ok so i have a 05 searay 4.3 mercrusier i am playing with props. i have a 19p on there now i found a 17p to try when i went to put it on and torque it down the prop will not spin. i removed it took it back to the boat place he told me turn the thrust wash the other way i have it the correct way he told me to try backwards i did and it spins free but it done sound right to turn the washer or is it me. i ask if there are different thickness he said there all the same size hope i explain the good any help would be great