trawlers@lists.trawlering.com

TRAWLERS & TRAWLERING LIST

View all threads

TWL: Beating to Wind

M
mikem@yachtsdelivered.com
Wed, Jan 9, 2002 3:58 PM

As you must realize every once in awhile I get a kink in my chain and feel
compelled to try to unkink it.
Today's topic has to do with that obscure force we call wind and it's
effect on progress.
If this doesn't make any sense, just bear with me.

At a certain level of discomfort and a certain level of lack of progress
beating to windward does not make sense. I have been thinking about this
problem for some years and today is the day. Since I spend most of my time
beating my way up the West Coast, you can imagine the amount of time I have
to daydream about "Mike's, Smooth Water Making Machine". As you can surmise
this machine is only in the prototype planning stage. In the meantime I
have to deal with reality. Which is to say that things are not all right in
OZ. On the other hand, I have had more than enough time to formulate a set
of "rules of thumb".

For small craft under 65 feet but at least 35 feet (and wind on the bow).

Making 3 Knots over the ground with 45 knots of wind on the bow, only makes
sense if the fetch is less than 30 miles or so, as it will take 10 hours to
get to the calm water up ahead.

Being out in the open (not inside a bight of land that provides some
protection up ahead), in other words a fetch of less than 100 miles, is not
smart at wind speeds above about 35 knots, ESPECIALLY at night.

You may recall that I have been harping on Gustiness recently. I have a
report from a yachtsman of their being out near Cape Mendocino during the
daylight in about 40 knots of wind and getting hit by a single wave about 3
times the average wave of about 15 feet. He reported that just before it
hit, things got real dark, as it was towering over them. He also confirmed
that it was quite gusty at the time. (this was on deep water about 20 miles
offshore).

This incident does not prove my point about gustiness and close coupled
waves, but it does provide ammunition for it. If they had been out at night
and this had happened and caught them off guard or a little broadside, they
might have had a lot of damage or lost the boat. The "book" on wave
prediction estimates that a wave 3 times the average height is about a one
in 4000 occurrence. This estimate is a mathematical calculation that only
relates to the real world in a loose sort of way.

Don't get me wrong about the science boys. I am a big fan of their formulas
and tables of prediction. But these things are only approximations and
everyone should keep that in mind.
We might not need or have a use for such approximations, if we could simply
visualize the real wave system, complete with nuances inside our heads, at
will.

Regards,

Capt. Mike Maurice
Near Portland Oregon.

As you must realize every once in awhile I get a kink in my chain and feel compelled to try to unkink it. Today's topic has to do with that obscure force we call wind and it's effect on progress. If this doesn't make any sense, just bear with me. At a certain level of discomfort and a certain level of lack of progress beating to windward does not make sense. I have been thinking about this problem for some years and today is the day. Since I spend most of my time beating my way up the West Coast, you can imagine the amount of time I have to daydream about "Mike's, Smooth Water Making Machine". As you can surmise this machine is only in the prototype planning stage. In the meantime I have to deal with reality. Which is to say that things are not all right in OZ. On the other hand, I have had more than enough time to formulate a set of "rules of thumb". For small craft under 65 feet but at least 35 feet (and wind on the bow). Making 3 Knots over the ground with 45 knots of wind on the bow, only makes sense if the fetch is less than 30 miles or so, as it will take 10 hours to get to the calm water up ahead. Being out in the open (not inside a bight of land that provides some protection up ahead), in other words a fetch of less than 100 miles, is not smart at wind speeds above about 35 knots, ESPECIALLY at night. You may recall that I have been harping on Gustiness recently. I have a report from a yachtsman of their being out near Cape Mendocino during the daylight in about 40 knots of wind and getting hit by a single wave about 3 times the average wave of about 15 feet. He reported that just before it hit, things got real dark, as it was towering over them. He also confirmed that it was quite gusty at the time. (this was on deep water about 20 miles offshore). This incident does not prove my point about gustiness and close coupled waves, but it does provide ammunition for it. If they had been out at night and this had happened and caught them off guard or a little broadside, they might have had a lot of damage or lost the boat. The "book" on wave prediction estimates that a wave 3 times the average height is about a one in 4000 occurrence. This estimate is a mathematical calculation that only relates to the real world in a loose sort of way. Don't get me wrong about the science boys. I am a big fan of their formulas and tables of prediction. But these things are only approximations and everyone should keep that in mind. We might not need or have a use for such approximations, if we could simply visualize the real wave system, complete with nuances inside our heads, at will. Regards, Capt. Mike Maurice Near Portland Oregon.