Prop theory again

[Kevin]

I think I am at my maximum potential for cruising.......but what the heck I will ask anyways.

With my current 3 blade 17 by 15 medium cup I am cruising at just over 23 kts at recommended cruise RPM. WOT is 27 kts and change at the correct WOT RPM.

Question: Can cruising speed be increased without negatively affecting WOT RPM by switching to 4 blades?

I do not need hole shot as I feel the boat is on plane almost immediately with existing 3 blade props.
I do not have any vibration issues either, but my understanding is 4 blades are smoother. How much smoother does it need to be?
I do not care about top speed end since I almost never use it. I would only want to be sure the RPM's get where they need to be at WOT.
Main concern would be faster cruise if it is even possible. I may be there already at the maximum cruise potential and I know the enemy of good is better.

I am guessing the expense of new props would not be worth it but would like to see if I have missed some key theory on the subject.

[CaptPatrick]

Kevin,

The short answer is: You're good as you are, so don't fix something that ain't broke...

Br,

Patrick

[Carl]

I'll toss my hat into the ring.

Find a good prop shop...not just one that can re-adjust and tweak a prop back into shape.

Lots of variables many shops don't play with...rake is one biggy that can make a huge difference.
You said 3 blade..are they Bronze or Nibral...Nibral being stronger can be thinner give more push with less resistance...the trade off is cost, more to purchase initially and more to fix should the need arise.
An extra blade...gives more push, takes more to push...its a variable.

If you find a shop willing to work with you...tweak your props or give loaners, and you can change the props without a haul out or get a cheap short haul it may be something to consider...but I doubt your going to find a huge mind blowing difference...you may even wind up going backwards. My guy added a little bit of rake to my spare wheels...dad had gained 2 knots with his boat doing this, same burn and WOT, that was a huge increase...prop guy felt it would work well with mine too...The result, I couldn't get on plane with the wheels...motors just didn't have the power to get her out of the hole. I went back to the dock, jumped in and changed them back to the old props. I don't modify my running props till after I prove out the spares or loaners.

My standard answer to your question...leave well enough alone, your running great! Go down that road and it can get real costly real fast...also many find props that get them moving along faster and....they sort of overlook the fact they are overloading the motors...write it off to dirty bottom...boat was heavier then normal..tach was off...it's almost there to WOT rating. Go down that road and you'll find yourself doing costly engine work.

My .02

[Kevin]

I figured I was about there at my maximum potential. THey are bronze and finding 1 1/8 bore is rather difficult in anything these days other than something that would go no a ski natique!
The convenient part I am on a lift so prop swaps are easy and I never have growth on the bottom.
Prop shop here in town did exactly what he said he could do the last time I brought the wheels in for the extra cup.
Thanks again for the input.

[Carl]

While not the best choice...1-1/4 bore with prop bushings are an option for trying out wheels.

[Keith Poe]

[Kevin]

Keith,

Those are some fancy looking props. Mine done look that good even after I put the wiz wheel to them.

Kevin

[Keith Poe]

Keith,

Those are some fancy looking props. Mine done look that good even after I put the wiz wheel to them.

Kevin

Hey Kevin i get them done at Wilmington propellers they computer dial them in and if you can believe it they had pieces missing and slices in them.


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