Anyone Added a 2nd Water Tank?

[jmain]

Has anyone added a 2nd water tank to their Grady? I have a 1996 Marlin 30 with the 35 gallon (I assume it is original) under the sea well at the transom. There appears to be enough room under the aft berth (in front of the waste tank) for a second water tank.

Does anyone have any ideas on how to plumb that, so 1 tank feeds the other and you don't have to switch a valve somewhere to go from one tank to the other?

Sorry if this is covered somewhere already, but searching anything with "water tank" gets a lot of hits on water in the fuel tank!

Thanks in advance!

 

[DennisG01]

Without an electrical/mechanical means of transferring water from the new tank to the old tank (where the pickup is), you'd need to rely on gravity. This can be done with a hose connection between the two tanks. The hose connections would be mounted as low as possible - essentially allowing water to freely flow back and forth between the two. As long as there's no part of the hose throughout the run that is higher than the connection points, this would work. Google for "bulkhead fittings" - that would be what you would use to make the connection at each tank.

Personally, I think a small transfer pump would be the better solution. When you lose water pressure, flip the switch for the transfer pump and the new tank will fill the old tank.

 

[jmain]

Without an electrical/mechanical means of transferring water from the new tank to the old tank (where the pickup is), you'd need to rely on gravity. This can be done with a hose connection between the two tanks. The hose connections would be mounted as low as possible - essentially allowing water to freely flow back and forth between the two. As long as there's no part of the hose throughout the run that is higher than the connection points, this would work. Google for "bulkhead fittings" - that would be what you would use to make the connection at each tank.

Personally, I think a small transfer pump would be the better solution. When you lose water pressure, flip the switch for the transfer pump and the new tank will fill the old tank.

Thanks, Dennis. That is a good idea and is along the lines of what I was thinking, because I don't see any way to run a hose along the floor of the bilge (which is where it would have to go) without pulling at least one of the fuel tanks. Plus, the new tank would be lower than the old tank when not on a plane, which would mean that the pickup would have to be there.
Having to switch a valve when one tank runs out isn't that big of a deal, I was just hoping someone had already done this with some eloquent solution that I hadn't thought of!
Thanks again!

 

[glacierbaze]

You don't have to connect the tanks, just run a pick up line from the second to the pump. For $10 or less, you can make a PVC manifold, with a ball valve for each line. Put it where it is easily accessible, open whichever one you want to pull from. Just remember, pumps push water much better than they pull it.

 

[DennisG01]

That ain't a bad idea, Glacier. Along those lines, a 3-way ball valve before the inline filter is another means to the end.

 

[jmain]

You don't have to connect the tanks, just run a pick up line from the second to the pump. For $10 or less, you can make a PVC manifold, with a ball valve for each line. Put it where it is easily accessible, open whichever one you want to pull from. Just remember, pumps push water much better than they pull it.

Agreed! That is the most straightforward of the solutions that I was thinking. The hard part is making it easy to switch the valve without having having to route the hoses several feet higher than the tanks. I would also have to add a new fill hose somewhere above deck.
Thanks for the feedback. I appreciate it.

 

[seasick]

A second fill would be necessary as would a second vent.

 

[DennisG01]

The hoses being a few feet higher than the tank shouldn't matter. However, as Glacier mentioned, the pumps are typically mounted close to the tank for a reason. But I think you'll be OK. I have a similar pump that I use for winterizing the cottage and it pulls from a bucket of antifreeze that's about 5 feet below it (through a 10' hose).

I don't know your layout real well, but can you go straight aft through over top of the wast tank then through the cabin/bilge bulkhead and then right over top of the gas tank?