replaced hard tanks with sacs, sacs won't stop draining???

[Sbt3]

So we replaced the hard tanks in my buddies 05 SAN with the 750 pro-x sacs. All of the pumps are aerator style pumps. The problem is when we fill them the water pushes by the drain pump and starts draining the sacs without the pump running. The pump is on the bottom fitting of the sac which is the only place I think it could go. If it is on top I think it would pull air when draining, plus I don't know if the fill could handle filling the sac from the bottom fitting.

My thought is a longer piece of hose that loops up higher not allowing the water to flow out.

Any other ideas from people that have done this and made it work??

[gride300]

RE: replaced hard tanks with sacs, sacs won

you can get a plug for the hole. they should have them at west marine. i actually got mine at home depot. just little rubber plugs with a t grip to tighten/loosen it.

[Chexi]

RE: replaced hard tanks with sacs, sacs won

You can't use aerator style pumps below the sack water level. Only impeller style pumps will seal when not in use. Move the pumps to the top sack valves. There should be a number of aerator style diagrams and pictures on this site and on wakeworld.com.

[WakeSlayer]

RE: replaced hard tanks with sacs, sacs won

You really need to just remove the aerators, and put in the Jabsco pumps.
You are halfway there, do the rest of the upgrade.

[bchesley]

RE: replaced hard tanks with sacs, sacs won

Chexi is right. The only way to make what you have work is to turn off the seacock once the bags are full. When you want to empty open the valve.

[Sbt3]

RE: replaced hard tanks with sacs, sacs won

I don't think he is going to want to remove the aerators, too much additional money for the pumps. I have impeller pumps in my 97 so I am familiar with building that type systems.

The pump was on the bottom of the hard tank for draining before, what makes it want to push past the pump now with the bag when it was fine with the hard tank??

I talked to the guy with the boat and he said they'd fill to about 3/4 before pushing by. I may try to run some longer hoses for him and see how that works. I'll keep you posted. I can't mess with it till this weekend though so if anyone has any other ideas besides looping longer hoses and adding valves I'm open for suggestions.

I'm afraid if I switch the fill to the bottom and the empty to the top it's going to start to drain back through the fill pump the same way as it's pushing past the drain. So that probably isn't an option.

[WakeSlayer]

RE: replaced hard tanks with sacs, sacs won

The aerators cannot act as check valves like the impeller pumps. You could try a check valve on the vent, it may work. That is the same thing as mentioned earlier with the plugs, except you don't have to do anything once they are installed. Or the ball valves.

[Chexi]

RE: replaced hard tanks with sacs, sacs won

I believe the hard tanks use a seacock mechanism that you can manually open and close (this is at least true on my hard tanks on my 99 Air).

SBT3, you are correct, it does not matter whether your fill pumps or empty pumps are on the lower sack fitting, with aerator pumps they will both empty when not in use if below the water line. The reason why some people will put their fill pumps on the bottom is because they install a manual ball valve on the fill side or what I think is an electrically switched solonoid with a gate.

Where are you emptying to? If your thru-hull is higher than the top of your sack, that might work. It has been a while since I studied siphons and water pressure though, so no guarantees. The only thing I can guaranty is that if your pump and your through-hull are below the water level of your sacks, with an aerator pump you will empty unless you have a manual shutoff (like a ball-valve) or an electrically switched one like a solonoid and a gate. If you do the later, once you are in for that much you are getting close to jabsco impeller pump prices I think.

[bowvan]

Sbt3,

You actually have a few options here:

1. The cheapest and the easiest is to use a cork or plug to stop the water from leaking through the empty pump. You will also want to shut the fill valves when you are done filling because water will leak back through there too. I used to leave the rear valves open and shut the front. The rear intakes have scoops, so while you are under way, they continuously top off the rear tanks. The front tank doesn't have the scoop, so it just leaks. Also run your vent lines as high up the gunnels as you can and from the front of the sac. This will help keep water from leaking out the vent when the boat is under way.

2. The most expensive way is to replace the pumps to the jabsco's. I decided against this because of the cost and because the pumps aren't as efficient as the aerators. You can nearly double the filling speed of the aerators when the boat is up to speed, because of the scoops. The JABCO'S also draw too many amps to fill/empty the boat without running the motor.

3. After using option #1 for six years, I finally got tired of using the corks and switching the valves. I installed 1" solenoid valves on both the fill and empty lines. The valves cost around $40.00 a piece. You would need 6 of them for around $240. Still cheaper than the jabsco's and a bit quicker.

BTW, I am using sacs on top of my tanks in the rear and a bow sac filling from the center tank. The principles should still be the same with just bags.

[Sbt3]

Thanks for the continued input guys. He does have the valves installed on the fills from the factory that he shuts off after filling to keep the sacs from continuing to fill while underway. He just replaced those cause the other ones didn't work anymore. I think they had an issue with those on most of the boats. The new ones are ball valves.

The drain hose exit is located up just under the rub rail. I think I'm going to try to put longer hose in and see how that works. If that doesn't work then I guess we'll just put in some manual valves to shut off so it doesn't drain out.

[Mikeski]

http://www.planetnautique.com/index....27&start=0

[WakeSlayer]

2. The most expensive way is to replace the pumps to the jabsco's. I decided against this because of the cost and because the pumps aren't as efficient as the aerators. You can nearly double the filling speed of the aerators when the boat is up to speed, because of the scoops. The JABCO'S also draw too many amps to fill/empty the boat without running the motor.

I disagree with this. Both the efficiency statement, and the power draw statement. I never run mine when the engine is running. And, I can fill a 750 bag in 6-7 minutes sitting still.
Also, if you look around, you can get Jabscos for $160-185ea . vs $240 for check valves. That doesn't seem too bad. There is a reason that Correct Craft changed the system to include the Jabscos and eliminated the aerator style. And, the same reason that so many of us have cut out the old system and updated them. They simply work better. Lastly, you are talking about a super efficient system vs. a rigged up mediocre system to save $200-300 on a $20k-$40k boat.
The logic there doesn't work for me.

Just sayin'

[MNSuperAir]

I agree with Slayer. I don't need to run the engine to fill my bags and my fill times are probably around 10 minutes. If I also put a scoop which I didn't I could improve that time to close to 5 minutes while driving, but I want to be able to dump tanks while driving so I went with the flat thru hulls. There is a reason almost every boat company has made the switch to Jabsco pumps. Another great reason is you can mount the pumps above the water line and they will prime on their own.

[bchesley]

I concur with the last two post as I have a similar system to what they have. It is so easy to use it will make you think why in the heck did I not do this sooner.

[CradGen2]

Don't hold me to this, but I think I have the old style pumps on my 07 216 (used them once) and the Jabsco on the 08 210. I would take the 210 any day. I actually think mine only take 3-4 minutes to fill.