The Chronicle has launched a new weekly Travel newsletter! Sign up here.

Lia Ditton, who rows small boats across big oceans by herself, says it’s not a good idea to know the name of the freighters and tankers that pass in the night.

“You never want to be able to read the name of a ship,” she says. “It means you’re way too close. You have to assume that a big ship is not going to move out of the way for a rowboat. You have to assume it’s trying to kill you.”

Ditton, a 38-year-old motivational speaker from London, spent three weeks this summer rowing a 21-foot boat from San Francisco to Los Angeles, for reasons that make sense primarily to her. Mainly, it was training for a modest little rowboat excursion across the Pacific, from Japan to San Francisco, she’s planning next year. It was especially important, she says, to get off the continental shelf, about 30 miles off the California coast, where the seafloor plummets and the rigors of ocean rowing come into sharp focus.

“It feels very wild. The transition point between the shelf and the deep water is huge,” Ditton says. “To go outside of that line is big.”

Ditton would be the first woman to do that, if she pulls it off.

Her track record speaks for itself. She crossed the Atlantic solo in 2010. Earlier this year she twice failed to row from San Francisco and around the Farallons and back, but she is gearing up to try that again this month. In December, she plans to be the first woman row from Redondo Beach, circle Catalina Island and return.

Initially a professional sailor, Ditton started rowing in 2009 after a Danish Olympic rower called her out of the blue and asked if Ditton would help her navigate across the Atlantic. Ditton didn’t end up joining that trip, but it opened her mind to the possibilities of solo rowing expeditions.

Asked why she rows boats in the first place, Ditton talks about setting personal challenges, human potential and setting records. But these days she also aims to set an example for young girls and to raise awareness for ocean protections and world hunger. Hunger, in particular, is something Ditton can relate to during her expeditions, during which she consumes upwards of 6,000 calories per day.

“When you’re rowing, to have that ticking clock on resources is powerful and motivating,” Ditton says. “It’s only when you’re down the wire yourself that you know that means. I realized this could be a very important platform for talking about hunger.”

Typically, Ditton consumes a mix of nuts, dried meats, freeze dried meals, Pro Bars, spaghetti and, oddly, baby food. On special days, she has a big bag of kettle chips — the greasy kind. On very special days, she changes her socks. A rower’s feet can become as pungent as any other seafaring scent. “Nothing,” says the mistress of the seas, “has the power to boost the spirits as a pair of fresh, dry socks.”

Her boat, a 21-foot-by-five-foot craft is made of plywood, glass and kevlar and weighs about 800 pounds. There’s a sleeping compartment at the stern and storage at the bow.

After 19 days at sea, Ditton pulled into the Los Angeles County port of Redondo Beach. In her log, she called Los Angeles a “cluster of tower blocks,” one of the city’s gentler sobriquets. Her problems were far from over after stepping ashore.

“On a Los Angeles freeway,” she said, “you go about the same speed as you do in a rowboat. It makes you want to turn around and go back out to sea and start rowing back.”

She didn’t do that, however. She had the rowboat shipped back to San Francisco. She herself returned by plane. When you are trying to get out of Los Angeles, you want to do it faster than 2 knots.

She said the trip was fun, at least when the large ships weren’t trying to do her in. That also goes for the storms, giant waves, wind, heat, airplane engines, short rations, sharks, jellyfish and inattentive fellow sailors that may have been trying to kill her too.

Here are the most challenging parts of Ditton’s trip, in her own words:

1. Jellyfish

Between Monterey and Santa Maria, I had the most incredible ocean wildlife encounters I have ever experienced in 150,000 miles of global ocean travel.

Whales breaching nearby always take my breath away, but these whales breached so often and came so close, they became company, my escort south. Sardines shimmered on the surface like a murmuration of starlings; sunfish flopped about and one afternoon I played peek-a-boo with a seal, the seal hiding behind the rudder and then popping his head up over the main cabin to look at me, doing this again and again.

So imagine my horror, when one night, I saw what I thought was a large white plastic bag floating alongside my boat. I gripped the rail and was about to launch my hand into the water to save the planet, when the white plastic bag pulsed. On close inspection, the white plastic bag had tendrils. The white plastic bag was not in fact a plastic bag, but the largest jellyfish I have ever seen in my life. Close call.

