3blade v 4blade props

[paulc]

Has anyone changed over, from 3 to 4 blade props? I have a 39 express.

It's my understanding that it'll help proformance, and reduce gas consumpion. Can anyone comment?

thanks
Paul

 

[Kevin Smith]

3 VS 4 Blade

Paul,

The most qualified persons in VA that mayb be able to help are the folks at Murphy's Propeller in Norfolk VA. Here is the link.

http://www.murphyspropellers.com

You also might want to talk to the Sea Ray dealer in Prince William VA. They are one of the largest in North America and maybe the world. They sell a lot of larger boats and maybe they can offer you some assistance. Here is the link.

http://www.pwmarina.com

Kevin Smith, Richmond VA
1991 250/270 Weekender, 454 ci, 330HP, Bravo II

 

[paulc]

Kevin Thank for the info. I'll take a look.

Paul

 

[CJ Martin]

I'm considering the same change on my 320DA, and plan to hit up the propshop reps at the Annapolis powerboat show next weekend to get their opions and quotes.

I'll let you know what I find out.

-CJ

 

[First Born]

I am making the switch from 3 to 4 per my dealers suggestion. Nothing was wrong with the 3 but he says that everyone that has switched it has loved it. I am going to give it a try this weekend. Will let you know what I find I think.

Wesley

 

[MarkD]

I have heard that the 390 will greatly benefit from this change. It was discussed in the old now defunct SRO forum, but we cant get that info any longer. Your greatest problems in the 390 are around the dock maneuvering and backing up. These can all be fixed with the use of the 4 blade props. More bite, means better control. You will also realize better speed at the same RPM. Not sure about gas mileage however. May lose 1-2 mph on the top end, but who is running these pigs at top speed anyway.

:grin:

 

[Alex D]

My comments regarding inboards only:
I would probably spend my money on a top notch prop scan for my three blades, rather than buying four blade wheels.

Four blades move more water at the same rpm and vibrate less, true. But you also need to consider that you cannot run the same size and pitch because you'd overprop the boat. This would have to be approached with a lot of thought and/or an experienced wheel shop.

Besides....I have never wanted for more thrust than my three blade props provide ... especially in close quarters.

 

[paulc]

Props (Wheels)

Update on my props

Last march when I first placed this question, I had not taken my props to Black Dog Prop Doctor on Kent Island. I fouund out two very important things. Pitch will play havoc with your boat's proformance. Also the wheel size makes a big difference. My boat came with the optional 21/19 wheels.
39EC came standered with I believe 17 or 18" props. My port wheel was out of pitch 1/2 in. The size does help at slower speed.(Docking especially)

The dealer who moved the boat to his marina, must have hit something and never told the previous owner. Haveing them scaned and blalanced, made an incredible difference. It's lowered my GPH by 7. I'm also able to get on plane faster. Prior to all this I was burning 25GPH at 2900 RPM doing 12K now at 2900 I do 13.5-15.5 depending on wind and tide. As far as docking goes I can turn the 39 on it's axes and stop it on a dime. I still may consider 4 blade props in the furture. But for now The $500 I spent on having my old wheels tuned has really helped. I figuer since the beginning of the season (April) I've saved much more then $500 in fuel cost so far this year. :smt038 So Have your wheels checked by someone who can laser scan them.

 

[CJ Martin]

So Paul I take it you stuck with three bladed wheels?

-CJ

 

[paulc]

3-4 blade propes

For now yes. I really dont see the need to change at this time. wiht the proformance I'm getting, and giving the cost of new 4 blade wheels. Maybe the next boat. :thumbsup:

 

[rondds]

i've had this 4-blade vs. 3 blade discussion with several people, including markd. i have NOT had my existing three blade props scanned (this is my third season with the boat) but i have my wheel-puller ready and will finally pop them off and take them in to a recommended prop shop this winter.

i have no vibration and all my numbers are pretty much right where they should be, so i really cannot justify the expenditure on new 4 bladers, other than to have a spare set of props. this tub is definitely tough to handle around the dock, but i've gotten pretty good rolling with her sloppy manners, so i'm sticking with my 3 bladers for now too!