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tcase10 12-22-2013 08:44 PM

Universal 5411....Hurth Transmission...propeller rotation
 
3 Attachment(s)
My boat is a 1982 Catalina 27. It has a universal 5411, 11 hp engine. Since I have had the boat I have never been able to reach hull speed under power. I recently pulled the boat out of the water for a bottom job and inspected the propeller. It is stamped with 12LH7, a 12x7 left hand prop. Reviewing the specs for the engine and transmission it appears I need a right hand propeller. And likely a larger diameter too.

I have attached a photo of the prop and transmission. Does anyone know why there would be a LH prop on this engine and transmission? Does anyone have any recommendation on a new prop?

deniseO30 12-22-2013 08:56 PM

Re: Universal 5411....Hurth Transmission...propeller rotation
 
Hull speed is a variable. seems to me if you have the wrong prop fwd would be Rev!

Faster 12-22-2013 10:01 PM

Re: Universal 5411....Hurth Transmission...propeller rotation
 
It's possible to connect the shift linkage in such a way as to 'reverse' the gear.. if someone did this and you were always technically in reverse when going forward that might explain the lack of boatspeed. (IIRC the gear ratios are different fwd vs rev)

EDIT.. from your pic it doesn't look like the shift linkage connection is reversed, so not sure what to think....

sony2000 12-22-2013 11:21 PM

Re: Universal 5411....Hurth Transmission...propeller rotation
 
From the picture, it is a left prop, so the LH is correct. If you put on the same pitch that is RH, ran the transmission in reverse by the control arm selector, you may get what you want.:)

tcase10 12-23-2013 12:02 AM

Re: Universal 5411....Hurth Transmission...propeller rotation
 
Thank you for the responses. When I put the gear lever in forward (by moving it forward) should the lever on the transmission move forward or backward?

Faster 12-23-2013 01:08 AM

Re: Universal 5411....Hurth Transmission...propeller rotation
 
According to the Hurth manual(s), if the gear shift lever on the transmission is moved aft (with standard straight/non V drive installation of engine) that's putting the engine in forward gear. It's a natural arrangement that works with pushing the control lever forward, it actually 'pulls' on the shift cable, moving the gear lever aft to the "A"/fwd position.

Where this can get confusing is if the cockpit controls are mounted unconventionally (ie sideways in the cockpit, or with the assembly 'backwards' on the cockpit wall)

If the boat's currently going forward when you 'shift to forward' at the control arm then the shifter arrangement and the prop are matched for direction.. however if it so happens you're actually running in reverse (arm Position "B") most of the time then you are probably using a less-than-ideal (or other than expected) gear ratio as they do differ.

One manual here:

http://www.c34.org/manuals/ZF_Hurth_Repair_manual.pdf

Quote:

Originally Posted by tcase10 (Post 1241714)
Thank you for the responses. When I put the gear lever in forward (by moving it forward) should the lever on the transmission move forward or backward?

Simply put, the lever on the tranny should move backward/aft.

MarkSF 12-23-2013 02:56 AM

Re: Universal 5411....Hurth Transmission...propeller rotation
 
The C27 with the 11hp is no ball of fire, and I wouldn't expect to reach hull speed either. Anything above 5 kts at 2/3 throttle would be good.

You have 7000 lbs, and 11hp. That's about half the hp per lb that is considered ideal.

I spent a merry hour learning docking techniques in one. The highlight was when I tried putting throttling up in reverse to stop in a slip, and the throttle lever came off in my hand. Nice work with a snubber avoiding so much as a scratch.

Capt Len 12-23-2013 03:15 AM

Re: Universal 5411....Hurth Transmission...propeller rotation
 
What is the difference in ratio ,,for'rd/ reverse? Hurth runs good either way. If you spring for a maxi you solve all the problems.

tcase10 12-23-2013 10:15 AM

Re: Universal 5411....Hurth Transmission...propeller rotation
 
Faster - I will have to check to make sure that the cable is moving as the manual says. I believe it is, but will check. Thanks.

Capt Len - I agree. My problem is when I call a prop manufacturer and give specs, they say right hand prop. That is not what is on there and I want to make sure I'm buying the correct prop.

More investigation required.....

Faster 12-23-2013 10:21 AM

Re: Universal 5411....Hurth Transmission...propeller rotation
 
Quote:

Originally Posted by Capt Len (Post 1241930)
What is the difference in ratio ,,for'rd/ reverse? Hurth runs good either way. If you spring for a maxi you solve all the problems.

Depends on models, but something like 1.8 vs 2.2 seemed typical


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