Autoprop

[lyle]

Looking at feathering prop options - has anyone installed an autoprop on their C350?

[Richard Thabit]

I have had the AutoProp on my boat since 2003 and it has been simply great. See the post under"cavitation" on section 2. It is dated Feb. 1 2006 where I give specific size and other details.
Richard Thabit
Three Sheets
C350 # 111

[lyle]

Thanks Richard. You said in your cavitation post you had to change the prop to a smaller size when you first got it. Did the first one cause vibration? Was the installation straightforward?

[Richard Thabit]

Yes, the original Autoprop was too large and caused vibration. The exact size of the replacement (my current) Autoprop is in the "cavitation" writeup. I did not do the replacement myself. My yard did it and AB Marine (Autoprop) paid for the short haul and mechanic's labor.
They were very responsive and helpful.

I have always believed that the original prop was sized according to the original prop supplied by Catalina which was subsequently proven to have problems. Some feel that more clearance was needed between the tip of the prop to the under body of the boat. So the slightly smaller Autoprop was the way to go and it has worked for me. As I mentioned, AB Marine had me do sea trials and record the data for them. They then used that information to resize a prop.
I can back out of a slip easily with much less prop walk and motoring is at lower RPM for comparable boat speeds. The only drawback is that it is a high priced prop. I believe that I paid about $2500 in Spring 2003.
I hope that this answers your questions.

[lyle]

Thanks Richard. That helps a lot. I was looking at a used autoprop that came off of a Catalina 36 and in talking to AB Marine it looked like it might work on the C350 but it was a 408mm (or 16") which is larger than the one you have on your boat (380mm or 14"). My fixed prop was changed from the original 15" down to a 14" before I bought the boat due to all the vibration problems documented on this forum so I would think that going to a larger diameter autoprop than what you have is going to cause problems. Too bad.... the price was right!