Holding tank vent - where?
 

I have a composite boat built in 1971 that had no holding tank up until a
week ago. The hull is carvel construction sheethed in fiberglass and is
2-3" thick. The boat is an 1850s design with internal ballast of concrete
and pig iron ( a boat with a concrete floor) and about 2 feet of freeboard.
She is 30' LWL, 9 tons with just over 700 square feet of sail.

The hodling tank is located amidships on the port side. The problem is
where to run the vent line? If it goes through the hull it will be
amidships and because of the low freeboard it will end up submerged quite
often. If I run it to the bow or stern it gets to be a very long line. I
thought about running it straight up to the cabin top with a filter on it
but that does not seem like a good idea either.

Any advice?

Thanks,

Tom Hunter

Holding tank vent - where?
 

Tom Hunter wrote:
I have a composite boat built in 1971 that had no holding tank up until a
week ago. The hull is carvel construction sheethed in fiberglass and is
2-3" thick. The boat is an 1850s design with internal ballast of concrete
and pig iron ( a boat with a concrete floor) and about 2 feet of freeboard.
She is 30' LWL, 9 tons with just over 700 square feet of sail.

The hodling tank is located amidships on the port side. The problem is
where to run the vent line? If it goes through the hull it will be
amidships and because of the low freeboard it will end up submerged quite
often. If I run it to the bow or stern it gets to be a very long line. I
thought about running it straight up to the cabin top with a filter on it
but that does not seem like a good idea either.

It's not...and neither is a long line to the bow or stern.

I do wish you'd asked questions before you selected the tank location,
'cuz that's not where I'd have recommended you put it. Since you're
still trying to figure out where to put the vent thru-hull, I'm assuming
you haven't used it yet...and also that it's an "off-the-shelf"
rectangular tank. If both the above are true, can you return it and
start over? It may mean you'll have add some length to the head
discharge hose, but one inline union isn't a disaster.

If you can...where's the head located in the cabin...forward or aft?
That'll tell me the best place for the tank.

--
Peggie
----------
Peggie Hall
Specializing in marine sanitation since 1987
Author "Get Rid of Boat Odors - A Guide To Marine Sanitation Systems and
Other Sources of Aggravation and Odor"
http://69.20.93.241/store/customer/p...40&cat=&page=1

Holding tank vent - where?
 

Peggie,

The tank is next to the head which is also on the port side amidships. Its
located underneath a quarter birth. Due to the location of the head and the
configuration below decks this is the only place it could be. The other
option involved moving the head, removing the V births in the bow, sealing
the old through hull, installing a new one and rebuilding some cabinets,
births and the dining table. In short I am stuck with the current location
of the tank and the vent is the only thing left to do.

I agree that its not the best place, but sometimes not the best place is the
only place.

Tom

Holding tank vent - where?
 

Tom Hunter wrote:
Peggie,

The tank is next to the head which is also on the port side amidships. Its
located underneath a quarter birth. Due to the location of the head and the
configuration below decks this is the only place it could be. The other
option involved moving the head, removing the V births in the bow, sealing
the old through hull, installing a new one and rebuilding some cabinets,
births and the dining table.

Noooo... I've yet to see a boat that would require doing ANY of that
just to install a tank. It would actually be fairly easy to put the tank
under the v-berth, provided it's the right shape...and I'll bet Ronco
Plastics has one that is, 'cuz they have more than 400 shapes and sizes,
over 100 of which non-rectangular, and they install fittings in the
sizes and locations specified by the customer when they make the tank.
Top quality and very reasonable prices too. Their catalog of tank
drawings is on their website at http://www.ronco-plastics.com.

If you want to explore your alternatives, email me at
peg(dot)hall(at)sbcglobal(dot)net.

If you're determined to stick with what you have, you can prob'ly get
away with putting the vent fitting right below the toe rail, with a
clamshell over it. Can't promise that'll keep the water out of it if
your decks are awash for any length of time, or that it won't gas
everyone aft of it every time the head is flushed though.

I agree that its not the best place, but sometimes not the best place is the
only place.

There has never been a boat built on which there is ONLY one place to
put a tank...or even ONLY 2 or 3 places. Just one BEST place.

--
Peggie
----------
Peggie Hall
Specializing in marine sanitation since 1987
Author "Get Rid of Boat Odors - A Guide To Marine Sanitation Systems and
Other Sources of Aggravation and Odor"
http://69.20.93.241/store/customer/p...40&cat=&page=1