Sea state for a comfortable first channel crossing. Channel light vessel

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FairweatherDave

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Along with MagicSeaweed you can get an idea of the sea state out in the channel from Channel Light vessel (wave height and period). I was wondering if anyone uses any rule of thumb as to whether to go across or not, eg under 1 meter and it'll be comfortable enough, or what? Obviously there are plenty of other factors, the forecast, wind against tide etc. And then we are all different regarding what comfortable means and we have different boats. But I have an average tolerance for a lumpy sea, stay on deck, chew ginger etc. Just wondering what others do other than consulting the wind biased weather forecasts. And I regard my 29ft bilge keeler as average size too, though perfect for our needs.
 
I'm of the view that the sea state is largely correlated to the wind strength I'd go on wind alone usually. Our experience has usually meant that we don't try and cross the channel when the wind is either on the nose or the forecast is more than F6. We have had some fairly boisterous crossings in F6 with the wind on a broad reach and I suspect if we looked at the wave heights we might not have gone as they felt considerably more than a meter but we enjoyed the faster crossings and would do them in those conditions again.
 
Especially down at the western end of the channel we've crossed fairly comfortably in a 24 foot boat when the swell was way way above head height when standing - but with a long peak to peak distance, and the "wind waves" on top are what you'd expect for a Force 3-4.

So I don't think wave height matters anywhere where swell is common except when going over a bar - the roughness of the sea does matter though but that's much more wind and tide based.
 
I'm reading these replies with interest! Perhaps I should say that as I understand it a wave height of 1m will have a trough of 1m, therefore a wave will appear as 2m from the bottom of the trough.
 
FairweatherDave said:
I'm reading these replies with interest! Perhaps I should say that as I understand it a wave height of 1m will have a trough of 1m, therefore a wave will appear as 2m from the bottom of the trough.
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Yes, but getting hung up on wave height is meaningless. I've sailed in the Bristol Channel in 12m waves. Fortunately these were generated by astronomical tides with a period of about 12 hours, so were imperceptible.
4m pelagic waves off the Portuguese coast are far more comfortable and less concerning than a 1m wind over tide chop in the Solent.
 
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I know what you are saying :)
But there is a big difference between a 1m reading at the Channel light vessel and a 3m reading.
It's 4m if you are in a trough. But I'm not hung up on it, I asked about it as it is all information that builds a picture. And obviously just cos the sea state in the middle of the channel is one reading, it can be very different elsewhere (so I am told :))
 
Where are you crossing from and to? If the classic solent to Cherbourg from a Portsmouth based boat, my ploy is to cross to the IOW and go somewhere you can easily escape from, eg anchored of hurst or buoy off Yarmouth not rafted four deep inside somewhere, and in settled summer weather go at first light: you will be too excited to sleep much, leave at 0500 and by the time the wind and waves wake up you will be half way across!
 
If there is a lot of wave action left over from a big blow, that should be treated with respect, but in general, I would make a decision based on mostly the wind forecast.
With a small light boat, I would probably not go with a forecast of more than 5 occasionally 6, and with that I'd be cautious of wind against tide where the tide is fast.
But blasting to Cherbourg on a beam reach is easier than beating to St Peter Port.
 
chubby said:
Where are you crossing from and to? If the classic solent to Cherbourg from a Portsmouth based boat, my ploy is to cross to the IOW and go somewhere you can easily escape from, eg anchored of hurst or buoy off Yarmouth not rafted four deep inside somewhere, and in settled summer weather go at first light: you will be too excited to sleep much, leave at 0500 and by the time the wind and waves wake up you will be half way across!
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Absolutely my plan. Either tucked inside Keyhaven entrance or Bembridge . The only time I tied up to a Yarmouth bouy I would not have fancied sleeping there. And on the bank holiday weekend we anchored in Priory Bay. Given the flat calm we found that remarkably rolly ........the tidal flow near HW holding us beam on
 
BoyBlue49 said:
For a first time crossing go by wind strength, about force 4-5 WSW round to North. If wind is south then f 3-4.
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I occasionally look at wave heights but have never used them in decision-making. I think you may be optimistic about F3-4 from the south, presumably meaning on-the-nose. I would be surprised if an average cruising 29-footer would get more than 3kn VMG in open water, and probably not much more than 2 in a full F4. This gives a passage time of 20-30 hours, which is not what I would call a comfortable crossing. This could be improved my motor-sailing, but it still would not be much fun.
 
lw395 said:
If there is a lot of wave action left over from a big blow, that should be treated with respect, but in general, I would make a decision based on mostly the wind forecast.
With a small light boat, I would probably not go with a forecast of more than 5 occasionally 6, and with that I'd be cautious of wind against tide where the tide is fast.
But blasting to Cherbourg on a beam reach is easier than beating to St Peter Port.
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Thanks.TBH I would not go if there is a F6 mentioned anywhere. I'll be taking BoyBlue49's line .....about force 4-5 WSW round to North. If wind is south then f 3-4.
(Weird, my inverted commas have died)
 
johnalison said:
I occasionally look at wave heights but have never used them in decision-making. I think you may be optimistic about F3-4 from the south, presumably meaning on-the-nose. I would be surprised if an average cruising 29-footer would get more than 3kn VMG in open water, and probably not much more than 2 in a full F4. This gives a passage time of 20-30 hours, which is not what I would call a comfortable crossing. This could be improved my motor-sailing, but it still would not be much fun.
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Point taken........
 
I think that you have to make your own forecast to some extent, especially on the basis of whether it is going to worsen before you get there. I have occasionally left in unpromising conditions and had a pleasant passage (and I'm trying to forget the ones that went the other way). We once left Brighton for Cherbourg in our then 29 with F6-7 from the NE. By lunchtime we were motoring in a flat calm, though the Royal Sovereign had reported F7 for the previous hour from only 50 miles away.
 
I ALWAYS consider sea state in a forecast. Once it starts showing over 2.5m and a shortish period, I start rethinking the passage. I'll take a bigger one from behind/on the quarter, assuming wind is similar direction over bashing into a smaller one any day of the week.
 
My experience of western Channel is that wind against tide is much less comfortable whereas wind with tide can tolerate quite high wave height while still comfortable ,in western Channel swell from Atlantic depressions become factor but usually the wave period is long.Try to arrive French side on flood tide so more comfortable wave train at end of trip.For me I would go in 5-6 but have a strong fin keel 28ft and really good crew.One thing I do know is that while some forecasts are good some will drop to motoring mode and worst was a forecast 5-6 nw with a due north course ended up as f8 north though was 20 yrs ago now we have so many forecasts you can pick the one you like.The one situation that often surprises is when anticyclone to middle north of the uk and depression to south can be plenty of breeze on French side.
 
johnalison said:
[...]

This could be improved my motor-sailing, but it still would not be much fun.
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The issue of fun doesn't come into it for me, but then I normally treat crossing the Channel as an exercise in getting there. For my 27' long-keeler I plan the passage of 60NM @ 5kn = 12hrs and calculate heading according to net predicted tides. So if the wind drops or goes too far ahead, or the sea-state is slowing us, then on goes the motor to help.

On the other hand, summer before last I crossed back from Alderney to the Needles in fine weather, a steady SE3 and a slight sea-state. Fab and very comfortable crossing entirely under sail, and went so fast that I actually got to the Needles an hour early!
 
steve yates said:
I ALWAYS consider sea state in a forecast. Once it starts showing over 2.5m and a shortish period, I start rethinking the passage. I'll take a bigger one from behind/on the quarter, assuming wind is similar direction over bashing into a smaller one any day of the week.
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Should clarify, this is in general, not for crossing the channel, as I haven't actually ever done it :)
 
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