I have the same boat as sailing buddy. Catalina 42 (sling weight 24,000 lbs). He put a Autohelm wheel pilot on when the boat was new in 1990. I think it was an ST4000 - it looked the same as the 4000 we had on a previous boat. About 3 years ago he replaced it with new ST 4000+. Both units worked fine in just about all conditions even though it is rated for 16,500 lbs. I wouldn't worry about an extra foot or two.