Carver Owners Forum

We recently purchased a 1991 36 aft cabin with 300 Cummins. We need new props does anyone know what size we need ? It currently has 20x21 4 blade

Welcome to the forum......how does the boat perform with those props.....is there an issue you are trying to resolve?

Assuming the engines are running as best as can be expected, what are your WOT RPM’s and what is the mfg’s suggested WOT? If those numbers aren’t close, you could be over/under propped or there are problems with the props, Is your running gear clean? It doesn’t take a lot of barnacles to kill performance and RPM’s.
A good prop shop can repair damaged props as good as new.

Is that a single or twin? I know they offered both in a diesel but they're pretty rare. What size shaft(s) is/are on the boat?

There props are badly damaged so I have no real performance numbers
I have a log from a previous owner and it states it had 20x21's

Not sure what you've explored as replacement options, but there is a member who listed a pair of 22x22 props in the "parts" forum here:

viewtopic.php?f=30&t=5779

Not sure what size shafts you have, but these 1 3/8 could likely be bored out to a larger size and the diameters and pitch could probably be changed at a prop shop for a lot less than a new set.

Take the props to a good prop shop. Unless they are totally destroyed, most likely, they can tell you the size and can advise you how best to move forward. Repair or replace.

And ebay has been my friend for spare props. Years ago when we had our 4207, I scored a brand new set of Nybrals for 600 bucks. Ya, I stole them.
For the 36 we have, same price, but smaller props.
And for the race boat, many stainless cleavers cheap.