Daydream believer
Well-Known Member
Looks like the sort of ripple we get in the marinas, here on the east coast
Waves
- Thread starter DangerousPirate
- Start date
johnalison
Well-Known Member
Not bad. It is terribly hard to show waves as they really appear, just as with skiing photos or video, it never looks as steep as it is. This was my best effort, off Beachy Head, but if you look closely the wave was probably only a couple of metres at most.
geem
Well-Known Member
It's those ones that make me glad we have a centre cockpit?
Daydream believer
Well-Known Member
I would have thought a high up centre cockpit would give more motion to the crew & increase the likelyhood of sea sickness. The feeling of height must also be a bit insecure as the boat rolls as well. Presumably the crew go through a wider arc
johnalison
Well-Known Member
I have twice sailed with a high following sea in company with much larger centre-cockpit boats. On one occasion the occupants got repeatedly wet while we remained dry, and on the other they had a very uncomfortable passage that we had quite enjoyed.
Neeves
Well-Known Member
I agree - and have stopped taking pictures of waves. The ones that are decidedly scary can look most innocuous on a photo.
Our Bureau of Met gives wave forecasts with the provision that these are averages and that reality might be twice as large (and you only need a few of 'reality' to temper your enthusiasm).
We thus have waves, we get a forecast but measuring what you have is what I find difficult. I belabour the point because if the forecast is for 4m waves how do you know you are in 4m waves or that worse is to come (as you are only in 3m waves and the average of 4m means there are rogue waves out there of 8m.....)
To me an inability to measure the waves you are in makes the forecasts a bit irrelevant.
. - except that maybe you should have stayed in bed.Jonathan
geem
Well-Known Member
True on some small high up centre cockpits. The sole of our cockpit floor is a foot lower than a Moody 44. Our cockpit is over the engine room unlike many aft cockpit boats that install aft cabins under the cockpit. Little to choose from in terms of cockpit height since modern boats have such high freeboard.
In addition we have a hell of a lot of boat under the water unlike lightweight modern boats with flat bottoms. This has the effect of lowering everything including the cockpit. The boat sits in the water instead of on it
LadyInBed
Well-Known Member
Too high is when they lift and crash down into the cockpit, that's when I retire into the saloon and keep an electronic lookout and hope that there is no other silly bugger out in it!
AntarcticPilot
Well-Known Member
Photos like that show one of the problems - you don't have a horizontal reference, so it's very difficult to work out the actual height of the wave. And the motion and visual clues all conspire to make you think it's taller than it is; for example, the stern of the boat is almost certainly pointed down, which automatically exaggerates the apparent height of the wave. But at that point it is likely that the stern of the boat is moving UP, so your body thinks that the stern which is actually pointing down is pointing up, exaggerating the apparent height of the wave even further.
Not saying it isn't a big one - but estimating wave heights from a small boat is extremely difficult. It's not easy even for trained and experienced observers based on ships, which provide a much more stable platform for observing.
Also, a wave height of a metre is a lot if it has a short wavelength and steep crest; it's nothing at all on an ocean swell with a wavelength of hundreds of metres. Perception is all!
Finally just to pick up on a point that others have talked round - the wave height quoted on forecasts etc. is the Significant Wave Height. That's something that is readily available from satellite observations, but understanding WHAT it is is important. It is NOT the maximum wave height; it is the height that about 90% of waves will not exceed. That means that about 10% of waves will exceed it - and about 1 in a thousand will be twice the SWH!
A further point is that for reasons to do with the physics, the satellite observations are averages over about 30km or so . SO they will never pick up bad areas like those around headlands - the resolution isn't (and can't) be good enough to pick such areas out. Higher resolution data are available from laser altimeters, but they suffer from the problem that the measurements are less statistically robust than the radar measurements, so their relationship to ship-borne observations is less secure. And even so, they are still averages over several kilometres.
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