When my son Sam was a baby, I used to rock him in my arms with a deep swing, trying to teach his body the fetch and sweep of the ocean.

I've been a sailor all my life, mostly in small sloops, and I really wanted him to have that, too.

I never dreamed we'd get the chance to go to sea together in tall ships. But that's what we do.

Today we're crewing on the Irving Johnson. She's more than 100 feet long, with two 90-foot masts and 12 huge sails. Today, while our shipmates show sightseers around the deck, Sam and I are going aloft.

Sam shouts "Laying aloft!" and a shipmate in the rigging calls back the traditional permission to start climbing, "Lay away!" It's an untethered climb, and it's a long way down, so you have to pay attention. Those calls let others know we're coming up, so there aren't collisions. Once Sam is well ahead of me, I call out that I'm coming up, wait for his answering "Lay Away!" then start to climb, too.

We meet on the lower topsail yard, a horizontal pole the size of a lamppost that holds a sail 40 feet above the deck. We clip our safety harnesses onto stainless-steel cables, then step out onto the slender footropes, which sway under our weight.

Up here, I can still hear the passengers milling around on deck, but being aloft concentrates the mind. The chatter below fades to a murmur.

When I started taking Sam sailing in my 25-foot sloop, the tiller could knock him off his feet, and he could barely see over the bow. He also had trouble with depth perception. Even stairs were a challenge. To try to help him, I invented what I called the "noticing game," seeing how many boats he could spot on the horizon. But now he's teaching me.

Sam sidles out along the footrope to the end of the yard and hefts the clew lashing, a length of braided line that is fastened to a wooden pulley and steel chain. The clew lashing holds the yard below us level. It's important to tie it properly so the yard doesn't swing down like a seesaw when somebody steps onto it.

When we aren't using the sails, we roll them up and tie them down. That's fairly easy here at the dock, but it's important to think about how you'll distribute your weight for stability with the ship surging through the waves. Details of posture and grip matter. Sam braces his torso against the yard and hauls the line in. It comes up easily at first.

"You have the line in your hand," he says, turning to show me.

"Yeah," I say, concentrating.

"Stick it through the back."

He threads the line through an eyelet in the sail.

"All right," I say.

Sam places his feet wide apart, leaning the bottom of his ribcage hard against the yard and leaning forward, sliding his hands down the braided line.  He heaves up on the line, straightening his back to strain against the weight of sail and chain.

"Stand up like this," he grunts. "You grab it, you bring it up, you brace it over and then you haul from here and here."

He's panting, but he has the lashing taught, and he ties it with a "slippery" hitch that holds fast but will be easy to undo with one hand when we need to.

It's easiest to balance on the footropes with the hips or stomach pressed against the yard. Since I'm tall, sometimes it's hard to get as low as I'd like to be, and frankly, doing this chore can make me nervous. I'm working on it. The Irving Johnson's captain, John Kraus, says the ocean has a way of teaching you about yourself.

"People have tattoos: 'The sea hates me,'" John says.

"There is no one to blame. It is simply, that is the natural state of the world. And how you want to deal with that is going to make up your character."

Sam loves computers. He's always telling me about the latest software or high-tech gizmo. Still, he says in those moments when we leave our home port of San Pedro behind, and Los Angeles slips over the horizon, he realizes how small we are.

"We keep on congratulating over all of these discoveries and they are very exciting," he says. "But some people tend to believe that we're master of all. And we'll never be master of all."

That's an important thing for a young man to learn.

At these sailing festivals, we take passengers out on mock cannon battles. We maneuver as though it were a real fight, and there's a lot to do, fast.

Hauling the lines is always hard physical labor and "sweating" them tight is a real workout. To do that today, my shipmate Marann pushes hard against a line, then hauls down sharply with her whole weight while I take up the slack.

She sets the rhythm.

"Forward, back, together," she says. "Forward, back!" The wind and the weight of sail overhead fights us, but the line inches in.

I used to think I had to tell Sam what to do. Now we often work different sailing stations. I'll glance across the deck and ... he's grown up.

"He has a high level of emotional intelligence, so he can keep his head in the game," First Mate Connie Allen says.

"That makes a great sailor."

One of the things Sam and I like best about crewing on tall ships is the shanty sings. We love the rhythm of those work songs, and know the words by heart. Looking around at my shipmates' faces as they sing, I realize what a tight bond there is between us. It's partly the shared love for the ships, partly the hard work, partly the absolute confidence in one another aloft.

Sam will graduate from high school next June and will soon enter college with a passion for technology. Whatever he does, he'll always know what it means to trust in his shipmates and to be trustworthy.

"It's kind of like accepting that gravity exists," he says.

Recently I stood on deck and watched Sam working aloft. I realized he's more than my son. He's my shipmate.