Fresh Water Tank Vent Location?

[SG]

One tank to each y valve port. Vent from each tank to relieve suction. Don’t hydraulically link tanks.

There are a lot reasons for that. If you want to add a transfer pump, make it a separate line and I would valve it off. That, in my opinion for your situation, is overkill.

 

[jviss]

Both tanks are vented. I can emulate a Y valve by opening only one ball valve at a time. Would be nice to have a gauge for the bow tank.

 

[jssailem]

Would be nice to have a gauge for the bow tank.

Use a water level to give a gauge of the water in the tank.
Run a piece of clear tubing from inside the tank to where ever you want to do the measuring. Put a control valve in the line Secure the line to your measuring site. Assure the tube is higher than the tank and open to the air. Fill the tube with water. Burp it. No air in the tube between the valve and the bottom of the tank.
With boat level open the valve. The water level in the tank will be displayed by the water level in the tube. Simple system.

 

[jviss]

Use a water level to give a gauge of the water in the tank.
Run a piece of clear tubing from inside the tank to where ever you want to do the measuring. Put a control valve in the line Secure the line to your measuring site. Assure the tube is higher than the tank and open to the air. Fill the tube with water. Burp it. No air in the tube between the valve and the bottom of the tank.
With boat level open the valve. The water level in the tank will be displayed by the water level in the tube. Simple system.

That's a great idea, a "sight glass." Reliable, accurate, and no power required!

 

[JamesG161]

That's a great idea, a "sight glass." Reliable, accurate, and no power required!

True in calm seas.
Jim...

 

[JamesG161]

What I liked about your system is...
1) Use the bow tank to fill the settee tank at sea. Only one gauge needed.
2) Common vent to bilge for overflows
3) No Y valve, which is "either or" use only.
4) No gauge on bow tank needed.

Why not on #4?
When you fill tanks, fill main tank first using gauge. Then fill bow tank next. Look at overflow to bilge to see when it is full.
Jim...

 

[thinwater]

Bilge vents are not that unusual. The reason given is generally to avoid seawater intrusion, but that's really not a good enough reason. If the loop is higher than the fill it can work just fin, but often it is not. I've seen them routed to the sink, which works.

And you still need a screen on the vent; bugs can and will crawl in. If it were on land, the building code requires this.

 

[GinGin]

I have just purchased a Beneteau 42, I think the forwardmost water tank vents through the hull via a vented loop, my concern with this is sea water entering the vent and contaminating the freshwater tank, is this method normal or am I too cautious?

 

[JamesG161]

I think the forwardmost water tank vents through the hull via a vented loop

The small white hose is not a Vented Loop.
But it is a loop to prevent sea water back flow on a "heel" while sailing.

The sea water can be Forced into your tank.
It will depend on the connection on the thru hull.

Read above[ post #3] for one type of connection to hull.
Jim...

 

[jviss]

I have just purchased a Beneteau 42, I think the forwardmost water tank vents through the hull via a vented loop, my concern with this is sea water entering the vent and contaminating the freshwater tank, is this method normal or am I too cautious? View attachment 215260

I am concerned about the corrosion on that fitting penetrating the hull.