I have a 2000 Johnson Ocean Pro 115hp. It has a black three blade prop on it now. It is starting to show some wear and I was thinking of replacing/upgrading. What do I need to know? Three blade vs. four blade? Difference in pich and teett? I like the way that the boat runs so I immagine that I need to stay with the same specs as the prop that is on it. Will I gain anyhing wiht a four blade?Shoud I get stainless? What are the benefits of stainless?
Thanks!!!
Steve
Unless you intend on pulling skiers/tubes a lot of the time, stick with a 3 blade prop especially since you have a relatively light boat. A 3 blade prop in inherently more efficient and will be faster.
Go stainless if you have the funds. If not, a quality aluminum will do fine. It is hard to beat a Mercury prop. They just require a hub kit to mount on your engine.
As for pitch, what is the pitch of the installed prop? What rpm and speed are you running at WOT? RPM at cruise speeds as well? You will want to achieve the manufacturers recommended WOT rpm range by selecting the right pitch. Preferably you will want to be on the upper end of the range for best all around performance. Slip calculations should also be done at cruise speeds to determine if the prop is grabbing the water and not slipping and wasting power, speed, and fuel. Slip needs to be between 10-15% for your boat. Anything more than that the prop is not working efficiently.
Iain Pelto
Edgewater 185CC “Jumpin’ Bean II”
stainless is worth the money IMO. much stronger- will not bend or ding as nearly as easily and could possibly get you a little faster due to less flex in the material. a 4 blade will get you on plane faster and allow you to stay on plane at lower speeds, but will sacrifice top end speed.
Remember, just because a prop has four or more blades doesn’t mean it will get you on plane faster. Diameter, blade area, blade profile, rake, cup, etc are all part of the equation. I can name several mercury 4 and 5 blade props that couldn’t put my boat on plane or hold water nearly as well a 3 blade mirage plus.
Iain Pelto
Edgewater 185CC “Jumpin’ Bean II”
Give these folks a call, they work on props everyday and I think they have run data on props:
Skips III Propeller Service, N Charleston
843-552-4000 or 800-422-8009.
Polar 23CC
to really help, we need speed and rpm #'s and current prop size
I’m now at www.teamcharlestonmarine.com
You say prop is black and showing wear.Is it aluminum or stainless, if its a stainless prop try skips and they can do a little magic on it. Is it drilled for venting,(slip for hole shot). Is motor turning max rpms? All the questions asked are relative. Some older stainless props were coated black so is it just the black rubbing off or does the edge of the blades show wear (dings etc.) Prop may be fine if you are tuning right rpms.
quote:Yep, Hairball's right!
Originally posted by hairballRemember, just because a prop has four or more blades doesn’t mean it will get you on plane faster. Diameter, blade area, blade profile, rake, cup, etc are all part of the equation. I can name several mercury 4 and 5 blade props that couldn’t put my boat on plane or hold water nearly as well a 3 blade mirage plus.
Iain Pelto
Edgewater 185CC “Jumpin’ Bean II”
The cost of Liberty, is eternal vigilance!!
A four blade can also help alleviate certain vibration issues.
A four blade can also create some interesting harmonics depending on the gear ratio.
Iain Pelto
Edgewater 185CC “Jumpin’ Bean II”
http://www.boatownersworld.com/Props/turbo/turbo_1.htm
You’ll want a 13 1/4" x 15" to let that engine run at 57-5900rpms.
Marine Surveyor
quote:
You'll want a 13 1/4" x 15" to let that engine run at 57-5900rpms.
I’m pretty sure that Johnson should not be revved past 5500. I don’t know of many 2 strokes other than the racing Mercs that go past 5800.
Iain Pelto
Edgewater 185CC “Jumpin’ Bean II”
