Waves/Swell height and spacing for fishing

So much good information here.

I'm in a Malibu 182, much more boat that my old 16ft aluminum bow rider, though I realize that I'm still really in a quite small boat. But regardless, I'm also looking to venture out off Winter Harbour and other WCVI spots.

A few spots this weekend have 2-3ft swell with 5-8s period at the worst times and 14-15s period at other times, so I'm thinking for the most part I'm good as long as I'm watching the afternoon wind and consider when the tides change directions, especially over the Nahwitti Bar (that's if I decide to head that far).

It seems like there's a consistent message about watching local conditions and not relying on a single model.

But regardless, is it safe to look at it like this - if the swell period is 2x or greater than the swell height, then you're generally good? Or do I need to add the predicted wave height?

I'm looking at Windy for Grant Bay this Saturday which is at 3ft waves, 2ft swell and period of 8.7-14.8 during the day, and then switches to ~5.5 period in the late afternoon/evening. Seems like the evening conditions will be really uncomfortable and getting potentially dangerous for a small boat like mine, but the morning and midday conditions should be really comfortable.

swell x2 is 2x2=4, so if the period is >4 then I'm good, though that seems tight and likely uncomfortable, or do I look at adding the wave ht on top? 3+2=5ft. 5x2=10, so a >10s period would be a safer calculation?

Same day for Sutil is looking like 2ft waves, 2ft swell and a consistent period of ~8.5. Seems like a good day, except for considering the early afternoon ebb over the bar that's likely to combine with a 10-15knot W-NW wind.

Same math. 2+2=4, 4x2=8, so if the predicted period is consistently 8.5, then I'm probably good to go? Especially when the wind is down. A 15knot afternoon wind adding a 2ft chop on top would change things to get toward uncomfortable.

I definitely have a lot to learn, and I will definitely be taking notes on my days out as far as predicted vs actual to figure out what was like a lake, what was swelly but good, what was swelly and white knuckle, and what was no-go or wish I'd gone back earlier!

I took my old 16ft bowrider to Grant Bay once, definitely was nervous going out, but the forecast was epic and it turned out really well. I didnt catch as many fish as I'd hoped, but the weather made getting around really comfortable. Tried again the next year with a similar forecast, but when I went through the notch and turned the corner things were not as favourable, and it was tricky to turn around and make my way back without being fearful of literally every wave. Since then I'd given up on Grant Bay and anything outside Kains until I got a bigger boat. It will be another good learning this year.
I think you should also keep in mind that the weather forecasts wave height at Average or Significant, but your plans should include Maximum wave height as well.


I read that wave height in relation to vessel beam is one of if not the most important consideration.
Consider the following in an engine failure situation.

(From Memory)
When wave height approaches the beam dimension of the vessel, the risk of a capsize event increases rapidly. If the wave height exceeds the beam dimension, and the waves are cresting, the unpowered vessel is at extreme risk of capsize.
 
I think you should also keep in mind that the weather forecasts wave height at Average or Significant, but your plans should include Maximum wave height as well.


I read that wave height in relation to vessel beam is one of if not the most important consideration.
Consider the following in an engine failure situation.

(From Memory)
When wave height approaches the beam dimension of the vessel, the risk of a capsize event increases rapidly. If the wave height exceeds the beam dimension, and the waves are cresting, the unpowered vessel is at extreme risk of capsize.
I’ll keep that in mind. Definitely many days where that’s the case and it’s pretty apparent when it is!
 
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