3 vs 4 blades propellers

[lateralinfo]

what are your thoughts on this matter?
i currently have the OEM 3x16x20 and i can only get up to 5,000RPM at WOT and no load in the boat; i need to get to 5,700-6,300 RPM.

[Murray]

https://www.suzukioutboardforum.com/...the-right-prop

A little reading material.

[lateralinfo]

Thanks. I actually read it already.
my problem is that i do not have the luxury of trying out different props and compare results: my local dealer doesn’t provide this service.
that’s why i was hoping for the input of some of the most experienced members who would maybe give me some shortcuts and good advice on which prop to go for.

[Moonlighter]

The issue of over propping is unrelated to whether you use a 3 blade or 4 blade prop.

4 blade props serve slightly different purposes and applications, and may suit some boat/engine combos better than others.

So it would be better if you also give details of your boat, model, weight and what you use it for, and the current engine model and horsepower. We could ASSUME that its a 250 or 300hp based on the prop being a 16” dia, but would rather deal with known facts than make any such assumptions.

On those figures it appears that you may be significantly over propped, but Murray’s suggestion is good, read the info on that link about propping your engine, and pay particular note to the engine height setting, thats where you should start to ensure that underlying issues are sorted before starting to look at alternative props.

[lateralinfo]

My boat is a 40 foot 4 tons. Engines are twin df300ap mod 2017. Boat is used for diving.
as for engine heights, i have the engines installed on hydraulic jackplates, so i i have been experimenting a lot with different heights. 5000rpm is the best i could pull off.
maybe right after a good scrub of the hull and even a new coat of antifouling, i might be able to get 300rpm additional but thats about it, nowhere near the acceptable range of 5,700-6,300rpm.

[tsturm]

I would try 3x16x17 or even a 15 pitch

[briscoe]

I go with tsturm, you need several inches off that 20" travel for one revolution. Where are you located. You need a prop shop. We have a guy in Houston, Baumman's Propellers. He's the bomb. Tell him your set up and he'll get you in the ball park by shaping your blades to correct pitch.

[nicolouris]

Try out 3x16x18 Suzuki props