pumpless ballast with sacs

[GuitsBoy]

Has anybody actually done a pumpless ballast setup before? Im curious to know what kind of pressure a 1" thru hull will generate at cruising speeds.

My setup is finished, and I'm hoping to put the boat in the water wednesday morning.

The setup works like this. I have a 1" thru hull scoop mounted through the hull, just to the port side of the tracking fins. I have a 1" full port ball valve for a safety shutoff. From there, I have a 1" Tee, , some reducers, and 5/8 hose barbs. I run two 5/8 hoses under the motor, through the bilge to the rear of the boat, then up and under the rear seat. The hoses have full port shutoff valves and blue adapters at the ends. This attaches to the bottom hole of each 540 sac on each side of the motor box.

The idea is that while under way, you open the inline valves hooked up to each of he two sacs. This allows water to fill the sacs. Once theyre full, close the valves and the water will stay in the sacs. To drain, while the boat is stationary, open the valves and gravity will do its thing.

If the proof of concept works well, Ill spend the money on upgrading to larger diameter hose. If the performance isnt quite what I was hoping for, Ill install a couple of aerator pumps inline to fill, and a couple more for drain.

[Wakebrad]

I would plan on adding some pumps to it. With the amount of time it takes for a system with pumps to fill and drain, this would take forever. Your physics is right though. You might as well go ahead and plan for the pumps when you consider the overall cost and time of the project.

[Christobull]

We're looking into installing an on-board ballast system in the ski locker that runs the length of our boat. We never ski anymore, and the thing keeps getting oil in it from the engine compartment, so it's wasted space otherwise. The pumps are not that expensive, so it wouldn't hurt to get them anyway; however, your concept does work just as well when the boat is in motion because I our washdown pump went out once and I just held the hose down to the spray off the boat, and it was flowing just like the pump does. I'm curious though, what are the logistics of installing a through-hull system on boats that don't have them? And what are the alternatives that still allow you to do it while the boat is in motion?

[Christobull]

Oh, to answer your question, the pump was a 10 gpm, and the flow was about equal. This doesn't say anything for pressure though. My guess is that there would be no way to fill the sacs full if you use the bottom holes. They would have to be in the top where the water would just flow in, and not have to displace the water already in the sac. For convenience, you could run a separate hose from the bottom holes with a valve to drain into the rear of the hull, then pump it out with the bilge or wait till you've trailered for the day and pull the plug out.

[GuitsBoy]

Well, we did it. And guess what... It works great.

The 1 inch pickup is in the bilge area right in front of the motor (direct drive). We have it Tee'd, and fed into two short lengths of 5/8 garden hose, each about 4 feet long. They come up though the floor through the hole left when we removed the ski pylon. The two hoses have full port ball valves right before the blue waterbed type adapters that screw into the sacs. We did attach to the bottom opening.

It takes about 18 minutes to fill both 540 sacs full at 25 to 30 mph cruising speed. The fill rock solid. If you don't watch out, the pressure could easily force the fitting and hose right off the sac. The bags are about 3/4 of the way filled by the time we cruise out to our usual riding spot. One additional lap around fills them up completely.

Draining takes a little bit longer. It seems to take about 30 minutes or so to drain the bags. Gravity takes care of most of the work, leaving only about 1 inch. Picking the bags up and draping them over the side will drain the last remnants in a few additional minutes.

So anyway, the proof of concept worked, and worked great! Im very happy with the performance the way it is now, but I may still make a few adjustments. Firstly Ill need to make some sort or right angle adapter where the hose goes into the bags. Trying to get a straight shot with the bag is kind of difficult. Secondly, I may upgrade to some 3/4 or 1" tubing to open things up a bit. Thirdly, I may end up using my two existing attwood 750 pumps to drain the bags, that way we can start dropping ballast while we're heading back to the cabin.

[Christobull]

Sounds awesome. Good idea with the drain pump. That should save you some gas and time if you spend much time moving from spot to spot.

[eeven73]

[GuitsBoy]

Here's a picture of the setup: