Sunday, November 13, 2005

Wrightsville Beach N.C.


No big events these past couple of days. We have been chugging down the ICW with the rest of the fleet! It's hard for boats to get away from each other since we all go about the same speed and there are only so many good anchorages. We are now anchored in Wrightsville Beach. We are in a fairly large inlet just off of the ocean. In fact tomorrow we will probably take the ocean route abouot 30 miles to Southport N.C. We could both use a change from the shallow water and searching always for the next buoy.

YES...we have been seeing DOLPHINS!

Today’s Sailing/Physics Question…Why do big boats have big winches?

Now I know that seems like a stupid question but just wait. The thing that gives you a mechanical advantage with a winch is that you are applying your effort at the end of the winch handle while the load is being applied at the radius of the winch. Your theoretical mechanical advantage is then simply the ratio of the length of the winch handle to the radius of the winch. For example, the winch handle is 12” (they all are) and the winch is 3” in radius, then your advantage would be 4. You could apply a 10 pound force to crank a line with 40 pounds of tension.

So, what if you buy a bigger boat with bigger winches, say 4” in radius, but have the same winch handles? Well, you lose! Your advantage would now be reduce to 3 making it harder to crank the winch hence my question.

(CLICK PIC FOR BIGGER VERSION)



Other factors…

  1. The true radius to use with the winch is the radius of the can itself plus the radius of the line. The load is actually applied somewhere in the middle of the cross section of the line. Therefore if you get a bigger winch AND fatter line you have reduced your advantage twice!
  1. The mechanical advantages above assume winches with no gearing themselves. You get another mechanical advantage with the low gear ratio within the winch. Still, if you kept that gear ratio the same between two winches you’d still lose by moving to a bigger winch.
  1. While it might look like you’d want pencil thin winches to greatly magnify your advantage there is a problem in around how tight a corner you can bend the line and have it adhere to the winch face. Plus there is some effort wasted in just bending the line that doesn’t help you to trim. For this factor fatter line would require bigger winches.

I ask all of this because on our new boat we DO have bigger winches than we had on our Catalina and we do have fatter line…3/4” sheets which I think is over kill. As our crew will attest from our run from Long Island to Norfolk, these winches are a bear to crank in any kind of wind! To solve this problem I am going to 1. replace the sheets with ½ inch or 9/16 inch line. Yes this is a bigger boat but it’s not the Queen Mary! 2. Change out the lead blocks so the line is lead more fairly through this block and into the winch. Right now the line comes into the winch at a pretty steep vertical angle causing a lot of friction where the line crosses the base of the winch. 3. Disassemble the winches themselves and grease. I hesitate on this one because I’ve seen these disassembled and just know I’ll forget something or drop something in the ocean!

Hey sailors! Let’s hear from you! Other ideas?

11 comments:

Gracie Liberation Front said...

My father once told me that greased wenches crank better - though I'd keep that bit of wisdom between you, me, Gracie and the ocean fauna (in other words - iznay on the mentioning it to the firstmate).

By the way - my favorite line from your many blog entries has to be, "a bigger wench AND fatter line you have reduced your advantage twice." Truely - wisdom for the ages.

Right On Me Hearty!

Chairman Meow
The GLF

Alan Silverman aka SilverSailor said...

Sue and Scott:

A fellow South Haven, MI sailor turned me on to your blog. I'm quite evnious of your adventure. As a native New Yorker I still dream of sailing down the Hudson. I'll work backwards in your blog and read about that portion of your trip latter. Scott, I too have this fear of dismantaling my winch only to watch parts dissappear overboard. Someone suggested taking a box top, cutting a hole, fitting it over the winch and then taping the hole tight around the winch base. Sounds like a sensible precaution. You id miss the most amazing fall that Illinois/MI have experienced for some time. Walm, balmy weather right up to now. Even today with winds gusting to 40mph it's still quite walm out. My personal hope is that it will soon start snowing and not stop until March 30th. I have a new boat on the way that draws 5'2" and we need more water in Lake Michigan.

Stay well and remember "don't Postpone Joy."

Irfan said...

What we do in the autoshop when when a bolt is too hard to turn is get a long pipe and put it on the end of the ratchet and turn (or get an impact gun). Maybe you should take the black knob thing off and put a big pipe on the end of the handle. I don't know how good my advice is, i don't know anything about boats or winches.

brian said...

Someone has a lot of time on their hands. Maybe bigger sails make for more force on the line, winch, and handle anyways. Could be time to put Gracie to work. Have a crew for your winches. Greasing would be the cheapest option provided you didn't lose anything. Think about it.

Jason said...

It seems to me that, on the farms, they used to attach oxen or a horse to a big lever and make them walk in a circle. I'm not sure why they did this...maybe they didn't like the oxen?

Anyway, I know you are probably short on oxen onboard the Enee Marie (although I guess I don't know that for sure...they used to carry livestock on long voyages, right), but you do have a four legged animal that might work nicely for turning your winches.

Make Gracie earn her keep!

Cindy said...

I'm thinking the dolphins probably know about what to do with bigger winches which are harder to crank :-/
I suggest spending mucho hours relaxing on the deck avec vino as you listen to their chatter and uncover such mysteries. That usually works for me.

Anonymous said...

Hi Scott,

Not all winch handles are created equal. Get a longer winch handle. Perhaps one with a double handle.

Randy

brian said...

Boy! If the students at Maine East had shown this much interest in a physics problem Scott might still be teaching.

Irfan said...

I am a student at Maine East.

brian said...

OK So?

Jack said...

How about a power wench?