Water tank gauge

We have a Wema water gauge on our recently purchased '05 Mainship 400. It has a switch with 3 settings; I, center, and II.
It will only read the water level on I and I'm wondering if that is the level for both tanks or should each tank read separately?

Greetings,
Mr. bw. As a very general answer, the fact you have 2 tanks and the switch has I and II positions, I would VERY strongly suspect you have a problem with tank #II. Logic would suggest each individual position reads one tank.

Hi Bwalz,

Our 2005 400 sometimes does the same thing. Not to be too low tech here, but I have found that wiggling the switch usually fixes it. I have heard that the gauges are prone to failure. If it is not that it is the sender on one of the tanks.

Climb down in your lazerette and use a flashlight to look at the water level in the tanks. Are they the same?

bwalz said:

We have a Wema water gauge on our recently purchased '05 Mainship 400. It has a switch with 3 settings; I, center, and II.
It will only read the water level on I and I'm wondering if that is the level for both tanks or should each tank read separately?

Click to expand...

The 400 only has one sending unit. Align the valves so both tanks are tied together and the single sender will register the correct level.

bwalz said:

We have a Wema water gauge on our recently purchased '05 Mainship 400. It has a switch with 3 settings; I, center, and II.
It will only read the water level on I and I'm wondering if that is the level for both tanks or should each tank read separately?

Click to expand...

Capt GB said:

The 400 only has one sending unit. Align the valves so both tanks are tied together and the single sender will register the correct level.

Click to expand...

BW, our sister-brand boat has two freshwater tanks, connected by a cross-over hose, and only one deck fill.

We have WEMA tank gauges (separate gauge for the holding tank), and with only one sender inserted into the input side freshwater tank.

Our gauge doesn't have your options, though. Our freshwater tanks self-level, so only one sender is required.

Perhaps you have two deck fills, and your freshwater systems can draw independently from each tank? Otherwise, I'd assume you've maybe got a cross-over hose, your tanks self-level, and your gauge switch is superfluous (perhaps meant for a different application, but installed in your boat because it was handy that day...)

-Chris