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Prop suggestions - 99 Montauk, Honda 90
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| txmntman |
Posted on 12/21/08 - 6:17 PM
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Hey folks,
I just bought this 99 Montauk with a Honda 90 HP. boat is currently lightly loaded and only does about 31MPH
so, I am starting some troubleshooting, as I expected a little more speed than that.
* I will weigh the rig to check for water soaked foam, but doubt that is the problem.
* For those with this type of setup (I know there are some) what type props are you running?
Thanks for your help.
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| Phil T |
Posted on 12/21/08 - 7:05 PM
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We need 5 pieces of information:
1) Was speed taken by GPS or speedometer?
2)What is the highest RPM you reach at wide open throttle (WOT)
3) what is the rigging height of the motor? One measurement is the location of the anti-cavitation plate in relation to the bottom of the hull. If you place a long ruler on the top and slide it toward the hull, is the plate at, below, or above the bottom of the hull and by how much.
4) what is the gear ratio of the lower unit
5) what is the make/model and size of the current propeller. The size is stamped on either the outside or inside the hub.
With this information, we can get you dialed in. I would expect 38-40 mph
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| txmntman |
Posted on 12/21/08 - 8:36 PM
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my answers to the questions....
We need 5 pieces of information:
1) Was speed taken by GPS or speedometer?
GPS
2)What is the highest RPM you reach at wide open throttle (WOT)
I believe it was 4300 rpm
3) what is the rigging height of the motor? One measurement is the location of the anti-cavitation plate in relation to the bottom of the hull. If you place a long ruler on the top and slide it toward the hull, is the plate at, below, or above the bottom of the hull and by how much.
the anti-cavitation plate is level with the bottom of the boat
4) what is the gear ratio of the lower unit
2.33:1 according to Honda website
5) what is the make/model and size of the current propeller. The size is stamped on either the outside or inside the hub.
The current prop looks to be a Michigan Wheel, Vortex (aluminum prop) 13 x 19
So, I'm guessing I need a 17 pitch prop....but, is there someone here who is running that setup?
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| txmntman |
Posted on 12/22/08 - 11:19 AM
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Additional info. This is a Montauk 17 (not the new 170)..
thanks
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| Finnegan |
Posted on 12/22/08 - 1:20 PM
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Montauks with 90's on them will usually run bewteen 42 and 48 MPH, depending on engine brand and setup. I would guess the Honda 90 will be at the lower end of that range, along with the E-tec 90's and Yamaha 2 stroke 90's.
The Honda 90's used the Mercury lower unit for years, with the 2.33 gears, so it sounds like that is what you have. I would install the engine 1-1/2" up (3rd bolt hole), and use a 19" Merc Laser II prop, whihc indicates around 42 MPH at 5500 RPM. 31 MPH top end indicates engine trouble to me. Way to slow.
I think Michigan Wheel aluminum props are among the worst performers made. Get rid of it. If you want to keep your costs down and stay with alum, get the Merc BLack Max, which is a surprisingly good perfromaer for an aluminum product.
If you simply can't get the RPMS needed for 42 MPH, I would consider the 39-40 MPH Merc Vengeance 18", but only install the engine in the 2nd holes, 3/4" up.
Edited by Finnegan on 12/22/08 - 1:28 PM |
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| txmntman |
Posted on 01/14/09 - 1:12 PM
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Well, it was not a prop problem at all. I took the Whaler out for a run a week or so ago, and it would not move above idle. I moved the throttle as far as I could, and could not ever get above idle. So, back on the trailer, and to a Honda Mechanic.
To make a long story short, the problem turned out to be a problem with sludge buildup on the outside of the carbs.....the throttle would simply not move! We took the carbs off and found the inside of the carbs in relatively good shape, but the carbs would simply not allow the engine to power up. After cleaning the carbs up, and buttoning it all back together, I took it out for a run today. Top speed was about 36 mph (gps) and the motor ran great, with no hesitation out of the hole. I still may try a 17 pitch prop rather than the 19 that is on there now, but today it worked fine. I guess time will tell, but right now I'm satisfied with the engine...
I will likely run additional tests, I'm not sure I have an accurate tach, and will have to just familiarize myself with the boat, since this is only the 2 or 3rd time I've had it out.....I'll keep you posted
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| Phil T |
Posted on 01/14/09 - 3:36 PM
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Before you mess with the prop, what was the WOT RPM's and mounting height of the motor?
