"Donal" wrote in message
...


The wave height is often less than 1m. That doesn't mean that the hatches
can be left open. Waves are not uniform in height. On the small lake in
Ireland that I go trout fishing on, the locals say that every 7th wave will
be twice as big as the rest.

Actually, wave height is usually measured as the average of the highest third of
all waves. Do the math and you'll find that the stated wave height is the
"seventh" wave.

But this is beside the point. I'm not talking about leaving the forward hatch
wide open in all conditions. Many boats, and most larger boats, have hatches
that will stay dry even if the bow is catching occasional spray.




A similiar thing seems to happen at sea.... especially after a wind shift.
It is often possible to pick out yesterday's waves travelling at 90 degrees
to today's wind/waves. Every so often these two wave patterns will combine
to produce a much bigger wave. I assume that this effect must be observable
in any strecth of open water.

Its particular obvious when you pass behind an island that blocks the direct
path of otherwise benign swells. Two wave fronts radiate from the sides of the
island and cause great mischief when you thought you were headed into the lee.
Close the hatches.

That is one of the reasons that I think that
you must sail in extremely sheltered waters.


Much of my sailing is inside of Boston Harbor, or in Buzzard's Bay. Frankly,
they are both often sloppier than the open ocean. But at least 10 times a year
(often more) for the last 30 years I've had 3000 miles of fetch to the East.
However, as I've said the prevailing winds are from the West, so there are
plenty of times where the waves just aren't that bad.




This isn't about what is appropriate for a Channel crossing, or the
Sydney-Hobart race. Donal has declared that all sailboats must always
stay
sealed up, regardless of the boat or the situation. It just isn't so.

In my experience, it is necessary to seal up before leaving the berth.

This may indeed be your experience. You must have a very wet boat. I've got
one hatch that hasn't been sealed in 8000 miles.

Even on calm days, you get the odd rogue wave that appears from nowhere.

Is that like the fog, which you claim can happen anytime without notice?


In the protected waters of the Solent, on an absolutely flat calm day, you
get the occasional big "slapper". I'm fairly sure that they are caused by
the wakes of big ships bouncing (reflecting) off one shore and crossing the
Solent for a second time.


Are you actually claiming that on a calm day everyone in the cockpit could get
totally soaked??? You must have a *very* wet boat.