4 blade propellers pros and cons

[DaveNkelly]

Hi all I have a 23.4foot glass boat with a single 225 honda with a 3 blade prop on it < unsure of the size and pitch>

its weight is 2200kg top speed 30kts flat stick, flat water 5400rpm.
cruze's at 4600rpm 24knts flat water uses about 45-50LPH of fuel.

The issue I have is in a bit of chop it seem to find it hard to pull its self out of the ditch, loses rev's and comes off the plane so I find I'm always playing with the rev's to keep it on the plane..

does all of the above sound about right?
I hear for heavier glass boat a 4 blade prop will often make it plane easier at lower rev's??

any info, pro's or con's to changing props either to a larger, steeper or to a four blade would be great.

Cheers Dave

[gofishin]

Hi Dave, current problem is not the number of blades, but the size of the prop. It's too big!

You will need to drop around 3 - 4" in pitch, as your rpm's are too low ( I assume max WOT is 6000?). Diam should be maximized (within appropriate prop size combo of diam and pitch) as you have a big heavy boat. This will also depend on the number of blades.

Also check your motor height.

You will need to advise the make and size of your current prop.
Cheers

[rexaway123]

what you describe problems are are exactly what 4 blades are designed to fix

I have a new heavy 7M noosacat with twin 150s on back. Changed to 4 blades shown in link and video below that my REP bought in from US rather than paying huge local Solas price and difference was so noticeable it was not funny.
These props specifically designed to lift a heavy arse up quickly and hold it there
http://www.boatownersworld.com/Props.../turbo_os1.htm

Used to have 19 pitch 3 blades MUST go down in pitch when going to 4 blade or you will lose too many RPM so I got the 17.

[mutineer]

24 ft glass cox craft , 3 blade prop loaded with 3 , full fuel ,water and eskies,tackle etc 5900 no dropping off plane and 35 kts flat cruze 27 at 4500 fuel 39-42 litres ..Yamaha 225 4stroke.don't know much about props too much but do understand the basics , you need smaller prop ..given that my boat is almost identical but I'm away from my boat , will put up its specs in a few days ...oh also that's without trimming as I'm waiting for new pump to arrive, hopefully be better then , and I need a tune just bought boat and its not spot on yet .
And probably a little more once I clean off the stupid antifoul and smooth the hull up .

[no chicken tonight]

I think your expecting a bit to much from your outboard. Ideal cruise rpm would be around 4200 and 30-35 lph. It might mean your cruise speed will be 20-22 knots. If your on the Goldy, see Gary, GD Marine Services. He might even have other props for you to try.

[DaveNkelly]

I think your expecting a bit to much from your outboard. Ideal cruise rpm would be around 4200 and 30-35 lph. It might mean your cruise speed will be 20-22 knots. If your on the Goldy, see Gary, GD Marine Services. He might even have other props for you to try.

I'm talking to Garry from GD marine services on email now, he's a very helpful bloke..
According to him I'm not expecting to much, highly recommends a 4 blade.

Cheers Dave