Hi need suggestions for propeller for a 1978 Catalina retrofitted with a Yanmar 2GM20

[hollyclouse]

Hi just pulled my boat out for bottom maintenance and hoping to solve a huge problem. Since I've had her when she's underway under a heavy load there is a ton of smoke, fuel discharging. Had injectors checked and they are fine. My propeller is plastic and has an extension that allows it room to turn. I think that is the problem. So, I'm wondering what propellors do you use with a modified engine and no, I can not afford a shaft extension...I'm still wrapping my head around that it's plastic.... I can supply a pic tomorrow if you want to see it.
Thanks.

 

[Tally Ho]

I have a different (but similar-sized) boat with a 2GM20F engine.

I run a Michigan Sailor 14RH14 2-blade fixed prop on my boat. This is what was on the boat when I bought it.

I also get unburned fuel in my exhaust (no smoke, but black stuff in the exhaust water) if I run the engine over about 3200 RPM’s. I can run it up to 3600 in neutral with no problem, but under load, she spews unburned fuel (I assume that is what it is). Even with a freshly painted and clean bottom, I cannot really push her over 3200 RPMs without getting the dark stuff in the exhaust.

Curious to see what others have to offer…

Greg

 

[sail sfbay]

Welcome to the forum!!

Sounds like you have a couple of things to address: 1) smoke and fuel discharging, and 2) propeller. I assume the Yanmar 2GM20 was a re-power. As far as the propeller, you need to decide type (2 or 3 blade fixed, folding, feathering, etc.) then contact a propeller supplier (or have your boatyard do that) with your engine model, transmission model and gear ratio and shaft diameter for a quote. Be sure to check propeller clearance.

 

[heritage]

My H27 was repowered with a 2gm20f and is fitted with a 3 bladed bronze 13 x 11 prop. I'm happy with it. Can get up to 3300-3400 rpm with some smoke and soot and runs at hull speed at around 2800 rpm.

 

[Ralph Johnstone]

A @GM20F is more than enough power for a Cat 27. I push an H310 loaded with more stuff than you could imagine when we're gone for a month or better. No visible smoke but a bit of discolouration on the transom. Cruises at 2800 and will make 3600 when loaded.

Went from a two blade to a three blade three years after buying the boat new in 1998.

Can you check and report the size and pitch on the plastic prop ? Pics as well would be nice.

 

[hollyclouse]

Thanks! Was thinking of a 3 propellor versus a 2. The plastic prop is all the way wrong.
Any feedback is greatly appreciated!
Thanks!
Holly Clouse

 

[jssailem]

@hollyclouse First, Welcome to the SBO Forum. Congrats on your choice of a Catalina 27. A great boat for a first ownership.

Before running out and spending a lot of money on a prop, perhaps it would be appropriate to identify the way you see yourself using the "Auxiliary power" on the boat. On a sail boat the primary power is the sails. If you plan to spend money on power focus your spending on the sails first.

For example, I cruise in waters that have strong tidal currents, some periods of little to no wind, and try to make passages of 20-30 miles a day when I am out. This is not a day sail or evening beer can sail boat. My prop needs are specific to the type of use I plan for my boat.

You may be greatly different, and sail in different waters. The type of prop you need will be relevant to the type of use you plan of the boat.

What are your plans?

 

[Tally Ho]

@hollyclouse First, Welcome to the SBO Forum. Congrats on your choice of a Catalina 27. A great boat for a first ownership.

Before running out and spending a lot of money on a prop, perhaps it would be appropriate to identify the way you see yourself using the "Auxiliary power" on the boat. On a sail boat the primary power is the sails. If you plan to spend money on power focus your spending on the sails first.

For example, I cruise in waters that have strong tidal currents, some periods of little to no wind, and try to make passages of 20-30 miles a day when I am out. This is not a day sail or evening beer can sail boat. My prop needs are specific to the type of use I plan for my boat.

You may be greatly different, and sail in different waters. The type of prop you need will be relevant to the type of use you plan of the boat.

What are your plans?

Excellent question…

I motor out of my marina, and back in to my slip generally… 15-30 minutes each sail. Occasionally I will motor back against the wind or if wind dies, but not often. So, 8 am hard pressed to spend a fortune on a prop.

And, I don’t race…so same logic…hate to spend several boat bucks on an extra 1/2 knot of speed.

OTOH, I hate losing to my buddy on his Hunter 33 (2006), with about 3 feet longer waterline and a folding prop!

But I can always use the prop as an excuse for getting beat…

I requested a quote on a Campbell Sailor prop to see what size and cost they recommend…maybe this would be a good compromise to a more expensive folding or feathering prop.

Greg

 

[hollyclouse]

Thank You! I am in Sarasota Bay and have been limited to mainly day sails with the engine issue and prop. By resolving this I hope to be a weekend cruiser - lots to explore around here and other places close by. I appreciate your help so much.

 

[jssailem]

Greg,
Looking at the two props in the previous post is it clear to see that the Campbell Sailor produced major improvements in my boat handling both under power and sail.

There is reduced noise and vibration while sailing. Under power my boat no longer drops the stern a foot under water. Prop walk has been significantly reduced. The CS prop has improved the thrust and I believe reduced the fuel consumption due to the more efficient thrust.

The design of the Campbell Sailor prop should not be confused with the design of the Michigan Sailor prop.

The CS has a blade curve and blade thickness shape which is designed to reduce cavitation and improve thrust.

The MS is a modification of the big ears used in the Michigan Wheel (the prop that came on my boat). Here is a picture of the MS prop. You can see the similarities to my old Michigan Wheel prop even though the new shape has been updated (improved).

MICHIGAN SAILOR 3 PROPELLER 12" DIAMETER

 

[jssailem]

have been limited to mainly day sails with the engine issue and prop. By resolving this I hope to be a weekend cruiser

This is a start. Day sails are mostly sailing. You have no specific place to be and you set your time based on the wind and how much you want to be on the water. Unless the wind dies and you are a long way from the marina with a need to get home for the evening, than you can sail home or anchor out. There is no pressure to be anywhere the wind does not allow. This a skipper who uses the power of the sails as sailors have for ions. The engine is the sails. The auxiliary power is a last resort.

There should be nothing limiting about sailing out for a weekend cruise unless the wind does not exist.

The getting in and out of the marina means a 15-25 minute motor experience.

 

[brazenarticle]

The prop size is determined by the hull length, the design, strut and rudder position as well as the engine size. A bigger engine and or bigger prop doesn't necessarily mean more speed, less prop wash or more control in reverse.
Older Catalina 27s had Atomic 4 engines and a two blade prop much closer to the strut than your plastic prop (probably polyurethane, looks like a CDI Xtendo Prop). Your engine may be different but the hull remains the same.
An efficient prop on someones 'other than Catalina 27 boat' might just make black smoke for you.
The good prop shops can take all your data and tell you what you need but $800 or more dollars might be a bit much for an older Catalina 27.
A possible starting point that may help is get a used, salvaged or borrowed old stock prop and see if it works better than what you have now.