3 blade 19P VS 4 blade 17P FYI

[scott449]

Bought a 2007 bayliner 205 with a merc 5.0
The boat came with a 3 blade 19 Pitch aluminum prop
I just picked up a 4 blade 17 pitch stainless prop made by solas rubux

Result:
Lost about 3 MPH on the GPS speedo from 50 to 47
Lost about 200 RPM from 4800 to 4600
Gained what seem like a lot better get up and go. I have not tested speed to plane but it seems much faster
Gained much better cornering at speed
Boat will now plane fully loaded at 2500 RPM before it would not plane till about 2900 RPM fully loaded
You can really feel the difference when the boat is fully loaded, there is less of a difference when it?s just me in the boat

Over all I like the result. I think if I had to do it again I might have gotten the 4 blade 16 pitch stainless prop to gain back the lost RPM?s but like a said I like the new one much better than the stock prop

 

[180shabah]

Re: 3 blade 19P VS 4 blade 17P FYI

if I had to do it again I might have gotten the 4 blade 16 pitch stainless prop to gain back the lost RPM?s

Dropping an inch when adding a blade is normal.

Anyway, glad you are happy with your results.

 

[junior1113]

Re: 3 blade 19P VS 4 blade 17P FYI

just did same 19x3 to17x4 turbo and liked results.i gained 2 mph. seams like mpg went up a little at mid range. cant beat that. reverse is also much stronger. 4 blades are awsome. rpms same

 

[Tail_Gunner]

Re: 3 blade 19P VS 4 blade 17P FYI

just did same 19x3 to17x4 turbo and liked results.i gained 2 mph. seams like mpg went up a little at mid range. cant beat that. reverse is also much stronger. 4 blades are awsome. rpms same

Note that Turbo's or Stilletto's four blade are at the very top of high performance props gaining all the advatages of 4blade's and losing very little to top end speed if at all. It is very concevable that some boat's could actually gain in top end speed. The props have so much overall lift the hull actually becomes a bit of wing which lowers both wetted surface and weight..Maybe hwsiii can calculate how much lift occurs when you have a 18' of hull lenght and 8' of beam being lifted with a wind speed of 45-50mph..that would be intresting...

 

[hwsiii]

Re: 3 blade 19P VS 4 blade 17P FYI

TG, I would love to do that, but there so many variables as to make that task a very long and tedious one. You would have to be on absolutely flat water, you would have to know at any moment exactly how much of the hull was still in the water as well as knowing the exact amount of bottom area out of the water, and exactly how the portion that is out of the water is configured because it won't be flat like an airfoil so you would have to take into account the different hull angles and their surface areas and that doesn't even start to include all of the variables that you would need.

SORRY, I don't have that much time available.



H