G'day all, we are running along today in a semi-following sea on our trip from St Martin to the BVI. A few penned thoughts that I have re waves and their combined effect on our boats progress thru the water. Many boaters spend their time coastal cruising and as such feel the effects of coastal waves with perhaps some swell from a max of 180 degrees either to the west or the east depending on which coast, in the US you boat on. As such the waves you encounter can only be a swell from the eastern or western quadrant. This can be accompanied by a local wind wave which may come from 360 degrees but will always be less from the "land side" than the "sea side" in a given wind strength. Once you get 100 miles or more offshore then you begin to have a broader number of degrees that a swell can come from. By the time you are 3-500 miles it can come from any point on the compass. Today is a good example of this. We are 40 miles from the nearest land which are just small islands in the scheme of things. To the south we are 400 miles from the nearest large land mass. To the west we are 1100 miles. To the north we are 1600 miles and to the east we are 2700 miles. So this allows us to see the swell patterns from 360 degrees with only the small island land masses to disturb it. We have a swell running from the SE of about 2 ft with a period of perhaps 6-8 seconds. A swell from the NW of maybe 1-2 ft but long period...12 secs or more as it is hard to time. Another from the NNE of about 2' and also long perhaps 10 sec's. Lastly one from the east of 2-3 ft of about 8 secs. A small wind wave of perhaps 2' with a 4 sec period. The tide is nearly slack right now. So what does all this mean from a weather nowcast? First the wind way SE of us is stronger pushing up a sea which is now long so might be 200 mile or so south to those winds. The one to the NW is a very long way away...500 miles or more so this is not a concern unless this swell is increasing which it is not. To the NNE again a long way 4-500 miles so again not a system of concern. East of us it indicates 3-400 miles to the wind that caused this swell so we'll need to keep an eye if this is increasing or not. If we look at the GRIB files for the wind for the Atlantic and Caribbean it basin they generally agree with what we are seeing with the exception of the SE component. The local area winds out to about 200 miles are forecasted to remain light. Now what do we see outside the pilothouse and feel in our seats?? 75% or so of the time the sea is a comfortable 3-4' in a generally following condition, +/- 30 degrees off our stern. Every 20-30 seconds we see a deeper sea and tend to nose down on the face and up as it passes from SSE to NNW. In a more random fashion we get 5-7 ft lumps and holes that are at the confluence of the various wave sets. We have seen two in the last half hour that we in the range of eight ft. So we have random waves that are twice the norm and the forecasted sig wave height. We have done this passage when the forecasted sig wave height was 15 ft and have seen some very much larger waves. The cruise ships were seeking alternate ports of call because of these larger seas! If we add the spring full moon to a mix such as this the we'd have many more holes as the moon rises with the tide pulling to the east and less as it sets pulling to the west. Just an additional item to deal with in passage planning. When one is exposed to the effects of the storms at sea that we hope we never encounter we must remember that they leave a very large footprint on the seas. Therefore we just might find ourselves in a pattern of swells that we wish we weren't in. Forecast's are a good help but learning to observe the sea, read the wave patterns and know what they are telling you is even more help. Sometimes they'll tell you to continue as conditions will improve and other times you need to seek alternative courses!! Just my observations of the waves/sea over my short period of living on the sea. As always YMMV. Dave & Nancy Swan Song Roughwater 58 Caribbean Cruise '07 787 990-6064 Sat 954 252-3830 fax