Boat Listing

[spudsdailey]

I have an Offshore 48.
Love the boat. I have 3 water tanks, forward, and each side aft. All tanks 100 gallons each.

Here is my issue. At anchorage, I seem to empty one side far quicker than the other 2 tanks. As such, the boat lists rather substantially to the one side with the full tank.

I know I can manually close and open tanks, but that is a hassle.

Any other ideas?

[Pelagic]

So the issue seems to be with the 2 aft tanks?

When outlet valves are left open to these 2 aft tanks, is the fwd tank left open also?
If yes, can it be draining to one aft tank?
If kept closed and isolated, then ignore this tank.

Is the list consistent to one side?.......If yes, then try to partially close the opposite tank valve to keep levels equal

If the 2 aft join with straight piping rather than looping down into bilge, it is easier for one side to become favored for suction.

You really need to clarify how your existing plumbing is set up with valves and eventually supply pipe to pressure pump.

[spudsdailey]

Thank you Pelagic.
I think you may be on to something.
The two aft tanks are connected aft at a Tee. From there, one line goes forward to the pump, where it Tee's into the forward tank. This is the first time I have opened the forward tank (had the boat only a few months). Prior to this, the boat was relatively on her lines.

[billknny]

Originally Posted by spudsdailey

I have an Offshore 48.
Love the boat. I have 3 water tanks, forward, and each side aft. All tanks 100 gallons each.

Here is my issue. At anchorage, I seem to empty one side far quicker than the other 2 tanks. As such, the boat lists rather substantially to the one side with the full tank.

I know I can manually close and open tanks, but that is a hassle.

Any other ideas?

You are missing a couple very important concepts here. The reason people like boats with multiple tanks is so they can separate them and keep any potential contamination of the water supply isolated. Leaving all the tanks open totally defeats this.

100 gallons of water should last two people at LEAST a week at anchor. If changing valves to draw from different tanks once a week is "too much hassle" you either need to change to locations of the valves, or redefine what you consider a "hassle".

Remember this too.. if all the supply valves are open, and you draw all the water from one tank so air is sucked into the pump, you can't pull the water from the other tanks, no matter how much is in them.

Trying to balance the draw out of the tanks by adjusting the valves will absolutely NOT work.

Having all your water tanks out at the extremes of the boat (either fore and aft, or out at the extreme beam, or in your case, both!) is poor design, but you can live with it. It just takes a bit of hassle.

[Pelagic]

Originally Posted by spudsdailey

Thank you Pelagic.
I think you may be on to something.
The two aft tanks are connected aft at a Tee. From there, one line goes forward to the pump, where it Tee's into the forward tank. This is the first time I have opened the forward tank (had the boat only a few months). Prior to this, the boat was relatively on her lines.

Firstly, billknny is right. It is good practice to isolate one tank for a reserve, in case you loose all the water from your other tanks.

So all 3 pumps combine prior to the pump inlet, before pressuring the outlets.

If the normally closed Fwd Tank outlet is even a little bit higher than the aft tank, it will gravity flow via the path of least resistance at the T's to one side of an Aft tank, thus causing the list.
Suggest you keep Fwd Tank closed and draw off of aft tanks
Then depending on Trim (fore and Aft)...or when aft tanks near empty..... Switch by closing aft Tanks first and then open Fwd Tank.

Remember to use up fwd reserve tank frequently to prevent water from going stale.

A good test at dock is to open up all tanks and see if the full Fwd tank gravity feeds aft, before refilling aft tanks

[Lepke]

You could put in 12v solenoid valves to control the tanks flow from the cabin. With some thought, a couple relays and a pair of old mercury switches, you could set it up so the down tank solenoid is open and the up tank valve closed.