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Author Topic:   Montauk 17: Honda 90-HP Four-stroke

captndon posted 08-19-2007 05:47 AM ET (US)
For use on a 2001 MONTAUK with a 90-HP HONDA four-stroke, what Honda [unknown acronym] prop I should order? Interested in power for wakeboarding kids, and not so much interest in speed as our lake has a speed limit of 40-KPH or 25 MPH. Thus a maximum of 45-MPH would be OK. The motor came with a gray, paintedm, three-blade 13.5 X 15inch propeller. I have spent the last hour reading all the material on propellers on this site [Fast reader!--jimh], and somewhere between "Bow Lift" and "Slip", I lost it.
Help Please?

Captndon
Perry posted 08-19-2007 01:01 PM ET (US)
Is it the new, fuel injected BF90? How does it perform with the 3 blade aluminum 15 pitch prop? That would be a good starting point.
There was another guy here who recently repowered his Montauk with a new BF90. Maybe you should search for the thread regarding his repower.
Perry posted 08-19-2007 01:03 PM ET (US)
By the way, what is a [unknown acronym] prop?
captndon posted 08-19-2007 01:35 PM ET (US)
Hi
It is a 2007 model BF90 with electonic fuel control.
I bought it packaged with a stainless steel propeller but do not know which one, the Honda Marine dealer has never powered a Whaler before, he has no idea. He gave me this [aluminum] propeller to play with until I know what I want, then he will order it.
The propeller does OK, it goes faster than I need, will have it in salt water next week and will be able to check for top speed. They use radar on our lake, so I cannot check top end.
I will search for the other BF90 reference.
Thanks
Captndon
captndon posted 08-19-2007 02:47 PM ET (US)
Noticed in the threads that this motor should be mounted in the upper holes, mine was mounted all the way down, last holes.
What difference does this make?
Again my Honda guy never hung a motor on a Whaler so he has no clue.
Thanks
Captndon
sixmile posted 08-19-2007 03:28 PM ET (US)
Best way to determine the correct prop size is use your tachometer. If you don’t have a tach get one. You want a prop that allows your motor to rev up and reach its maximum recommended rpm range. In my opinion it is always better to be able to rev a little higher as opposed to rev a little lower than this. You can always throttle down and lugging (not reaching the minimum rpm range) is far worse. Figure each 100-rpm increase equals about one inch of pitch. If you operate in deep waters that are obstruction free Stainless steel is great. If you operate in shallow waters where hitting something is likely S/S can do far more damage than aluminum. Stainless props are much stronger than aluminum and produce better performance due to the fact of having thinner blades. Problem with Stainless is they are so strong hitting something could damage your gearcase. Aluminum will give and the prop will absorb the hit before the gear case would. Also keep in mind that S/S props are much heavier than aluminum and on some outboards with smaller gear cases this added weight puts unnecessary strain on them. I imagine you will need more pitch though due to your boats power to weight ratio. 17-19 Just my 2 cents, Ed
Perry posted 08-19-2007 03:50 PM ET (US)
Test the current prop. See how many RPM the motor will reach at wide open throttle (WOT). This will serve as a baseline so you can go from there, You want the motor to reach as close to the maximum RPM (6300) as posible for best all around performance.
You should also raise the motor at least one hole up, maybe even two.
Read this thread:
http://continuouswave.com/ubb/Forum4/HTML/005446.html
captndon posted 08-20-2007 02:40 AM ET (US)
Thanks,
I will do my tests in the next two weeks, and as
soon as I am back from Spain I will have the Honda
dealer lift up the engine two holes. I thought deeper
was better due to cavitation......
Thanks
DD
Perry posted 08-20-2007 04:12 AM ET (US)
Deeper is better if your prop is ventilatng but the only way to know if it is ventilating is to test it out. A motor that is mounted too low has increased drag due to the lower unit being deeper in the water. A motor mounted too low can cause porpoising.
Remember that a stainless steel prop with cupping can run higher than a aluminum prop. The thinner blades and cupping on a stainless prop increases performance and decreases ventilation.
