Peter Arno

Peter Arno was a New Yorker cartoonist in the middle decades of the last century. His cartoons were often politically incorrect - he might have said risque - even then. The top one is from 1941, the priceless bottom one 1949, I think. Enjoy.

Bowline Strength Test - Conventional Wisdom Bites the Dust

My November 13 post was about the "correct" way to tie a bowline. Searching the web, I came across some comparison testing of the correct and incorrect methods (http://user.xmission.com/~tmoyer/testing/pull_tests_11_98.html). The testing was by a member of the Salt Lake City Sheriff's Office, which does a lot of mountain rescue. The protocol looked a little unorthodox but sound (see below). Here is the result of the bowline test:

            11/23 Test #14
              Pull a bowline knot to failure. A bowline was tied in each end of a piece of
              new 11 mm Blue Water rope. One knot was tied "correctly". The other was
              tied "incorrectly", with the tail of the rope outside the loop formed by the
              bowline. The load was applied between the two bowline knots, on a single
              strand of rope.
              Result: Material failure at the "correctly" tied knot at 4840 lbs.

The caveat I will add is that these knots were presumably both drawn up tight before they took a load. Just maybe the correctly tied knot is more stable and less likely to trip while drawing tight, a consideration if - but only if - the line is so big and stiff that it cannot be drawn up by hand - not a common scenario for the yachtsman. Also, with the tail inside the knot the correct bowline is a bit less likely to hang up, if that is an issue.

Here is the testing protocol:

"We used a vehicle winch on a Hummvee to apply forces. A second Hummvee was initially used as an anchor. However, with an end-to-end pull, and with all four wheels locked, we were able to drag both vehicles across the concrete floor with 5000 lbs force. (good number to know if you use vehicles as anchors.) We ended up anchoring one vehicle to a tank (yes - really) and the other to eyebolts mounted in the wall. A Sensotec load cell was used to measure forces. It is calibrated internally with a shunt resistor."

Flashlight holder

I use little Mag-Lites on Journeyman, the ones that take AA cells. The Mag-Lites are rugged, waterproof, bright and focusable, and you can keep one in your pocket at night on watch.

I keep one just inside the companionway to starboard, and I added another to the bulkhead separating the salon from the forward cabin. That new one is almost a spare, but it comes in handy when we are sleeping forward at anchor.

The flashlights come with a ballistic nylon holster. To make a mount, I trim the holster off short with a hot knife, then screw it to the bulkhead as shown, with two short fat screws. It is an effective and easy mount.

Every spring I put in fresh batteries, so the flashlights will be ready for emergency use.

My First Yacht

The New Yorker once ran a cartoon of a fellow lettering his yacht's name - "My First Yacht"- while leaning over the transom. The name was upside down.

I did have a slightly inspired idea for a yacht name, perhaps appropriate for someone new to yachting and a bit nervous about the whole thing. Here it is for the taking:

Tipping Point

How to Tie a Bowline?

My son Willie can tie a bowline with his feet. Pretty good.

A few years ago I sailed to Bermuda with a very accomplished sailor. (Circumnavigated in his 60 foot schooner when in his 20's, in the 1970's.) I tied a bowline in a jib sheet, and he instantly admonished me: "That's the wrong way." Huh?

 I had tied the knot with the tail on the outside of the loop. see photo at right. Tied "correctly", the tail is on the inside of the loop, see left.

Ashley, whose Book of Knots is the ultimate authority, here shows the knot correctly tied. The bowline ends up "correct" when it is thrown into the line, as shown in Ashley's illustration. (If you don't already know this trick, it's a good one to have.)

There are at least two ways any knot can fail. It can fail under load, and it can trip, or fail to attain the correct configuration before the full load is applied. I don't know if the "correct" bowline is more stable before the load is applied or if it is stronger under load - or neither. Anybody know?

Chock

When I got Journeyman both bow chocks were original equipment and a little small for my taste. I have mentioned before that my mooring is exposed (a five mile fetch to the west) and I pay close attention to the mooring tackle. If a bow chock tore out the pennant would likely quickly chafe through on the headstay. So I bought a new, nicely polished bronze chock, slightly oversize I suppose. A high polish is more than a matter of aesthetics: if the casting is burred or rough, chafe will increase.

The chock was an improvement but after a season it it shifted a bit under load, a bad sign.

When I rebedded the deck hardware two years ago I replaced the 1/4 inch (6 mm) bolts with 5/16 inch (7 mm) bolts, which seemed better matched to the forces and to the size of the chock. The bolts are backed by good size washers, and I think I used lock washers too. Everything is silicon bronze, so electrolysis will not be an issue. I am very happy with the installation, which is tight and movement-free after two full seasons.

I use this chock for the mooring pennant and for anchoring. The opposite chock seems ok for dock lines, so I will leave it for now.

Toolbox

Here are five handy items for a boat's toolbox. On the left is a calipers, useful for accurately measuring the diameter of line, standing rigging and bolts. Next is a spool of stainless steel seizing wire, for seizing rigging pins, shackles etc. Then a spool of Teflon tape, so useful in keeping threaded fittings from leaking. Then a bottle of medium strength thread locker (Loctite), good for masthead fittings and other parts that you do not want to vibrate loose. Finally, an extension mirror, for inspecting around the engine etc.