View Full Version : How many pumps can efficiently run via one thru hole?

06-28-2014, 05:00 PM
I added a jabsco pump to the old star last year, 3/4" thru hole with 1" hose feeding both rear sacs via a valved tee. Fill time is not a big deal for me so no need for lots of pumps.

That said, I want to add a sac up front so I have two options, run a diverter valve on the current setup or add a new pump. If I ran a diverter I am asking one pump to fill about 1300lbs ballast and to be able to tune this it would become a pain as I would be manually opening and closing valves . So the easier option is to run a second pump. For ease, I could run this second pump from the same 3/4 thru hole or go down the route of a second thru hole. How much would running the second pump through existing fitting throttle it down by? Do I need to add a second thru hole??

Or, as a totally different option, could I repurpose the vent from the KGB sac and piggy back the new sac up front? Bearing in mind the KGB is run via an aerator I am not sure if this will work. Certainly the cheapest option...

06-28-2014, 09:49 PM
Cheapest and best option is adding a second thru hull. It's the most efficient and will require the least amount of check valves and diversions. Go simple and just be done. While drilling through a perfectly good boat is mind numbing, once you get passed that you will appreciate having that second thru hull

06-29-2014, 07:25 AM
I believe that the 1" only supports one jabsco at a time. You will burn impellers running two, go extra thru hull and save a lot of time.

You can get a double seacock thru hull and add two pumps to it.

06-29-2014, 04:37 PM
Cheers for the input. Looking at the cheapo option which would hopefully work until I have time to install another thru hole and dedicated pump. I have a diverter valve lying around from my old nauti, so can build this in for free. I am thinking I could piggy back the vent line on the centre sac to feed another sac. The only thing on my mind is that the second sac is above the floor and I'm not sure what pumping head an aerator can work with?

06-29-2014, 05:49 PM
My advice, don't piggy off the center tank unless you know how to vent it properly. If you mess up the venting, you'll collapse the hard tank and it will crack. That is a big problem that you'll want to avoid.

06-30-2014, 02:35 AM
kahuna he should have a bladder style center sac. Not a hard tank.

I know plenty of guys that ran the vent/overflow from that center sac to a bow sac. The aerator can push it up that way. You'll want to put a ball valve somewhere between the center sac and the bow sac because when that bow sac gets filled the back pressure will most likely leak back out the fill pump. I am not certain it will.....kind of depends how big of a sac you are going to fill..... So you can always try and see if that extra sac looses it water then you'll know it's pushing back out the fill line and need to add the ball valve.

Emptying is easy as all that water from the bow sac will easily run back down to your ski locker sac by pure gravity so that empty pump will empty both.

The only down side to doing this is that the fill rate of that bow sac will take twice as long as the center sac even if it's the same size because the pump looses its efficiency when it has to push water through that vent hole up to the bow sac.

06-30-2014, 05:57 PM
Granted regarding the fill time. What about swapping out the cartridge on the fill pump to a 1000gph?

07-01-2014, 02:32 AM
Easily done you won't gain the full 1000gph because that requires a 1inch out but it will still be way faster than the stock which I believe was 500 if not 750

07-01-2014, 11:46 AM
just checked, it would appear both fill and drain are indeed 1000GPH. I'll piggy back the bow sac for now and take it from there. I'm only running 2x450lbs in the rear and have around 500lbs lead distributed under the helm, passenger seat and into the bow so I am not convinced that I will need to go the whole way and run the 450lb sac in the walkway too. Maybe I could keep a little more lead in the rear however and fill it...........

07-01-2014, 01:28 PM
Depending on what line length and speed you run that 450 in the nose should really change up your wake. It will harden up the lip a bit and really give you a solid boot. It will also help you cran up the forth at lower speeds so you can ride a longer line. This boat loves bow weight

Give that 450 a fill before you plumb it and I guarantee it will make huge difference. To be quite honest if you are not doing any skiing the boat cruises across the lake and handles chop much better with a little weight towards the bow. I always leave my KGB full and about 200 lbs of pop bags in the nose. If you don't have to tow very far leaving that 450 filled in the walkway permanently could be an option

07-16-2014, 03:17 PM
Swat, you were right, the 450 in the bow makes a big difference even with "only" running 2 x 450's in the stern. I'm working out how best to redistribute the lead (around 500-600 lbs in 40lb bags). So far around 120lbs under the bow front seat, 80lbs under port seat in the bow + a big 2nd battery, and 120lbs under the helm. That leaves me with approx 200 lbs extra, I need to run around 100lbs more on port to even the boat out, so leaves the final 100lbs to play with. Thoughts - bow or stern?

07-18-2014, 03:11 PM
Yea I would throw it in the bow. The added bonus with the lead/bags is when you are completely empty that little bit of bow weight helps the boat cruise better across the wake. The bow weight really cleans up the wake, gives it a nice hard kick, and make it much more firm.