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