Heavy weather, can we be honest?

[Snowpetrel]

Originally Posted by Diesel Bill

So when measuring for true wave height imagine an alternating current (AC) wave form.
the zero line is in the middle of the sine wave with 1/2 above the line and 1/2 below the line. So the wave is only 1/2 of the whole from top to bottom? Is this right. If this is correct then my huge waves of 25-30 ft were only 12-15 ft?

No, we measure waves from the bottom of the trough to the crest at a line that is normal to the horizontal. The problem is judging horizontal in large waves, when you don't have a decent reference line to work from.

[weavis]

I recall as a youngster, we would take our 17 foot cuddy cabin 40 HP powered fishing boats, out to the entrance of the river Ribble in Lancashire and wait for a P&O ferry or cargo ship to enter the estuary to berth.... On the large boats, the bow wave was incredible.. we would try and sit on top of it and then slide off down the side. Ive been out there in weather on the bow wave and the 40 hp would not even keep up still.

In the pub at night, we would sit and tell stories about the height we attained and what we could see as we rose up to eye level of the helm etc... all lies but a good memory...

Wind over tide and a bow wave... good training..

[Dockhead]

Originally Posted by TJ D

This is s good point. I spend lots of time in big seas, somewhere between 20 and 40 feet above the water or thereabouts. Perspective has a lot to do with sea height estimates. Seas do look much bigger when your butt is right on the water.

From the perspective of a sailboat cockpit, I think we have little ability to estimate wave height. All I know is that when they start to blot out the stars, they are freaking big!

Actually, I think we may often UNDERestimate the height. I think steep inshore waves may appear bigger and scarier than they really are, but big ocean rollers may look smaller.

I trust Beaufort more than my own eyes. That said, my first spreader is 10 meters about the water, and sometimes seems to give some kind of reference. Fully developed F9 waves are supposed to reach 7 to 9 meters; that sounds about right to me. Blotting out quite a few stars. That in itself is no big deal, but when the crests of them start to fall off, all bets are off, at least for us in our little boats. Your massive f/v will handle such conditions very differently. Do you have stabilizers BTW or are those just for passage vessels?

[Kenomac]

Regarding the estimate of wave height, when I'm standing at the helm with my feet up on the seats as I was in the video of the Bonifacio Strait crossing, my eye level view is 11ft above the water, the camera view is 8ft above waterline (I just went out and measured this).

I only had the ability to record one hour during a 10 hour passage due to battery life of the Gopro, so only the beginning was recorded while we were somewhat sheltered from the larger waves by nearby land. I can tell you with complete honesty, that towards the end of the day and in the middle of the passage when we were exposed, the waves we experienced, were around 20ft or 7 meters on average in sets (meaning that not every wave was this size, many were smaller). Well above our field of view and above the horizon. And it's not like I could run and get the camera whenever I saw a big set coming at us, I had other things on my mind at the time.

The only other way we have in those conditions to estimate wave height is comparing what is coming at us with the known length of the boat. What I mean by this, is standing at the helm, I'm 18ft forward of the backside of the dinghy on the davits, so that gives me a reference point to length. So now I have two reference points height 11ft and length 18ft to try and extrapolate approximate wave height.

I'm sure the sail-by-desktop folks will also pick this apart too, since it seems to be the norm here on the forum. However, guys like Dockhead know what I'm talking about, and that's really all that matters.

[TJ D]

Originally Posted by Dockhead

From the perspective of a sailboat cockpit, I think we have little ability to estimate wave height. All I know is that when they start to blot out the stars, they are freaking big!

Actually, I think we may often UNDERestimate the height. I think steep inshore waves may appear bigger and scarier than they really are, but big ocean rollers may look smaller.

I trust Beaufort more than my own eyes. That said, my first spreader is 10 meters about the water, and sometimes seems to give some kind of reference. Fully developed F9 waves are supposed to reach 7 to 9 meters; that sounds about right to me. Blotting out quite a few stars. That in itself is no big deal, but when the crests of them start to fall off, all bets are off, at least for us in our little boats. Your massive f/v will handle such conditions very differently. Do you have stabilizers BTW or are those just for passage vessels?

HI Dock, no stabilizers here. We've got big rolling chocks running down the whole chine, about 100' worth. Actually, I'm unaware of any F/V's in Alaska using stabilizers. Very few using birds/flopper stoppers for that matter.

We displace about 2000 tons, depending on loading, so this is an entirely different way of going to sea, for sure. Horsepower and tonnage are your friend when things so south on the weather front.

Still, we avoid going beam-on when it's really nasty out. If for no other reason than it dumps all the frozen cases all over the hold...

TJ

[Snowpetrel]

Originally Posted by Kenomac

Regarding the estimate of wave height, when I'm standing at the helm with my feet up on the seats as I was in the video of the Bonifacio Strait crossing, my eye level view is 11ft above the water, the camera view is 8ft above waterline (I just went out and measured this).

I only had the ability to record one hour during a 10 hour passage due to battery life of the Gopro, so only the beginning was recorded while we were somewhat sheltered from the larger waves by nearby land. I can tell you with complete honesty, that towards the end of the day and in the middle of the passage when we were exposed, the waves we experienced, were around 20ft or 7 meters on average in sets (meaning that not every wave was this size, many were smaller). Well above our field of view and above the horizon. And it's not like I could run and get the camera whenever I saw a big set coming at us, I had other things on my mind at the time.

