installing a bilge in ballast tank

[sunman]

Ok, who's got the skinny on emptying the water ballast tank before you retrieve the boat while at the ramp?

been thinking about adding a bilge pump in the ballast tank and emptying out the tank while I'm getting the boat ready to get on the trailer..I've read post where some have used an air mattress gun to pressurize the tank and force out the water.
Id rather turn on a switch, and go about my business while the 12v bilge pumps out the tank.
so I gotta install a water tight floor plate, to ingress into the tank area, and inspect/service/replace the unit as needed.

BTW:I did a leak test on a West Marine Deck plate and it isnt water tight in this configuration, water below the unit vs. water on-top of the unit! < at least not the one I have!
Any thoughts on this idea?

 

[MrBill_FLL]

IIRC,
ballast is 600 gallons. a rule 550 is 550 gal / hour.....
-Where is this water going to exit the ballast?


personally I would not cut into the ballast.

I would (have) thread a fitting on the ballast vent hole and add a 3/4" hose barb, and run that to a mattress inflaitor. plug the pump to the hose, and go about your business.

I've only used mine 3x, but when I needed it, it lifted the boat up about 4" in 20min.


The risk reward of cutting the ballast is low. IMHO.

 

[sunman]

600gal x 8.3( lbs per gal) =4980lbs of ballast, no wonder I want to drain my ballast before putting the QEII on the trailer........
no seriously I thought we only carried 150 gal or 1200+ lbs of ballast
U dont think a S.S plate w/a gasket and bolted to the floor will be structurally sound enough?
I planned on venting the water through a tube/pvc pipe to the outside of the hull
how long did it take you to empty the tank using your method?

 

[walt]

I have not timed it.. but would guess at 10 minutes +/-..

This is a 1 psi pump but it actually puts considerably less pressure on the tank as long as the bottom valve is open.

Pump uses about 7 - 8 amps while its running.

 

[monkeybars]

IIRC,
ballast is 600 gallons. a rule 550 is 550 gal / hour.....
-Where is this water going to exit the ballast?


personally I would not cut into the ballast.

I would (have) thread a fitting on the ballast vent hole and add a 3/4" hose barb, and run that to a mattress inflaitor. plug the pump to the hose, and go about your business.

I've only used mine 3x, but when I needed it, it lifted the boat up about 4" in 20min.


The risk reward of cutting the ballast is low. IMHO.

Ballast if far from 600gallons, try 140 is much closer.

 

[MrBill_FLL]

My mistake. OK, 140gal's


But, how are you going to push water out of the ballast?

 

[sunman]

total submergable pump w/float switch:dance:

 

[willsnow]

think about vacuum, too... if you open the water valve and pump air into the tank with the inflater pump, the space inside is nicely displaced. make sure your bilge pump doesnt try to collapse your ballast tank

 

[walt]

Once on a dock sitting by the boats drinking beer at night (which by the way is about as good of a place for a discussion as it gets), someone had brought up that if you calculate the pressure on the tank from for example a 1 psi pump, it ends up being some scary high numbers.

But the actual pressure in the tank is only whats needed to push the water out the bottom valve. As long as the valve is open on the bottom of the boat, the pressure from the pump is only incrementally higher than when you first put the boat in the water and open the bottom valve but not the air access hole at the top of the tank. When you open the bottom valve, air rushes out the top hole because of pressure in the tank and its close to the same amplitude as when you pump the ballast out of the tank.

My new rule for using this electric pump - the valve must be open at the bottom of the tank if the pump is on. If you follow this rule, I think using the pump is completely safe.

And.. if you have the pump on and the valve closed so the tank is sealed, be worried even at 1 psi.

FYI, I keep both the electric pump and a manual pump in the boat, both weigh little. One time I did something really dumb and sailed right up onto a sand bar.. DOH.. I took the sails down, used the manual pump to blow out some ballast which lifted the boat off the sandbar and I got a 26 foot boat off myself - easy..

 

[walt]

By the way.. I do like the idea of just flipping a switch to empty the tank..

What these boats do exceptionally well is trailer. Keeping the boat simple to setup/take down (which this is part of) means they are easier to use - and you use them more often. If you really want to keep it simple, just dont bother to blow the ballast.. I did that for years no problem. Im doing it now because Im using a barely rated tow vehicle to get the boat up the ramp.

 

[MrBill_FLL]

I'm not sure how you seal the exhaust hose.

they make bait well pumps with a 'snorkel' you might be able to drop into the ballast. but sealing it, not so sure.

otherwise, how do you get the water out of the ballast and over the side?


http://shop.sailboatowners.com/prod.php?16267


now that I look at the baitwell pumps, this could work.
just vent the tank, and get the pump about 2' off the cabin sole.
-if the pump can lift that high.

or just a long hose extending to the bottom of the ballast attached to the pump pickup.

