pitch for the new BF150, I have a Stiletto Advantage II for sale that will both fit the Honda and lower the RPMs. It is a very fast propeller.
http://continuouswave.com/ubb/Forum2/HTML/013108.html
I also have a 21" Mercury Laser II which performs very similarly to the 19" Stiletto Advantage II and which I could sell for $200.
I would also be willing to trade either propeller straight across for the Offshore.
galtsfan posted 01-23-2007 01:31 PM ET (US)
Thanks Tom, I'll keep that in mind. I'll try it and see what kind of performance I get. I don't want to go through all the problems David is having with matching his. Did you say the hub kit for the Optimax is identical?
Tom W Clark posted 01-23-2007 02:15 PM ET (US)
The Flo-Torq II hub kit you have been using on your OptiMax should fit your new Honda. You can also buy a Honda Flo-Torq kit which will differ by only the substitution of a different nut and a cotter pin instead of a tab washer.
Now that I think about it, you need to verify the nut uses the same threads. Yamaha uses a metric threading. I am unsure of Honda but the motor should come with a propeller nut.
I just reviewed the Flo-Torq application chart and it ambiguous. They do not show the BF150. The 225 uses a different thrust washer. Either way the drive sleeve and aft adapter are the same parts.
Whether you will experience prop rattle or not, we will have to wait and see.
galtsfan posted 02-01-2007 10:38 AM ET (US)
I've set up a simple ratio of engine speed to gear ratio of my previous Optimax and the new Honda using my Mercury Offshore series. Known are the Optimax engine speed and gear ratio as well as the Honda's gear ratio. I solved for the theoretical engine speed for the Honda without consideration for the difference in horsepower. How valid is this value? I'm waiting for parts to arrive to complete the rigging. I'll hopfully know the answer by this weekend. I could live with 5,992-RPM with a maxium of 6,000.
The OptiMax was 135-HP, the Honda 150 HP or maybe even more according to Honda.
http://www.honda-marine.com/pdfs/BF150_advantage.pdf
Optimax Honda
2.0 2.14
--- = ----
5600 (5992)

galtsfan posted 02-01-2007 11:10 AM ET (US)
The difference in torque between 2 and 4 stroke engine is well documented. Has anyone seen any benefit in using the Mercury Performance Vent System (PVS) http://sites.mercurymarine.com/portal/page?_pageid=126,50050,126_50060& _dad=portal&_schema=PORTAL on four-stroke engines to get a better holeshot?
jimh posted 02-03-2007 10:11 AM ET (US)
Re the Mercury Performance Vent System (PVS):
I have run a boat (with big two-stroke motors) with Mercury propellers using plugs in the PVS vents which had holes. The behavior of the boat was much like a car with a "loose" transmission. When the boat was accelerated to planing speed, the engine throttle would be cut back to sustain a particular speed. The boat would continue to accelerate as the propellers began to obtain a better bite. Often the engine throttle would have to be reset to prevent the boat from going faster than desired.
This behavior seemed much a car with a slipping transmission. After a while, you become accustomed to it, and your operation of the engine throttle changes to match the slipping propellers. In the long term, it is possible to get accustomed to almost anything, but initially I did find the PVS vented propeller behavior a bit odd.
The use of a PVS vented propeller might be especially helpful on a four-stroke motor, as most four-stroke motors seem to lack torque at low engine speeds. I would also be interested to hear of any experiences with four-stroke motors.

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Author	Topic: Mercury Prop on Honda
galtsfan	posted 01-21-2007 05:18 PM ET (US) I'm repowering my 17' Outrage with a Honda BF150. The Optimax I'm replacing has a a nice 4 blade Mercury Marine OffShore Series Prop the Part number is 45-525900-19. My question is will this prop fit on the Honda. Is a hub kit all that's required? It measures about 14 1/2 dia. and I assume the -19 means it has a 19" pitch.
