Why is steering harder with a four blade prop?

[jberenyi]

Today I took the boat out to test two props at Acme's request. One is the 3-blade #1413 and the other is the 4-blade #537. Both props performed admirably and had their pro's and con's. Here are the results:

CNC 3-blade #1413 13.5 x 15.5
WOT 4750 RPM @ 37.8 MPH---- Cruising 3 Hg vacuum 4250 RPM @ 35 MPH----21 secs to top speed
. Tad more vibration
. Hole shot not as powerful as 4-blade
. Steering in to turns easier
. At cruising the bow is rock steady at about 6-8 degrees


CNC 4-blade #537 13.5 x 16
WOT 4500 RPM @ 38.2 MPH---- Cruising 3 Hg vacuum 4050 RPM @ 35 MPH----16 secs to top speed
. No vibration and smooth
. Much better hole shot
. Steering is very hard left or right. Even notice it slightly harder in gear at 600 RPM
. At cruising bow is not as steady and will porpoise up down tightly averaging about 8-10 degrees

I really wanted that 4-blade to work out. The hole shot was incredible especially with my power slot transmission and its time to top speed was better as well. Keep in mind the 3-blade was not a shabby performer either. It was so close on some issues I had to do the test three times today. However the deal breaker was the hard steering. That 4-blade must be pushing a fierce column of water past the rudder and it's resisting movement. The 3-blade prop was fine for steering. And yes I have a brand new steering cable and its greased. The rudder was torn down and cleaned and greased and it has acceptable play from what I have researched. So I ask everyone, is it normal to have harder steering with a 4-blade prop? Its hard enough that I don't think my wife would be able to turn the wheel past six inches before she would give up. For me it took some strength to overcome the hard steering past 6-8 inches of steering wheel movement.

[kixtand]

Your situation is odd, at least compared to my experience... I found the steering to be much lighter and more accurate with the 4-blade prop...

Edit: For reference, my experience is with a '91 PS190.

[mikeg205]

I have a 4b on my 205 - did not feel a change from 3b to 4b

[jberenyi]

Your situation is odd, at least compared to my experience... I found the steering to be much lighter and more accurate with the 4-blade prop...

Edit: For reference, my experience is with a '91 PS190.

Yes it does seem odd. One thing I know I forgot to grease the rudder before leaving. It was done a month ago but not lately. I noticed when I got home there was more play in the rudder than usual indicating lack of grease. I went one step further and removed it, cleaned it and re-applied the grease. I think the grease I'm using is not good enough. I plan on getting some Lucas Marine grease today and repack with that stuff. My IXL grease is nice but I don't think its rated for marine use and is not tacky at all like the marine stuff. I will try one more time after using Lucas marine grease using the 4-blade and see what happens. If its still stiff for me and wife...she goes back and its 3-blade for me I guess.

[DooSPX]

I never noticed a difference with my 4 blade OJ other than BETTER response and tracking. Steering effort was unchanged.

[JohnE]

I had both a 3 blade and 4 blade for my '09 X14 and didn't notice any difference in the steering. Seems odd to me.

[jberenyi]

Well I bought some Lucas Marine Grease and a new grease coupler for the gun. What a difference the new coupler made. I was able to inject that new grease in the rudder shaft while my daughter spun the wheel back and forth. I witnessed plenty of grease coming out of the weep hole. The steering is nice and free now. I will test the boat with the new 4-blade prop tomorrow while taking the family skiing and report back. Based on everyone's comments, if its still harder to steer its probably an indication I have to replace the rudder and/or the rudder port due to excessive wear. Thanks for the responses

[jberenyi]

Took out the 4-blade today with the family and she works fine this time after the grease job. Guess I did too many power turns with the 3-blade before changing out to the 4-blade LOL. Anyhow, the 3-blade goes back tomorrow. The 4-blade just performs much better on the hole shot and top speed. I feel like I'm in a muscle car when that puppy is on. Too be on the safe side I will probably replace the O-rings in the Spring on the rudder port.