I have a 31' 1983 Seahawk (Sim. to a Scarab of that time) it has 2-525 hp Pfaff motors w/ Arneson drives 1.32 gear ratio.
I have two sets of props 23 x 16* that go's 68 @ 5600 RPM & 27 x 17* that go's 65 @ 4800, both are 3 blade cleavers. With the 27 x 17* the boat wants to lean to the side a little and feels loose / unstable when turning at a lower speed. It seems that the boat should go faster and handle better. What could I do to one of these props to achieve something like 71 MPH @ 5200 with better handling.

I'm assuming the props with the listing problem are 17" diameter and 27 pitch? The boat doesn't want the 17" diameter. Who made the props? I have some ideas. Call us so we can discuss it further.

Here is a photo of the 17" dia. the 16" dia has the word "record" ingraved on the hub.

Can you tell me what is engraved in the 17" hub. We most likely can rework these to get the rpm you need and improve the handling and top speed.

After looking at the picture again they look to have been worked on before but are still in box stock condition. Hard to tell from a picture.

no engraving on the 17"

I see some stamping on the hub. Does it only say

17x27

or are there other letters and numbers?

We should talk more. Call us if you have a chance.

yes, 17x27 no other markings

do you think that the 17 need to be cut down to a 15 1/2"

No that's too much.