propeller not turning - Page 3 - SailNet Community

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Go Back   SailNet Community > On Board > Gear & Maintenance
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  #21  
Old 08-21-2012
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Re: propeller not turning

Every boat is different....it seems yours has a soft "key" to protect the prop and possibly the engine from damage if you hit something hard. A sacrificial part like this is a good thing to have - just carry spares. If you replace the key with something stronger (SS), then if your prop hits something, instead of losing the key, you'll likely damage the prop. Typically a new prop is a lot more expensive than a new key.....
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  #22  
Old 08-21-2012
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Re: propeller not turning

My money goes on the PO changing the prop to a larger size but had to make a stepped key to fit the used prop he bought. It's unlikely the prop/shaft combination came with the stepped key. They are notoriusly weaker than straight key. But, shearing the key may have saved other more expensive parts.

John
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  #23  
Old 08-21-2012
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Re: propeller not turning

The prop is a 14LH11. It is a 1" bore and fitted with a collar to fit my 3/4" shaft bore. the engine is 13 old HP, Volvo Penta MD7A running very good. The diver stated that the propeller could be over-sized; but, he cannot confirm it is not right for the boat configuration. This problem never happened to this boat. He checked the boat power after installation and told me that the right RPM for my configuration was about 1100. What I take from all this is..... it is best to have a secondary outboard.

Most important is the fact that the diver has fixed this problem many times before. Gert it happens, yes it does. So be aware that it can happen, and it will. I be live it happened to me because I shifted from forward to reverse and back to forward to make a perfect landing at too high RPM. I also know that Bronze is no where the strength of SS. So I am re pacing the key to Stain Steel this winter when I get the boat out dry-dock.
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  #24  
Old 08-22-2012
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Re: propeller not turning

verestsailnet,

Without knowing what size/weight/configuration boat you are talking about the prop size is just a complete guess.
Yes, LH 14 x 11 sounds big and maybe over pitched for a 30' Catalina but it could be just fine for your Cheoy Lee 36', if that is what you indeed have.

Other factors:
- is the prop in clean water, eg., no deadwood from the hull in front of it or is it tucked behind the hull?
- do you have a reduction gear in your transmission that allows you to spin a bigger prop at somewhat slower rotations? Or, is your transmission 'direct drive'?

I went through this with my own boat this spring when replacing the prop shaft, shaft log tube, stuffing box, cutless bearing. My boat is about 7200#s, a Tartan 27 with an Atomic 3 or 4 (30 HP max) with direct drive. Folks with Catalina 30's said they used an 12' x 6' 2 blade prop and found it just fine. Catalina 30 weighs just a little more then my Tartan 27. The big difference is that the prop shaft on the Catalina 30 sticks out into clean water but on my boat the shaft sticks out the back of the hull "deadwood". I've been using a 13" x 8" prop all this time and wondered if it was too much for my engine to spin. The deadwood causes a lot of loss of power to the prop so I've stuck with the original 13" x 8" prop which has been just fine.

We need to know the weight of your boat, plus the hull shape where the prop is to even make a somewhat intelligent guess if your 14" x 11" prop is too much, too little or just right.

I'd also hazard a guess that having a "T" shaped, or stepped key is not really a good thing on your propeller. It should be a straight key, with no change in width throughout. If it popped out once it will pop out again.

Also having a collar to adapt a 1" bore prop to a 3/4" shaft sounds like asking for trouble. I'd rather have a prop that fit MY shaft without adapters.

Used props can be had or a good prop shop could make your 1" bore a 3/4" bore for a price.

Your boat, your money, your choices.
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