SailNet Community - Reply to Topic
Thread: Propeller Question Reply to Thread
Send Trackbacks to (Separate multiple URLs with spaces) :
Post Icons
You may choose an icon for your message from the following list:

Register Now

In order to be able to post messages on the SailNet Community forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
Please note: After entering 3 characters a list of Usernames already in use will appear and the list will disappear once a valid Username is entered.

User Name:
Please enter a password for your user account. Note that passwords are case-sensitive.


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:


Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.

  Additional Options
Miscellaneous Options

Click here to view the posting rules you are bound to when clicking the
'Submit Reply' button below

  Topic Review (Newest First)
02-19-2003 04:59 PM
Propeller Question

Actually the correct answer depends on the propellor and the transmission. There was a lot of research done on this a few years back.

The pretty widely reported results came up that a two blade prop fixed in the vertical position has less drag than a two blade prop either freewheeling or fixed in any other position.

A three or more blade prop with minimal resistance on the shaft will have less drag free wheeling, BUT if there is much friction on the shaft, the turbulence of the semi-free wheeling propellor is greater than that of a fixed prop in the ''Mickey Mouse'' position, which is the lowest drag position for a fixed three bladed prop.

Then there is the issue of transmission wear. In all cases freewheeling causes more transmission wear than being fixed. On most small marine transmissions there is no problem with lubrication or heat build up. That said some larger transmissions have shaft driven lube and cooling pumps which are not being turned when freewheeling.

02-19-2003 03:19 PM
Propeller Question

Free wheeling will create less drag than a stopped prop. One of the problems with this is that this can generate heat in the transmission. If the transmission is water cooled, there is no water circulating with the engine off-ergo a potentially damaged transmission. Best check with the engine people first.
02-18-2003 06:47 PM
Propeller Question

Hi Scurvy
You bet it works the same. as far as puting it in gear. Depends a whole lot what type of trans you have. Trans that are fluid coupled putting it in gear does nothing. there are several folding props both two and three blade for that purpose. As to effectiveness. What? You going for the world cup. You would never know the differance on a Sunday cruise around the bay.
02-18-2003 03:33 PM
Propeller Question

This question comes up often enough to generate considerable discussion on occasion, with various anecdotes, but the upshot is what you know applies in the air also applies in the water. The trick is to mark your propshaft when the blades (of a two -bladed prop) are vertical and thus not projecting beyond the "shadow" of the keel. Then you engage the clutch when the mark shows, and you''re done until you need the engine.
02-18-2003 01:33 PM
Propeller Question

I am new to sailing. I am an ex cooperate jet pilot and flight instructor. I understand the dynamics of a propeller in the air. Just wondering if when sailing does a free wheeling prop (eng in neutral) create more drag than a stopped prop? If so how much difference? In a propeller aircraft a stopped prop can offer considerably less drag. Talking to the mechanic who works on my engine he claims it will do no harm placing the engine in gear after shutdown.


Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On

For the best viewing experience please update your browser to Google Chrome