There is a chance you can get your speed up to 40 mph if the motor is currently too low (on the transom) by raising it up two holes.
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| Tom W Clark |
Posted on 01/14/09 - 7:21 PM
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36 MPH is a little weak. I would expect 40 MPH with the correct propeller.
The Honda BF90 did use same 2.33:1 gear ratio as the Mercurys but it has a much higher redline, 6000 RPM if I remember correctly.
You will want a 17" or *maybe* 18" pitch propeller. The 18" Mercury Vengeance or the 17" Stiletto Advantage 4.25 would my first two choices, not necessarily in that order.
Edited by Tom W Clark on 01/14/09 - 7:23 PM |
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| bottomfish |
Posted on 01/15/09 - 11:21 AM
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I have a 83 Montauk with a 2001 Honda 90 on it. At what height should the cavatation plate be in relation to the bottom of the hull? I typically run 33 to 35 mph top end. RPM's in the low to mid 5000's. I can't measure where it is now since I pulled the motor to rehab the boat but I think it is flush with the bottom now. I can change the position when I remount if I can increase top end.
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| Tom W Clark |
Posted on 01/15/09 - 11:54 AM
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Raise it one bolt hole (3/4") and you will see a little more speed.
Edited by Tom W Clark on 01/15/09 - 11:55 AM |
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| bottomfish |
Posted on 01/15/09 - 3:00 PM
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Thanks Tom. I will try it when I re-hang the motor.
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| Joe Kriz |
Posted on 01/15/09 - 3:20 PM
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bottomfish,
That doesn't sound anywhere near close to the speed you should be getting.
I had a 1985 70 hp Evinrude on my Montauk and it would do 31 to 32 mph...
My engine was all the way down and could not raise it without drilling new holes in the transom. I'm sure if I raised the engine up one hole, I would have gotten a couple more mph at top end.
It also appears you are not getting anywhere near the max rpm's out of the engine.
As Tom mentioned above, you should be getting near the red line of 6,000 rpm with 1 person and a light load.
What size prop are you running?
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| bottomfish |
Posted on 01/16/09 - 7:29 AM
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Joe, I think it is the stock prop. 3x13.25x17R aluminum. I looked at the transom last night when I was stripping bottom paint and I would have to redrill to raise the moter. Really do not want to do that. If a different prop would give me a little bit more I could live with that. I also am in the process of removing what looks like 3 layers or more of bottom paint which should help as well. Any more suggestions would be greatly appreciated. Wayne
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| Tom W Clark |
Posted on 01/16/09 - 8:26 AM
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Wayne,
Why would you have to redrill to raise your motor? All outboards use the same BIA bolt hole layout and have multiple mounting hole options.
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| Phil T |
Posted on 01/16/09 - 9:10 AM
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A photo of your transom and motor position would really help this discussion.
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| bottomfish |
Posted on 01/16/09 - 9:10 AM
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Tom, the motor was originally mounted fully dow utilizing the top and bottom mounting holes. If I raise it I would have to plug 1 set of holes and then drill a new set for the top bolt. Not sure I want to do that. Any other suggestion? Thanks, Wayne
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| bottomfish |
Posted on 01/16/09 - 9:17 AM
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I can post a pic of my transom and motor bracket but not until monday. The camera is at home.
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| Joe Kriz |
Posted on 01/16/09 - 11:17 AM
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The upper holes should not have to be repositioned.
Where are your holes as related to this article?
http://www.whalercentral.com/articles...icle_id=82
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| bottomfish |
Posted on 01/16/09 - 12:34 PM
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You are correct the upper holes would not have to be redrilled I would have to drill a new set to try and utilize the lower mounting holes. It is mounted using the top holes @ 2 1/4" down and 4 1/4" down from the top of the transom. The lower area is not utilized at this time. Since I have it off now I can make a change when I re-hang it. That article is great. I can measure and try to hit it in the bottom of the splashwell. How about the prop I am running? Thanks, Wayne
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| Tom W Clark |
Posted on 01/16/09 - 1:00 PM
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Wayne,
Whoever put your Honda on your Whaler did not know what they were doing. That is too bad.
You need to fill those two lower bolt holes. That is not a difficult job at all.
Drill two new holes where the green is in Joe's drawing. This will allow a "two holes up" mounting position for your Honda.
With a good stainless steel propeller this will work well and give you more speed as well as lighter steering effort.
Edited by Tom W Clark on 01/16/09 - 1:01 PM |
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