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Posts: 156
| Hey guys, I recently purchased a used boat. It's a Sea Nymph FM161 with a BF50A Honda 4 stroke. The boat is 16.4' x 72" side console aluminum boat.
I took it out for a trial run. With just me in the boat it would hit 6,000rpm before full throttle was reached - maybe 3/4 or 7/8 of full throttle. According to the "Honda" tach in the boat (which I assume was installed along with the motor) redline is 6,000 rpm. Current prop is a "Scott" 11 1/4 x 13.
Normally I would think the thing to do is move up in pitch to bring down RPM. The problem is that the prop is damaged. The tips of all 3 blades are sheared off around 1/8" or 3/16" and all dinged up.
So my problem is I don't know if I put a new 13 pitch prop if that will bring the RPM down off redline, or should I get a 14 pitch prop and assume the prop damage is not effecting RPM very much? On a budget and only want to buy one prop.
Thanks guys.
Edit - Speedo showed around 30mph on the trial run.
Edited by Makintrax73 8/19/2009 11:12 AM
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| some prop guys will let you try out a prop. Go buy one and return if it doesnt hit the rpm range. I would imagine the prop damage would have an effect on the rpm. I have a bigger engine and have noticed small adjustments have had a dramatic effect on my rpm at wot. |
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Posts: 3508
Location: Elk River, Minnesota | Hiya,
I would look at purchasing a 15 pitch prop. Even with dinged prop fins, you would not gain too many rpms that would put you way over the top of the motor range. With that set-up I would highly suggest a solas alcup 3 prop as a replacement. It will perform better since it has a squeeze casting design which allows for thinner blades but less flex than a normal aluminum prop. Price is decent as well.
Much of the choice of prop pitch has to do with normal loading of the boat. If you always have 2 - 3 people in the boat plus their gear, the 13 pitch could very well be the right prop to perform well. In most cases, one should set up their rig to hit max rpms when the boat is lightly load and only you as the occupant. Then, when you do get extra passengers and gear, the same prop will still do the job.
Steve |
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Posts: 156
| Thanks for the advice guys. The prop that is on there definitely wanted to turn more than 6k, and I found the manual which states full throttle should be 5,500 to 6,000.
I was planning on just buying a prop online since I don't know of any prop places. The couple of dealers I have called around me have no Honda props in stock and would have to order so I assume they wouldn't let me try it out if they have to order it. |
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Posts: 3508
Location: Elk River, Minnesota | Hiya,
Some places will allow you to return a prop (undamaged and in original condition) for a one...although you will be out shipping charges I believe.
Here is where I have purchased a few props from over the years...they've been good to me: http://propline.com/ |
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Posts: 395
Location: NW WI | The idea of going to a dealer and working with them on a new prop is your best bet.
You could try calling North American Propeller at 715.359.5264. THey rebuild props for many dealers and might have something for you. They are located in Wausau WI.
Edited by Ifishskis 8/20/2009 4:19 PM
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