water deck fill geyser - old faithfull

[rossny]

Hi all,
Isn't there supposed to be a vent in the water tank">fresh water tank? In my new to me boat after I get the tank somewhat full it starts to geyser water with a large burp, then I fill some more and again burp. Have to go thru this 20-30 times until water level equals deck level and its full. I don't see a vent like the holding tank and that to me is whats obviously missing. So where do I add the vent? Would the best place be the top of the tank or in the deck fill hose? Should it go out the hull or just into an inside locker? What size hose will suffice? Thanks

[cptcptcpt]

try sliding a small hose in alongside the waterhose, it might be a qwik fix

when your fill cap is off you might see a little hole that is gunked up

[rwidman]

Before you try to install a vent, find the existing one and make sure it is clear. If you tank had no vent you wouldn't be able to draw water out of the tank once you put the cap back on.

[Smokeys Kitchen]

My water tank vents turned out to be spigots that emptied into the galley sink. If that is the case, make sure that is clear. As stated earlier, you should have a vent line already otherwise you wouldn't be able to get water to flow out very efficiently

[Tayana42]

My water tank vents are also spigots at the galley sink. That's a good arrangement because any overflow when filling the tanks goes harmlessly in the sink. The vent lines are much smaller than the fill so they can't keep up with the inrush from city water pressure, consequently I get the geyser burping too if I try to fill rapidly. For reasons of keeping the water clean I decided to use an inline pre-filter on my hose (one I use only for filling the water tanks). That slows down the rate of fill and inadvertently solved the geysers.

[Terra Nova]

Check the fill hose to eliminate any traps.

[David B]

Originally Posted by rossny

Hi all,
Isn't there supposed to be a vent in the fresh water tank? In my new to me boat after I get the tank somewhat full it starts to geyser water with a large burp, then I fill some more and again burp. Have to go thru this 20-30 times until water level equals deck level and its full. I don't see a vent like the holding tank and that to me is whats obviously missing. So where do I add the vent? Would the best place be the top of the tank or in the deck fill hose? Should it go out the hull or just into an inside locker? What size hose will suffice? Thanks

I don't know your boat, but many have a vent on the hull in the vicinity of the deck-fill. Usually a small chrome or stainless steel fitting with the opening pointing aft. Could be that a mason bee or something, has started living in there.

When we fill, the normal flow from a domestic type hose is no problem. These days I also filter through a two-stage (20 micron, then 5 micron) filter to avoid accumulation of sediment in the tanks. That slows the flow a little, but either way, we only have water coming out at the last few litres.

If you can't find a vent on your hull (there will also be one for your fuel tank, then trace the filling line down from the deck to the tank. The vent will either be tee'd into the filling line, or come from a separate spigot on the tank.

Also, there is often a valve or baffle in the vent line to minimise chance of sea water getting in when heeling, while still allowing air to get out when filling, and in when draining. That could also be blocked.

See how you go with that.

David

[Seriously Slow]

We have had 2 different boats that hid the vent in one of the lifeline stanchions.
The stanchion had a 5/16 or 3/8 inch hole near the base of it. You could have one of that style that is blocked.
Bill

[rhubstuff]

I've had the same problem in several boats. At the first belch, I would turn the fill hose down to a mere trickle and then just wait until the fill pipe runs over. If your faucets work fine, there is a vent somewhere and it is working. Trying to top off a tank using a shore-side full pressure source is the problem. Reduce the flow (a lot) and be patient. The fill pipe can be your vent pipe too if you don't force-feed it.

[sailormed]

Most boats build these days have polymer tanks. Great tanks, but they are "burping". The water inflow builds up pressure and the tank walls get pushed to the outside. Then suddenly the tank walls are stretched to much and recover to their initial position, burping water out of the filing tube.