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Old 30-07-2015, 02:04   #136
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Re: Do you sail with your transmission in gear?

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Originally Posted by Jim Cate View Post
Ah, yes, wooden props are laminated... what then is this one?

Jim
Yes indeed, what is that? You have to go back to 1906 or something to find one that is not laminated. They found out right away, that kind of prop did not hold up and started laminating and putting metal leading edges on them. Anybody who knows anything about propellers knows that. Wooden propellers are a true work of art and that is a foolish example.
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Old 30-07-2015, 03:06   #137
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Re: Do you sail with your transmission in gear?

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Yes indeed, what is that? You have to go back to 1906 or something to find one that is not laminated. They found out right away, that kind of prop did not hold up and started laminating and putting metal leading edges on them. Anybody who knows anything about propellers knows that. Wooden propellers are a true work of art and that is a foolish example.
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For general information, wooden Props are laminated.
Well, Guy, my foolish example refutes your foolish claim.

I'll not argue that laminated wooden structures of most types are stronger and more durable than ones made from monolithic chunks of wood, but it is obvious that all wooden props are not laminated.

Your arguments are struggling, mate. I think that it has been pretty well established that there is no direct analogy between aero props and maritime props, and that flying and sailing practices have no useful associations... so why not give it a rest and stop attacking a fellow CF contributor?

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Old 30-07-2015, 04:43   #138
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Re: Do you sail with your transmission in gear?

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...Yachting Monthly showed in a repeatable test that allowing a fixed blade prop to free spin produced less drag than locking it in reverse. They also showed that a feathered prop produced virtually no drag in it's feathered state which would be the ideal scenario.

Funny isn't it that despite reputable organisations coming up with the same result we still end up arguing which is best. If MIT and YM have shown beyond doubt that allowing a fixed blade prop to free rotate reduces your drag why do some people keep insisting that you lock it?...
I don't post here any longer...yet came out of 'retirement' because of this thread.

Excerp from the Volvo manual...
http://www.catamaransite.com/files/V...ction_Book.pdf

When sailing
When sailing the control lever should be in the neutral position if the
boat is equipped with HS25 reverse gear. If the boat is equipped with Sdrive
or MS2/MS25 reverse gear the control lever should be the reverse
position if a folding propeller is used and in neutral position if a fixed
propeller is used.
IMPORTANT! S-drive and MS2 with fixed propeller: When
sailing long distances the engine should be started for five minutes
every 10 hours to cool the drive/reverse gear. If this is not possible
then a propeller shaft brake must be installed.


Every Propeller drag test reached the same conclusion regardless of where it was performed, or who ran the test. A freewheeling prop causes less drag. As I said earlier, documentation to contradict this doesn't exist.... yet here are these 'sailors' arguing about it.

Sometimes you have to wonder if some people on this forum actually own a boat, as a self test takes an hour and would confirm the propeller test conclusions.

http://www.catamaransite.com/propeller_drag_test.html
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Old 30-07-2015, 07:55   #139
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Re: Do you sail with your transmission in gear?

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Originally Posted by Jim Cate View Post
Well, Guy, my foolish example refutes your foolish claim.

I'll not argue that laminated wooden structures of most types are stronger and more durable than ones made from monolithic chunks of wood, but it is obvious that all wooden props are not laminated.

Your arguments are struggling, mate. I think that it has been pretty well established that there is no direct analogy between aero props and maritime props, and that flying and sailing practices have no useful associations... so why not give it a rest and stop attacking a fellow CF contributor?

Jim

Boy I now know how it is to be misunderstood. I have not claimed the they act the same for a couple of years. To bad people don't bother to read the posts.
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Old 05-08-2015, 20:20   #140
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Re: Do you sail with your transmission in gear?

I am right. And an airplane expert.

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Old 05-08-2015, 20:33   #141
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Re: Do you sail with your transmission in gear?

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I am right. And an airplane expert.

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You are not much of an expert if you think all prop airplanes have piston engines.
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Old 05-08-2015, 21:44   #142
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Re: Do you sail with your transmission in gear?

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You are not much of an expert if you think all prop airplanes have piston engines.
Please show us all where i said that.

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Old 05-08-2015, 21:48   #143
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Re: Do you sail with your transmission in gear?

