Fall in New England means changing weather fronts and the greater possibility of rough seas. On the Massachusetts coast, rough seas often are the result of an Easterly wind. The larger wind fetch of the open ocean to the east results in larger waves and more rough seas than on days when the wind comes from the West or Southwest.
In the area of Massachusetts Bay outside Boston Harbor and to the South, we are well protected by Cape Cod. Normal days with convection-generated Southwest winds, this land mass to our South and Southwest protects agains a long wind fetch. Boaters in Rhode Island, Connecticut and even Buzzards Bay know that the boating can get very rough, even on a fair weather afternoon due to the long southwesterly wind fetch over Long Island Sound and the Block Island area. But in Boston, it’s the Northeast and Eastern exposures that tend to kick up the roughest seas. Here are a few considerations if you are heading out in less than ideal conditions:
1) Check the marine weather forecast at wunderground.com. A series of buoys along the coast can give you real time data on wind speed and wave height. The closest station to the open waters outside Boston Harbor is the 44013 Buoy, which is very useful to monitor.
2) A general rule of thumb is that if the wind speed in kts is higher than the length of your boat in feet, stay in. But don’t push your luck on this one! Here are a few more potentially helpful bits of advice for boating in rough seas:
3) Go slow. Most obviously, this results in a smoother ride with less pounding. Rough seas also negatively impact fuel economy, so the slowest speed you can achieve while getting the boat to plane may be optimal.
4) Quarter the waves. This means approaching at a 45 degree angle. Approaching head-on will be rough and innefficient, leading to poor fuel economy. Riding parallel to the waves subjects your boat to potentially dangerous roll.
5) Use trim tabs to keep the bow down in an oncoming sea, and when quartering, trim up the side hitting the waves. This results in more comfort and stability as the “V” of the hull will be hitting the waves straight on, instead of having the underside pound flatly against the water. Given that we just saw the olympics, here is a diving analogy: Putting your V-hull head on into the chop is the boating equivalent of diving- pounding flat against the underside is like a belly-flop. The former is smooth, the latter?….ouch.
6) Be careful of following seas. If you go out to see in head on chop, you will experience a following sea when you return (unless the wind changes completely when you are out). A following sea is more pleasant, but be careful not to bury the bow. Too much trim tab usage can be dangerous here- I usually don’t use them at all in a following sea. Boats with narrow beams can be especially tricky here, as they tend to dig in more.
Finally, here is a good link from Boatsafe about handling your boat in rough seas:
http://www.boatsafe.com/nauticalknowhow/waves.htm
Below are a couple of videos I have taken while boating in some rough seas. The first is in Massachusetts bay while approaching Provincetown (seen in distance) in large but smooth rollers. The second is while returning from fishing on a rough day in a following seas while several miles East of Boston Harbor. The roughness of the sea is not greatly visible in these videos, although the technic for keeping the ride smooth should be:
