Adding T Connections for Fat Sac

[toomuchhype]

Hey all,

I have been searching and reading the forums, and learning lots. This is a great forum.

Question - I have a '07 VTX and am wanting to plumb in my 750 fly high in the back port-side locker for surfing. I've been researching adding thru-hulls, but wondered if I could do this:

Fill:

1. T or Y off of the Starboard hard-tank fill line with a new pump.

2. Add Check Valves, Aerator Pump, and run hose into fill side of port-side fat sac

3. Add seperate switch on the dash to power the pump

Drain:

1. T or Y off of the Starboard hard-tank drain line

2. Add aerator pump, check valve, hose, etc

3. Plumb into the drain side of my fat sac for draining

Vent:

1. T or Y off of Starboard hard-tank line for venting of port-side fat sac (no siphoning effect)

Would this work? I've read that people don't seem to lose much performance when T'ing off of fill/drain lines, but the debate doesn't matter given I wouldn't be filling my starboard hard tank for port-side surfing. If this would work, I can still get the benefits of captain-chair filling/draining, but avoid the work of drilling new thru hulls.

Let me know your thoughts!

[Brad B]

Problem I've seen with T's on the drain side is it not keeping prime to totally empty the sac.

However the ez fix for that is to roll ithe sac up somewhat when it starts to sputter.

Some don't like this extra manipulation because they want a total hands off operate by a switch method.

But I guess it is possible if you position it all just right it will at least drain enough.

I generally don't worry much about complete drain because we are filling and draining and rolling alot - and at the end of a season or before a week or 2 lay up I would manually drain everything

[Bobby Light]

I would get the bakes add a bag system. Foolproof and works great.

[toomuchhype]

Wanting to give this thread a bump for more feedback, because I'm wanting to tackle this upgrade in the next week or two before winter is upon us.

I have looked into the Bakes add-a-bag, but the problem with the piggy-back type is that they require 1 pump for two bags/tanks. The Bakes full ballast package requires drilling holes. The more I think about this, the more I think it could be done and done cheaply given that it only requires a few parts.

Any more feedback Crew?

[Tao of Wake]

One thing that comes to mind is that when you are filling one of the hard tanks, you will get water going into the sac. Aerator pumps are passive, so the water that is being pumped by the "stock" pump will push through the aerator pump past the tee and go into the sac. Or were you thinking of putting the tee before the stock pump, and then attaching the stock pump and the new pump to that tee? That is actually how it is setup on my '07 VLX for the center and port stock pumps. You just want to make sure to put the shut-off valve before the tee.

I'm not picturing how you would do the drain line. Would you put the tee between the hard tank and the stock pump or somewhere in the drain line between the stock pump and the thru hull?

Don't be scared of drilling new thru hulls. It's really not that bad. The worst part is finding space in the engine compartment to mount the new pumps and then turning yourself into a pretzel getting them installed.

To Brad B's point, if you install check valves on each line going to/from the sac, I find that the drain pump empties the sac completely to the point that it starts wrinkling up. I've never had to roll or tilt the sac to get all of the water out.

[toomuchhype]

One thing that comes to mind is that when you are filling one of the hard tanks, you will get water going into the sac. Aerator pumps are passive, so the water that is being pumped by the "stock" pump will push through the aerator pump past the tee and go into the sac. Or were you thinking of putting the tee before the stock pump, and then attaching the stock pump and the new pump to that tee? That is actually how it is setup on my '07 VLX for the center and port stock pumps. You just want to make sure to put the shut-off valve before the tee.

I'm not picturing how you would do the drain line. Would you put the tee between the hard tank and the stock pump or somewhere in the drain line between the stock pump and the thru hull?

Don't be scared of drilling new thru hulls. It's really not that bad. The worst part is finding space in the engine compartment to mount the new pumps and then turning yourself into a pretzel getting them installed.

