Doug Dotson wrote:

To be really safe, put them in the cockit. That way they will drain
out the scuppers and not be so prone to taking in sal****er. Another
option is to put them up the mast a bit. I know someone that did this.
Overflow will go out the fill rather than out the vent. Problem solved
forever.

I set my water tank vents on the outside of the cockpit coaming just
down hill from the deck fill. When the tank is full water flows across
the side deck and out the scupper. You do have to be careful to locate
the vents so that the overflow will not flow back into the deck fill.

Chartered a boat once that had the vent lines run up inside the
stantions with a vent hole just under the top lifeline. Worked great
but if you were holding the hose when the tank overflowed it would spray
you in the face. :-)


--
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

Air vents for the water tanks are just for venting air (to allow air to
enter when water is being pumped out and to allow air to escape when
filling the tank) not for water escape. If you are using them for water
escape, be very careful. WHen filling the tanks you better NOT have too
much pressure. Even .5 psi can put a lot of pressure on the tops of
tanks - 2'x 5'lid = 24"x 60" = 1440 sq in x .5= 720 pound of pressure,
enough to cause the lid to buckle and separate.

When filling, we always remove the input vent on the top of our tanks
and 'watch' the water filling. Even the exhaust vent in the tanks can
cause pressure.


Hanz

Glenn Ashmore wrote:


Doug Dotson wrote:

To be really safe, put them in the cockit. That way they will drain
out the scuppers and not be so prone to taking in sal****er. Another
option is to put them up the mast a bit. I know someone that did this.
Overflow will go out the fill rather than out the vent. Problem solved
forever.


I set my water tank vents on the outside of the cockpit coaming just
down hill from the deck fill. When the tank is full water flows across
the side deck and out the scupper. You do have to be careful to locate
the vents so that the overflow will not flow back into the deck fill.

Chartered a boat once that had the vent lines run up inside the
stantions with a vent hole just under the top lifeline. Worked great
but if you were holding the hose when the tank overflowed it would spray
you in the face. :-)

Not likely that too much pressure can build in the vent while
overflowing out the fill.

Doug
s/v Callista

"hanz" wrote in message
...
Air vents for the water tanks are just for venting air (to allow air to
enter when water is being pumped out and to allow air to escape when
filling the tank) not for water escape. If you are using them for water
escape, be very careful. WHen filling the tanks you better NOT have too
much pressure. Even .5 psi can put a lot of pressure on the tops of
tanks - 2'x 5'lid = 24"x 60" = 1440 sq in x .5= 720 pound of pressure,
enough to cause the lid to buckle and separate.

When filling, we always remove the input vent on the top of our tanks
and 'watch' the water filling. Even the exhaust vent in the tanks can
cause pressure.


Hanz

Glenn Ashmore wrote:


Doug Dotson wrote:

To be really safe, put them in the cockit. That way they will drain
out the scuppers and not be so prone to taking in sal****er. Another
option is to put them up the mast a bit. I know someone that did this.
Overflow will go out the fill rather than out the vent. Problem solved
forever.


I set my water tank vents on the outside of the cockpit coaming just
down hill from the deck fill. When the tank is full water flows across
the side deck and out the scupper. You do have to be careful to locate
the vents so that the overflow will not flow back into the deck fill.

Chartered a boat once that had the vent lines run up inside the
stantions with a vent hole just under the top lifeline. Worked great
but if you were holding the hose when the tank overflowed it would spray
you in the face. :-)

On Sat, 26 Jun 2004 10:03:56 -0400, hanz
wrote:

WHen filling the tanks you better NOT have too
much pressure. Even .5 psi can put a lot of pressure on the tops of
tanks - 2'x 5'lid = 24"x 60" = 1440 sq in x .5= 720 pound of pressure,
enough to cause the lid to buckle and separate.

I was thinking of writing along this line because I had that issue
with my fuel tanks. It's easy to get a lot of pressure. Say a water
tank vent outlet (or filler cap) is 6 feet above the tank. By the time
water comes out the vent or filler cap you have about 1/5 atmosphere
or 3 psi in the tank. Fuel is similar, probably 75% of that pressure.
My tank vents are fairly high up a coaming on a center cockpit and the
fuel tanks are under the sole. There's 7-8 feet of head. My tanks
oozed around some fittings that were not used to pressure and around
an inspection port that wasn't really adequately gasketed.