To continue this vexing question (well, it does vex some, and hexes others, with possibly some sex in there as well, because what is more romantic than a tropical full moon with the palms whispering in the breeze?) of whether Bali & Indo surf is better on the full (or new) moon.
The first thing to keep in mind is that those deep ground swells that make for Bali’s epic surf take about five days or so to hit the island’s coasts and reefs. Which is why you can track the swell ahead of time and travel to your favorite surf spot to be there when it arrives. So the swell is actually being produced by the “mid moon” (if in fact the moon has any influence).
So the question becomes whether the moon affects weather systems and atmospheric disturbances.
The short answer (provided by a number of meteorologists, but I can’t locate the file where I saved the Internet references): the influence is so small as to be negligible.
Although I suppose that if the flap of a butterfly wing in Mexico can cause a storm in Japan (chaos theory) you could say this minute lunar influence on atmospheric systems can seed a swell. If that’s the case, then doing belly-flops off the back of your surf charter boat into flat flat flat ocean will do the same—for the next charter.
The moon has a dramatic influence on the tides and tidal currents, though. That undeniably (by a factor of duh!) has an effect on the surf. Those spots that you prefer at the highest or lowest of tides (famously Outside Corner and Desert Point on the lowest of the low) will be better on full and new moons.
However, I suspect that a simple statistical analysis of historical swell data will show that the phases of the moon has no effect on whether there is swell or not to begin with. And for good surf, we do have to begin with the swell, right?
Also, there’s probably a psychological influence. Big swell combined with big tides means wave surges will wash dramatically, and memorably, onto and over the beaches and berms. You’ll remember that swell more than a same size swell that keeps itself safely to the reefs and lower beach strands. This contributes to the “full moon, bigger swell” meme.
In my opinion, the best time for an Indo surf trip is during the mid-moon, when there is little tidal change. Why? Because those breaks that are best high/low will still be good, and will be good for longer hours of the day. Also, there will be little to no current to struggle against or worry about. And if you lose your board in a big swell with tide current at some spots, in a week or so you could be saying hello to the penguins (hyberbole aside, scuba divers lost off Nusa Penida have been rescued off the coast at G-Land).