The angle of incidence of sunlight on a stationary flat panel would be a
sinusoidal curve between sunrise and sunset but I don't think the power
output would quite follow the Rule of 12ths. For one thing the amount of
atmosphere the light has to pass through would squeeze the peak output
towards the center where both the filtering and the angle of incidence would
be least. If the panel were mounted so it tracks the sun the output curve
would be flatter.

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

"Geoff Schultz" wrote in message
.. .
Does the hours of sunlight follow the rule of 12ths? I suspect that it
does, but I'm too busy to figure it out by myself and I thought that
someone might now the answer off the top of their head.

-- Geoff

I'm not thinking about solar panels. I was just watching the daylight
disappear while thinking having to move BlueJacket from the Chesapeake to
Ft. Lauderdale at the end of the month. I was thinking about how quickly
we're loosing daylight and wondered if rate of change was the same as tidal
change and thus the rule of 12ths. I couldn't see why not.

-- Geoff

"Glenn Ashmore" wrote in
news:fHsVg.23885$rg1.377@dukeread01:

The angle of incidence of sunlight on a stationary flat panel would be
a sinusoidal curve between sunrise and sunset but I don't think the
power output would quite follow the Rule of 12ths. For one thing the
amount of atmosphere the light has to pass through would squeeze the
peak output towards the center where both the filtering and the angle
of incidence would be least. If the panel were mounted so it tracks
the sun the output curve would be flatter.

On Fri, 06 Oct 2006 08:44:21 -0500, Geoff Schultz
wrote:

I was thinking about how quickly
we're loosing daylight and wondered if rate of change was the same as tidal
change and thus the rule of 12ths. I couldn't see why not.

The daily rate of change is highest at the spring and fall equinox
since that is where the sine curve has the steepest slope (when it
passes through zero).

Short days are definitely an issue when you bring a boat south in the
fall but it gets somewat better as you get further along towards lower
latitudes.

I assume you are comfortable running at night with all the cruising
you have done. If so, wait for a good weather window and head
offshore for a few days at a time. That's what we did last year and
it worked out well. As long as we are not in the ICW, or coming into
strange harbors, running at night is not a problem.

In that case you will probably get pretty close. The Rule of 12ths is
actually a way to estimate the slope of a sine wave and except for a few
minor variations the seasonal variation in day length is sinusoidal.
--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

"Geoff Schultz" wrote in message
.. .
I'm not thinking about solar panels. I was just watching the daylight
disappear while thinking having to move BlueJacket from the Chesapeake to
Ft. Lauderdale at the end of the month. I was thinking about how quickly
we're loosing daylight and wondered if rate of change was the same as
tidal
change and thus the rule of 12ths. I couldn't see why not.

-- Geoff

"Glenn Ashmore" wrote in
news:fHsVg.23885$rg1.377@dukeread01:

The angle of incidence of sunlight on a stationary flat panel would be
a sinusoidal curve between sunrise and sunset but I don't think the
power output would quite follow the Rule of 12ths. For one thing the
amount of atmosphere the light has to pass through would squeeze the
peak output towards the center where both the filtering and the angle
of incidence would be least. If the panel were mounted so it tracks
the sun the output curve would be flatter.

On Fri, 6 Oct 2006 12:14:25 -0400, "Glenn Ashmore"
wrote:

In that case you will probably get pretty close. The Rule of 12ths is
actually a way to estimate the slope of a sine wave and except for a few
minor variations the seasonal variation in day length is sinusoidal.
--
Glenn Ashmore

Glenn, what's the latest estimate for splashing noises coming from
your direction?

Glenn, what's the latest estimate for splashing noises coming from
your direction?

I keep saying that if I can keep my ass in gear I can be in the water in the
Spring. The problem is keeping it in gear. :-)

I am down to the picky and painful parts now. Laying the teak on the side
decks, setting plumbing fixtures, final fairing and painting the topsides
and a whole bunch of interior sanding and varnishing. The big plus is that
everything but the electronics, spars, rigging and sails is on hand and paid
for so no more time wasted waiting for the boat kitty to refill. :-)

You know you are getting close when you go to the Annapolis show and don't
look at the boats. Spent all my time in the tents looking at parts and
discovered a downside to gradually acquiring things as bargains are
presented. I picked up 350' of NE Ropes 3 strand last year and they just
introduced a new nylon plait anchor rode with a soft hand that stacks in
about half the space of 3 strand. I will be setting my two Atlantes heads
this weekend and Raritan has a new model that is simpler and uses less amps.
Fortunately I have not bought any electronics yet. There are some amazing
things happening in autopilots and nav systems.

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

On Sat, 7 Oct 2006 08:20:13 -0400, "Glenn Ashmore"
wrote:

The big plus is that
everything but the electronics, spars, rigging and sails is on hand and paid
for so no more time wasted waiting for the boat kitty to refill. :-)

Don't under estimate the cost of spars, rigging and sails. I once
rerigged a Cal-34 from the deck up, and it was a big number even 20
years ago.

On Sat, 7 Oct 2006 08:20:13 -0400, "Glenn Ashmore"
wrote:

Glenn, what's the latest estimate for splashing noises coming from
your direction?

.... The big plus is that
everything but the electronics, spars, rigging and sails is on hand and paid
for so no more time wasted waiting for the boat kitty to refill. :-)

I knew you had to be joking with that throw-away line:
ONLY the spars, sails, rigging, electronics?

Yowza!

Brian Whatcott Altus OK

The strategy has always been to get the topsides, deck and interior all nice
and shiny looking and THEN invite the bank out for a cockpit party. :-)

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

"Brian Whatcott" wrote in message
...
On Sat, 7 Oct 2006 08:20:13 -0400, "Glenn Ashmore"
wrote:

Glenn, what's the latest estimate for splashing noises coming from
your direction?

.... The big plus is that
everything but the electronics, spars, rigging and sails is on hand and
paid
for so no more time wasted waiting for the boat kitty to refill. :-)

I knew you had to be joking with that throw-away line:
ONLY the spars, sails, rigging, electronics?

Yowza!

Brian Whatcott Altus OK