I've had a few random questions rattling around the

brain for a while - figured I'd pose them there.



When a sub dives to a certain depth, is that depth

measured from the bottom of the sub, the middle,

or the top. In other words, if it dives to 200 feet,

does that mean there is 200 feet of water above

it or that the bottom of it is 200 feet below the

surface?



On modern gas car engines and when it's cold

outside, is it still better to let them warm up a

bit and how warm (how long) is necessary?



Anyone have a good way to find the total surface

area of my boat hull while it's in the water? It's

a 22' boat, not very deep V, "square" transom. I

did some estimating, but wonder if there are any

creative ways to get more accurate.



Gary

On Tue, 6 Jan 2004 19:24:30 -0500, "Gary Warner"
wrote:

I've had a few random questions rattling around the

brain for a while - figured I'd pose them there.



When a sub dives to a certain depth, is that depth

measured from the bottom of the sub, the middle,

or the top. In other words, if it dives to 200 feet,

does that mean there is 200 feet of water above

it or that the bottom of it is 200 feet below the

surface?



On modern gas car engines and when it's cold

outside, is it still better to let them warm up a

bit and how warm (how long) is necessary?



Anyone have a good way to find the total surface

area of my boat hull while it's in the water? It's

a 22' boat, not very deep V, "square" transom. I

did some estimating, but wonder if there are any

creative ways to get more accurate.



Gary


Gary, I can tell you only that the surface area of your boat is the
same both in and out of the water.

John H

On the 'Poco Loco' out of Deale, MD
on the beautiful Chesapeake Bay!

Gary Warner wrote:


When a sub dives to a certain depth, is that depth
measured from the bottom of the sub, the middle,
or the top. In other words, if it dives to 200 feet,
does that mean there is 200 feet of water above
it or that the bottom of it is 200 feet below the
surface?

Normally "depth to keel."


On modern gas car engines and when it's cold
outside, is it still better to let them warm up a
bit and how warm (how long) is necessary?

RTFM

Anyone have a good way to find the total surface
area of my boat hull while it's in the water? It's
a 22' boat, not very deep V, "square" transom. I
did some estimating, but wonder if there are any
creative ways to get more accurate.

Assuming you are seeking the "wetted area" rent one of those laser
thingys that scan a surface into a computer. Turn your boat on its side
and scan. Read computer generated results.

Rick

When a sub dives to a certain depth, is that depth
measured from the bottom of the sub, the middle,
or the top. In other words, if it dives to 200 feet,
does that mean there is 200 feet of water above
it or that the bottom of it is 200 feet below the
surface?

Normally "depth to keel.

I don't know squat diddly about submarines, but I think I can answer this
question. *If* the dive indicator reads "zero" when the sub is on the surface,
the submerged depth would be measured from the normally ballasted waterline to
the surface. It wouldn't seem logical, otherwise.

On Tue, 6 Jan 2004 19:24:30 -0500, "Gary Warner"
wrote:
I've had a few random questions rattling around the
brain for a while - figured I'd pose them there.

When a sub dives to a certain depth, is that depth
measured from the bottom of the sub, the middle,
or the top. In other words, if it dives to 200 feet,
does that mean there is 200 feet of water above
it or that the bottom of it is 200 feet below the
surface?

Interesting question but I have no idea.

On modern gas car engines and when it's cold
outside, is it still better to let them warm up a
bit and how warm (how long) is necessary?

Not necessary at all assuming everthing is in tune and the engine is
running smoothly. Just don't over rev the engine until it's up to
operating temperature, usually within a few miles.

Anyone have a good way to find the total surface
area of my boat hull while it's in the water? It's
a 22' boat, not very deep V, "square" transom. I
did some estimating, but wonder if there are any
creative ways to get more accurate.

If you piece it out into a rectangle and a triangle on each side, you
can get pretty close with a deep V hull. Given the deadrise angle and
length we could develop a trig formula that would be a good
approximation, but it's easier to piece it out, and you'll have a
better intuitive sense of the answer. (Length x Beam) + a small fudge
factor will also get you pretty close.

"Gary Warner" wrote in message
...
I've had a few random questions rattling around the

brain for a while - figured I'd pose them there.



