My dad wanted a stainless prop for his 21' Tritoon with a 150 Yamaha four stroke. We got him a Solas Titan 15 1/2x15p and put it on yesterday. The prop spins smooth and free in neutral but as soon as you put it in gear it's makes a loud knocking sound. I put the aluminum back on and it's perfectly quiet.

 

Anybody experience this with a prop swap? I emailed Solas and waiting to hear back. I thought you guys might shed some light on this.

Did you put the proper thrust washer on the back.  It's suppose to fit down inside the prop with the flange over the back and not move any side to side. 

 

Did you torque it.

1 hour ago, Way2slow said:

Did you put the proper thrust washer on the back.  It's suppose to fit down inside the prop with the flange over the back and not move any side to side. 

 

Did you torque it.

Yes the thrust washer is more snug on the stainless than the aluminum so I don't think it's wobbling.

 

I torqued it to 38 lbs per the manual.

 

I used a caliper to measure both props and they are identical. The only difference is the weight.

If you reused your old thrust washer, see if Solas says it's compatible.  It may be too thin or something.  The only time I've seen this problem, it's been the thrust washer or loose prop. 

 

Is the length of the hub from front to back measuring through the inside of the prop the same.

 

I had a friend using a universal prop that used different hub kits for different motors that said his made a noise if running on the hose in gear but didn't in the water.  I personally wouldn't have that.

 

I know this is not related to your problem but a 21' Triton with a 150 4 stroke that can only turn a 15p prop has to be one of the most under powered boats I've seen.

1 hour ago, Way2slow said:

21' Triton with a 150 4 stroke

 

7 hours ago, Crappiebasser said:

21' Tritoon

 

I'm thinking it's a tri-hull pontoon.

OK,  that makes more since.