Propping a 16 xpress

[SOS]

I just recently got into a '04 16 express welded modified v jon with a Zuke DF50. The aluminum prop is a bit dinged up and I was considering changing it out as it cavitates a bit when trying to lift the bow.

Since I havent had to swap props before on my previous rigs I have some questions. I'm getting the proper RPM's, or close to it before it cavitates at the top end trimming it out.
1. One should I have the prop repaired?
2. Should I just replace instead? (normal scarring on the prop edge and one half of a quarter sized chunk taken out of one blade.)
3. Try a four blade to get more stern lift?

With that said, I'll mention that it jumps out of the whole very quickly, I get a good amount of bow rise in the process but it basically jumps the bow up high, then flattens out and takes off like a rocket in about 3 seconds would be my guess.

Thanks guys! Love the forum!
SOS

 

[juggernot]

Put a 4 blade on it. I put one on my 1860 and it totally changed my boats performance for the better. it now steers like it's on rails. Better holeshot, better steering response ,eliminated chine walking in tighter turns and getting the boat on the trailer, raises the stern while on plane, stays on plane at lower rpm/speed. My factory Alum 3 blade was not damaged before I changed to a Solas Rubex 4 blade Alum. and I'll probly never have a 3 blade again on this boat. Have that prop repaired and keep it onboard for a spare!

 

[SOS]

Thanks Jug, did you go with a 4 blade SS or AL?

I like everything you just said about handling!

SOS

 

[juggernot]

I got an Aluminum Solas prop. on sale for about $115 w shipping ! If you have any of the problems I mentioned I'm sure a 4 blade will help fix it.

 

[Motv18]

Iirc that's the 5300-6300rpm one. Try low rake and a good bit of cup. You'll want to lift as a whole unit while trimming out preventing the stern from digging. This keeps the angle of the bottom from creating more drag even though more bow is out. Also will keep the bow from going past balance and porpoising limiting pitch by uncontrollability.

 

[SOS]

Great price on that solas! I'll keep an eye out for that.

Motv18, it will spool up to the 5500-6500 range. What's low rake mean?

Thanks!

 

[Motv18]

The angle from the point of blade attachment to the hub to the peak of the blade. 90degrees to the hub is low moreangle to the stern or raked back is high. Normally with greater rake the more the bow lifts per degree of trim. Other factors also change lift.

 

[SOS]

Thanks for the follow up! Makes sense.

The three blade that is currently on there is a 11.5 X 13. Is it accurate that a four blade should drop in diameter to recover lost RPM from going to the four blade? I thought it was pitch, but the Solas site recommends going from the 11.5 X 13 to the 10.5 x 13.
Thus I would need an a 10.5 X 13?

Thanks again! Props are not my forte! =D>


EDIT: I should add that with this prop it's cavitating as mentioned due to the condition of it I assume. However with that said I can wind up to 6400-6500 and I have not yet been able to really "fly" the boat yet. Operating range per the manual is 5900-6500.

My thought is that I could go with a 10.5 X 14 and still be around 6200-6300 and turn the higher pitch prop. Is that sound logic?
SOS

 

[SOS]

I figured I'd give an update. I tried a few different things and ended up going with the Solas Amita 4 blade 10.5 X 14. I am still able to get it up to about 6300 with just me in the boat. I picked up 3 mph on the top end and she still jumps on plane in a heartbeat.

Very happy with the change!

I have some porpoising going on when I try and trim it up but I guess there not much I can do about that short of adding tabs.

Thanks for the input fellas!
SOS

 

[juggernot]

Moving or adding some weight towards the bow will help w the porpoising.