Wave Height

How big was that wave? Recently, as Fish and I paddled towards Buoy 11A next to the Southport shipping channel, we found ourselves in wall height waves. Thankfully, these were green ocean swell, not breaking or we would have been crushed for sure. They had a roller coaster quality, and were moving very fast. We both agreed they were 6 to 8 feet high. But it really is so hard to tell. One way I measured them was watching Fish ride up the wave in front of me and noting that his boat seemed a few feet longer than the back of the wave he was climbing. His boat is just shy of 16 feet. But the back of a wave is longer than the front. This is the kind of thing that makes wave height so tricky, when sitting in a small craft on a big sea.

I found the quote below helpful:

"In the excellent Sea Kayak: A Manual for Intermediate and Advanced Sea Kayakers, Gordon Brown lists a nice standard rule for sea kayakers and canoeists, “If you have a distant horizon the waves are less than one metere. If your horizon is the crest of the wave immediately in front of you, the waves are over a metere.”

Using this rule, you’ll know that if you can see the horizon, the waves were less than 3 foot. If you can’t, they were over 3 foot. To refine the rule further, when under 3 foot if you loss sight of just your partner’s boat when they’re in the trough of the wave, then the waves are 1 foot. If you lose sight of your partner’s shoulders and just their head is visible above the crests of the waves, then the waves are 2 foot.

Estimating wave height on overhead waves is much harder. To get a reference sit on the floor in the kitchen and look to the top of the refrigerator. Most refrigerators are 6 foot tall, so if the wave looks like a refrigerator coming at you, then it’s probably 6 foot tall.

Remember when in a kayak, the waves always look bigger than they are." Credit Bryan Hansel, 2009