4 Blade?

[Paw Paw]

Good morning, I am new to forums. I've been trying to find advice concerning 4 blade propellers. I have a 2022 Excell 203 bayboat with a Yamaha 115hp. Right I have 3 blade 13.25 X 17" on the motor. My question is should I go with the same pitch and diameter with a 4 blade prop? Second question is a 4 blade suitable for this particular boat?

 

[Chris1956]

That looks to be a bass boat. They are usually light and fast. 3 blade props are usually preferred for light and fast boats. A 3 blade prop with a large amount of rake is usually a good choice for speed and performance, on that style of hull.

 

[QBhoy]

Why do you want a 4 blade ? You’d need to have a good reason really.

 

[Scott Danforth]

Please answer all 6 of the mandatory questions listed in the stickies at the top of the prop forum

 

[Paw Paw]

Why do you want a 4 blade ? You’d need to have a good reason really.

from what I've read a 4 blade would give more control of the boat for maneuvering in strong currents and would also help in fuel mileage.

 

[QBhoy]

from what I've read a 4 blade would give more control of the boat for maneuvering in strong currents and would also help in fuel mileage.

I’ve heard folk mention around better slow speed manoeuvring apparently. Must admit I’ve not ever noticed a difference between them.
As for the fuel mileage. That’s certainly not going to be the case I’m afraid. The more blades a prop has….the less efficient it is. Absolutely I’m afraid. They can be good for getting heavy boats out the water quicker and perhaps even for slower planing speeds of that a thing. On the serious side of things, above late 60’s and 70’s…on light v hulls…they can have a stabilising effect. 4 blades really suffer on prop slip at the top end of things though. Very very inefficient compared to a 3 blade there. There is loads to love about a really well chosen and suited 3 blade stainless of a quality brand.

 

[Scott Danforth]

from what I've read a 4 blade would give more control of the boat for maneuvering in strong currents and would also help in fuel mileage.

if you want fuel mileage get a boat with oars or a sail.

4 blade props and 5 blade props are for more bite on the low end if you have enough motor for them

115hp isnt a lot

and you have not answered the mandatory 6 questions in the prop sticky

the one labeled read this first

Read This First!!

ESSENTIAL DATA REQUIRED When posting a question about propellers, you cannot get a reasonable answer unless you provide the following information in your post: Items 1-4 are essential for meaningful response to most questions. 1) Performance issue you are trying to correct. 2) Current prop...

forums.iboats.com

 

[airshot]

from what I've read a 4 blade would give more control of the boat for maneuvering in strong currents and would also help in fuel mileage.

Generally speaking, a 4 blade will give better boat control at low speeds, generally will get your boat up on plane a little quicker, better fuel mileage will only be a slower speeds, as your speed increases a 4 blade will use more fuel due to the extra drag in the water. For that same reason, you will loose top end speed and rpm. This is the reason you need to have a specific problem with your boat/motor that yoy want fixed !!

 

[Scott06]

Good morning, I am new to forums. I've been trying to find advice concerning 4 blade propellers. I have a 2022 Excell 203 bayboat with a Yamaha 115hp. Right I have 3 blade 13.25 X 17" on the motor. My question is should I go with the same pitch and diameter with a 4 blade prop? Second question is a 4 blade suitable for this particular boat?

I use 4 blades on my bowrider for better hole shot, stern lift, and lower planning speed. My typical use is loaded down watersports...

Generally would drop in pitch assuming current prop is hitting correct WOT rpm, but there are so many variables in terms of blade design and cup that you can't 100% rely on rules of thumb.

I would think you would get better prop bite in strong current. Fuel economy... unless you are going long distances and putting a lot of hours it won't add up to a cup of coffee...

What is your current prop - al or ss ? Best bet based off your questions I would think your best bet would be to find a marina or prop shop that will let you try a few out as prop selection is very boat and use dependent.

 

[jlh3rd]

agreed...rules of thumb get you in the ball park...sometimes it is spot on and you avoid the prop run around...
The OP hasn't responded with the needed answers to the stickies, so it's hard to help....but:
1 inch increase in pitch = 2-300 rpm drop @max power
1 inch increase in diameter = 2-300 rpm drop @ max power
1 increase in number of blades (3 blade to 4 blade) = 2-300 rpm drop @ max
cupping a prop = 2-300 possible drop in rpm @ max power......
Mercury "command thrust" motors have bigger gear case diameters than a "standard" motor......so ( as I found out) some props will fit, but not work .....

these #'s aren't hard and fast...so don't beat me up....but it's researched results I came up with when propping my boat. A lot of this info came from iboats......

 

[ahicks]

I use 4 blades on my bowrider for better hole shot, stern lift, and lower planning speed. My typical use is loaded down watersports...

YUP!!! Same story with a deck boat, especially the ability to stay on plane at lower speeds.

And I think pontoons work well with them too. There, the extra thrust available at low/maneuvering speeds IS noticeable.