I have been reading here and there on the fuel savings of going from a 3 blade to 4 blade prop. I understand the top end drops off, but I did not buy a Grady because of her speed. :wink: When switching from a 3 to 4 blade prop does the diameter typically stay the same, but the pitch changes usually getting smaller? I am turning a 15 x17.5 saltwater series II. Ideally, I would like to find a dealer where I could use a test or demo prop to get it right, but in the absense of that opportunity I am trying to figure our what the appropriate size prop to turn. Thanks for any ideas.
3 blade to 4 blade prop pitch question
- Thread starter SmokyMtnGrady
- Start date
lots of discussion on this issue. check out power tech web site. yes, we need to have a whole bunch of props to test with, and right now, more fuel economy is more important to me then top end.
I don't think you can make a statement that a 4 blader will give better economy than a 3 blader. A 4 blader usually presents more drag and that works against economy. Of course, a smaller diameter will reduce drag. There is no magical answer. The correct prop is determined by your specific needs and planned boating, your specific hull and of course your motor. If you find a really good prop shop, you are indeed lucky. There is no substitue for experience.
Thanks Captain on the power tech site.....I want better cruise performance, holding while turning is a plus for water sports and overall performance while offshore fishing. Before I plunk down $500 or more bucks for a new wheel, I am hoping to find the best answer.....
Bob ...from everything that Ive read I believe that when going from 3 to 4 blade the pitch GENERALLY stays the same while the diameter gets smaller. Think propgods.com can answer some of those questions and make some suggestions. I also believe that they will let you try some props which is a plus. Ive attached some back and forth between them and a guy with a parker and a 250 ob asking about 3 blade vs 4 blade. Hope it helps. Its possible that theyve tested your boat/ motor combo and have some input.
posted this question on propgods.com:
I'm driving a 2006 Parker 2520xl with single F250 four-stroke. I primarily use the boat in the Chesepeake Bay and inshore (VA Beach area)...occasionally I will run 15-20 miles offshore under moderate sea conditions. I want to replace my stock black Yamaha prop with a SS 4-blade prop. Can you recommend the correct or preferred prop for this make/model application? Thanks.
I received this response:
"We tested that boat with a couple of props.
The Mirage Plus is a 3 blade, the OFS4 and Rev 4 are both 4 blades.
The OFS4 cost $450 shipped.
The Rev 4 cost $494 and you need a hub kit for $35.
The Rev 4 was a little faster on top end, but both gave good lift and held the boat well.
Smooth Conditions.
Little over 1/2 tank of fuel.
2 people.
17 pitch Yamaha black stainless
4000rpm 20mph 2.1mpg
4500rpm 25mph
5000rpm 30mph
5900rpm 40mph
17 pitch Mirage Plus
4000rpm 16mph
4500rpm 27mph
5000rpm 34mph 2.2mpg
6000rpm 40.5mph
17 pitch Revolution 4
4000rpm 22mph 2.0mpg
4500rpm 30mph 2.2mpg
5000rpm 35mph 2.3mpg
5800rpm 40mph
17 pitch Powertech OFS
4000rpm 20mph 1.9mpg
4500rpm 27.5mph 2.2mpg
5000rpm 35mph 2.3mpg
5900rpm 38mph "
posted this question on propgods.com:
I'm driving a 2006 Parker 2520xl with single F250 four-stroke. I primarily use the boat in the Chesepeake Bay and inshore (VA Beach area)...occasionally I will run 15-20 miles offshore under moderate sea conditions. I want to replace my stock black Yamaha prop with a SS 4-blade prop. Can you recommend the correct or preferred prop for this make/model application? Thanks.
I received this response:
"We tested that boat with a couple of props.
The Mirage Plus is a 3 blade, the OFS4 and Rev 4 are both 4 blades.
The OFS4 cost $450 shipped.
The Rev 4 cost $494 and you need a hub kit for $35.
The Rev 4 was a little faster on top end, but both gave good lift and held the boat well.
Smooth Conditions.
Little over 1/2 tank of fuel.
2 people.
17 pitch Yamaha black stainless
4000rpm 20mph 2.1mpg
4500rpm 25mph
5000rpm 30mph
5900rpm 40mph
17 pitch Mirage Plus
4000rpm 16mph
4500rpm 27mph
5000rpm 34mph 2.2mpg
6000rpm 40.5mph
17 pitch Revolution 4
4000rpm 22mph 2.0mpg
4500rpm 30mph 2.2mpg
5000rpm 35mph 2.3mpg
5800rpm 40mph
17 pitch Powertech OFS
4000rpm 20mph 1.9mpg
4500rpm 27.5mph 2.2mpg
5000rpm 35mph 2.3mpg
5900rpm 38mph "
Parthery
GreatGrady Captain
SmokyMtnGrady said:
I found a substantial difference between a stock Yamaha SWS wheel and the corresponding Merc Mirage Plus. You might try one of them before you move to a 4 blade. And - they are readily available on eBay (I bought mine there.) Buy one...try it...if you aren't happy...take it off and put it right back up for auction. It will sell quickly.