2. Weather

Santa Ana winds, known locally in Santa Barbara as ‘the sundowner’ are common in October maybe, but July? That was a surprise!

I was rowing steep seas and hitting top speeds as the sun sank to the west. The rowing felt wild, verging on out-if-control and I was concerned. Then the wind snubbed out with the sun. Poof. Just like that. There was a whiff of warm air off the Santa Ynez mountains that smelt divine, of cedarwood.

The sea knew before I did what was about to happen next. The waves began jumping about all over the place. I looked to the land and felt an apocalyptic blast: 90 degree wind screaming at 40 knots. At that moment, I was 2.5 miles upwind of oil rig Harmony, feeling anything but harmony.

Later that night when I had lost the shelter of Point Conception, I heard a huge wave roaring towards me, a terrifying sound like that of an oncoming train. The wave - known locally as a “growler” - out of sequence with the wave pattern, smashed into the back of my boat like a car crash. Water rained over the cabin and swamped the deck. This happened 3 or 4 times before I realised that being hit by a growler was more dangerous than crawling on deck, hauling in the sea anchor and letting the boat drift across the shipping lane.

3. Other Ships

I had 5 close encounters with ships. The first was an empty car carrier. When I saw the boat’s light in the dawn, my whole body began to shake, which has never happened before.

I dove into the cabin for the radio:

“Big ship, big ship, this is rowboat,” which sounded ridiculous even as I said it.

Nothing. No reply.

Back at the oars, I picked up the pace.

“Big ship, blue hull, this is rowboat.” I tried the radio one more time. “We are on collision course.”

The response to those words was immediate. The ship turned 30 degrees to port.

“I don't see you, are we clear?” asked a sleepy sounding voice.

A few minutes later I stopped shaking and gulped down some breakfast.

My fifth close encounter wasn’t with a commercial ship, but a pleasure boat. When I saw the boat charging towards me, I was excited! It had been almost two weeks since I’d seen people!

The powerboat rounded my bow adeptly and came along my starboard side. I expected the vessel to slow down, someone to appear outside, open a window; hang out of a door.

No one came outside.

Through the window I could see there was no one in the wheelhouse at all. My boat was 40 feet from ploughing into the boat’s stern. The boat's name was Sand Dollar on autopilot, and the owner-operator will never know how close we came.

4. Sleep

I slept in 40-minute (one sleep cycle) or one-hour 20 (2 sleep cycles) chunks, checking for ships and resetting my alarm maybe four or five times in one night. I was surprised how well my body adjusted to this pattern.

On the night of the freak Santa Anas, sleep was impossible. My boat was being buffeted - worse - being dragged backwards, upwind and up waves, because my sea anchor (a giant underwater parachute to minimise drift) had hooked into a westbound current determined to trawl me back out to sea. According to my heart rate monitor I rowed 19 hours and 45 minutes that day, in an effort to round Point Conception before nightfall. I was desperately tired. I began hearing voices, people’s voices! I would open the hatch excited to see people… that weren’t there.

Hours later, as I was pulling in the sea anchor, waves crashing over the boat, I looked forward to the forward cabin and saw a small hand trying to open the window from the inside. “That’s not real!” I told myself.

I’ve heard voices before, racing a sailboat single-handed across the Atlantic. Never an apparition. That was new.

5. Rowing Nude

For the most part I didn’t row naked down the coast of California. It was too cold and windy! But that changed after I turned the corner to Santa Barbara and on to Redondo Beach. It was really hot!

I have been working with Under Armour since January, to create seam-free clothing for rowing. The pants they made for me are amazing! However I have been wearing their off-the-shelf SPF long-sleeve top, as there didn’t seem a need for anything custom… until I took off my vest layer. The shoulder seam had given me a chafe burn under the arm making clothing unbearable to wear.

(At least, that’s my story and I’m sticking to it!)

South of the Channel Islands, the Coast Guard cutter was out on patrol. The cutter’s engines are quiet and so I didn’t hear them approach. As the boat got nearer, they slowed the boat right down to a crawl. There was a flurry of activity by me to find clothing, which I suspect looked suspicious. They did not call me on the radio. They just sat there watching.

I was just about to take a bucket bath, so glad I waited! Naturally I saw the Coast Guard again later, as I was indeed taking said bucket bath.

Steve Rubenstein is a San Francisco Chronicle staff writer. Email: srubenstein@sfchronicle.com