The only other way we have in those conditions to estimate wave height is comparing what is coming at us with the known length of the boat. What I mean by this, is standing at the helm, I'm 18ft forward of the backside of the dinghy on the davits, so that gives me a reference point to length. So now I have two reference points height 11ft and length 18ft to try and extrapolate approximate wave height.

I'm sure the sail-by-desktop folks will also pick this apart too, since it seems to be the norm here on the forum. However, guys like Dockhead know what I'm talking about, and that's really all that matters. [emoji2]

Its ok ken, we believe you. So at the time of the video the waves were about 3-4 meters or so?

[BandB]

We realized very quickly upon starting in ocean boating that people tossed wild numbers about. Someone would talk about 8' crossing the Gulf Stream and we'd check and everything we saw said 3-4' with up to 5'. We'd go to various sites such as windy and passage and buoy. So, we realized quickly that we had no idea how to estimate and weren't all that sure others around us did. That led us to testing ourselves, looking, forming an opinion, then checking various sources. If it's 30' I am still sure I'd have no idea if it was 20 or 30 or 40 and the only way I'd know is mentally thinking of sizes I'm good at and then saying, ok it's twice a 10' wave, maybe a little more, but not three times so maybe 20-25'. But then what does it matter? It may seem 50'. All I know is it's much taller than me or the boat.

It's like our place at the lake, my aunt was always worried because the water at our dock was 50' deep. My father said, "It's not how much is under you, it's how much is over you." Well, once it hits about 8' in depth, it no longer really matters to me. I can't stand in it. It's over my head. I better not sink. Once a wave exceeds 20' it doesn't matter how big it is, it's big.

And for the smaller ordinary ones, I check my guesses and have gotten much better.

For those who come in talking about the huge waves, I then look up what size they really are.

[Dauntlessny]

Originally Posted by Kenomac

Regarding the estimate of wave height, when I'm standing at the helm with my feet up on the seats as I was in the video of the Bonifacio Strait crossing, my eye level view is 11ft above the water, the camera view is 8ft above waterline (I just went out and measured this).

I only had the ability to record one hour during a 10 hour passage due to battery life of the Gopro, so only the beginning was recorded while we were somewhat sheltered from the larger waves by nearby land. I can tell you with complete honesty, that towards the end of the day and in the middle of the passage when we were exposed, the waves we experienced, were around 20ft or 7 meters on average in sets (meaning that not every wave was this size, many were smaller). Well above our field of view and above the horizon. And it's not like I could run and get the camera whenever I saw a big set coming at us, I had other things on my mind at the time.

The only other way we have in those conditions to estimate wave height is comparing what is coming at us with the known length of the boat. What I mean by this, is standing at the helm, I'm 18ft forward of the backside of the dinghy on the davits, so that gives me a reference point to length. So now I have two reference points height 11ft and length 18ft to try and extrapolate approximate wave height.

I'm sure the sail-by-desktop folks will also pick this apart too, since it seems to be the norm here on the forum. However, guys like Dockhead know what I'm talking about, and that's really all that matters.

When I'm standing at my pilot house door, my eye level is about the same as the deck of my flybridge on my Kadey Krogen and that's about 15 feet above water level.

But even with the paravane stabilizers the boat will roll into the trough, so the key is to judge the height of the wave when on even keel.

But as Kenomac said above, it seems while I have many pictures of bad conditions, I have none of the worst. Usually by then I was hunkered down on the pilot house bench feeling miserable.

TJ D's observation about duration is pretty good too.
Winds caused my synoptic weather systems, (highs, lows, etc) are usually moving about 20 to 25 knots, or 450 to 600 nm in a 24 hour period. In the meantime, I'd be plodding along at 6 knots at best, usually 5 in bad seas, so I'm only going 125 nm a day.

Thus the Low pressure system may have sustained winds of 40+ knots for days, but we only see 18 hours of it.

My experience on the North Atlantic, while minimal, confirms my observations when I was forecasting for the North Atlantic, which is there are usually 18 hours of "Bad" , then as the Low moves east of a given spot, the winds veer to the NW and will probably be half the speed, but that only lasts about 6 hours, as the next Low starts to dominate.

Richard

[Kenomac]

Originally Posted by Snowpetrel

Its ok ken, we believe you. So at the time of the video the waves were about 3-4 meters or so?

Yes, that's accurate. Maybe an occasional 5 meter thrown in, but yes 3-4 meters.

[weavis]

I do quite a bit of video.
There is HUGE frustration in trying to show the seastate both in height and intensity... it just does not capture it.

3-4 metre waves sometimes show as a minor ripple in video.. .

[carstenb]

This was taken from the cockpit of Dockheads boat in a gale in the Channel - weather was Force 9 and we estimated that these waves were running about 6 meters with a few larger sets and smaller sets thrown in. You can just spot the outboard on his dinghy sitting it its Davits
Should give you some indication of size

[carstenb]

This was taken from the cockpit of Dockheads boat in a gale in the Channel - weather was Force 9 and we estimated that these waves were running about 6 meters with a few larger sets and smaller sets thrown in. You can just spot the outboard on his dinghy sitting it its Davits
Should give you some indication of size

[sailorboy1]

waves are like fish, they get bigger with the telling

[Kenomac]

Originally Posted by sailorboy1

waves are like fish, they get bigger with the telling

How would you know this? Have you ever had the opportunity to try and estimate a twenty foot wave from your cockpit?

From the picture, it looks to me like Dockhead and Carstenb have been there.

Nice photo.

Here's a favorite of my wife.

[sailorboy1]

Originally Posted by sailorboy1

waves are like fish, they get bigger with the telling

and I guess they start to smell just as bad after a while on a forum