Prop change

[Patti]

Hi All,

At the rendezvous in Apollo Beach we talked about the prop size and the larger one that Catalina was making available to us. I am now somewhat confused as the post here from Gerry Douglas states that the new prop was going to be put on all 350's after hull 400. I have 415, and my prop is smaller than the one shown at the Rendezvous. Can someone furnish me with the correct size/model please?

Thanks!
Patti (Ti) Zur
Knot Dreaming #415

[digitalvillager]

We had the original 15x9 re-pitched to 15x11 and are very happy with the performance. Our M35b now maxs out at 2900rpm's wide open throttle (wot) and we cruise at 6+ kts at 2250 rpm's. Cavitation is only a problem if you move the throttle too quickly. The M35b is governed at 3000 rpm's. Universal has a white paper stating the engine should cruise at 80% of wot (2400 rpm's).

[yodagwb]

The boats were originally set up with a 15/9 prop. Due to the beam of the boat and the weight of the boat this prop posed a cavitation issue when motoring into a strong chopped. In many cases it was a sever cavitation issue. Catalina then decided that the fix was a 14/10 prop (never understood how they got there) which they sold to owners at a reduced price. I bit. It really didn't do much for the problem. I guess they figured the smaller prop would be a greater distance from the hull and that the 10 pitch would offset the smaller diameter. My boat went slower. The cavitation was reduced but not eliminated and top end speed was the price. After much reading, research and many measurements, I came to the conclusion that the problem was not the distance to the hull but instead the distance to the deadwood or the shaft log. Moving the prop back 1" or 2" and the caviation issue goes away. The boat is under powered, at lease the ones with the Universal engines are and in turn can only deal with a given resistance from the prop. If you over size or over pitch the prop you overload the engine, not good. You can move the prop back in one of two ways, either replace the shaft with a longer shaft or replace the prop with a folding or feathering prop. In the case of a folding/ feathering prop the hub design tends to move the blades about 2" to 3" back from the deadwood and in turn the cavitation problem seems to disappear. Personally I did everything. I had been so tortured by the whole thing I replaced the cutlass bearing, installed a 1" longer shaft and bought a Flexofold 15/10 prop. Overkill? Probably. Life is better now. The Flexold 15/10 may be a tad over propped but I would make the same choice again. Only wished I did it 10 years earlier. If you do go the folding prop route you need to tell them the Engine, HP, Boat model and transmission gearing(on the plate on top of the housing). in the case if Flexofold they came back with a 15/9 prop but they need to CTA, for me I still feel the 15/10 was better.

[Pgtjs]

Hi friends,

I think it is much easier than portrayed. I have hull #392 delivered with a Yanmar 30 engine. Shortly after delivery I was not happy with the performance and the engine was overheating at higher revs. I did two things - one, installed a spacer on the shaft also known as a "shaft saver" and in the West Marine catalgoue at that time - it may still be. It extends the shaft about 1 inch and provides protection to the gear box if the prop hits a log which is a real risk here in the Pacific Northwest. Second, I installed a KIWI feathering prop. The pitch can be adjusted in situ - the Kiwi factory folks recommended a setting of 27 degrees as I recall and after testing we eased it off a half degree in the water - by a diver with an Allen wrench as I recall - and viola it runs up to 3000rpms before the engine starts to go above 190 degrees. I run all day at 2800 rpms and in flat water with no tidal current get about 6.5 knots per the spinner meter. I have adjusted the meter a couple of times and think it is reasonably accurate but it tends to fade a bit over time and the margin with the SOG (GPS) expands for reasons I dont understand. I dont hear any cavitation noise at all - I have had such in an earlier boat so know what to listen for. Finally the KIWI prop blades are designed to break off if they hit any submerged object and such happened on my previous boat. A lot cheaper to replace the blades in situ than replace a bent shaft/fixed prop etc plus the KIWI unit costs about half of a Max Prop. Hope this helps.

Cheers, Geoff. C350-392, Taeko !V, Blaine WA.

[Triumph]

This has been thoroughly discussed in the past, solution and causes determined years ago, and it's over. Please be cautious in reading and taking for gospel anything you read in the forum about this subject. I'm talking about the original factory supplied prop and the final solution prop offered by Catalina. Read Gerry Douglas's solution, or call the factory for the right prop.

The issue with the original prop was more of an issue of the blades not being wide enough, resulting in cavitation. Several solutions were tested, and the final solution was quite good.

Folding and feathering props are a different issue altogether.

[yodagwb]

I beg to differ. I went with Gerry Douglas's solution, bought his recommended prop( 14/9 for the discounted price of $300 and some odd dollars) and while it may have worked for you, it most definitely did not work for me. When I pulled off Catalina's recommended prop the tips had a pinkish shade to them and the sound when tapped was not correct. Metal degradation. This is an indication classic cavitation burn. So while you may think you have the only possible correct answer from Gerry Douglas you will have to excuse me I do not so blindly follow. Things change, upgrades are made, new owners acquire used boats and need to fine their way. I am pretty sure that's what this form is about.

" Please be cautious in reading and taking for gospel anything you read in the forum about this subject" I believe is a valid statement, but that also has to include any emphatic and definitive answers from anyone, including Gerry Douglas. The amount of time Gerry Douglas has spent operating a Catalina 350 is only a small percentage of the time which many of us have spent operating and living on/with a 350.

[yodagwb]

With regards to the prop, it wasn't 300 and change but instead 200 and change. Sorry