When a sub dives to a certain depth, is that depth

measured from the bottom of the sub, the middle,

or the top. In other words, if it dives to 200 feet,

does that mean there is 200 feet of water above

it or that the bottom of it is 200 feet below the

surface?


8 years on submarines and it is bottom of keel. Most
subs read about 65 feet at periscope depth which has
the sail about 5 to 10 feet below the surface.



On modern gas car engines and when it's cold

outside, is it still better to let them warm up a

bit and how warm (how long) is necessary?

Not an expert but, cold starts are a major
cause of engine wear. The oil is too thick to get
through all the passages quickly. Yes, let it warm
at least a little before raising rpm's to drive.





Anyone have a good way to find the total surface

area of my boat hull while it's in the water? It's

a 22' boat, not very deep V, "square" transom. I

did some estimating, but wonder if there are any

creative ways to get more accurate.

No idea!!

8 years on submarines and it is bottom of keel. Most
subs read about 65 feet at periscope depth which has
the sail about 5 to 10 feet below the surface.

Fascinating. What does the depth indicator say when the sub is surfaced?
Obviously it would not be zero.

The experts say in cold weather (below freezing) to warm the car up for a
couple of minutes and then drive away at a moderate pace.
Apparently it's much easier on the engine.... very inefficient to let a car
sit at idle...as oil not circulated as well as when on the move.

Gary Warner wrote in message

On modern gas car engines and when it's cold

outside, is it still better to let them warm up a

bit and how warm (how long) is necessary?

"Wayne.B" wrote in message
...
On Tue, 6 Jan 2004 19:24:30 -0500, "Gary Warner"
wrote:
I've had a few random questions rattling around the
brain for a while - figured I'd pose them there.

When a sub dives to a certain depth, is that depth
measured from the bottom of the sub, the middle,
or the top. In other words, if it dives to 200 feet,
does that mean there is 200 feet of water above
it or that the bottom of it is 200 feet below the
surface?

Interesting question but I have no idea.

On modern gas car engines and when it's cold
outside, is it still better to let them warm up a
bit and how warm (how long) is necessary?

Not necessary at all assuming everthing is in tune and the engine is
running smoothly. Just don't over rev the engine until it's up to
operating temperature, usually within a few miles.

Anyone have a good way to find the total surface
area of my boat hull while it's in the water? It's
a 22' boat, not very deep V, "square" transom. I
did some estimating, but wonder if there are any
creative ways to get more accurate.

If you piece it out into a rectangle and a triangle on each side, you
can get pretty close with a deep V hull. Given the deadrise angle and
length we could develop a trig formula that would be a good
approximation, but it's easier to piece it out, and you'll have a
better intuitive sense of the answer. (Length x Beam) + a small fudge
factor will also get you pretty close.

When the boat is in the water, draw a line on the side a short distance
above the water line, say 1 inch, with a grease pencil or sharpie
marker. Then when the boat is out, use a 1 foot square of cardboard and
trace around it to make a grid from the keel to the waterline. Only
have to do half the boat, and so only will have maybe 50 or 60 squares.
you could make smaller rectangles or triangles to fill in gaps if you
are going for ultimate accuracy.

Suggestion 2. Instead of the squares, cut black plastic and tape to
exactly cover wetted surface. Weigh on accurate scale. Weigh a known
area. divide.

del cecchi

On 07 Jan 2004 02:04:19 GMT, (Gould 0738) wrote:

When a sub dives to a certain depth, is that depth
measured from the bottom of the sub, the middle,
or the top. In other words, if it dives to 200 feet,
does that mean there is 200 feet of water above
it or that the bottom of it is 200 feet below the
surface?

Normally "depth to keel.

I don't know squat diddly about submarines, but I think I can answer this
question. *If* the dive indicator reads "zero" when the sub is on the surface,
the submerged depth would be measured from the normally ballasted waterline to
the surface. It wouldn't seem logical, otherwise.

You want to read depth to keel because you want it to be consistent with
the depth markings on charts. If the depth was to anywhere else, you'd
have to figure that in and it can contribute to mistakes that might
cause a grounding. I.e., if you're in an area where the min charted
depth is 250 feet, you can order a 200 foot depth safely. If it was
measured to the top and you ordered a 200 foot depth in 250 feet of
water, you'd hit the bottom.

Steve