Bigger prop for Catalina 30

[No Mondays]

We have a 1984 Catalina 30 with a 23 hp Universal diesel. The prop on this boat is a small two blade that does not move the boat out of the slip or stop very quickly, the reverse motion once we get it moving. This is the most critical time for us, not cruising under power.
Has anyone put on a slightly larger prop to improve low speed, or marina maneuvering? What are the negative consequences?

[MarkSF]

The Universal 24hp on my Bristol has a 3-bladed prop. This was a factory option vs. the standard 2 blade. It has many benefits for motoring - less prop walk, more power, including in reverse, less vibration. Unfortunately, you lose a tiny bit of speed when sailing.

However, based on what you say, I think the main thing you should try first is adjusting your expectations. It'll never stop as well in reverse as you would expect.

[capt jgw]

Do you know if the boat was repowered from the original 11hp diesel or factory installed? If repowered, it may still have the original prop which would be way too small for that motor. As said above the only down side would be more drag when sailing, especially if you went with a fixed three blade.

[JPA Cate]

Hi, No Mondays,

We have had 2 blade folders, a three-blade featherer, and a 3 blade folder, and fixed 3 blade. The fixed prop is like towing that size bucket all the time you're sailing, but of course, it motors well, and stops well.

The two blade folder was lovely sailing, very little drag, would move the boat forward well, and take a loooooooong time to stop her.

The 3 blade featherer was okay sailing, and stopped the boat better, but caused a 25% increase in fuel consumption.

For us, the 3 blade folder has been the best, but, it requires a lot more revs in reverse than one would expect. We normally cruise at 2,000 rpm (normally aspirated diesel), but if I'm serious about stopping it, I almost redline it, and she stops when she stops, to me, more like dragging your foot on a bicycle than using the brakes in a car.

However, it is possible that the pitch on your prop is not right for your boat, if it needs changing, that can improve performance in forward, but it will still be slow to stop.

Ann

[markwesti]

Are you sure that you are actually in gear ? ( I think you are slipping). A good friend of mine, Rodger ( the cave man) had the same problem , turns out the cable was never set up right .
Hint! The ends(the cable jacket) must be secured . Catalina has a problem with securing the ends , for some reason . As this was a problem on my buddies 96' 32' . Here is a pic of my buddy (the Don) texting the Catalina support group .

[JPA Cate]

One thing I didn't mention before is tip clearance, you need to have a certain amount, can probably find out that on a Catalina forum. Basically, you need to have clearance between the blade and the hull of thus and such amount, if the tips are too close, that will impair prop performance.

Ann

[Me-and-Boo]

I have a 1984 Catalina 30 with the Universal 25 (850 block) with a three blade prop. It works fine for most situations. Backing up is something that is more of a wish than an actuality. I do like the prop walk when docking, she docks port. What I do have is a prop shaft that is too long. Next time I have her on the hard I will have the prop specialist adjust the length.

[Stu Jackson]

They made over 6,000 C30s. There are at least two if not three websites devoted to that particular boat and the variety of engines installed over the years. There is also a yahoo or Google group currently active.

Missing the vital information of prop dimensions (dia and pitch) there's not much else to help you out with. Ann's summary of prop types and responses is very good.

You might want to slow down first either in gear or in neutral, before engaging reverse.

Most people use far too little throttle when reversing out of their slips.

Good luck.

[sony2000]

No Mondays should speak of numbers. What is your maximum RPM, and what are the numbers on the prop that you have? Especially the last number for pitch.

[westwinds]

Did a google on Universal 25XP which is 23 hp. A 15X11 propeller was used on a Catalina. Also the 14X14. Use the bigger propeller if you can get an inch and a half tip clearance or more. The water thrown off the tip of the propeller makes noise when it hits the bottom of the sailboat. That is why you need the tip clearance. Three blade propellers are better about the noise problem. Oddly enough the two blade is slightly more efficient than three because there is less turbulence, but a three blade usually has more surface area so cavitation is less likely.