Prop and Rudder Measurements.

Paul and All:
I have a few dumb questions as I try to think ahead in preperation for installing the 454 SOMETIME in the next couple of weeks. Here are some photos of what I have to work with. The original prop was a 13x13 and I am not sure this is the one that came with the boat or was purchased later. It does have a CC part number of 4554 on it and if anyone needs it, I will be glad to part with it. What was the original prop metrics for some of the different engine configurations? The original engine in Swift was a 350, I believe. The shaft is 1 inch stainless, the engine will be a 454 with a high rise manifold.

First the photos, then the questions.







Are there "rules of thumb" for how much distance should be between the prop and the rudder? As it stands now I have about 5 inches between the prop and the rudder, with about 3 inches of gap between the hull and the tip of the 13 inch prop. (See photos) This is important because at these distances, I could go with a much larger, maybe 18 or maybe 19 inch prop if I maintain the 5 inch gap. Closing the distance between the prop and the rudder would allow me to go to an even larger prop diameter because the limiting factor is the radius of the prop, not the diameter. I could gain another inch of diameter.

Also As it stands now, the rudder is about 1 inch lower than the 13 inch prop. Closing the gap would decrease this distance and place the prop lower than the rudder.

Is the "real money" in the degrees of twist in the prop or in the diameter when it gets down to the margins of effectiveness? Would another inch of prop diameter be desirable?

Is there a need to limit prop diameter (with its appropriate twist) other than hull, rudder, shaft limitations?

Thanks in advance,
Jerry