* McNamara holds record for biggest wave ever surfed
* Hoping to find one nearly double the size in Portugal
* Nazare's coast, underwater canyon produce "monsters"
By Axel Bugge
NAZARE, Portugal, April 9 (Reuters) - World-renowned American surfer Garrett McNamara holds a record for riding a 78-foot (24-m) wave - the largest ever surfed. Now he wants to find one almost twice as big.
"You know every wave is so different," McNamara said, looking out at the Atlantic Ocean from the village of Nazare in Portugal.
"It just depends on the ride, like when you come down and you don't make the wave and you get blown up and you just feel like so small, but also so alive, because you're at the mercy of this monster and its gotten hold of you and shaking you and rattling you," he told Reuters.
McNamara, 46, from Pittsfield, Massachusetts, has had countless experiences like that scouring the world for the wildest rides.
He set his first record on what he calls the "Holy Grail of huge waves" in Nazare (Portuguese for Nazareth) in 2011. Ever since, he has been scouring the horizon for the next one.
"It would be nice to ride a 100-foot wave next. Well, actually I'd probably go for a 120-footer," he said.
McNamara has achieved what few athletes have managed - to follow his passion all his life. He started surfing aged 11 and never stopped.
At 35 - a mature age in many demanding sports - he sat down and sketched a plan on how to keep going as a professional.
"I was about to retire, start working 9-to-5, and I wrote my goal - surfing," he said. "What do I do? Win this, win this (competition). How do I do it? Train, focus, and it worked."
Just as importantly, he got all sponsorships he needed.
THE "PERFECT BOARD"
McNamara has begun to design what he calls the "perfect board" with the help of engineers from Mercedes-Benz, which began sponsoring him two years ago.
Inside his warehouse on the dock in Nazare, the first prototypes are on display - sleek and silver-coloured. Their in-built weights and flexible tops help absorb the chop as he rides down waves.
"I rode it for the second time today and it feels so much better than all the boards I ever rode," he said.
McNamara has lived most of his life in Hawaii. But he has chosen Nazare over other surfing hotspots as the place where he is most likely to find his monster.
"These are the biggest that I have come across," he said, looking out at the sea from a hotel balcony.
"There's giant waves in numerous occasions around the world, it's a matter of the wind being offshore. Here, you have so many giant swells every year, more than anywhere I have encountered."
The Atlantic pounds Portugal's western coast unimpeded by islands or other barriers. But Nazare is unique in having an underwater canyon that runs right to the beach, compressing the water and making the waves burst higher.
"It starts pretty wide, a few miles wide, then it comes down so it just compresses everything," McNamara said. "And when it finally reaches a shallow enough point, it breaks and you have sideways waves, so it creates even bigger waves."
The effect is breathtaking, pushing waves nearly as high as the lighthouse sitting at the tip of a headland in Nazare, where McNamara often sits watching the water.
McNamara was first invited there in 2010 by the local city hall. "They wanted to know if their waves were any good, if it was good enough for an event," he said.
McNamara went on to put the village on the global surfing map and boosted local tourism. In 2012, he married his wife Nicole there.
"I'm here to have fun," he said. "I'm here to show the best kept secret in Europe - Portugal - and the 'Holy Grail' of huge waves." (Editing by Michael Roddy and Andrew Heavens)