The longer the period of the north swell the more energy in the swell. When cruising the BVI I usually have 3 weeks of time (what I get in my passport when I clear in) so I am not under any pressure to visit a number of sites in a week; and since I prefer calm to rolly when given a choice I will seek sheltered anchorages when there's just a chance of getting a north swell roll. So a period of over 10 seconds gives the waves a lot of energy, but in 20 feet of water they won't be affected by the bottom and a swell of 1m won't have me scurry to the North Sound; I'd probably stay in Cane Garden Bay if it were a Sunday and I could see the Elmtones play live.

I got caught in Cane Garden Bay by surprise once, as I'd not checked the weather. Shortly before sunrise the swell set in, I believe it was 1.5 to 2m with a very long period. I left the anchorage at sunrise and was worried about bottoming out while departing the CGB channel with surfers coming right by me surfing the break.