 

[finding41]

I just do this:
Open the valve, remove the plug. (Put it in the sink.)
Drive up the ramp. I find the water just falls out the bottom...
If you can't get up the ramp with your vehicle you may want to look into an alternative tow vehicle. Or hiring one to do the job.
I use a mid size SAAB 9-5 Wagon. (It's a 4 cylinder with 250 hp!) The hp doesn't get me up the ramp. Going at it slowly does. Here is a picture of the slope of the ramp at our yacht club. I pulled the boat out last when it was raining and there were wet leaves scattered on the ramp.
The first picture is of my SAAB with the clubs "utility" trailer about to remove my dock. (I float it onto the trailer.) 2nd pic is Squeaky power washing the gunk off the boat just after we pulled it out.

 

[walt]

In my particular case, I dont have any trouble with the "marginal" tow vehicle at the ramp with our without the ballast. It really takes very little power to get the boat out of the water. Its traction that you need and you can either get this with weight - or all or four wheel drive. Ive got all wheel drive, never slips. The main reason that I have blown out the ballast may not be a good reason: "because I can". However, it does make things marginally easier.

The thing that really requires the larger tow vehicle is speed. Both kinetic energy and wind drag go up with the square of speed. Rate of vertical change for a particular slope goes up linear with speed. Stability problems always show up at speed. Huge difference in loads on the vehicle (and the stopping ability) going from 30 mph to 75 mph. Ive towed enough that I stick to under 30 mph with the smaller vehicle. Idiot proof (and Im an idiot about 1/4 the time with boating stuff, just happy its not 50% of the time ) definitely requires the over rated vehicle.

 

[MrBill_FLL]

4 cyl with 250hp? -that must have a blower... doubt you get much boost on the ramp.

I have wheel chocks I use sometimes when the ramp is wet. there have been times when I didn't get traction initially...

Anyway, those bait pumps pickup will need to stick down into the ballast tank if you want to pump them out. probably a weighted hose would work best. (flexes)

air is just simpler.

I'd like to see the water pump tried. it might work better...

 

[Chris & Lenore]

And to add a comment about making it even easier with air....

Screw a brass fitting into the vent hole (the proper size will cut its own threads). Screw a 90 degree barbed fitting into it. Use Teflon tape or some other dealer on all threads. Run 3/8 line from the barbed fitting up the space between the liner and hull - as far up as you can - then back down and onto the air pump. This creates a "loop" so the ballast water cannot back up into the pump. You can put the pump anywhere - run the line to the front and put the pump under the V berth. Wire the pump to a switch and then all you do is open the main ballast valve and flip the switch.

In reality, you can even remove the ballast valve and screw a plug into the top hole. The tank will fill but will not overflow...

This is as easy as you can get- for both filling and emptying. No "pressure issues" either.

It has been tried and proven to work perfectly by several people.

BTW, my pump empties the majority of the ballast tank in about 3 minutes. I can't imagine a bilge pump being that fast...

Chris

 

[Sumner]

And to add a comment about making it even easier with air....

Screw a brass fitting into the vent hole (the proper size will cut its own threads). Screw a 90 degree barbed fitting into it. Use Teflon tape or some other dealer on all threads. Run 3/8 line from the barbed fitting up the space between the liner and hull - as far up as you can - then back down and onto the air pump. This creates a "loop" so the ballast water cannot back up into the pump. You can put the pump anywhere - run the line to the front and put the pump under the V berth. Wire the pump to a switch and then all you do is open the main ballast valve and flip the switch.

In reality, you can even remove the ballast valve and screw a plug into the top hole. The tank will fill but will not overflow...

This is as easy as you can get- for both filling and emptying. No "pressure issues" either.

It has been tried and proven to work perfectly by several people.

BTW, my pump empties the majority of the ballast tank in about 3 minutes. I can't imagine a bilge pump being that fast...

Chris

Chris I like the idea but have a couple questions. Is the 3/8 inch line not restrictive to the air flow of the pump. I can see maybe pumping air through a 3/8th inch opening and into the tank, but I'd think that a 3/8 inch line even 4-5 feet long might be restrictive to the air flow volume wise. I guess if this is proven then I'm obviously wrong.

I would keep the ballast valve as even if it leaks just a bit it keeps all of the water in the tank so that it is ballast and not connected to the actual lake water. We probably don't heel enough, but I've seen some boats heeled to the point that water might be able drop on the high side of the ballast tank. Maybe if no air can enter that might not be the case?? I'd still keep the ballast valve functional though.

