need help identifying prop and size

[ready_4_the_water]

i have a 1977 american starcraft 22'
the machanic said that its a v8 omc stringer drive
235hp
the model number i was given is
981105
seial number
w135330

i have spoke with a couple of companies that sell props and was told that i need the size of the prop to buy the correct replacement.

all help is very well appreciated thanks in advance