Challenge: You Are in Your Home Marina, and There's a Tsunami Warning . . .

[boatman61]

Anything here would be generated somwhere between here and the Azores 900 miles away.... don't know if I'd make it outa the shallows... be safer running for high ground...

[TaoJones]

There's a very interesting, on-point discussion of this topic in today's 'Lectronic Latitude, including information that Harbor Masters in three marinas around Banderas Bay closed their harbors, making it a crime to put to sea.

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March 14, 2011 – Pacific Ocean
Given the chaos of 'tsunami Friday', it's a little unclear to us what kind of instructions port and other officials gave to boatowners. In many cases it was reported that ports were closed, but that might have happened once the effects of the tsunamis began to be felt.

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For the full report, go to:

Tsunami -- Stay or Leave

TaoJones

[barnakiel]

I would give a 5 minute check-up to the boat and immediately leave for deep water. At the same time I would be calling all my sailing friends from the same marina ant tell them the news.

My reasoning: most damage will come from my boat's interactions with other boats and the docks. Our marina will take 3m tsunami in the stride, but why take ANY risks? (e.g. the risk that the speaker misread some numbers they have no idea about?).

b.

[Dockhead]

Why does everyone assume we would need to be in deep water to be safe?

In deep water, a tsunami is hardly noticeable and so of course it would be at the very least nice to be in deep water when it comes through. But why do we assume that the bigger wave in shallow water would not be survivable?

A 3 meter tsunami is really a 6 meter wave, since we measure regular waves crest to trough, and tsunamis from normal level of the water. I've been in 6 meter and bigger waves in my boat, and by themselves they did not create a survival problem. I had one of those break on the beam once, and it was unpleasant, and washed the decks, and some green water even got into the cockpit, but it was not a survival situation.

So why wouldn't we go to sea even if we couldn't get to deep water? As long as we're well clear of land and obstructions, won't we be much better off fighting even a 3 meter tsunami out there, then right at the interface between sea and land where the devastation is at maximum?

[boatman61]

Originally Posted by Dockhead

Why does everyone assume we would need to be in deep water to be safe?

In deep water, a tsunami is hardly noticeable and so of course it would be at the very least nice to be in deep water when it comes through. But why do we assume that the bigger wave in shallow water would not be survivable?

A 3 meter tsunami is really a 6 meter wave, since we measure regular waves crest to trough, and tsunamis from normal level of the water. I've been in 6 meter and bigger waves in my boat, and by themselves they did not create a survival problem. I had one of those break on the beam once, and it was unpleasant, and washed the decks, and some green water even got into the cockpit, but it was not a survival situation.

So why wouldn't we go to sea even if we couldn't get to deep water? As long as we're well clear of land and obstructions, won't we be much better off fighting even a 3 meter tsunami out there, then right at the interface between sea and land where the devastation is at maximum?

True... but then again...
Was it travelling at 40Kms +/hr....
It makes a lot of difference... water hardens if imacting at speeds...
and an engines gonna be no use against that...
Wave build up involves sucking in the water ahead... its a different dynamics from the standard wave...
Did you see the video of the motor yacht caught in a giant whirlpool of Japan..

[David_Old_Jersey]

At home I would stay ashore (and head for the hills ).

But further afield would likely mean that boat ready to go at short notice and me no shoreside resources (or probably come off second best with the locals, in knowledge and numbers).........so preserving the boat as a refuge for at least the next week would mean me likely to head to sea (as long as the time was sufficient to get an hour offshore).......and then I'd keep on going from the looks of the TV the debris field extends a longggg way offshore.

[Dockhead]

Originally Posted by boatman61

True... but then again...
Was it travelling at 40Kms +/hr....
It makes a lot of difference... water hardens if imacting at speeds...
and an engines gonna be no use against that...
Wave build up involves sucking in the water ahead... its a different dynamics from the standard wave...
Did you see the video of the motor yacht caught in a giant whirlpool of Japan..

Well, I accept the fact that the dynamics are different. So - does anyone know what it would be like - 100 feet of water and a mile from any obstruction - survivable or not? My instinct is that with enough sea room hardly any wave in the world could destroy my boat, but I don't understand enough about tsunami waves to have an answer to this situation.

[SaucySailoress]

Depends on how deep the water is. You'd obviously need to be far enough out for there to be no risk of the wave breaking. But the surge would also be massive I imagine, even beyond the break point - and you clearly don't want it to drag you back inshore.

[sailorboy1]

If you believe that you could ride out the "wave" you must not have watched the videos on the news. That's not a wave it's a wall! And it isn't breaking anytime soon. If you can not get out beyound where it is deep enough for the wall to have not started you aren't riding it out!

Did you notice that on almost all the videos what was leading the "stuff" in front of the wall were boats and ships..........and buses........and trains........and buildings!

[boatman61]

Well.... if I were gonna make a run to sea I'd be racing for 500ft minimum...
To many 'bottom' variables in less...
subterranean hills, valleys abound off the Portuguese coast so that walls gonna be running uneven...

[Juniper]

Well lets see, I'm 11 hours from the boat now, the boat is 5-6 hours up a river, then another 70 miles out of the Chessy, then a bit more to deep stuff, I'd say cry. But the only way a wave will bet there will be if it goes all the way over Deleware-Maryland-Viginia into the Chessy. Say if La-Palma were to go off.

[Rob Toronto]

Some great comments, and I kind of assumed that there would be mixed opinions, but you've all brought up some very interesting points that I hadn't anticipated.
One interesting point is that some of you have referred to the differences in the mechanics of a tsunami wave compared to other types of wave makes me curious as to the what you think you would experience in a 40ft'er in say 500ft of water as the wave(s) passed.
Also actual tsunami data would also be interesting to see as well. Does anyone have a link, or reference to point me to that might actually give a real world example and data?

[skipmac]

Originally Posted by Wannafish

Ok.. Looks like I'm in the minority here. Though I think the world of my boat, she's the LAST thing I'd be thinking of. If she can't take care of herself, so be it but it's MY problem. The other things that are my problem happen to be my family, then those around me. I am I the only person who feels this way??
I can't believe more people aren't chiming in. Maybe this isn't the site for me...

I think everyone else has answered the question based on the assumption impled in the original question that the family was safe elsewhere. I doubt any member of this forum would give a second thought to saving a boat if there was the slightest risk to family, friends or neighbors.

[David M]

It depends on a LOT of factors. My boat was fine because of its location inside of SF Bay, miles around a point well away from the Gate. Bash, well, he got a bit of a ride.

[barnakiel]

Originally Posted by Dockhead

So why wouldn't we go to sea even if we couldn't get to deep water? As long as we're well clear of land and obstructions, won't we be much better off fighting even a 3 meter tsunami out there, then right at the interface between sea and land where the devastation is at maximum?

Judging from the videos I have seen, this man is right. If water is same deep everywhere around, being offshore seems more survivalable.

b.