On Mon, 17 Nov 2008 18:53:02 -0600, Vic Smith
wrote:

On Mon, 17 Nov 2008 18:27:39 -0500, "Roger Long"
wrote:

"Larry" wrote

Huh?? Air temp rises....tank pressurizes and air flows out.
Air temp drops....tank gets vacuum and breathes in.


This is the simple thinking that vastly overstates the problem.

More accurate rewrite:

Air temp rises. Air volume increases very slightly. A small amount of air
is expelled from tank.
Air temp drops. A small amount of air enters tank.

There is a lot of thermal mass in half a tank of fuel and the tank itself is
protected from the sun and inside a hull. The air volumes are not that
great nor are the temperature swings.

Condensation hysteria.

Everybody's favorite boat expert.
http://www.yachtsurvey.com/myth_of_c...fuel_tanks.htm

--Vic

I've seen worse cases of arm-waving but who needs advice from
'experts' who cannot do simple arithmetic (*9/5+32) and have not
analysed the situation very well, or done any actual measurements
etc..