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Old 29-04-2013, 15:26   #1
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Backwards prop?

Ok,

PO repowered in 2009 and put in a 3YM20 and the KM2P trans. I bought it last year, knew it was a little under powered, but shocked when I couldn't at least make hull speed. Unhappy that I couldn't point into the wind in 20knts. So, I bought a Campbell Sailor.

The boat came with a 13x9 LH 2 blade, CS insists that a 13x9 RH 3 blade is correct, and that someone hooked up the linkage backwards... (maybe PO didn't want to splurge on a new prop, IDK)

Thoughts? Has anyone heard of someone hooking up the linkage backwards just to use a LH prop? They Yanmar website seems to indicate a RH prop...
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Old 29-04-2013, 15:48   #2
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Re: Backwards prop?

never heard of this problem, I guess depending on the transmission, there will be two different gear ratios. not too sure if running in reverse will do any harm either. I don't know there mate. why take the chance?
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Old 29-04-2013, 15:53   #3
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Re: Backwards prop?

Yes, the reduction are 2.6F and 3.0R So, it's not a huge difference, but big enough to actually explain, maybe, why I can get to hull speed on flat water...
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Old 29-04-2013, 15:55   #4
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Re: Backwards prop?

Yes! It happened to me a long time ago. I bought a 26-foot Seafarer with a small Universal diesel, and right from the get-go it had limited power in forward, but could stop on a dime in reverse. I thought it was very strange behavior, but discovered from the surveyor as I was selling it that we were going forward in reverse and reverse in forward.
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Old 29-04-2013, 15:56   #5
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Re: Backwards prop?

Why can't you just look underwater at the prop turning at idle while it's tied up at the dock to see for yourself which way it's turning? Or better yet, look to see which way your drive shaft is turning at the backside of your engine?
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Old 29-04-2013, 16:03   #6
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Re: Backwards prop?

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Originally Posted by Kenomac View Post
Why can't you just look underwater at the prop turning at idle while it's tied up at the dock to see for yourself which way it's turning? Or better yet, look to see which way your drive shaft is turning at the backside of your engine?
well, it's on the hard up here in Great Lakes land... but all that is not necessary. We know that it is hooked up so that in "FWD" the LH prop pushed the boat forward, and backward in "REV". What is unclear is if the linkage got hooked up backwards so that a LH prop could be used. That would mean that the 3:1 reverse gear is actually being used for "FWD", and the 2.6:1 is being used to back.
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Old 29-04-2013, 16:46   #7
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Re: Backwards prop?

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Originally Posted by bluemoose View Post
Ok,

PO repowered in 2009 and put in a 3YM20 and the KM2P trans. I bought it last year, knew it was a little under powered, but shocked when I couldn't at least make hull speed. Unhappy that I couldn't point into the wind in 20knts. So, I bought a Campbell Sailor.

The boat came with a 13x9 LH 2 blade, CS insists that a 13x9 RH 3 blade is correct, and that someone hooked up the linkage backwards... (maybe PO didn't want to splurge on a new prop, IDK)

Thoughts? Has anyone heard of someone hooking up the linkage backwards just to use a LH prop? They Yanmar website seems to indicate a RH prop...

I upgraded from a completely dysfunctional 13 hp yanmar to the engine you have, and I did need a new prop. I'm sorry but I don't remember the specifics, but I chose a fairly experimental prop from Perfect Pitch:

Perfect Pitch Propellers-Propeller Sales and Repair Servicing Utah

Their chart was absolutely accurate. The prop performs like a champ and even better in reverse. It is very slightly flexible and actually changes shape slightly in reverse. I couldn't be happier with it. They cost about half the cost of a traditional prop, and they're so lightweight that if you break a blade off you can still use the engine without risk of damage.

If it turns out you need a new one, might be worth looking into ...
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Old 07-05-2013, 09:10   #8
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Re: Backwards prop?

BTW - the linkage was reversed.... I won't be towing any skiers, but I should at least make hull speed this year. What a PITA.
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Old 07-05-2013, 13:55   #9
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Re: Backwards prop?

When you buy a previously owned boat, there's no telling what he or she might have done to it. Two or more previous owners and it's anybody's guess.

Reading some of the repair suggestions on this forum, you soon understand that not everybody is concerned with doing things the right way.

A good boat mechanic can probably figure out what's wrong and how best to fix it.
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Old 07-05-2013, 14:56   #10
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Re: Backwards prop?

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Originally Posted by bluemoose View Post
Ok,



Thoughts? Has anyone heard of someone hooking up the linkage backwards just to use a LH prop? They Yanmar website seems to indicate a RH prop...
I have a friend who delivered yachts for many years, who once picked up a million dollar yacht at the factory, started to back out of the slip, and found the boat had been rigged with the transmissions backwards where forward was reverse and reverse was forward. The yard wanted to just switch the propellers.
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Old 07-05-2013, 15:40   #11
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Re: Backwards prop?

But you said that when you had the linkage in Fwd the boat would go forward. Was the Fwd on the controls at the helm or at the transmission?

It's not good for some transmissions to run in reverse continuously so it definitely is not the way to correct for having the wrong hand prop.

Glad you got it straightened out.

kind regards,
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Old 07-05-2013, 15:50   #12
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Re: Backwards prop?

LH prop with a backwards linkage means thst FWD at the helm makes you go forward, but you are using the reverse gear to do it. (so maybe 80% ofthe max RPMs at the prop, even though the engine is at max)
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Old 07-05-2013, 15:58   #13
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Re: Backwards prop?

Know an owner of a heavy wooden 45 Ft sportfisherman who was pissed that the professional captain was not working fast enough to get the boat back in the water. He put the 2 28 x 24 4 bladeds back on himself.
travel lift puts the boat in. owner starts up, and pulls both engines in reverse to back out, and splits the stem open. props on in opposite positions.
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