|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.
|The only thing I would question would be the drain. I dont think the sacs will drain back through the bottom of the boat even if it is stationary. I think the only way to get it to gravity drain would be to put another through hull on your transsom with a shut off valve and then open it up when you are on plane to empty. I could be completely wrong on this though. |
The fill side should work as described. I have an aerator system that goes from a 1.5" scoop to a manifold that feeds 4 sacs. They will definitely fill with the pumps off but it is usually a lot quicker to turn them on.
(Message edited by maxx_wake on June 29, 2009)
|Thanks for the info on the filling question... |
I was thinking about doing like you said, but just didnt have the time to do it at the moment.
Still I think the bags will drain, the only question is how quickly. Think of the way a water level works. The water level of the ballast bag will drop until its level with the water level of the lake. Its going to be close, but I think the floor is right about at water level. If thers a couple gallons left over, Ill pick the bags up to fully drain them.
|Here was a good write up that I found on the DIY website. Maybe you have seen it, maybe not |
Just click on the pumpless ballast system. It opens up in MS Word
|Yep, Ive seen it. This only works for rigid ballast tanks though, since it relies on air pressure/vacuum from the vent tube to control the water. Wont work for fat sacks. Youll need to valve the fill line instead. Thanks for the heads up though!|
|Alan Plotz (alanp) built a pumpless system in a Prostar. He used solid aluminum tanks instead of bags. i forget how he drained the tanks... |
You could always run your drain hoses down into the bilge them just bilge pump them the water out. Doesn't sound like you're talking about a lot of water. I'd stick a pump in there if it were me...
|Yeah, its a substantial amount of water. Twin 540's on either side of the motor box, plus the locker sack which we'll keep filled. Its a good 10 - 15 minute cruise out to our favorite riding spot, so I dont really mind if it takes a little while to fill them up. |
But yes, chances are we'll eventually upgrade to using pumps.
|My aerator system runs off of a 1.5" scupper and will fill on its own if the gate valve is left open. It would take a LOT longer than 10-15 min to fill two 540's without pumps, my guess would be over an hour at 20+ mph. The locker sack would fill quicker because it's at a lower elevation, but still not fast enough to be practical.|
|If you decide to go pumpless, I'd put the scoop as far back as possible. There should be more pressure at the transom as it sits the deepest. But it would still take a while. |
You can find a single aerator on the cheap. Stick it on the fill side and drain into the bilge.
|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.
|I'm working on the same thing right now ,But my lines are 1". I might have to use pump as I do not have room to run circles around the lake for 20 min.|
|Very cool! I stand corrected on the fill time. Glad it worked out.|
|I attribute the quick fill times to the short hose lengths, and the lack of restrictions (full port valves). Had I been pushing teh water through stopped aerator pumps and longer hose lengths, Im sure its would have been much slower. Appreciate the help though.|
|Sweet! Definitely thought it would take longer, especially with 5/8" lines. You can definitely open that up a little with 3/4 or 1" lines. Maybe save that extra lap around your cove. Nice work.|
|If you typically have to drive 15 minutes to ride, that sounds like a great solution for you. |
For many others, installing pumps would be much cheaper over the long run - vs. the wasted gas running around for 15 minutes to fill your pumps.
|Oh it works, it works big time: |
|Oh and put your cross-member back in. especially since you're running ballast...|
|Wow, thats a hell of a setup. Thanks for that link! Crazy to think that he made tanks completely out of wood!!! I guess theres room for improvement as far as my setup goes. Some slightly less restrictive tubing just might do the trick.|
|Yes, Nacho, Im going to see what I can do to hack up that crossmenber to fit back in there. I actually just posted about that on MC TeamTalk.|
|Here's a pic: |
|I bet that crossmember doesn't do much but support the pylon. I bet you'd be fine without it.|
|I don't know, man... The boat was flexing bad enough for the windshield to slip under the lip it usually rests on. What a pain in the ass to get it back.|
|I stand corrected twice in 23 posts! I will shut up now.|
|Well, I dont know for sure that the brace would have prevented the flex, but it certainly made me double guess my decision to remove it. Besides its always good to hear the other side of things. Keep posting away, better safe than sorry...|