[davidpm]

My friend just bought a Catalina 30 with the original very low power diesel, raw water cooled universal maybe 11 HP.

The prop might make it this season so he should start thinking about a new one.
it has a fixed two blade 12" 11 pitch RH prop now.

1. Where is the best place to replace this prop.
2. Is it worth it to think about any other prop configuration considering the small engine.
3. It is a 1" shaft but how do you specify the taper and other considerations for the prop?

 

[tommays]

The 1" should be 1" with no issue that I have ever seen unless it was made wrong

Mainsails guide about lapping the new prop to fit the shaft is VERY important

I cant even begin to say how superior my flex-0-fold prop is compare to the fixed blade

I ended up with a 12 X 7 on the A4 and with the direct drive I run the prop at 1500 RPM so depending on the gear reduction of 2:1 or 2.4:1 a diesel at 3000 RPM would have a similar prop RPM

You would have to consult with who ever makes the prop as the folder has a massive blade area compared to the fixed







It is astounding to have a reverse that pulls the boat like a tug boat compared to the close to useless two blade fixed prop

 

[JimsCAL]

Sounds small. IIRC, the prop on the Universal 5411 I had on my previous boat was a 14D 12P Martec folder. Pushed the Cal 9.2 to almost 6 knots. But the Cat 30 was designed initially for the Atomic Four which used a small prop due to the direct drive. Prop/shaft taper is standard, so no need to specify. This link has good info on Cat 30 props.

Catalina propellers

 

[Alex W]

If you are going with a fixed prop I would look at Campbell Sailor, sold by West by North Enterprises . They are very nicely made props. The design has a proper foil shape on the blades which makes them more efficient and allows for increased thrust for the same blade area. I had a 3 blade, but a 2 blade would have been fine.

I had one of those last year, but switched to a feathering prop (Featherstream) for 2014. I love the reduced drag while sailing and the very strong reverse is nice too. A good folding or feathering prop is not inexpensive, but it's a great performance upgrade for the boat.

 

[Jaramaz]

My friend just bought a Catalina 30 with the original very low power diesel, raw water cooled universal maybe 11 HP.

The prop might make it this season so he should start thinking about a new one.
it has a fixed two blade 12" 11 pitch RH prop now.

1. Where is the best place to replace this prop.
2. Is it worth it to think about any other prop configuration considering the small engine.
3. It is a 1" shaft but how do you specify the taper and other considerations for the prop?

1. pass - but some googling will tell.
2. Doubtful, unfortunately. Old engine? How many HP does it really deliver to the shaft? How long will the engine last?
3. There are standards for tapering, one for metric and another for inches. Look it up on internet (it is easy to find), and compare with some measurements. Even if standards are to be used, some #¤% make their own, to fit some old prop they have found cheap somewhere (happened to me, had to buy a new shaft).

Agree that an old narrow fix 2-blade is nearly worthless, a new flex-o-fold folding prop is certainly superior. But it costs! Cheaper props are not as good - some old folding propos are disasters.
And it somewhere here the crux is: investing in a new quite expensive prop for an old tired (?) engine is not good economy; if engine later on is renewed then it is necessary to get a new prop as well.

Agree that I assume the engine is old (a) and tired (b).

/J

 

[asdf38]

If you are going with a fixed prop I would look at Campbell Sailor, sold by West by North Enterprises . They are very nicely made props. The design has a proper foil shape on the blades which makes them more efficient and allows for increased thrust for the same blade area. I had a 3 blade, but a 2 blade would have been fine.

I had one of those last year, but switched to a feathering prop (Featherstream) for 2014. I love the reduced drag while sailing and the very strong reverse is nice too. A good folding or feathering prop is not inexpensive, but it's a great performance upgrade for the boat.

I second this. I went campbell sailor 3-blade last year and have seen a full 40% performance increase over my original 2-blade.

Personally I like the simplicity of the fixed blades and the campbell sailor has reduced area compared to most other props. The 3-blade has similar surface area to my old 2-blade for example, so I don't believe drag has increased (I certainly haven't noticed if it has).

 

[Donna_F]

Geeze. Thanks. New engine on our Catalina 30 (replaced the 5411) and now I'm thinking new prop. Something else to add to the list.

 

[Alex W]

And it somewhere here the crux is: investing in a new quite expensive prop for an old tired (?) engine is not good economy; if engine later on is renewed then it is necessary to get a new prop as well.

This is not a given. If using a Beta (or Yanmar) you can probably get a transmission that gives the same final prop RPMs as the original engine and transmission, allowing you to continue using the same prop. The original engine is RH and so are the common replacements.

As an example the high RPM on this engine is 3000rpm and the final drive ratio is 2:1, for a maximum prop rotation speed of 1500rpm. A Beta Marine 16 is available with 3600 maximum engine rpm and a 2.45:1 transmission, which gives a final drive of 1470rpm. That's close enough.

A feathering prop can also have it's pitch adjusted, which would allow you to use the same prop even if you didn't have the same prop speed after engine replacement.

11" does seem small. If there is room for a larger prop you might be happier with it's performance. My boat (which is 3000lbs lighter) uses a 16" prop.

 

[davidpm]

I second this. I went campbell sailor 3-blade last year and have seen a full 40% performance increase over my original 2-blade.

Personally I like the simplicity of the fixed blades and the campbell sailor has reduced area compared to most other props. The 3-blade has similar surface area to my old 2-blade for example, so I don't believe drag has increased (I certainly haven't noticed if it has).

Do you suspect that a 3 blade higher performance prop will really work with the 5411.

I'm concerned that the extra resistance will hasten the demise of this marginal engine.

What did your prop cost, size?

 

[Alex W]

My Campbell Sailor (3-blade, 14" diameter) was around $550 delivered in Jan 2013. Flex-O-Fold was around $1200 (2 blade, 16" diameter) or $2000 (3-blade), and my Featherstream (3-blade) prop was a hair under $2000. A Max-Prop in 2-blade is around $1600 and a 3-blade is around $2500.

 

[tommays]

Props are as much art as science for example this 4 HP 3 blade HT has what looks to be ridiculously large blades yet it allows the motor to reach RPM at displacement speed which was its design purpose

IF you have ever worked in a (good) outboard shop every motor has a test prop which allows full loading of the motor with pretty much NO THRUST

A prop that allows full RPM on a motor of hp X with gear reduction Y will perform on 99% of the SAILBOAT DISPLACEMENT HULL boats it is used on regardless of there size

You look look across the board using a prop slip calculator and there all going to be in the 50% slip range

unless you go to and epic gear reduction of 3:1 or more with a massive prop that will ensure the boat will not move under sail


If you go to sterndrive power boats there are three basic gear ratios based on HP of 2:1 / 1.65:1 / 1.35:1