Prop Swap opinions...

[Swedefj40]

Going for a rip tomorrow. I had to clearance the trim tab as the prop just nicks it. I have about 3/8" clearance now. I hope that's enough.

 

[Swedefj40]

Well what a difference! The wife and I went for a rip today with a full tank of fuel and some picnic supplies. We also had the dinghy with us too. Wasn't a heavy "fishing trip load" by any means.

1st thing I noticed was the boat seemed to track a lot better going through a "No Wake Zone". Very little steering input to keep it straight. I wasn't expecting that.

2nd was the Hole Shot... big difference there. Probably got me up on step in a 3rd of the time if not quicker! Massive improvement! With the other prop, when I punch it, it hit about 3200 rpm and then it would gradually get to 4000-4200 where I would ease it back as it got up on step, then run it at 3900 @ about 27-28 mph. Now it climbs to 4000 3 times as fast. I am a bit slower at cruising speed now, maybe by 1 mph at 3900 rpm. It was a little rough out so it was hard to compare. I dropped it back to 3700 and 3600 even 3500 and it still stayed on step, so that was a nice change. With a little trim tab adjustment, I could keep on step down to 3200 rpm @ around 22 mph.

All in all, I'm very pleased. I couldn't have asked for a better result.

 

[jimmbo]

Do you know what the WOT Rpm is with this Prop?

 

[Swedefj40]

Do you know what the WOT Rpm is with this Prop?

Not yet. I'd like to make sure my tach is accurate before I try it. I did push it to 4500 briefly and it went there no problem. Seemed like it wanted to keep going.

 

[Stinnett21]

BTW, assuming your 4.3 has power steering you don't need the trim fin zinc. You can use the flat zinc disk. Glad you're getting great results with the 4 blade.

 

[Swedefj40]

BTW, assuming your 4.3 has power steering you don't need the trim fin zinc. You can use the flat zinc disk. Glad you're getting great results with the 4 blade.

I have power assist with the Mercruiser and the trim tab zinc helps to keep a neutral center on the steering. I did have the flat one on it and it turns hard to port if I let go of the wheel. The fin helps stay centered.

 

[Texasmark]

The tab is fixed as is the prop. Neither move from the set position. I have run as close as 1/4" with no problems.

 

[Scott06]

Well what a difference! The wife and I went for a rip today with a full tank of fuel and some picnic supplies. We also had the dinghy with us too. Wasn't a heavy "fishing trip load" by any means.

1st thing I noticed was the boat seemed to track a lot better going through a "No Wake Zone". Very little steering input to keep it straight. I wasn't expecting that.

2nd was the Hole Shot... big difference there. Probably got me up on step in a 3rd of the time if not quicker! Massive improvement! With the other prop, when I punch it, it hit about 3200 rpm and then it would gradually get to 4000-4200 where I would ease it back as it got up on step, then run it at 3900 @ about 27-28 mph. Now it climbs to 4000 3 times as fast. I am a bit slower at cruising speed now, maybe by 1 mph at 3900 rpm. It was a little rough out so it was hard to compare. I dropped it back to 3700 and 3600 even 3500 and it still stayed on step, so that was a nice change. With a little trim tab adjustment, I could keep on step down to 3200 rpm @ around 22 mph.

All in all, I'm very pleased. I couldn't have asked for a better result.

this has been my experience with 4 blades as well, not only for my own boat but a neighbors as well. be interested to see if you can hit 4800 maybe a tad higher. Not that you have to wind it out that often but when pitched to the top end of the WOT rpm range throttle response is much better through out the rpm range.

With my neighbors boat - they have a 20-21 ft larson BR VP 4.3 MPI, was running a 19" 3 blade AL VP prop. Was hitting like 4300 rpm at WOT, went to a 17" VP aluminum 4 blade, was night and day in terms of holeshot, and being AL prop was relatively cheap in terms of boat costs

 

[Swedefj40]

I checked the RPM accuracy of the analog (dash) gauge against my timing light. The dash gauge was showing 100 RPM more than the timing light at 3000 RPM (timing light showed 2900 RPM vs the gauge's 3000 RPM reading). The same difference at 3500 RPM. I was a little apprehensive to run it higher than that with no load on it. Anyway, it looks like I have a little more room in the RPM range than i thought. Something I'll keep in mind.