Originally Posted by neilda
I tend to look at the Met Office site, but wonder what others do.
The Met Office posts High Seas warnings and Strong Wind warnings; http://www.metoffice.gov.uk/weather/..._forecast.html
(Generally more applicable to the Shipping Forecast areas, but useful information)
You could also visit one of the forecast sites that gives swell height, such as Magic SeaWeed; http://magicseaweed.com/UK-Ireland-Surf-Forecast/1/
If you're not familiar with the terms used, this is the key for wave height:
Smooth 0.1 - 0.5m
Slight 0.5 - 1.25
Moderate 1.25 - 2.5
Rough 2.5 - 4
Very Rough 4 - 6
High 6 - 9
Very High 9 - 14
Phenomenal over 14m
I've been out once in a "phenomenal" sea (not in a RIB!!) and I didn't like it much. Advice to stop at "moderate" in a RIB is not a bad guide, but even moderate seas are likely to be uncomfortable (it's not just wave height that matters, it's the distance between the waves too) for boats of medium size. Remember also that when the wind and tide are in the same direction the sea surface will tend to be calmer than when the tide turns, so you need to plan for that.
As a very very simple rule-of-thumb for people who have passed Level 2 and are looking for guidance we suggest that if there are white horses on the water they check the tides again; if wind is against tide, consider waiting until the tide turns and the sea eases. If wind and tide are together, don't bother going out - it's only going to get worse.