A Little Madness posted 08-21-2007 11:59 AM ET (US)
captdon, I have a Honda Titan Solas 13 1/4 15R Stainless Steel Prop installed by my Honda dealer who has a lot of experience w/Honda's and 17' Montauk. It just so happened that the area tech rep for Honda was in the shop the day we began the installation and he reaffirmed his choice. She seems plenty strong to me to move 4 adults down the waterway w/no indication of sluggishness. The motor is just plain sensational in all aspects. I don't think you'd be at all disappointed w/the tital solas. For more information on our overall renovation project, see our personal page at:
http://www.whalercentral.com/infusions/personal_page/view_personal_page.php?user_id=4006
Good Luck
Perry posted 08-21-2007 12:42 PM ET (US)
Madness, what is your RPM and top speed at WOT with a light load?
How high is your motor mounted?
Fishcop posted 08-21-2007 05:22 PM ET (US)
I just re-powered my 1986 Montauk with a 2007 Honda BF90D 20" shaft, mounted all the way down. Solas 17p Aluminum prop. Turns 6000 rpm and 40mph with a full load. I just have 25 hours on it and will get some better performance specs after its first service.
I have been told to raise the motor a hole or two, but will see what performance I get after the service.
Here is a photo of her:
http://img.photobucket.com/albums/v219/Waha/HPIM0176.jpg
http://img.photobucket.com/albums/v219/Waha/HPIM0170.jpg
The 17p holds really well would be a good all around prop for this setup.
Andy
A Little Madness posted 08-22-2007 12:03 PM ET (US)
Perry, 5900 rpm @ 41 mph trimmed pretty much all the way down in the ICW w/my 250lbs & 28 gal of fuel. Sorry, but I don't know what WOT is. I too have about 28 hours on mine. Motor is mounted all the way down. Here's a link to my personal page which has pictures. Good luck
captndon posted 08-24-2007 09:08 AM ET (US)
Have a tach, speedo and gps, so will be able to
do some speed runs in the Med, need to be out before the
bumps start in the AM.
Terms WOT is Wide open throttle.....cavitation/ventilation
how do I know that? Porposing, noticed UpDown ossicalation
at about 40KMH, could not go any faster due speed limit.
Will this porposing get worse or better with more speed?
Looking up the suggested props, and a little relieved that everyone else seems to be running with the motor in the
bottom position.

Captndon
Perry posted 08-24-2007 12:50 PM ET (US)
Moving the motor up one hole should help with porpoising. Just because a couple of people here have it mounted all the way down doesn't necessarily mean it is the correct mounting position.
Are you trimming the motor up (out) at WOT? This also helps to gain more speed and help with porpoising.
40 KPH (46 MPH) is a very good top speed for your boat/motor combination.
Did you get a stainless prop from your dealer to try?
Fishcop posted 08-24-2007 02:48 PM ET (US)
40kph is equal to about 25mph.
I would be supprised to see 46mph from that boat / motor combo with a 15p aluminum prop. I could be wrong, but my boat with the same motor and a 17p aluminum prop produces:
6.4mph @ 2000rpm
11.9mph @ 2900rpm
16.5mph @ 3200rpm (on plane)
23.1mph @ 3800rpm
31mph @ 4500rpm
40mph @ 6000rpm
Boat has full 24gal fuel tank, two persons, aluminum T-top, two group 24 batteries, anchor, fishing tackle and 5gal live bait well. Motor is mounted all the way down. I plan to raise it one hole when I go in for the first service.
Let us know how your prop hunt goes. Forum member Tom W. Clark has some great info on props. You may want to contact him.
Andy
captndon posted 08-24-2007 05:14 PM ET (US)
Have a tach, speedo and gps, so will be able to
do some speed runs in the Med, need to be out before the
bumps start in the AM.
Terms WOT is Wide open throttle.....cavitation/ventilation
how do I know that? Porposing, noticed UpDown ossicalation
at about 40KMH, could not go any faster due speed limit.
Will this porposing get worse or better with more speed?
Looking up the suggested props, and a little relieved that everyone else seems to be running with the motor in the
bottom position.

Captndon
Perry posted 08-24-2007 10:22 PM ET (US)
I confused KPH with Knots
Perry posted 08-25-2007 01:43 AM ET (US)
Moving the motor up one hole should help with porpoising. Just because a couple of people here have it mounted all the way down doesn't necessarily mean it is the correct mounting position.
Are you trimming the motor up (out) at WOT? This also helps to gain more speed and help with porpoising.
