MacGregorSailors.com

Dimitri-2000X-Tampa wrote:I tried to empty my ballast once with a raft inflator through the vent hole. My boat was level on a lift. ...

Hmmm - level on your lift? - really level, not bow-down? I'd expect it to drain naturally when level and elevated above the water, forget the air pressure. That's a mystery.

Never tried the air pressure idea, but always seemed to me it couldn't work for very long - as soon as there's any air passage out the very top of the gate valve, pressure dissipates. Seemed one idea here had merit, which was attaching a large PVC elbow to the aft gate, turned down to exit under the water's surface. This should permit the trapped air to push most of the ballast out. After hearing your experience, not so sure the elbow would work either! With the Suzuki-60 available, I've never felt the need to try.

My 12v inflator will empty my ballast to the top of the fill hole. Once it reaches that point the air just runsout over theremaining water.

Gets it all bu 2".

If the 12V inflator works to the top of the transom valve, try getting the transom valve deeper in the water by moving weight aft and starboard to pitch the boat in the same direction; also try closing the transom valve most of the way.

Seems to me any of these would only work in pretty calm waters; if the boat is pitching or rolling on its own or even if you have waves against the transom, every time the valve is uncovered you'll lose all the progress you made when it was covered.

Even still, I can think of only one instance in which there would be occasion to empty the ballast while on the water without the motor. If you're hard aground on a falling (or no) tide and can't power or kedge yourself off, and a few inches less draft is all you need to get the boat afloat.

Otherswise, put it on the trailer, pull it out and empty it.

Dimitri doesn't use a trailer. Since his boat is stored on a boatlift behind his house, he needs to empty it on plane with the outboard. 'Course if he insists on docking with ballast tank full, then it seems that pushing the ballast out with a high-volume air pump makes sense.

How long does it take to drain using a low pressure inflator?
What if you just used the step drain valve instead of the aft one (for those that have both...)
Could a bilge pump connected to a vent hole & dip tube piped back to a thru-hull do the same job without having to worry about air pressure ?

I'd be careful how you plumb that bilge pump, but sure you could empty your tank using a bilge pump. You'd have to get a pickup tube down to the lowest point in the tank. You'd also have to make sure you had airflow into the tank. If it were me, I'd probably not rig this as a permanent installation and just hang the output tube over the side...

CatalinaOwners.com forum archives - browse
&ptl=Blowing%20the%20ballast%20on%20water%20ballast%20boats] Blowing the Ballast on Water Ballast Boats

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Steve Paul
Nashville, IN
05/09 at 06:05PM
General interest

Not that way
Roger, the 26D and S have the ballast in the bottom of the boat. It will not empty with just boat movement. There are two suggestions and yes the boat does reload on the trailor better without the ballast.
Many of the folks here use a 12V high volume inflator pump to blow the water out with air pressure. Do this via the air hole ( with the trailer water plug in it).
Another way is to buy a 12V water pump and pump the ballast water out. I believe the air pump is faster. You'll need a nozzle that fits the air hole and a weight to hold down the fill plate stopper so the water can leave the bottom of the boat.
Good luck
Steve P.
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Cruising Log of the Murrelet

The effect is probably similar to using an air inflator device to blow ballast

I could not believe myself but i red through all 5 pages. Interesting topic. I pull my boat out sometimes with ballast sometimes without, depending of situation. If I am sailing I do not feel like motoring around in circle and burning fuel just to empty ballast. On the other hand if tides are low I know that my trailer will sit too high in the water (they should clean that ramp) and I am sure to empty the ballast. Trying to winch it up with the bunks high and ballast full is a lot of hard work and a lot of tension to the winch. Also if I am launching with Civic I am sure that the ballast is empty, with my Astro i do not care. I agree with Chip, and I do not think that there is any overload to the trailer if you are puling boat out with the ballast. I had instances were ballast out is a must, and other times when it was easier to empty it on the ramp. Therefore my conclusion is, either approach is right if it works for you at that particular situation.


Zoran

I'm interested in this aspect as well.

What is meant by the term 'high volume' in regard to the air pump? Is there a common rating system, ie; cubic metres per hour?

It would also be useful to know what kind of pressure differential is acceptable in regard to the tanks, but I guess this would be a big unknown.

I know that the 16' plywood trailer sailers that I used to sail unsuccessfully experimented with bouyancy tanks at one stage. In standard trim they are fitted with foam bouyancy, as the Mac is. To save weight (yes, in that class, even the weight of foam was important), some folks expoxied the joins in areas under the front bunks, and the cocpkpit seating and showed some numbers that proved that the bouyancy of the volume of trapped air exceeded the laden weight of the boat, and got the go-ahead to do it.

The very first one that went over burst the cockpit seat tanks and went down until only the foredeck and forward cabin window were above water. It got outlawed after that, but I know from that experience that even a small pressure differential can exert a tremendous amount of force. Even commercial airliners are only pressurised to a difference of something like 8.5psi and that is enough to rip them apart.

Hmmm - level on your lift? - really level, not bow-down?

I suppose I've never actually put a level on it, but by design, a hanging cradle like that is pretty level bow to stern. If one motor runs more than the other, the level can go off side to side (width). I suppose I could tilt it more towards the valve side but I doubt it will make much difference.

Btw, I did try to shut down the ballast valve much of the way to try to keep the pressure up in the tank. It didn't do much.

Anyway, the only reason I had a full ballast in is because my overheat problem (one of the intermediate times I thought I had it fixed) made it so I couldn't run the engine hard enough to empty the ballast. 99 times out of a 100, I empty the ballast on the last leg home (protected 3 mile long channel) which is almost always a high power leg especially after a long sailing trip up the bay.

I dont use the inflator to emppty the ballast exclusively. It does speed up the job and makes it work at a lower motor speed. Besides if I am emptying for trailering, I am not that worried about trailering it with 2" of water in it.

Our ramp is a quiet on and I usually trailer with the ballast valve open and pull it up the ramp a bit at a time to empty. 7th year this way and no problemss.

Scott, did you end up getting that FJ for Jennifer?

I'll have a verdict in a few a few days as to how Leslie's (Voodoo Blue) FJ likes towing the Mac.

With the locking diffs there should be plenty of traction at the ramp!

Scott, did you end up getting that FJ for Jennifer?

Not yet, were still nursing the Mini at 60 k.

Shes been making noise though.