Tom W Clark	posted 01-21-2007 05:30 PM ET (US) Yes, your Offshore will fit the BF150 without any additional parts. Same hub kit. I think you actually have #48-825900-19 which is a 14" diameter x 19" pitch Offshore propeller, and an excellent one at that. Be aware that the gear ratio of the BF150 (2.14:1) is not the same as the 150 OptiMax (1.87:1) and that the WOT ranges of these motors are not the same. The Honda relines at 6000 RPM while the OptiMax redlines at 5750 RPM. In reality, the higher redline of the Honda may partially compensate for the gear ratio difference, but ceteris paribus, you will need more pitch with the Honda if it is as powerful as the OptiMax. All this assumes the OptiMax was a 150...
galtsfan	posted 01-21-2007 07:37 PM ET (US) Actually, the The optimax was a 135. Thanks for the insight Tom
Perry	posted 01-21-2007 07:41 PM ET (US) Tom, since he has a 135 Optimax for sale in the Market place forum, I assume he had this motor on his 17 Outrage. The 135 Optimax has a 2.0 gear ratio which is closer to the BF150's. The 19 pitch Mercury Offshore prop should be a good starting point although some here might think a 4 blade prop is overkill on a 17 foot Whaler.
Tom W Clark	posted 01-22-2007 01:33 AM ET (US) The OptiMax 135 has a 2:1 gear ratio and only a 5600 redline. This will net out closer to the Honda except for the Honda's extra power. Try the 19" and see, but I suspect you will need to move up to a 21" to accommodate the Honda.
Tom W Clark	posted 01-23-2007 09:40 AM ET (US) If the Offshore proves to be not enough pitch for the new BF150, I have a Stiletto Advantage II for sale that will both fit the Honda and lower the RPMs. It is a very fast propeller. http://continuouswave.com/ubb/Forum2/HTML/013108.html I also have a 21" Mercury Laser II which performs very similarly to the 19" Stiletto Advantage II and which I could sell for $200. I would also be willing to trade either propeller straight across for the Offshore.
galtsfan	posted 01-23-2007 01:31 PM ET (US) Thanks Tom, I'll keep that in mind. I'll try it and see what kind of performance I get. I don't want to go through all the problems David is having with matching his. Did you say the hub kit for the Optimax is identical?
Tom W Clark	posted 01-23-2007 02:15 PM ET (US) The Flo-Torq II hub kit you have been using on your OptiMax should fit your new Honda. You can also buy a Honda Flo-Torq kit which will differ by only the substitution of a different nut and a cotter pin instead of a tab washer. Now that I think about it, you need to verify the nut uses the same threads. Yamaha uses a metric threading. I am unsure of Honda but the motor should come with a propeller nut. I just reviewed the Flo-Torq application chart and it ambiguous. They do not show the BF150. The 225 uses a different thrust washer. Either way the drive sleeve and aft adapter are the same parts. Whether you will experience prop rattle or not, we will have to wait and see.
galtsfan	posted 02-01-2007 10:38 AM ET (US) I've set up a simple ratio of engine speed to gear ratio of my previous Optimax and the new Honda using my Mercury Offshore series. Known are the Optimax engine speed and gear ratio as well as the Honda's gear ratio. I solved for the theoretical engine speed for the Honda without consideration for the difference in horsepower. How valid is this value? I'm waiting for parts to arrive to complete the rigging. I'll hopfully know the answer by this weekend. I could live with 5,992-RPM with a maxium of 6,000. The OptiMax was 135-HP, the Honda 150 HP or maybe even more according to Honda. http://www.honda-marine.com/pdfs/BF150_advantage.pdf Optimax Honda 2.0 2.14 --- = ---- 5600 (5992)
galtsfan	posted 02-01-2007 11:10 AM ET (US) The difference in torque between 2 and 4 stroke engine is well documented. Has anyone seen any benefit in using the Mercury Performance Vent System (PVS) http://sites.mercurymarine.com/portal/page?_pageid=126,50050,126_50060& _dad=portal&_schema=PORTAL on four-stroke engines to get a better holeshot?
jimh	posted 02-03-2007 10:11 AM ET (US) Re the Mercury Performance Vent System (PVS): I have run a boat (with big two-stroke motors) with Mercury propellers using plugs in the PVS vents which had holes. The behavior of the boat was much like a car with a "loose" transmission. When the boat was accelerated to planing speed, the engine throttle would be cut back to sustain a particular speed. The boat would continue to accelerate as the propellers began to obtain a better bite. Often the engine throttle would have to be reset to prevent the boat from going faster than desired. This behavior seemed much a car with a slipping transmission. After a while, you become accustomed to it, and your operation of the engine throttle changes to match the slipping propellers. In the long term, it is possible to get accustomed to almost anything, but initially I did find the PVS vented propeller behavior a bit odd. The use of a PVS vented propeller might be especially helpful on a four-stroke motor, as most four-stroke motors seem to lack torque at low engine speeds. I would also be interested to hear of any experiences with four-stroke motors.