Type prop for Catalina 30 with Atomic 4

[rjkerby]

Can I get a few opinions on the best prop for a Catalina 30 Mark 1 with an Atomic 4.
The boat is raced and cruised and it doesn't have much power in reverse. Cruises at 6 Knots @1800 in calm seas,with an 11x7 2 blade but I'd hate to have to make an emergency stop.
Thanks

[JOHN COOKSON]

Maybe you need a trany adjustment? Because reverse is not fully engaging and slipping a bit?
Disconnect the shift cable and try shifting by hand with the lever and see if you notice any difference in lever travel or performance. Or maybe the trany itself needs to be adjusted?
I'm going to go out on a limb and say a 12X8 sounds more suitable for a 30 footer. Wait till the Cat 30 folks come along for the final word.

TRUE GRIT

Edit: Welcome to the forum. Tell us a bit more about yourself. How long have you owned an A4? Anything you can tell us about the engine? This is a safe place. We learn by sharing.

[Mo]

Just a couple of things:
-sounds like you have the right prop, or at least very close. John mentioned 12/8, anywhere in that ballpark depending on conditions you work it in.
-are you holding handle up in reverse and allowing it to engage? We have to continue to hold the handle in reverse, not the same as forward.
-Not the same as stopping a powerboat and not the same thrust as in forward: I hold my boat at 2 kts coming into the marina; once about 100 feet from my spot I reduce speed and want to be doing 1.5 kts when I make the turn to park at my dock. At this point I am 40 feet from where my bow will sit and the engine is idled down. When lined up I put it in reverse 20 feet back and hold in reverse. The boat will slow more and you can give it a shot of fuel for the final thrust to stop. It is very hard to stop a sailboat if we come in at 4 kts, pull the handle and throttle up...takes time and room.
-reversing gear adjustment: ensure the linkage from the cable is attached firmly to the piece on angle iron on the reversing gear. If that is loose it can cause issues.
-there should be about 2-3 second delay from when you hold that handle in reverse firmly until you hear it engage. You will hear
a winding of gears then a different sound as it engages.

[JOHN COOKSON]

Ps

I presumed you have a 12X7 fixed blade - not a folding prop?

TRUE GRIT

[rjkerby]

History

Hi John, it's an 11-7?? (11" for sure) two blade fixed. I've replaced the 1/4" shift cable with a 5/16" cable. The reverse goes in and make a lot of noise and has wash at the front of the boat dockside. I've just rebuilt my A4. the prop is my spare and I'm going to buy another or get my old 12-7 rebuilt.
I know the Cat 30 is not a race boat but I enjoy the PHRF racing in the Puget Sound. My wife feels she would be a lot more comfortable if we could stop in an emergency.
I've had this boat since 2009, 1975 Catalina 30 Std. #103. I've replaced all the rigging , rebuilt the compression post and bilge, fixed the smile and we really enjoy the boat and Sound sailing. During the spring we race as often as I can and summer and fall we cruise the beautiful area we call home

[Dave Neptune]

rj, consider the Indigo. The prop works well and as it is not very big it compares with the two blades for drag however you will get a 3 BLADE RATING which is an advantage. This has worked nicely for me.

Dave Neptune

[rjkerby]

Thanks Dave, Have you noticed much of a difference in speed?

[CalebD]

I am pretty sure that some of the Catalina 30 guys here used fixed 2 blade 12" x 6" props.

[JOHN COOKSON]

One More Thought

Has a diver been under the boat? How clean is the prop?
Maybe there is some KRAP wrapped around the prop.
I had some fish line wrapped around my prop once which to put it midly affected performance. I thought the A4 needed a tune up.
You can turn the prop vertical so it lines up behind the keel and reduces drag when you race.

TRUE GRIT

[rjkerby]

Clean and free

[Dave Neptune]

rj, I do better on speed as I can get more power with the additional RPM's on my 35 footer. On the 30 you will get the same "hull speed" albeit at a bit higher RPM's. This is a good thing as the cylinder and bearing pressures are reduced. The engine will run much "free-er" with less load on the crank. I also got a gain in fuel economy as well.

Dave Neptune

[thatch]

Catalina 30 props

Hi rj, A few years ago I did some prop tests on my 1978 c-30 to try to raise my engine speed closer to 2000 rpm's. For some reason Catalina used the same 12-7 prop on their 27's as they did on their 30's which I feel was just too much prop for a much heavier boat. I tested a few different styles, which included the Indigo 3-blade. I finally settled on a "cut down" (11-7) standard Catalina 2-blade and have been happy with it. As Dave has noted, the Indigo performs quite well in forward but I noticed a definate tendancy for it to cavitate in reverse. This is most likely caused by the "winglets" on the trailing edges. If you are concerned about having good reverse thrust, this would be the last thing you would want to have happen. Others have mentioned that reverse noises on these A4's is normal, so I would say that it is operating normally. You may want to try adjusting the reverse band a little tighter which will make the reverse shift a little quicker. Because of the excellent gearbox access on our C-30's, it's a relatively easy job. Hope this helps. Tom

[rjkerby]

Thanks , Took it out for first time with new engine and I think I can rev way to high. With the 11-7 it shot to 3000 really quick. Think it really wants to be in the low to mid 2Ks. Gets warm pretty quick revving that high

[thatch]

rj, Having as fresh "bullet" in your C-30 may account for it's ability to power past the 11-7 2-blade. Going back to the factory 12-7 may put you back to where you want to be. To add a little info about the "noisey reverse", when you engage the reversing gear, you are going from a 1 to 1, locked-in ratio to a 2 to 1 ratio that is fed through a group of "planatery gears". These straight cut gears are what is causing this very noisey, but normal sound. The "no detent" feature of reverse means that you must keep pressure on the shifter to provide maximum thrust in reverse.
Tom

[rjkerby]

Thanks Tom, makes sense