Prop Questions

[Will Pierson]

I have a 84 Cat 30 with XP24 Diesel. I have 2 blade prop and would like advice about size for a 3 blade. I have not motored much as I just bought boat but I am very familiar with the usual benefits of 3 blade vs 2. I need size and advice if on this boat 3 blade is much better for motoring into head seas etc. Thanks, Will

 

[Gary Nickel]

Proper Prop Size

Will Ask your Catalina dealer for the proper size prop. Catalina puts out the information based on the size engine and year of boat. Too small of a pitch decresses motoring speed. Too much pitch over powers engine and it will over heat.Gary

 

[Jeff Walker]

3 Blade Considerations

I just replaced my 2 blade prop on my 83 Cat 30 with the M-25 diesel 21 horsepower. I ended up going to a 15X10 (3) blade which works pretty well but I still have some reservations. The clearance between the blades and the hull are down to 1/2 inch. I motor at 2200 rpm normally so I don't feel excessive vibration due to cavitation(higher rpm's might cause some increased engine temp and vibration). I do think this is a little tight however and I am thinking of cutting it down to 14X10. I have not experienced any overheating but I replaced the standard heat exchanger with the 2.5 inch diameter upgraded version last year and our seawater temperature is usually around 55 to 60 degrees which gives me a 165F max. engine temperature. I do see a big difference in performance especially in reverse. I get up to hull speed very quickly and heavy seas and dinghy towing doesn't slow me down the way it used to. Hope this helps. Jeff