Big waves

[AusCan]

I'm convinced that it is not only the wave height which makes it sometimes nasty for us. Even smaller waves will force our boat into serious motions if they hit us with a frequency matching the rolling Eigen-frequency of the hull. We have been in (long) waves as high as 9' without any inconvenience, but experienced very nasty rolling angles up to 35-40 degrees in 4-5' (short and steep) seas on other trips.
Rolling Eigen-period of our hull is in the range of 3.5 seconds. Based on the forecasted seas (heights, direction and period) we try to predict the period with which the waves will hit us depending on our intended course. Sometimes we can avoid resonance by adjusting the speed and / or course, sometimes those measures won't give us enough safety margin. That are the days where we nowadays stay in port even if the forecast is below 5'.
And then there are those days where the forecast fails and you see the equipment flying through the pilot house ...

Ahhhah! A new word for me. I always just called it my boat's natural roll cycle, but it has a name - Eigen period.

Yes - it does get ugly when the swell period and the Eigen period match up.

Thanks Waddencruiser.

 

[waddenkruiser]

Ahhhah! A new word for me. I always just called it my boat's natural roll cycle, but it has a name - Eigen period.



Yes - it does get ugly when the swell period and the Eigen period match up.



Thanks Waddencruiser.

AusCan,
No need to learn new vocabulary. Natural frequency / period and Eigen frequency / period are two designations for the same physical effect ...

 

[Al]

AusCan- having the same length boat that is heavy laden with ballast, in our part of the world, your observation; "That are the days where we nowadays stay in port even if the forecast is below 5'." has to be modified to read 'below 3'. I am,was, heading long gone, to a anchorage with 3' never the less 5'!!!

Al-Ketchikan

 

[Fletcher500]

Gulf of Tehuantepec, Winter, 1985. Wish I had taken some pictures, but sick as a dog.

 

[waddenkruiser]

AusCan- having the same length boat that is heavy laden with ballast, in our part of the world, your observation; "That are the days where we nowadays stay in port even if the forecast is below 5'." has to be modified to read 'below 3'. I am,was, heading long gone, to a anchorage with 3' never the less 5'!!!

Al-Ketchikan

Al,
I agree that a wording "stay in port if ..." is strongly linked to a certain area with its particular characteristics. I was talking about the Baltic Sea - i.e. no tides and no currents.
It's another story when we are cruising the German Bight / Wadden Sea where we focus on "avoid wind against tidal current", especially in a narrow passage between islands or sands. Swell of even less than 3' is able to build up terribly on / between the sands in case of tidal currents ...

 

[Al]

Al,
I agree that a wording "stay in port if ..." is strongly linked to a certain area with its particular characteristics. /QUOTE]

Yep, that was the point of my response, just didn't go into the detail that confirms what you witness in a (Your) specific cruising area. Here 3' seas are not friendly even to 45' plus boats. Not that they can not nor even our smaller boat, handle them it is just so uncomfortable that seeking a harbor till a tide and or wind change is more the desirable decision. Hard to make sometimes hence the stories of those of us who have ventured out knowing exactly what we are not discussing, is the case. 'Do what I say not what I do' perhaps is the conclusion.

Regards, enjoying the thread.

Al-Ketchikan

 

[Bigsalmonfish]

Typical Thanksgiving cruise in the PNW. Never hit Rosario Strait on a ebb, even the last of one and a big south wind. Pretty nautical today. 3-4 foot very close together. Right on the beam if your transiting to Anacortes.

 

[78puget-trawler]

What size/type of boat?

 

[Bigsalmonfish]

1922 64 foot Custom Classic. Green hull. Westerly. I see your from LaConner. Sure you know the boat. We have a private dock across from the yacht club

 

[78puget-trawler]

Sure, I know the boat. Nice looking old woodie.

 

[Al]

Pictures!!! God I love classics!!

Al-

 

[dhays]

Typical Thanksgiving cruise in the PNW. Never hit Rosario Strait on a ebb, even the last of one and a big south wind. Pretty nautical today. 3-4 foot very close together. Right on the beam if your transiting to Anacortes.

Yes, that can be a very unpleasant combination in Rosario.

We were heading North on Thanksgiving and so the the wind waves were all going with us, making for a mild ride most of the time. No strong current/wind combinations either. However, the wind was blowing pretty good on Thanksgiving and would have been even worse up your way.

 

[78puget-trawler]

It was breezy but it didn't come up as predicted. Couple days later it blew more.

 

[Al]

Big waves?? How about this for fun at sea:

WATCH: Insane Helicopter Landing on Rolling Ship in North Atlantic – gCaptain

Al-

 

[mplafleur]

I've had my share of open-cockpit boating. Now enjoying an enclosed pilothouse, thank you.

Looks nice, I like it! I hope to be piloting indoors in a few years. I do have a hardtop with canvas.

Mike

 

[Tad Roberts]

Cape Mudge, wintertime....flood tide against SE wind....

 

[jrs1958]

I went out Charleston Harbor last week in calm conditions and they have a long 4 mile breakwater jetty on each side that runs out into the ocean. Well the tide was ebbing and all of a sudden we hit 5' breaking waves until we were past the jetties. Really caught me off guard!

 

[MurrayM]

Cape Mudge, wintertime....flood tide against SE wind....

Nasty.

On our sea kayak trip south my wife and I were loading our gear on a dock in Campbell River, about to scoot around Cape Mudge and head up the other side to Heriot Bay.

The wind was briskly blowing from the south and the tide was just about to turn and start flowing north again, so it must have been snotty out there.

Some guys came into the marina in an open boat, soaked to the skin. "Better not go out there. It's crazy!" they warned us.

No duh...

 

[Al]

Cape Mudge, wintertime....flood tide against SE wind....

View attachment 59275

View attachment 59276

I resemble the second photo. Being short and fat tends to be a bit of hobby horse in such conditions. A dock in a (any) harbor really starts to be looked upon with desire!!!

Al-Ketchikan