May 13, 2010

On the perils of learning

MY FRIEND MIKE REED recently suggested that I apply for a sailing instructor position going at the local community boating center. I told him I wasn’t interested because it’s a paid position. I only teach on a volunteer basis. That way, I can choose my pupils. I can hand-pick them, and they can’t blame me when they end up just as landlubberish as when they started.

But I have to admit that my choice of pupils is not always without flaws. Many years ago I agreed to teach a soldier to sail, a rather highly placed army officer, as a matter of fact.

I took him out in a small dinghy and explained that we were going to learn to beat. Anyone can sail a boat downwind but it takes a modicum of skill to sail upwind.

I trimmed and cleated the jib and told him to steer the boat according to the wind. Let her come up, up, up, slowly, slowly until the jib luff just starts to lift, and then pull off just a little. Up, up, up, lift, full and bye. Up, up, up. Follow the wind as it wavers back and forth. Concentrate on the jib luff, that little rippling bubble lifting right next to the forestay. Concentrate.

We were at it for about an hour, just beating to windward, and he did very well. By the time the hour was up he was doing it instinctively, as a good sailor always does. He didn’t have to think about it any more. His eyes just told his muscles what to do, bypassing the brain. He was pretty much a natural and I said so.

He told me afterward (and I say this with a blush) that I was the best instructor he’d ever had. Of course, all his other instructors had been instructing him on soldierly affairs. He’d never come across a sailing instructor before. So I take no credit for my role.

But anyway, two weeks later he committed suicide. Shot himself through the head with his service revolver.

I don’t know what part if any I played in that decision. I said to my wife: “I didn’t notice any suicidal tendencies.”

She said: “He went sailing with you, didn’t he?”

She’s a great one for irony, my wife. Or sarcasm. Or whatever you call it. Anyway, for some reason I found it a great relief that I hadn’t charged him for his lesson. And I’ve never charged anybody since.

Today’s Thought
Teaching is not a lost art, but the regard for it is a lost tradition.
— Jacques Barzun, Dean of Graduate School, Columbia University

Boaters’ Rules of Thumb, #51
Diesel exhausts (1). Black smoke. The gases should normally be quite clear. Black smoke is an indication that the engine is overloaded, or that the air supply is insufficient, or that an injector is malfunctioning. Improperly burned particles of excess fuel are being blown out of the exhaust.

Tailpiece
Definition of the word edible:
Something nice to eat. For example, a worm to a frog; or a frog to a snake; or a snake to a pig; or a pig to a man; or a man to a worm.

6 comments:

nikolay.roshtainsky said...

Speaking of learning experiences,
I had an interesting one this past week ordering a piece of standing rigging.

We noticed at the end of last year's season that our furling 150% mylar genoa has reached the end of its useful life. Getting new sails for the furler was quite a ways from our budget and since we already had two hank-ons in our wardrobe(a working 95% jib and 130% genoa), we decided to just get a regular forestay for the time being and put the furler aside. Unfortunately we could not reuse the original forestay as it was cut down to accommodate the drum assembly of the Harken MkII.

So on we went to measure the current assembly. After 3 times using 3 different methods we arrived at the same result, but I was perturbed because the figure was a foot short of the forestay measurement off of the boat's sailplan.
After careful observation we found several missing inches at the top, where tangs were added between the forestay's top eye and the masthead attachment (supposed to be toggle) as well as at the stemhead fitting and tangs attached to it.

The rigger I was in discussion with was looking at me like I was a mad man when I gave him the specifications. At first he was surprised that both ends were toggles, more so when we told him we're not doing furling, and he was flabbergasted when we said no turnbuckle.
We also got into quite a discussion on length because of my questioning the initial measured length so far off from it's calculated brother.
And end fittings; for some reason he was determined to prove to me that standing rigging did not break most often at the end of the hydraulically swaged terminal body where the wire exited and all the stress and fatigue was concentrated.

What do you think John?

John Vigor said...

