How do touchscreen ballast systems know how full their chambers are?

[IDBoating]

I've seen some of the touchscreen ballast systems (photos in glossy sales brochures) displaying things like "56% full", etc. How do they know that? Do they have sensors like fuel sending units in the ballast sacs? I'd think that would be exceedingly unreliable, just like such readings are unreliable in boat fuel tanks. Calling out single-digit percentage accuracy on something like that is silly.

So... how do these "recall from memory" ballast systems get themselves back to a known fill state?

Thanks!

[dingleberry]

I think that they are based on fill time (duration). So, if you change the size of the ballast sac that is plumbed into the system, you have to adjust the length of time that the system thinks will take to reach 100% full.

But maybe others who know better can correct me.

[rensink]

Correct they are timers that run however when they show "100%" or "0%" when filling full or emptying completely I always would use the general let them run tell they are peeing out over the side through the overfill hose's or when they are done peeing over the side for emptying.

[chpthril]

Its nothing more then a firmware calculation based on flow rate x time. The system is not actually measuring the flow/speed of the water. Its just populating the LCD gauge based on the programed pump flow rate and how long the switch has been on. If you upgrade to larger sacs, recalculate. If you upgrade to faster pumps, recalculate.

Its not like back when MC and CC used those POS timer modules that crapped out so often and needed reset about every other trip out.

[IDBoating]

Its nothing more then a firmware calculation based on flow rate x time. The system is not actually measuring the flow/speed of the water. Its just populating the LCD gauge based on the programed pump flow rate and how long the switch has been on.

What if air gets in the line? It would throw off the relationship between what the microcontroller believes and the actual water level. How do they accommodate that?

[Timmy!]

What if the water was flowing faster? It's not exact, I agree that they shouldn't put an exact percentage but they do and it is what it is.

[robert theisen]

It's really just plain and simple.It's MAGIC!

[thtrog]

It's really just plain and simple.It's MAGIC!

[JreisRZR]

It calculates flow x time to give you 25% incriments. If you put in bigger sacs you can adjust the time ine the computer required to read 100% mine were a bit off from the factory so i adjusted the time down by about 2 min per sac and they read 100% within a few seconds of the sound of the fatsac peeing overboard; thisgoes for tige

As far as other boats go my buddys boat seems to have a slider like the gas tank in each rather than a timer, if you partially fill a ballast tank the percentage jumps all around as youre running similar to his gas gauge so basically its annoying unless the tank is filled all the way.

[duffymahoney]

When I fill sacs I always watch them fill and burp whatever air gets in out. I want as much weight as possible.