Maybe Next Time

By Peter Cassidy

Published in AB Vol.45, No. 7 (Sept. 03)

Recently, a friend apologized to me for opting out of a dive opportunity due to a weather forecast predicting the ‘possibility of rain.’ Although a prediction of rain implies something unpleasant to most, my response to him was that “it’s summer, it’s warm and we’re going to get wet anyway”. It occurred to me while talking to him that many divers have some confusion about dive suitability and site selection as it relates to weather forecasts. Wind speed and direction have a far greater effect on the probability of a pleasant dive experience than any forecast of rain. Rain will probably have little or no effect on the prospects of a quality dive. The exception of course, would follow a torrential downpour. Then there could be poor visibility from surface runoff clouding up the water. Certainly if the overall climate is cold and damp, the pre-dive and particularly the post–dive may be increasingly more uncomfortable when you add the element of rain. If your likelihood of being miserable before, during and after a dive were assured due to a forecast of rain, I would be inclined to cancel also.

Wind will have a much more adverse effect on the quality of a dive. Wave action is enhanced if the wind is coming onshore. A protected site would be one that clearly has the wind from offshore. The morning of a dive would be a good time to check the latest forecast, paying close attention to the wind speed and direction. If the weather is calm with wind speeds from 0-5 in any direction, you are probably safe to dive anywhere you choose. If the speed is moderate (5-15) you should select a dive site where the wind will be offshore. If the wind speed is high (15 or greater) you should precisely select a protected spot or better yet, wait until another day.

Since many days have moderate wind speed, it would save time and sanity to be able to use the latest forecast with a map or nautical chart as a tool to predict the dive sites with the least probability of wave action. Consider some possible scenarios; (see map pg. 9) Let’s say there is a moderate wind out of the west, both Pebble Beach and Old Garden Beach are likely to be calm for diving. On the other hand, let’s say there is a moderate wind from the south-southeast, then Old Garden would be a better choice. This is a simple formula to follow and can narrow site choices in minutes. I can remember many times when meeting at Burger King for a club dive that a 'look and see' approach was chosen by the group. Picture four or five cars and trucks driving from one site to another to check each prospective dive site. I call this the “grand tour”. This takes a considerable amount of time and gasoline and can usually be avoided.

It’s not a perfect world so obviously the arrival at the selected site will only give the final verification of the conditions. The above approach clearly doesn’t work when there is a major storm system at sea, even a hurricane centered in Bermuda can give rough seas in what should appear to be a protected area. This article is not meant to imply any hard and fast rules for site selection but rather a guide that will often help in making pre-dive decisions.

	Maybe Next Time
By Peter Cassidy Published in AB Vol.45, No. 7 (Sept. 03) Recently, a friend apologized to me for opting out of a dive opportunity due to a weather forecast predicting the ‘possibility of rain.’ Although a prediction of rain implies something unpleasant to most, my response to him was that “it’s summer, it’s warm and we’re going to get wet anyway”. It occurred to me while talking to him that many divers have some confusion about dive suitability and site selection as it relates to weather forecasts. Wind speed and direction have a far greater effect on the probability of a pleasant dive experience than any forecast of rain. Rain will probably have little or no effect on the prospects of a quality dive. The exception of course, would follow a torrential downpour. Then there could be poor visibility from surface runoff clouding up the water. Certainly if the overall climate is cold and damp, the pre-dive and particularly the post–dive may be increasingly more uncomfortable when you add the element of rain. If your likelihood of being miserable before, during and after a dive were assured due to a forecast of rain, I would be inclined to cancel also. Wind will have a much more adverse effect on the quality of a dive. Wave action is enhanced if the wind is coming onshore. A protected site would be one that clearly has the wind from offshore. The morning of a dive would be a good time to check the latest forecast, paying close attention to the wind speed and direction. If the weather is calm with wind speeds from 0-5 in any direction, you are probably safe to dive anywhere you choose. If the speed is moderate (5-15) you should select a dive site where the wind will be offshore. If the wind speed is high (15 or greater) you should precisely select a protected spot or better yet, wait until another day. Since many days have moderate wind speed, it would save time and sanity to be able to use the latest forecast with a map or nautical chart as a tool to predict the dive sites with the least probability of wave action. Consider some possible scenarios; (see map pg. 9) Let’s say there is a moderate wind out of the west, both Pebble Beach and Old Garden Beach are likely to be calm for diving. On the other hand, let’s say there is a moderate wind from the south-southeast, then Old Garden would be a better choice. This is a simple formula to follow and can narrow site choices in minutes. I can remember many times when meeting at Burger King for a club dive that a 'look and see' approach was chosen by the group. Picture four or five cars and trucks driving from one site to another to check each prospective dive site. I call this the “grand tour”. This takes a considerable amount of time and gasoline and can usually be avoided. It’s not a perfect world so obviously the arrival at the selected site will only give the final verification of the conditions. The above approach clearly doesn’t work when there is a major storm system at sea, even a hurricane centered in Bermuda can give rough seas in what should appear to be a protected area. This article is not meant to imply any hard and fast rules for site selection but rather a guide that will often help in making pre-dive decisions.