February 23, 2014

Of bubbles in compasses

The Disease Called Cruising

15. Hello Kero, Goodbye Gin

BUBBLES IN COMPASSES are pesky things. Small ones don’t really affect the performance of the compass much, but they wobble and get magnified and attract attention to themselves all the time.

A bubble in your main steering compass is not only very distracting for the person at the helm but socially unacceptable, too. Sensitive visitors will ignore it, as they would a cockroach in the galley, but others more crass will comment loudly and make dire predictions about the accuracy of your landfalls.

Decades ago, when I started sailing, nearly all compasses developed bubbles. It didn’t seem to matter much. In fact it was a marvelous excuse to get out the gin bottle.

The compass fluid then was colorless alcohol, which didn’t freeze in cold weather. Gin was another colorless alcohol with warming qualities in cold weather. Furthermore, it was carried aboard every well-found sailboat. So we simply drove the bubbles out with gin, and then we swallowed some ourselves to celebrate our cleverness.

But expansion chambers and seals on compasses have improved over the years. Bubbles don’t occur as frequently any more.  Nevertheless, I thought I knew exactly what to do when my Sestrel porthole compass developed a bubble. I poured myself a large gin and shared it with the compass.

To my horror, the gin turned into a little glob of sludge that crouched menacingly at the bottom of the bowl, plainly visible to visitors.

I took the compass out, drained all the fluid, and took myself off to the Sestrel agent to get some more. To my astonishment, I learned that the modern manufacturers had abandoned alcohol while I wasn’t looking. They had gone over to a petroleum-based damping fluid. The Sestrel people called their fluid Sestroil.

As usual, it was unreasonably expensive. But that wasn’t the worst part. The agent simply didn’t have sufficient of the precious Sestroil to fill my whole porthole compass. They could let me have enough to top it up, to eradicate a bubble, but that was all. I said thanks, but it was too late for that.

Since the fluid in my compass was petroleum-based, I called the technical department of an oil company to see if they had a substitute. They were no help at all. They couldn’t help me unless I could furnish the technical specs of the oil required.

So I called the manufacturers of the compass, Henry Browne & Son, in Britain, to get the information. It turned out that they’d gone bust. There were plans to start production again, but meanwhile there was a world-wide shortage of Sestroil.

By now, however, I had the bit between my teeth. I had a friend who was a chemist, and by dint of some clever detective work he discovered that Sestroil was not the secret magic potion that Henry Browne & Son had made it out to be.  It was, in fact, basically kerosene.

So I filled my Sestrel with lamp-quality clear kerosene at a fraction of the cost of Sestroil and it worked perfectly.

Unfortunately, there’s no longer any excuse to get out the gin bottle to celebrate the birth of a new bubble, but there are compensations. For instance, it’s comforting to know that next time the kerosene cooker runs out of fuel at sea, all I have to do is drain the fluid from the compass.

Today’s Thought

Change as ye list, ye winds! In my heart shall be

The faithful compass that still points to thee.

— John Gay, Sweet William’s Farewell to Black-eyed Susan


Demographers tell us that one in five people in the world is Chinese. There are five people in my family, so  one of us must be Chinese. It's not me. It's either my Mom or my Dad, or my older brother Fred, or my younger brother Hing-Cho-Cha. But personally I think it's Fred.

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