Did you get a stainless prop from your dealer to try?

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Author	Topic: Montauk 17: Honda 90-HP Four-stroke
captndon	posted 08-19-2007 05:47 AM ET (US) For use on a 2001 MONTAUK with a 90-HP HONDA four-stroke, what Honda [unknown acronym] prop I should order? Interested in power for wakeboarding kids, and not so much interest in speed as our lake has a speed limit of 40-KPH or 25 MPH. Thus a maximum of 45-MPH would be OK. The motor came with a gray, paintedm, three-blade 13.5 X 15inch propeller. I have spent the last hour reading all the material on propellers on this site [Fast reader!--jimh], and somewhere between "Bow Lift" and "Slip", I lost it. Help Please? Captndon
Perry	posted 08-19-2007 01:01 PM ET (US) Is it the new, fuel injected BF90? How does it perform with the 3 blade aluminum 15 pitch prop? That would be a good starting point. There was another guy here who recently repowered his Montauk with a new BF90. Maybe you should search for the thread regarding his repower.
Perry	posted 08-19-2007 01:03 PM ET (US) By the way, what is a [unknown acronym] prop?
captndon	posted 08-19-2007 01:35 PM ET (US) Hi It is a 2007 model BF90 with electonic fuel control. I bought it packaged with a stainless steel propeller but do not know which one, the Honda Marine dealer has never powered a Whaler before, he has no idea. He gave me this [aluminum] propeller to play with until I know what I want, then he will order it. The propeller does OK, it goes faster than I need, will have it in salt water next week and will be able to check for top speed. They use radar on our lake, so I cannot check top end. I will search for the other BF90 reference. Thanks Captndon
captndon	posted 08-19-2007 02:47 PM ET (US) Noticed in the threads that this motor should be mounted in the upper holes, mine was mounted all the way down, last holes. What difference does this make? Again my Honda guy never hung a motor on a Whaler so he has no clue. Thanks Captndon
sixmile	posted 08-19-2007 03:28 PM ET (US) Best way to determine the correct prop size is use your tachometer. If you don’t have a tach get one. You want a prop that allows your motor to rev up and reach its maximum recommended rpm range. In my opinion it is always better to be able to rev a little higher as opposed to rev a little lower than this. You can always throttle down and lugging (not reaching the minimum rpm range) is far worse. Figure each 100-rpm increase equals about one inch of pitch. If you operate in deep waters that are obstruction free Stainless steel is great. If you operate in shallow waters where hitting something is likely S/S can do far more damage than aluminum. Stainless props are much stronger than aluminum and produce better performance due to the fact of having thinner blades. Problem with Stainless is they are so strong hitting something could damage your gearcase. Aluminum will give and the prop will absorb the hit before the gear case would. Also keep in mind that S/S props are much heavier than aluminum and on some outboards with smaller gear cases this added weight puts unnecessary strain on them. I imagine you will need more pitch though due to your boats power to weight ratio. 17-19 Just my 2 cents, Ed
Perry	posted 08-19-2007 03:50 PM ET (US) Test the current prop. See how many RPM the motor will reach at wide open throttle (WOT). This will serve as a baseline so you can go from there, You want the motor to reach as close to the maximum RPM (6300) as posible for best all around performance. You should also raise the motor at least one hole up, maybe even two. Read this thread: http://continuouswave.com/ubb/Forum4/HTML/005446.html
captndon	posted 08-20-2007 02:40 AM ET (US) Thanks, I will do my tests in the next two weeks, and as soon as I am back from Spain I will have the Honda dealer lift up the engine two holes. I thought deeper was better due to cavitation...... Thanks DD
Perry	posted 08-20-2007 04:12 AM ET (US) Deeper is better if your prop is ventilatng but the only way to know if it is ventilating is to test it out. A motor that is mounted too low has increased drag due to the lower unit being deeper in the water. A motor mounted too low can cause porpoising. Remember that a stainless steel prop with cupping can run higher than a aluminum prop. The thinner blades and cupping on a stainless prop increases performance and decreases ventilation.
