"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!!