Wind/Wave maxium for a fun dive? How is 12 knots?

[lowtech]

I have found that, for offshore dives, it is not the wave height that is the biggest factor in how challenging a dive may be but the correlation between wave height and wave period. The closer together the two are, the steeper the face of the wave will be. 8 foot seas with a 20 second period are nothing but a ground swell and in many cases easily diveable, where a 4 foot wave height on a 4 second period will eat you alive. Try to get the most recent information from the buoy closest to your dive site and make the best decision possible by factoring in wave height and period, wind, and diver experience. A bad day on the water can be very ugly indeed and sometimes the best decision that can be made is to simply dive another day.

I find that shorter period waves produce less dramatic surge.
For shore dive I'm generally just looking at wave height to gauge if it's dive-able.
If it's dive-able then periods, winds, tides temps, etc play into how much effort I feel like putting in.
A shorter period would constitute less effort for me.

I generally don't do anything over 3 feet from shore, and I haven't had any real experience on a boat in more than 3-5 seas.

 

[Quero]

I assumed GrannyScuba was talking about a 12 kn wind speed and what sort of wave height that wind would produce....

 

[g2]

The other consideration (one of many!) is the wind direction.

For instance, I have declined to shore dive when the seas were flat (inshore) but the wind was blowing 20-30knots out to sea. The concern was contingency plans if we had to surface away from shore... There was no hope in getting back or being seen.

Likewise, I've had great dives in nasty storms where the winds were blowing inshore. After getting below any waves, turbidity and surge, the conditions were great. YMMV.

The wildcard in the PNW (dunno about Florida) is current. Windy conditions can cause unpredictable currents, especially in areas subject to tides.

 

[Quero]

Yes! Currents arising from winds are something of a problem here too, primarily for shore diving. During our southwest monsoon season, wind-activated waves breaking on our sandy western-facing beaches create sand bars, and even though the waves themselves are not huge, lulling swimmers into a belief that they are easily manageable, there are dangerous rip currents with water rushing through the channels between the sand bars, and these rips claim dozens of lives every year here. (Right now authorities have spent two days searching for a missing swimmer presumably caught in a rip. --Edit: sadly, she was located about 1 km from shore this morning and brought to shore. RIP Jennifer May Laidley.) If a diver were caught in a rip while trying to get back to shore, it would certainly make things "interesting" in an unpleasant way.

 

[TMHeimer]

Wind speed, wind direction (blowing from land to sea is OK), surge created by the waves (how deep are you going to be affected, and what nasties can you be flung into?), entry/exit difficulties (obviously shore is worse than boat).

 

[Quero]

entry/exit difficulties (obviously shore is worse than boat).

"obviously"??? Spoken like a shore diver.

But no, not "obviously," in my opinion. Perhaps that might be a little true for entries, but certainly not exits, and I'm not even sure about entries. Getting back on a boat in heavy seas is no picnic, and getting in from a bouncing deck when you're off balance anyway due to the weight of the equipment high on your body has its own challenges. (I have seen divers fall on the pitching deck of a boat and suffer greater injuries than divers I've seen fall going through waves in shore entries, though the indignity seems to be about the same.)

Either way, shore or boat, diving in waves isn't for the faint of heart!

 

[turnerjd]

Realistically, a 12-knot current is undiveable. I doubt you could even drift with it ... water moving that fast would tend to create whirlpools that could eat a boat, and a human simply wouldn't have the strength to do anything except get pulled along at the mercy of wherever it decided to take you. Swimming against, or even across, that kind of moving water wouldn't be possible.

<snip>

I read it as a 12 knot wind rather than current. This is between 3 and 4 on the Beaufort scale, and classed as a gentle or moderate breeze. Nothing to worry about.

Look at the Beaufort scale.

My limit, when diving from small boats is a 5, this is where the journey unpleasantness outweighs the diving.

As a general rule, unless you are in shallow water wind and waves don't have too much effect on the dive itself, but can churn up the water giving poor visibility. The problems are on small boats getting to and from the site, and then the actual entry and exit from the boat.

Jon

 

[MXGratefulDiver]

I read it as a 12 knot wind rather than current. This is between 3 and 4 on the Beaufort scale, and classed as a gentle or moderate breeze. Nothing to worry about.

True that ... I think the OP was referring to wind. But I was responding to a follow-on comment ...

I've never dived in 12 knot current, that's BRISK... I think before I did that I'd want to be very comfy with my buddy and our skills. 12kn is not something you can just swim against to get to a struggling buddy.

... Bob (Grateful Diver)

 

[MXGratefulDiver]

entry/exit difficulties (obviously shore is worse than boat).

"obviously"??? Spoken like a shore diver.

... or just someone who's never had to approach a boat that was pitching so badly that the ladder went airborne ... just before the swim step got slammed under the next wave. Those kind of exits can be pretty scary, since about the only thing you can do is time it, grab the ladder as it's stabbing into the water on the downswing, and hold on like a pencil monkey as it lurches skyward on the next wave ... and whatever you do, stay the heck away from the swim step as you're waiting your opportunity to approach the ladder.

... on the other hand, exiting a rocky shoreline in pitching waves ain't a lot of fun either ... rocks don't move much when you get slammed into them. Did my last dive with a console that way ... recovered the pieces and turned them into wrist gauges ...

... Bob (Grateful Diver)

 

[turnerjd]

Ah yes, I just need to read more carefully.

There is a drift dive on the west side of Scotland, near Oban called the "Falls of Lora" if I remember correctly. Minutes after slack low water they drop you in the water just outside the entry to Loch Etive. As the current builds (and it sure does) then you go flying down through the narrow entry to the loch (there is a 2 or 3m standing wave at the narrowest part). I don't know what the current is I've heard the figure of just under 10 knots quoted, but it is quite something. You have to do the dive at low tide so you get taken into the loch, rather than high water, to avoid being swept out to sea!

Jon