Thanks for the idea and I might think seriously about doing the mod even though we have never pumped out the ballast with air. We are set up to do it though with the proper fittings and carry the air pump as we use it on the dinghy if needed. We grounded once in Florida where raising the boat like Walt did might of helped. We were able to get off with the outboard after a couple minutes though,

Sum

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[sunman]

41; I can get up the ramp w/a full ballast, up the ramp isnt the reason for my Q; I feel a lighter boat is better to load back on the trailer. I have to step the mast after I get wet as we have powerlines accross the ramp.....I have to step the mast befor leaving so why not take advantage of the time spent and empty the ballast and have a lighter boat to load? I also have to swing her around the floating docks and into the ramp area w/4 ft guard rails..
10-15 kts tide going out of in( BTW, the end of the ramp at minus tide can look pretty nasty)...under the same conditions, it was always was easier to maneuver her to the slip and get her ready to sail empty then full...and hire someone or get a bigger tow vehical..vs. get a $20 air pump

Or how about the running aground issues and being able to float off? or do I call to get towed off or wait for high tide assuming it was low when I came up on the sand bar, and if not! then what? I think theres a need to empty the tank, cuz ya never know!
I see where theres bait well pumps(405FC's) being used to fill and empty theses wake board pulling boats, perhaps one can drop in a 500-800 w/a 3/4 hose through the vent hole and pump it into the cockpit and let drain from there ?

 

[vizwhiz]

Just a quick comment to add some more fun and insight to the thread...

1 psi of pressure in the ballast tank, or in anything, is equal to 2.31 feet of water height. This would be the equivalent of making the water ballast tank into a kiddie-pool that is 2-1/2 feet tall. I would not be concerned that the amount of force on the walls of the ballast tank that was generated by the 1 psi inside the ballast tank was going to "pop it" or something...the fiberglass is very strong, especially down there, and 1 psi isn't much pressure for what we're talking about.

If you are still interested in the pumping idea instead of the air pump idea (which i would personally prefer because the water goes out the "right" holes and can't really get in the boat accidentally like if the hose popped off the pump or got misplaced) then you can also find a small plastic "vacuum breaker" or "vacuum release valve" which will allow air to flow in when the ballast tank starts to get under vacuum (as soon as you start to pull water out with the pump).
As a matter of fact, you can get "air-release vacuum valves" which will do both jobs, release the air when you are filling it with water, and then let air in when you are pumping the water out, all without handling the valve.

 

[walt]

Pressure in the tank is also less than 1 psi. Ill leave it to someone to calculate what the pressure is but it’s just enough to force the water out the valve on the bottom of the tank.

I mentioned this in another thread but the last time I blew the ballast, I accidently left the valve fairly tightly shut with the 1 psi pump running. My valve still leaks a bit (project to fix this one of these days) and when I got back to the boat, the screw on "air pump inlet" for the vent hole on the top of the tank was on tighter than I have ever seen because of air pressure in the tank. I got it loose which was considerably harder than normal and there was a good rush of air out of the tank. I opened the valve so that water could be pushed out the bottom of the boat by the air pump and the pressure in the tank was significantly less than when I had the valve accidently closed.

What someone needs to calculate (assuming you like calculting stuff like this, Im not sure exactly how to do this) is what exactly air pressure is required in the tank to force out water and essentially lift the boat. The pressure probably depends on the rate the boat is lifted but I wonder what the threshold pressure is to begin forcing water out the bottom??

 

[monkeybars]

Pressure in the tank is also less than 1 psi. Ill leave it to someone to calculate what the pressure is but it’s just enough to force the water out the valve on the bottom of the tank.

I mentioned this in another thread but the last time I blew the ballast, I accidently left the valve fairly tightly shut with the 1 psi pump running. My valve still leaks a bit (project to fix this one of these days) and when I got back to the boat, the screw on "air pump inlet" for the vent hole on the top of the tank was on tighter than I have ever seen because of air pressure in the tank. I got it loose which was considerably harder than normal and there was a good rush of air out of the tank. I opened the valve so that water could be pushed out the bottom of the boat by the air pump and the pressure in the tank was significantly less than when I had the valve accidently closed.

What someone needs to calculate (assuming you like calculting stuff like this, Im not sure exactly how to do this) is what exactly air pressure is required in the tank to force out water and essentially lift the boat. The pressure probably depends on the rate the boat is lifted but I wonder what the threshold pressure is to begin forcing water out the bottom??

as long as one is going to extremes to just emty the ballast tank why not just plumb in a big tank of helium from your local welding store. that's 3000psi and you could be just almost floating above the water when your tank is empty.:dance::dance: