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Old 16 November 2009, 06:45   #51
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best email that to the met office then
http://www.metoffice.gov.uk/weather/...fortscale.html

I think they already know, it is highlighted with reference to probable & probable maximum wave height.

*1.These values refer to well-developed wind waves of the open sea.

A reference to a particular "Force" assumes that the interpreter of the information knows the above information.
Reference to a particular force where there is not a condition of "well-developed wind waves of the open sea" should be interpreted to mean "winds associated with a particular Force"
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Old 16 November 2009, 06:57   #52
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probably,possibly right then. next time it blows a 60knt wind in the solent i shall tell everyone dont panic its only a force 5 because of the wave height fancy the red jet boys cancelling services because of a force 5
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Old 16 November 2009, 08:22   #53
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60 kn winds can affect vessels (particularly high sided ones) from a berthing / unberthing / keeping a vessel alongside.On many high sided vessels 15kn of beam wind can be equated to an effect on the vessel the same as that of 1 kn of current & so on. These winds can also cause adverse sea effects eg short steep seas particularly in a wind against tide scenario.
Is is possible to have 60 kn winds associated with a F11 & sea conditions associated with those of a F5. It would be completely inaccurate to say that every time there are winds gusting to 60kn that there is a "violent storm".
If you were in a river / fjord etc which is flanked by high ground on either side where there can be localised winds for example of 64kn plus you couldnt sat it was F12 as you wouldnt have the sea conditions, you would have winds associated with Beaufort F12.
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Old 16 November 2009, 09:06   #54
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Quote:
Originally Posted by Zubenelgenubi View Post
60 kn winds can affect vessels (particularly high sided ones) from a berthing / unberthing / keeping a vessel alongside.On many high sided vessels 15kn of beam wind can be equated to an effect on the vessel the same as that of 1 kn of current & so on. These winds can also cause adverse sea effects eg short steep seas particularly in a wind against tide scenario.
Is is possible to have 60 kn winds associated with a F11 & sea conditions associated with those of a F5. It would be completely inaccurate to say that every time there are winds gusting to 60kn that there is a "violent storm".
If you were in a river / fjord etc which is flanked by high ground on either side where there can be localised winds for example of 64kn plus you couldnt sat it was F12 as you wouldnt have the sea conditions, you would have winds associated with Beaufort F12.
You are quite right. In the Burry Estuary it is quite possible to have 30' waves with hardly any wind. It is also possible to have 70kts of wind with only 6' waves.

All it needs is a storm in the Atlantic with the big rollers sweeping in!!!
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Old 16 November 2009, 11:18   #55
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Beaufort lived in the days of sail. His scale was devised to help sailing ships choose the right amount of canvas for the conditions. A way of estimating the wind strength in open ocean was to look at the sea state, which gives an indication of the Beaufort scale. Thus the frigate captain knew which sails to leave set and which to hand. The Beaufort scale is not linear, being based on the pressure of wind on sails.

For a sailing boat wind strength (and direction) is what matters, whether in open ocean or sheltered waters. For motor boats, it's sea state that's more important than wind strength. So setting off in a forecast F11 in sheltered waters is not particularly foolhardy. Turning round when the sea state becomes too much is a seamanlike thing to do.

Of course, in such strong winds you have much less time to react should you have a breakdown, for instance. In (smallish) RIBs there's also the tendency to fly if going fast into a gale of wind, so you do have to be careful.

I can't imagine a professional skipper not working out a passage plan and doing a risk assessment before setting off - more than likely in this instance just a mental exercise. Whatever the qualification level, the gulf between professional charter skippers and amateur boaters, in terms of boat handling and sea experience, is huge. It will take the average amateur eight years or more to accumulate the sea time and experience a professional accumulates at the end of his first year in the job.
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Old 16 November 2009, 13:51   #56
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you want to go and check what the weather was doing saturday morning at 11.00am the wind was gusting to over 60knts,so go check your scale now...
Given that Ribnobburs are more inclined to exagerating the wind speed upwards than downwards, especially if they've made the wise decision to curtain a trip, I was more inclined to believe the lower number... but as you told me to check I did...

http://www.isleofwightweather.co.uk/ which appears to be in mph and based in Newport -- suggests max all day was a gust of 51 mph, and that 10-12am was gusting < 40 mph.

http://www.weather-file.com/hurst2/archive.htm in Lymington -- gusts typically < 50 knots in the morning (and < 40 before 10am).

http://www.bramblemet.co.uk/archive/...14Nov2009.html is broadly in agreement with that... as do their sister sites at southampton and chichester.

So, not withstanding Zubenelgunibi's comments, it sounds like it certainly wasn't a force 11... probably better described as something along the lines of F6 gusting 8, increasing to F8 gusting 9 occassionally 10 later.

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..still think its sensible to go out in that ?
I wasn't there, I didn't see the conditions, I wasn't familiar with the forecast etc - so its not "my call" if it was right to go out - it was Tim's. But I don't see that the call was any different because at completely differnet times the boat is used to carry passengers. Given that he came back in one piece with no reported damage to the boat or crew it sounds like, empirically, his trip was safe.
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Old 17 November 2009, 04:01   #57
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check again on chi met and camber met,which is closer to pompey,bored of this now,we seem to be going round and round in circles.
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Old 17 November 2009, 04:06   #58
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alystra,some charter skippers are still pretty young,so have some catching up with many people on this site
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Old 17 November 2009, 05:04   #59
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It seems reasonable for someone in the business of chartering RIBs to test the limits of the 'safe operations' envelope occasionally, in a controlled way. How else can he be expected to define them? That's what Tim appears to have done.
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Old 17 November 2009, 07:08   #60
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check again on chi met and camber met,which is closer to pompey,
I stand corrected the cambermet archive shows a single gust of 60.2 knots at around 11.30 am. I don't think its reasonable to take one result from one single gust at one single location (some distance away) and therefore claim that it was F11, or gusting >60 knots. All the other data points clearly indicate that this was not a representative picture.

It really makes little difference because I would defend Tim's right to assess the situation any make up his own mind, based on all the available information, as for any other pleasure or charter skipper.

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bored of this now,we seem to be going round and round in circles.
well don't make comments on public forums if your not prepared to defend them.
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