Catalina 30 Prop

[dnimigon]

Heh Catalina owners. My Catalina 30 having a 25 HP Universal engine just doesn't seem to have the get up and go. Having bought the boat from previous owner, he had switched out the gas and installed a diesel. When I had the boat out for bottom paint I thought the prop was small but I wasn't sure. 2 bladed. The boat I know is heavy but when backing out of slip and then going into forward I have to rev it like snot to get it moving. Rev's are good, just no fast movements. I see other boats here in our marina moving around like no problem. Wind becomes an issue when coming into slip. Is this the norm for this size of boat. I've looked at a different prop on Catalina direct. Possibly a 3 blade but not sure if this is the fix. From a stand still it seems to take forever to get it moving. Yes it's heavy but is this normal. I'm not driving a ocean liner. Once moving the boat will move about 4-5 knots at full throttle going off my GPS.

[JK n Smitty]

Originally Posted by dnimigon

Heh Catalina owners. My Catalina 30 having a 25 HP Universal engine just doesn't seem to have the get up and go. Having bought the boat from previous owner, he had switched out the gas and installed a diesel. When I had the boat out for bottom paint I thought the prop was small but I wasn't sure. 2 bladed. The boat I know is heavy but when backing out of slip and then going into forward I have to rev it like snot to get it moving. Rev's are good, just no fast movements. I see other boats here in our marina moving around like no problem. Wind becomes an issue when coming into slip. Is this the norm for this size of boat. I've looked at a different prop on Catalina direct. Possibly a 3 blade but not sure if this is the fix. From a stand still it seems to take forever to get it moving. Yes it's heavy but is this normal. I'm not driving a ocean liner. Once moving the boat will move about 4-5 knots at full throttle going off my GPS.

This all seems normal. When you are moving at 4-5 knots, what are the RPMs?

I have a Catalina 310 (31 feet so a little bigger and heavier) with a 23 hp diesel and 3 blade prop. I can get to hull speed, 6.5 knots, at WOT (3,200 RPM) and cruise at 5 knots at around 2,600 RPM. My buddy has the same setup as you. He reaches the same speed as you under WOT. So I have to slow down to cruise with him on windless days when we are powering. Another couple I know have a Catalina 36 that has a 25 hp diesel with a 2 blade folding prop. They said they have the same type of performance. Going into a headwind with some chop I know both of them have trouble making 3 knots.

A 3 blade prop will definitely help with some of these issues and give you more bight/torque when in reverse. But it will slow you down some when sailing. Might not be to noticeable to you if you cruise/day sail but if you race it may be a problem.

We cruise and wouldn't even think of doing it with a 2 blade prop. I would spend the money and get a 3 blade if I didn't have one already.

Hope this helped.

Fair winds,

Jesse

[jeepbluetj]

I can cruise at 6kts at 2000 rpm pretty easily. I can get it 6.5kts if I rev it. Boat's not light either, lots of crap on board.

I have the A4, with an indigo prop. I drive around the harbor at idle (800rpm) doing 3kts or so. Back out at idle too.

The a4 in a C30 is direct drive - that's why the props look small, they spin pretty fast. If the diesel conversion had a reduction gear (likely) - you're just not spinning the prop fast enough. (And you'll need to rev the snot out of it to get it to go)

If that's the case, a new prop properly sized for your gearing could help.

[The Garbone]

If they left the stock 12x7 Atomic 4 prop on there that would be the problem.

I have a 12x9 replacing with a Indigo 3 blade. I am repowering my C30 to to an Atomic 4 from diesel.

[jeepbluetj]

Originally Posted by The Garbone

I have a 12x9 replacing with a Indigo 3 blade. I am repowering my C30 to to an Atomic 4 from diesel.

Holy smokes man! Don't ya know that's the wrong way! Your boat will explode!

[The Garbone]

Yup, but look at all that money I am saving.

And me with no propane aboard.....

[Stu Jackson]

Universal never made a 25 hp engine. It's either an M25 (21 hp) or an M25XP (23 hp).

You need to tell us what the diameter and ptich are or else nothing else makes sense except for the idea that they left the A4 engine prop on the boat.

They've been making the C30 or variants since the 70s, so there is a database of information the proper prop for this boat. It's not a secret.

International Catalina 30 Association would be a good start.

[Cheechako]

A 3 blade of the correct pitch will make a big difference.

[dnimigon]

Thanks for all the replies. It is a Universal 25XPB rated at 26 HP, 3000 RPM. I believe it probably is the Atomic 4 setup still in it. When we had it out for paint I thought this sure is a tiny prop. We were actually out today ( boat is in PVR, Mexico) Had probably a 15-20 knot head wind. Had engine pinned and I could of walked faster coming out of marina. at idle one member says he can do 3 knots. This one at idle you could walk away and go get a coffee. Not really but almost like that. At idle it will basically crawl around. Have talked briefly with Catalina Direct regarding a prop and they said they could fix me up with the proper prop. I was wondering what the list thought about all of this and if I was heading the right way with a different prop. I knew something was wrong with others zipping by me going out into the ocean. Yes the boat is heavy but I thought this is wrong the way it gets moving. I'm thinking too small of a pitch and it'll take time to get up to speed. Kind of like a big car with a small engine. Will do 70 MPH. Just takes awhile to get there. Is this correct. Not sure what kind of train is in it. Whatever came with the engine. I'll have a look tomorrow. Original shaft and prop I'll assume.

[Cheechako]

Well, there should be plenty of users with that engine in a Cat 30. Put the largest diameter prop you can on leaving 15% of the diamter in clearance tip of blade to hull.

[dohenyboy]

I would ask the question on the Catalina 30 owners forum. Someone will tell you exactly what they use.
How clean is your prop?

[Stu Jackson]

The systems on our boats are remarkably similar. This link also had=s a lot of information about your engine.

Catalina 34 - C34

Good luck, the C30 association has prop info.