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soopad00pa · 12-05-2022, 18:36

I've been at anchor in various areas around FL and the keys for a couple of months now and I've had a variety of stormy, windy, bouncy and calm nights.

Tonight is weird - there's practically no wind - maybe 3 knots. Maybe and it's been like that for hours. The water is smooth. But I am rolling around almost as much as I did in a big storm a couple weeks ago.

What gives? I have A LOT to learn about the water...

Tetepare · 12-05-2022, 19:24

Big storm offshore right now, even hundreds of miles away? A storm drives roll well ahead of itself. Usually this is a warning.

Check the pressure in the area that will do it too.

**GordMay** · 13-05-2022, 03:36

Storm "swell or surge".

A swell is a series of mechanical or surface gravity waves, generated by distant weather systems, that propagate thousands of miles across oceans and seas. It's a succession of massive and crestless wind waves characterized by a narrow range of long wavelengths.
➥ https://www.weather.gov/jetstream/waves

Storm surge is a very complex phenomenon, because it is sensitive to the slightest changes in storm intensity, forward speed, size (radius of maximum winds-RMW), angle of approach to the coast, central pressure (minimal contribution in comparison to the wind), and the shape and characteristics of coastal features such as bays and estuaries (concavity of coastlines, bays, rivers, headlands, islands, etc.=greater storm surge impact).
Other factors, which can impact storm surge, are the width and slope of the continental shelf. A shallow slope will potentially produce a greater storm surge than a steep shelf.
For example, a Category 4 hurricane hitting the Louisiana coastline, which has a very wide and shallow continental shelf, may produce a 20-foot storm surge, while the same hurricane in a place like Miami Beach, Florida, where the continental shelf drops off very quickly, might see an 8 or 9-foot surge.

soopad00pa · 13-05-2022, 04:48

Interesting, thanks. That makes sense, I guess.

pjShap · 13-05-2022, 04:58

It doesn't have to come from an offshore storm. Sometimes the "normal" sea swell gets amplified as it reaches the shallow water, like watching waves break on a beach. The swell can be hardly noticeable in the deeper water but roll the boat ferociously in shallow water. I find that more common in light wind. Tidal currents can be parallel to the beach and the incoming swell can be perpendicular to the beach, so it's on your beam and you roll.

tamicatana · 13-05-2022, 05:25

Google "swell bridle" and learn how to rig one, and you'll find it handy I'm sure

**GordMay** · 13-05-2022, 05:51

Quote:

Originally Posted by tamicatana

Google "swell bridle" and learn how to rig one, and you'll find it handy I'm sure

Particularly, when wind is against wave, swell, or current.
I’ve know them as “Anchor Spring Lines”
See ➥ https://www.cruisersforum.com/forums...ml#post2917149

wingssail · 13-05-2022, 07:16

Quote:

Originally Posted by soopad00pa

I've been at anchor in various areas around FL and the keys for a couple of months now and I've had a variety of stormy, windy, bouncy and calm nights.

Tonight is weird - there's practically no wind - maybe 3 knots. Maybe and it's been like that for hours. The water is smooth. But I am rolling around almost as much as I did in a big storm a couple weeks ago.

What gives? I have A LOT to learn about the water...

Waves will advance ahead of the arrival of wind. It does not have to be a storm, even a fresh breeze can send waves ahead.

And if there is some meteorological or geographic situation which prevents the wind from actually arriving, the waves can still extend far beyond the area where the wind is blowing. You might feel waves but the the wind never actually gets there.

Often while cruising or racing we start to feel and see waves coming towards us and we expect wind to arrive shortly. If we are prepared we can take advantage of the breeze when it arrives.

JC Reefer · 13-05-2022, 14:49

Where are you in the Florida keys? Ocean or bay side?
What was the wind direction?

20 hours ago it was calm but 36 hours ago it was blowing like stink, + 30 kts. I was out both days.

Last night

Click image for larger version

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ID: 257706

thomm225 · 13-05-2022, 15:03

Quote:

Originally Posted by soopad00pa

I've been at anchor in various areas around FL and the keys for a couple of months now and I've had a variety of stormy, windy, bouncy and calm nights.

Tonight is weird - there's practically no wind - maybe 3 knots. Maybe and it's been like that for hours. The water is smooth. But I am rolling around almost as much as I did in a big storm a couple weeks ago.

What gives? I have A LOT to learn about the water...

This can happen any time you are in an open water anchorage.

You should find a more protected anchoring spot if possible in the future.

I've anchored early in very peaceful spots only to have the wind rotate and bring in waves.

A cold front came in here.

First video is crossing the Bay as the temp dropped from about 85 to 65 degrees as a front rolled in

It was early October.

2nd video is my anchorage with still strong winds but I got into a good protected spot.

I'd had too many crappy anchorages with strong onshore wind anchored 50-70 yards off the beach with my old CQR anchor.

https://www.youtube.com/watch?v=Q3I2zc0_7wY

https://www.youtube.com/watch?v=uWwQ4iUfiyM

thomm225 · 13-05-2022, 15:04

Of course though sometimes it doesn't matter where you anchor....

https://www.youtube.com/watch?v=okRZs6os5Eo

https://www.youtube.com/watch?v=6gcZKr25UUM

wingssail · 13-05-2022, 16:51

Quote:

Originally Posted by JC Reefer

Where are you in the Florida keys? Ocean or bay side?
What was the wind direction?

20 hours ago it was calm but 36 hours ago it was blowing like stink, + 30 kts. I was out both days.

Last night
Attachment 257706

If that photo is from your anchorage spot, I'm not surprised you get some winds and rolly nights.

I prefer "bullet proof" anchorages and I'll go 100 miles to get to one rather than anchor in an open roadstead.

As for sailing in protect waters in strong winds, that's fun, but I don't anchor there.

**Don C L** · 13-05-2022, 17:58

Quote:

Originally Posted by soopad00pa

I've been at anchor in various areas around FL and the keys for a couple of months now and I've had a variety of stormy, windy, bouncy and calm nights.

Tonight is weird - there's practically no wind - maybe 3 knots. Maybe and it's been like that for hours. The water is smooth. But I am rolling around almost as much as I did in a big storm a couple weeks ago.

What gives? I have A LOT to learn about the water...

I believe you may have had a mild swell whose period exactly matched the roll frequency of your boat. Hitting that harmonic frequency, I believe it is called, can make any boat roll like crazy. My little skinny boat is a bit prone to this so “flopper-stoppers” are regularly employed.

soopad00pa · 14-05-2022, 06:17

I'm on the west end of marathon right now, pretty close to shore. It's been rolly for a couple of days but there's been pretty much no wind for a couple days (1hr squall at 2am last night) and what little there is just keeps goin in circles. Looks like it's gonna be this way for another few days. Blah.

The singular blue line is from the rainstorm last night.