I am also an expert at seeing who is here for information and those here to stir up the holding tank.

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Old 05-08-2015, 22:09   #144
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Re: Do you sail with your transmission in gear?

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Ok poeple the prop on an airplane is NOT freewheeling. It is spinning the whole motor making it way more draggy than a boat prop with the trans in neutral. Apples and oranges no comparison.

Andy

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That is what you said.
If you knew anything about a turbine, you would know that you are probably not spinning the motor when the prop is freewheeling. This is why it's way more relevant to use a turbine as an example. Your boat prop is never going to turn the engine so why would you use a piston engine airplane as an example? So a turbine prop, which pretty much freewheels in the breeze, needs to be feathered to cause less drag.
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Old 05-08-2015, 23:46   #145
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Re: Do you sail with your transmission in gear?

Your not understanding the dynamics at work here. An airfoil making lift is also making drag so a free wheeling prop on even a pt6 or any turbine is making drag because it is in laminar flow therefore making lift and drag. Again it is because the prop blade, or wing, is flying. So to get rid of that induced drag caused by lift you need to stop the prop from flying by stopping its rotation. If your in a Champ with 65 horsepower, you slow down and the prop stops spinning. If your in a Commander 690f you put the prop in feather.

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Old 06-08-2015, 01:02   #146
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Re: Do you sail with your transmission in gear?

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Originally Posted by wellin View Post
Your not understanding the dynamics at work here. An airfoil making lift is also making drag so a free wheeling prop on even a pt6 or any turbine is making drag because it is in laminar flow therefore making lift and drag. Again it is because the prop blade, or wing, is flying. So to get rid of that induced drag caused by lift you need to stop the prop from flying by stopping its rotation. If your in a Champ with 65 horsepower, you slow down and the prop stops spinning. If your in a Commander 690f you put the prop in feather.

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And that has ZERO relevance to a sailboat auxilliary engine's propellor in water.
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Old 06-08-2015, 16:54   #147
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Re: Do you sail with your transmission in gear?

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Originally Posted by Stu Jackson View Post
You gentlemen are missing the point. It is not Catalina, Universal or Yanmar or any boat or engine builder that makes this distinction.

It is the manufacturer of the transmission that determines what position is proper to avoid damage to the transmission.

In general, Hurth says neutral or reverse, NEVER forward. The Right Transmission Gear for Sailing - C34

Most transmissions on Yanmars require neutral - there was a long discussion about this for years and finally Yanmar issued a service manual on behalf of their transmission builder for their engines which usually have K transmissions.

Do an internet search on "Transmission position" and find out.
Borg Warner is neutral. If you are concerned about gear or bearings moving and wearing I'd install a shaft stop.
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Old 06-08-2015, 17:13   #148
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Re: Do you sail with your transmission in gear?

I like Roverhi's high tech shaft stop. I think vice grips are the best invention on earth except for maybe duct tape and post it notes. Just don't use your necktie for a shaft stop whilst wearing it.
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Old 06-08-2015, 19:38   #149
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Re: Do you sail with your transmission in gear?

Sailing with the prop locked is more than speed under sail. some transmissions require the engine to run to provide adequate lucubration. Personally I like a reversing feathering prop ie. Maxy prop etc.
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Old 06-08-2015, 21:00   #150
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Re: Do you sail with your transmission in gear?

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Sailing with the prop locked is more than speed under sail. some transmissions require the engine to run to provide adequate lucubration. Personally I like a reversing feathering prop ie. Maxy prop etc.
Another slight drift ; In some early Perkins 107's, the engine and transmission used a common oil oil supply. In other words, there was no rear seal so the oil in the engine was shared by the transmission. If you don't have a trans lubed that way, you still have the sealed bell housing. So if the rear seal, on your Perkins starts leaking it will fill up the bell housing to the point it floods the starter. There was a special starter for these type transmissions that had an oil seal. The good news is, almost all bell housings leak so it drips out the bottom most of the time. I was so lucky to have a bell housing that didn't leak, so the starter quit. I have since tqpped a 1/8" pipe fitting in the very bottom of the bell housing to collect any oil from either the trans front seal or the engine rear seal.
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