They embarked upon their journey before detouring to Gran Canaria on February 23. The crossing resumed on March 12, with two members absent.
The crew's charity website, rowforwater.org, estimates each member would have taken at least 800,000 strokes to complete the feat. They initially moored themselves to a buoy in Baracoa Harbour, believed to be the arrival point of Christopher Columbus in 1492, and waited for immigration to grant them a return to landlubbing.
Giesen is coy describing how six turned into four.
"We had major problems on the fifth day, and had to divert to the Canarys to fix the water maker.
"Two left the boat, for personal reasons."
When pressed, Giesen says: "They weren't physically and mentally up for it, really."
After waiting for a low pressure weather front to roll through, Giesen's own barometer went into a spin when they returned to sea.
"I had a stomach virus for the first four to five days and ended up s**tting into the bucket four times over one two-hour shift."
Despite the hardship, Giesen observed time-honoured etiquette.
"You fill it with about 20-30cm of water, do your business, then throw it overboard, wash the bucket… and life goes on."
Giesen relished the faintest luxuries. He washed his "Jesus" hair every 10 days, which he describes as "a nice time to become normal for two hours". He also raved about using the handgrips cut from an old 6mm wetsuit; a nifty innovation recommended by veteran long-distance rower Kevin Biggar to protect hands from the elements.
Those frills mollified the setbacks.
"It would've been about the middle of week four when we lost our steering cable for the hydraulic system," Giesen says.
"We couldn't run our autopilot and had to hand steer from then on. We'd row for six hours a day, then steer for six.
"The boat was under-steering the whole time, too. At 15 knots you'd go all over the shop overcorrecting one way or the other."
The turmoil at sea cemented Giesen's desire to go it alone when the next solo event rolls around in December.
"I can't wait to do that, after going with other people. I really enjoyed most of it out there, particularly the simple routine.
"We had a meal and a couple of beers after finishing, but have since parted ways. I needed my own space. A lot had gone on from planning, to going solo, then meeting these guys, who each had pretty different personalities."
Giesen welcomed the chance to sleep in the front cabin. The back one saw water seep through a couple of times when the hatch was left open.
"It was humid and smelt horrible. Mine was a luxury penthouse by comparison. That made for two different experiences."
Giesen enhanced his logistical knowledge ahead of the next attempt.
"I'm still trying to turn negatives into learning curves, but one thing I know is that the 2am-6am shift is awful; that's definitely the time I'll be sleeping out there.
"I also learned that when you see horsetails, or lines in the cloud, you get hit with wind from that direction within a couple of hours.
"I'll also be taking oranges and apples onboard because, if you vomit, they're one of the best things you can have to freshen up afterwards."
Eating on the voyage proved less about concocting Michelin-star meals and more about chowing down enough energy for stints on the oars.
"I lost a bit of muscle, but only about 6kg," Giesen says.
"We had different food to what I would've had [solo]. There were freeze-dried, 1000-calorie meals but there was no flavour to them. Chicken noodles were probably the best thing to add.
"I bought 400 Euro of extra sauces and spices to add, and I included olive oil with every meal so they didn't taste like they were."
Regardless of whatever was on Giesen's menu, it was for a cause close to his heart.
He lost an aunt and two mates to suicide in recent years.
Giesen believes the next generation can change the way New Zealanders think about mental health.
His original campaign, under the moniker "The Blue Rower", has raised $20,266 in the name of mental health for the Bravehearts, Black Dog Institute and Victim Support charities.
Giesen says he has never officially suffered from depression, but that should not stop New Zealanders talking about it.
He might make his next Atlantic attempt on his lonesome, but there will be no lack of support from afar. An important message worth remembering for anyone.
