Thursday, November 18, 2010

Onshore Offshore Sideshore Frontside Backside

I had fun windsurfing at the Nahant Causeway on Wednesday afternoon. The wind was "side-offshore" from the Southwest, and it picked up throughout the session up to the point that I was overpowered on my 4.7 meter squared sail. The waves were waist to chest high and nicely set up for long "frontside rides". Here's the video. The song is by the band "Air".

SW Wavesailing Nahant 17 Nov 10 from James Douglass on Vimeo.

Also, since I'm always blogging about "onshore, offshore, sideshore, frontside, backside" etc., I figured I ought to put in some pictures that illustrate what those terms actually mean in the context of riding waves with a windsurf. I defined the terms earlier in my "windsurfing slang" post, but I think the pictures will help.

First up there are the wind angles, which are defined relative to the line of the shore. Onshore wind blows from the ocean directly towards the beach, in roughly the same direction that the waves are moving. Offshore wind blows from the shore to the sea, in the opposite direction of the incoming waves. (Waves often originate from hundreds of miles away where the wind is blowing in a different direction. That's why there can still be waves when the wind at the beach is blowing offshore.) Sideshore winds are blowing parallel to the shore, from the right or the left. Side-onshore and side-offshore winds are diagonal to the shore.

You can ride waves on a windsurf in any wind direction, but you have to ride the waves in different ways, depending. In onshore wind, the wind and the waves are moving in the same direction- towards the shore. So you have to ride downwind with your back to the wave. This is "backside" wave riding. It's generally considered the least desirable kind of wave riding, because the wave's movement subtracts from the apparent wind speed, the waves are often disorganized and bumpy with wind-driven chop, and after you're done riding the wave you have to work your way upwind through a bunch of waves to get back where you started. Onshore wave riding is still awesome, though.

Offshore wind can be cool for waveriding, because you can ride with your body facing the wave, banking off of it like a nascar driver on a raised track as it pushes you upwind towards the shore. It's also a fairly easy downwind trip to get back where you started and catch another wave, like riding an escalator up and taking a waterslide down. This is "frontside" wave riding. It can be a bit hard to initially catch the waves, though, because you have to ride upwind to do so. It's also impossible to get ahead of a wave in straight offshore wind, so once you're on it you either have to ride it to the end or sneak out over the back of it before it breaks. Also, offshore wind tends to be gusty and light near the shore, and it has an element of danger, because if you break down you might get blown out to sea. For these reasons, folks usually prefer side-offshore wind over pure offshore wind.

Sideshore wind is probably the best of both worlds, because it allows you do both frontside and backside wave riding. Backside waveriding in sideshore wind helps you get upwind at a steeper angle than you can normally sail because you're getting a boost from the wave. And frontside waveriding in sideshore wind has a dynamic feel where you alternate between riding powered by the wind and riding powered by the wave. You can even mix frontside riding and backside riding on the same wave in sideshore conditions. What a lot of people do is ride the wave backside at first to grind upwind, then when wave the wave gets closer to shore and starts to steepen up and break, they swoop downwind do some frontside turns on it. Super cool.


Catapulting Aaron said...

Nice! Looks like there are some "off the lip" opportunities out there.

James Douglass said...

Aaron- Yeah, a good waverider could totally rip those waves up. Whenever I watch video of my own wave rides I'm like, "Doh! I should have smacked that section instead of scooting away from it." I'm a much more aggressive wave rider in my imagination than in real life. One of the other guys who was out that day, Fred, was doing a real good job of throwing spray off the lips during his top turns. I need to learn how to do that.