A Little Madness	posted 08-21-2007 11:59 AM ET (US) captdon, I have a Honda Titan Solas 13 1/4 15R Stainless Steel Prop installed by my Honda dealer who has a lot of experience w/Honda's and 17' Montauk. It just so happened that the area tech rep for Honda was in the shop the day we began the installation and he reaffirmed his choice. She seems plenty strong to me to move 4 adults down the waterway w/no indication of sluggishness. The motor is just plain sensational in all aspects. I don't think you'd be at all disappointed w/the tital solas. For more information on our overall renovation project, see our personal page at: http://www.whalercentral.com/infusions/personal_page/view_personal_page.php?user_id=4006 Good Luck
Perry	posted 08-21-2007 12:42 PM ET (US) Madness, what is your RPM and top speed at WOT with a light load? How high is your motor mounted?
Fishcop	posted 08-21-2007 05:22 PM ET (US) I just re-powered my 1986 Montauk with a 2007 Honda BF90D 20" shaft, mounted all the way down. Solas 17p Aluminum prop. Turns 6000 rpm and 40mph with a full load. I just have 25 hours on it and will get some better performance specs after its first service. I have been told to raise the motor a hole or two, but will see what performance I get after the service. Here is a photo of her: http://img.photobucket.com/albums/v219/Waha/HPIM0176.jpg http://img.photobucket.com/albums/v219/Waha/HPIM0170.jpg The 17p holds really well would be a good all around prop for this setup. Andy
A Little Madness	posted 08-22-2007 12:03 PM ET (US) Perry, 5900 rpm @ 41 mph trimmed pretty much all the way down in the ICW w/my 250lbs & 28 gal of fuel. Sorry, but I don't know what WOT is. I too have about 28 hours on mine. Motor is mounted all the way down. Here's a link to my personal page which has pictures. Good luck
captndon	posted 08-24-2007 09:08 AM ET (US) Have a tach, speedo and gps, so will be able to do some speed runs in the Med, need to be out before the bumps start in the AM. Terms WOT is Wide open throttle.....cavitation/ventilation how do I know that? Porposing, noticed UpDown ossicalation at about 40KMH, could not go any faster due speed limit. Will this porposing get worse or better with more speed? Looking up the suggested props, and a little relieved that everyone else seems to be running with the motor in the bottom position. Captndon
Perry	posted 08-24-2007 12:50 PM ET (US) Moving the motor up one hole should help with porpoising. Just because a couple of people here have it mounted all the way down doesn't necessarily mean it is the correct mounting position. Are you trimming the motor up (out) at WOT? This also helps to gain more speed and help with porpoising. 40 KPH (46 MPH) is a very good top speed for your boat/motor combination. Did you get a stainless prop from your dealer to try?
Fishcop	posted 08-24-2007 02:48 PM ET (US) 40kph is equal to about 25mph. I would be supprised to see 46mph from that boat / motor combo with a 15p aluminum prop. I could be wrong, but my boat with the same motor and a 17p aluminum prop produces: 6.4mph @ 2000rpm 11.9mph @ 2900rpm 16.5mph @ 3200rpm (on plane) 23.1mph @ 3800rpm 31mph @ 4500rpm 40mph @ 6000rpm Boat has full 24gal fuel tank, two persons, aluminum T-top, two group 24 batteries, anchor, fishing tackle and 5gal live bait well. Motor is mounted all the way down. I plan to raise it one hole when I go in for the first service. Let us know how your prop hunt goes. Forum member Tom W. Clark has some great info on props. You may want to contact him. Andy
captndon	posted 08-24-2007 05:14 PM ET (US) Have a tach, speedo and gps, so will be able to do some speed runs in the Med, need to be out before the bumps start in the AM. Terms WOT is Wide open throttle.....cavitation/ventilation how do I know that? Porposing, noticed UpDown ossicalation at about 40KMH, could not go any faster due speed limit. Will this porposing get worse or better with more speed? Looking up the suggested props, and a little relieved that everyone else seems to be running with the motor in the bottom position. Captndon
Perry	posted 08-24-2007 10:22 PM ET (US) I confused KPH with Knots
Perry	posted 08-25-2007 01:43 AM ET (US) Moving the motor up one hole should help with porpoising. Just because a couple of people here have it mounted all the way down doesn't necessarily mean it is the correct mounting position. Are you trimming the motor up (out) at WOT? This also helps to gain more speed and help with porpoising. Did you get a stainless prop from your dealer to try?