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Posts: 158
| My engine currently has no prop at all, so I need a starting point.
Engine is a 65hp Johnson.
Boat is barely 17' long. Beam is 78" Rear of the boat has a very shallow V.
In fact it is the boat in this thread.
http://muskie.outdoorsfirst.com/board/forums/thread-view.asp?tid=62...
It is being converted to a Tiller, and I would say that the weight will be relatively close to what it was new/stock.
Maybe another 100-200lbs extra.
Any ideas where I should start? Because I have NO idea.
Edited by LonLB 2/20/2011 8:09 PM
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Posts: 3508
Location: Elk River, Minnesota | Year of motor?
Do you know the gear ratio, the max RPM's of the motor?
All of this will help out..
Thanks
Steve |
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Posts: 158
| It is a 73 3cyl.
I don't know the gear ratio. I can't say what the max RPM is I don't have a manual yet. The engine isn't RPM limited though. I think some of the other 3cyl engines had power packs that didn't have an RPM limiter.
I'll try and track down that info. |
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Posts: 158
| Gear ratio is 2.42.1, and RPM is 5-6000 RPM. |
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Posts: 3508
Location: Elk River, Minnesota | On that boat, I would bet you will be in something like 11-3/4 x 17 pitch depending on the weight of the boat. Much of this will be dependent on the engine displacement and the overall weight of the boat, mounting position of the motor, etc.
Is this a 2 cylinder engine? If so, it will be the same size displacement as the workhorse 40hp and 50hp and a really strong engine. If the boat gets up to around 800 pounds, a 15 pitch might be in order. Good strong gear ratio, though, which allows the motor to have higher RPM's at lower speed...that equals torque!!
Steve
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Posts: 158
| 3 cyl loop charged....I think it's 56ci
I can't say for sure how effective they will be but I was going to add a set of automatic trim tabs. I have them since they came on the boat I pulled the engine off of.
They are about 8" wide, but don't protrude from the boat very far. Approximately 5". They are spring loaded.
Not sure if that would effect the prop selection or not, but figured I would throw that out there.
Edited by LonLB 2/20/2011 10:00 PM
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Posts: 3508
Location: Elk River, Minnesota | They will help with keeping the bow down if you decide to use them. In many cases getting the right prop will allow you to NOT need the trim fins..
Since it is the 3 cylinder model, it is the same as the 70hp platform. a 17 pitch should be a good start.
Steve |
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Posts: 158
| Thanks Steve, that helps a bunch, and that's what I'll go with.  |
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Prop Selection help