Intake for ballast

[chpthril]

If I go through the bottom of the boat with brass thru hull connectors (Not a scoop) would there be a signifigant force of water that would continue to fill the fat sacs?

Not in my experience, and that is why I prefer shrooms over scoops........no electrical or manual shut-off is needed to stop unwanted filling. I've even seen scoops mounted backwards with impeller pumps siphon out under way.

Could the water in the fill line reverse itself and flow through the pump and empty? Would the pump allow water to escape? I suppose check values are required on ALL fill lines? With check values it would restrict the flow to the bags somewhat wouldn't it?

Yes, water in the fill line can create a siphon and draw the water out of the sac. This is why a vented-loop is sometimes needed on some boats. With most Tiges and most typical sacs, the fill hose can be run high in the gunwale, creating an upside down drain trap, and this breaks the siphon. Check-valves are cheaper then vented-loops, and will achieve the same thing in most instances. They do reduce the flow a little though.

[jason@wakemakers.com]

If I go through the bottom of the boat with brass thru hull connectors (Not a scoop) would there be a signifigant force of water that would continue to fill the fat sacs?

Yes, you can still encounter a scenario where there is enough pressure to auto-fill the bag.

Could the water in the fill line reverse itself and flow through the pump and empty?

It depends on what type of pump you're using, but with aerator pumps, yes the water can move in both directions (both into and out of the bag).

Would the pump allow water to escape?

Yes, with aerator pumps they will allow water to flow through the pump when turned off. Flexible vane impeller pumps (like the Jabsco or Johnson) will not allow water to pass through the pump when turned off.

I suppose check values are required on ALL fill lines? With check values it would rescrict the flow to the bags somewhat wouldn't it?

Check valves will only prevent the flow of water in one direction (out of the bags), and will not prevent the bag from passively filling. The only 100% effective solution to prevent the transfer of water into or out of the bag is either a valve (manual ball, electronic gate, etc.) or, what we prefer to use, anti-siphon vented loops. Simply routing the hose up high is absolutely not sufficient to prevent the water level in the bag from changing.