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Need bigger prop?

 
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Ted655



Joined: 19 Mar 2007
Posts: 10
Location: Louisiana

PostPosted: Tue Apr 24, 2007 10:50 am    Post subject: Need bigger prop? Reply with quote

1987 Yamaha 2 stroke 115 hp.
I just installed this used motor onto my big jon boat. 24' X 8'. Aluminium 3/16 plate. A fairly heavy boat. Motor moves the boat BUT boat seems "weak" or slow to respond. Yet motor isn't straining. Prop sounds like a "blender unless throttle is applied slowly as momentum builds.
We had it planing at 6500 RPMs before it shut its self off. Also reverse is not as strong as it needs to be. When fully turned, rear of boat won't pull in that direction but continues backing in a more straight path.
I think I need a different prop.
Motor came off a 20' fiberglass V hull.
Top end is too high, right? Question
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Ted, In the Atchafalaya where gators get blamed for bull shark deeds
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MikeW
Senior Member


Joined: 01 May 2006
Posts: 680

PostPosted: Tue Apr 24, 2007 4:41 pm    Post subject: Need bigger prop? Reply with quote

Hello Ted65, you are under proped! Depending on the length of the boat you should be running a prop somewhere in the neighborhood of 13" X 19". I will make another posting tomorrow going into more detail.
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Ted655



Joined: 19 Mar 2007
Posts: 10
Location: Louisiana

PostPosted: Tue Apr 24, 2007 7:09 pm    Post subject: Reply with quote

Smile Yea, I thought it was small. Hard to reach off back of boat, but current prop is 12" dia. (maybe a tad more) I was thinking of 13.5 or 14 inch gia., 17 pitch.
===="I just installed this used motor onto my big jon boat. 24' X 8'. Aluminium 3/16 plate. "=========
We use this boat at mostly slow speeds BUT, in tight close quarters. Pushing & towing other boats. Power and responce is most important, not high end performance.
Thanks, Smile
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MikeW
Senior Member


Joined: 01 May 2006
Posts: 680

PostPosted: Wed Apr 25, 2007 6:25 pm    Post subject: Need bigger prop? Reply with quote

Hello Ted 655, I will do some calculations and get back to you Thursday. I'm sure I can come up with a Propeller that will greatly improve your performance.
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MikeW
Senior Member


Joined: 01 May 2006
Posts: 680

PostPosted: Thu Apr 26, 2007 3:45 pm    Post subject: Need a bigger prop? Reply with quote

Hello Ted, I talked with a couple of Propeller manufactures. We have come to the conclusion the best Propeller for your application is a 13" X 15" 4- Blade Aluminum Propeller. This will make a significant improvement in performance! Volvo is the only manufacture to make a 4-Blade Propeller to fit the V-4 Yamaha Gearcase. We have the Propeller and Hub Kit in stock. To see the Propeller Click Here 4-Blade Propeller
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Hal C
Senior Member


Joined: 09 Jun 2006
Posts: 68

PostPosted: Thu Apr 26, 2007 5:50 pm    Post subject: Need bigger prop? Reply with quote

Here is the link for the hub that fits the 13" x 15" Volvo 4 blade prop (mentioned above by Mike W)
Prop Hub by Volvo
Good luck and please let us know how the prop works for your boat.
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Ted655



Joined: 19 Mar 2007
Posts: 10
Location: Louisiana

PostPosted: Sat Apr 28, 2007 5:13 pm    Post subject: Reply with quote

Smile Thanks. I'm also looking at a 14 X 11 3 blade SS. Aluminium props don't last long here in stump/sinker country.
What does the extra blade add? 13 still seems small but I may be comparing apples & oranges.
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Flying J



Joined: 10 Oct 2006
Posts: 13

PostPosted: Sun Apr 29, 2007 11:47 am    Post subject: Need bigger boat prop Reply with quote

Usually the 4th blade helps with the low end power when sized right. If you do go with a stainless steel blade better check your zincs often, I've heard electrolysis can be a problem with the aluminum lower units.
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Hal C
Senior Member


Joined: 09 Jun 2006
Posts: 68

PostPosted: Mon Apr 30, 2007 5:44 pm    Post subject: 4 blade props vs. 3 blade props for workboats Reply with quote

Ted655, concerning the 4 blade prop vs. the 3 blade, the 4th blade does make a big difference at lower end speeds as Flying J states. It simply gets more propeller blade surface in contact with the water. It also helps get a boat on a plane and keep it there at the threshold speeds. In your case where power and low speed performance is important for pushing and towing, it should help considerably.

Another thing to consider is that a 4 blade prop will help when cornering, and that is especially important in the tight quarters you mention. Same is true when using reverse.

Concerning the use of stainless steel props, it is really a maintenance issue since you have to keep after your zincs and change them as needed.

If I remember right, the Atchafalaya area is sort of a river delta area with wetlands influenced by the Gulf storms and tidal conditions. Saltwater influence could cause severe electrolysis so you will want to inspect your zincs often when using stainless steel props just like boat owners with inboards, especially if you keep the boat in the water constantly.

Hope this helps, you can find all types of props at Go2marine Propellers or give the Call Center a call. Good luck.[/url]
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Ted655



Joined: 19 Mar 2007
Posts: 10
Location: Louisiana

PostPosted: Mon Apr 30, 2007 6:12 pm    Post subject: Reply with quote

Very Happy Thanks. All things I didn't know. We are at the top of the Basin, so no salt water here. We do wander down to the Gulf occasionly. The boat does live in the water, here , behind the house.
A lot to think on. Thank you again.
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