Nicolay, I think you need to find yourself a new rigger. This one doesn't seem to understand the absolute basic rule of rigging economics, viz. the customer is always right.

Yes, toggles at both ends is a very good idea. No turnbuckle is daring, but perfectly logical if you measure right, because the backstay turnbuckle will adjust both stays fore-and-aft. The cowards among us only order a forestay turnbuckle because we're scared we can't measure accurately enough.

Remember to allow for the two kinds of stretch in wire rope. Construction stretch is permanent and results from the strands settling into place when the load is first applied. Elastic stretch comes and goes with every use. the wire stretches and then returns to its original length when the load is removed.

I'm afraid I can't remember how much to allow for construction stretch (if I ever knew) but as far as elastic stretch goes in 1 x 19 stainless-steel wire, when a 10-meter (33-foot) wire OF ANY THICKNESS is loaded to half its breaking strength, it will stretch 5 cm (2 inches).

The actual formula is Load in kilograms = (stretch in centimeters times breaking strength in kilograms) divided by total length of stretched wire in meters.

As for end fittings, I think most yacht riggers would agree that most stays and shrouds give up the ghost at the lower swaged terminal.

If the backstay turnbuckle has a reasonable amount of play left, I would use a forestay cut 3 inches too long, with a mechanical terminal fitting such as a StaLok. Then, if it proves too long, you can lop off an inch or two and re-use the StaLok. That's called trial and error. It's the method used by the cautious and incompetent like me, and it works.

Incidentally you can use a swaged terminal fitting at the top end, where they rarely give trouble.

Whew! I should be charging for all this. That's the basic rule of rigging economics that I never get right. The customer, in additon to being right, should always pay.

Cheers,

John V.

nikolay.roshtainsky said...

Thank you John,
Your wisdom is very well received and quite reassuring.

I'd like to think the stretch is taken into account as the basis of the measurement is the assembled original (shortened)forestay inside the foil and the drum. It worked before we took it off and we made no adjustments to it.

And just as you said, the forestay tension can be adjusted via the backstay turnbuckle which is exactly what the boat manual specifies.

I'm curious though how come its the lower terminal that gives while the top one stays?
Does it have anything to do with sail area distribution?

And incidentally, the mechanical fastener that was provided with the MkII kit that was put on the bottom of the cut forestay was, and still is, brutally unmovable. I could not, after 2 hours of trying remove it from the bottom of the stay, nudge it even a millimeter. the ferrule over the core wires is pulled in so tight I had to saw the cable right above the terminal - it was the only way I could disassemble the foils for transport.

Cheers,
Nikolay

John Vigor said...

Nikolay, my "wisdom" is worth every penny you paid for it.

The upper terminal is more protected from water running down into the swage.

In the lower terminal, water running down the wire can seep into the swage and start corrosion, which then expands and splits the terminal. The lower terminal also is vulnerable to spray and saltwater intrusion, which is even worse.

Mechanical fasteners are mostly designed to be reused, with new cones if necessary, and do not need to be over-tightened. It's also a good idea to fill the inside with silicone sealer before final assembly. That keeps the water out and forestalls corrosion, which will weld the whole thing together and make it impossible to reuse.

Cheers,

John V.

nikolay.roshtainsky said...

While we're on the subject of s.s. wire, I'd like to ask your opinion on spliced standing rigging.

Larry Pardey swears by liverpool splicing thimbles into the ends of his s.s. wire rigging.

What are your thoughts?

John Vigor said...

I don't have any thoughts on splices except that they are probably the strongest and most time-consuming way to terminate wire rigging. You can't easily splice 1 x 19 stainless-steel wire, so you'd have to have to find something more amenable, maybe something galvanized that would need a lot more maintenance. If you know how to splice and you find the right rigging wire and the necessary equipment, good luck to you. The rest of us, who swear by swages and StaLoks, will watch and applaud loudly.

Moitessier scorned both splices and mechanical terminals with Gallic disdain. He just used clumsy wire-rope clamps and wended his inelegant way all over the world.

Cheers,

John V.