Need help with prop choice. New to me 1999 Scarab 1, 21' with a 383 Stroker engine. Alpha SS outdrive, prop was a 4 blade SS but no clue what pitch it was, from measuring it looks like it was less than a 15" diameter. Any help from anyone that has a similar setup?

What is wrong with the current prop?? Does the prop have a part number on it or brand name??

The prop is currently at the bottom of the Gulf somewhere.. lol.. it spun off. Prop lock nut failure. Prop didn't have a name on it that I noticed before losing it.

What pitch you need will depend on what gear ratio the drive is. I would think you want to be around a 14.5 diameter.

Your 383 build consists of ? 383’s can range from 325hp to 500hp.

Gear ratio ?

Have a friend nearby with several props and/or marina with prop swap program ?

Try find 19" pitch merc revolution 4 to test.