Questions on building my ballast system

I'm gathering my material list to install a ballast system in my 98 Comp. the plan is to have a 225lb bag under the bow, and a 400 lb bag in the rearmost locker behind the rear seats. I have already weighted it like that and it works great. For surfing I add a 500 lb bag on one side and everyone sits on the rail.

I am planning on using tsunamis for speed and cost. I won't go with reversibles.

Questions:

If I add a vented loop in the fill line, will the bags not suck flat when I empty since the vented loop will just introduce air when I'm emptying?
Can I just run a loop in the line up high instead of running a vented loop? I'm thinking when I empty I'll pull water through the fill pump.
I'm planning on runnin a spring check on the vent so the bags are a little under pressure. Doable or would the water piss out the empty pump or the fill pump when off?


The back bag I'm not too worried on, since the fill line has to go to the front and then the back. The empty line is comin up to the front

Nor-cal,

On the older boats with shallow bilges and low free-board, we have experienced priming issues when using aerator style pumps. I would consider using a reversible. Also, with the height of the rear sac, you will experience passive draining through the fill line, unless a check-valve is used. This is not a problem with a reversible as the impeller acts as its own check-valve.

Check-valves are less expensive then anti-siphon. With an in-line check-valve, no need to have the line or anti-siphon above the sac, This may be easy with the bow pair, but going to be tough with the aft sac.

On boats with high free-board, looping the hose above the height if the filled sac does work. Dont know if you can accomplish this in your application.

I would stay away from the spring loaded check-valves commonly found at the hardware stores. They are problematic and restrict flow. Yes, as water pressure builds, the pressure will bleed off through the aerator drain pump.

Also keep in mind that aerator pumps are very suseptable to head pressure. The larger the hose, longer the run and higher the elevation, the more the flow slows. In some cases, the flow at the sac may not be any faster then that of the slower reversible pumps. They are a positive-displacement type pump and less effected by head-pressure.

Thanks for your reply.

I have a decent bilge as this year had the fiberglass. The floor is pretty high up and not like the older comps. You practically almost sit on the floor. I looked at where I'll be mounting the fill pumps and I'm confident that they will be below the water line.

I'd like to use check valves, but wouldn't the empty pump essentially pull water through the fill pump and through the fill check valve when emptying?

I was planning on bringing both fill hoses through the front under the dash, and looping up high under the dash. One will dump to the front bag, the back will follow on the starboard side of the boat all the way to the back.

I looked at cost and I'd be saving about 150 bucks by going with 4 aerator pumps, instead of 2 reversibles. I don't want to do aerators if it won't work though.

Aerators can and do work, but not in all boats and in every setup. No check-valves or vented loops needed with reversible pumps, so be sure to factor that into the cost difference. Also less hose and less sac fittings.

No, the aerator drain pump will not pull water through the fill plumbing. They are not self-priming, so they do not suck water. The push water, so they must have the inlet on or below the water source.

As long as the bilge space will allow for a continual up hill flow through the intake thru-hull, ball-valve, into the pump and out the outlet, then you should be ok with the aerator pumps. If at any point there is a dip or downward turn, there will be air trapped.

Yeah, I should be ok. I have the room for the intake to come in, the hose to go to a manifold and supply the two pumps without any dips.

Thanks for your help. Makes sense that the empty pump won't pull thru the fill pump. They don't suck, they just move water :)

Talked with wakemakers today. I'll definitely need the vents since I have a low freeboard. He said I could get away without them on a boat that has a high freeboard, but with my boat there's no way.

Just did my ballast install, and tested today. Everything works great except the vented loops.

Once the boat is dunked in, I hit the switch and the bags filled. Picked up a passenger and idled out, bags still filling. Drove off and air was just being pulled in thru the check valve and going out the thru hull. Bags did not self empty but you could hear the duckbill valve whining the whole time while driving.

I will be removing them and going to Check valves. Everything else on the system worked great, Zero priming issues. Working on the writeup and pictures...