To Brad B's point, if you install check valves on each line going to/from the sac, I find that the drain pump empties the sac completely to the point that it starts wrinkling up. I've never had to roll or tilt the sac to get all of the water out.

Yes - I would install the T before the two pumps. I have the same existing brass T before 2 pumps, accessible via the middle transmission seat. I'm not sure where they go, but I assume they are the same as yours - port and center. I would essentially mimic this exact setup for the pump that is on the opposite side of the trans that only has 1 pump connected directly to the thru-hull. Here is a diagram:

[Tao of Wake]

No reason why that shouldn't work just fine.

I did confirm that the flow through the two 800GPH pumps sharing a 3/4" thru hull were not inhibited. I timed how long it takes to fill the port and center tanks independently (only 1 pump running at once) and then did it again with both pumps running simultaneously. The tanks filled in the same time in both scenarios. One thing to consider is the size of the pumps you will have sharing the thru hull. Maybe two 800GPH pumps sharing a 3/4" is the cutoff. That is, if you were to have a 800GPH and a 1200GPH sharing, possibly the flow would not be enough to keep up with both. You did say that you would only be running one of the pumps at a time, though. Just pointing out a possible limitation.

Now, how about the drain setup?

[toomuchhype]

No reason why that shouldn't work just fine.

I did confirm that the flow through the two 800GPH pumps sharing a 3/4" thru hull were not inhibited. I timed how long it takes to fill the port and center tanks independently (only 1 pump running at once) and then did it again with both pumps running simultaneously. The tanks filled in the same time in both scenarios. One thing to consider is the size of the pumps you will have sharing the thru hull. Maybe two 800GPH pumps sharing a 3/4" is the cutoff. That is, if you were to have a 800GPH and a 1200GPH sharing, possibly the flow would not be enough to keep up with both. You did say that you would only be running one of the pumps at a time, though. Just pointing out a possible limitation.

Now, how about the drain setup?

Cool. And that is great to know about the two pumps not being affected by the thru-hull size.

Drain setup would be easy - I would simply tie into the existing drain port out the side of the boat with a Y connection. I'd use check valves in each line so that the draining of one hose wouldn't fill up the other. Diagram below for visualization. Port side surf sac would drain to the Starboard side drain (to prevent siphoning effect when the boat is weighted). I guess I would also need to add one of those siphoning loops as well, right?

[Tao of Wake]

You shouldn't need an anti-siphon valve on either the drain or fill lines. I don't have them on the pumps I installed for the fat sacs, and I haven't had an issue. I have the drain & vent lines from both sacs (one in each rear compartment) routed to the opposite side of the boat. I have had no issues with siphoning.

I don't see any reason why this setup wouldn't work just fine. To help improve flow, I would go with "Y' connectors rather than tees on the drain line. It shouldn't matter on the fill line, since it will be below the water line, and the vent is only for air, so that could have a tee. I chose full flow check valves to get the best flow rate. They have a low cracking pressure and a magnet to help keep the valve open. I got them at plumbingsupply.com

[toomuchhype]

You shouldn't need an anti-siphon valve on either the drain or fill lines. I don't have them on the pumps I installed for the fat sacs, and I haven't had an issue. I have the drain & vent lines from both sacs (one in each rear compartment) routed to the opposite side of the boat. I have had no issues with siphoning.

I don't see any reason why this setup wouldn't work just fine. To help improve flow, I would go with "Y' connectors rather than tees on the drain line. It shouldn't matter on the fill line, since it will be below the water line, and the vent is only for air, so that could have a tee. I chose full flow check valves to get the best flow rate. They have a low cracking pressure and a magnet to help keep the valve open. I got them at plumbingsupply.com

Awesome. Thanks for the tips and confirmation Tao.

[surfdude]

are there check valves on the stock fill lines after the pumps?

[TallRedRider]

are there check valves on the stock fill lines after the pumps?

There is an antisiphon valve on the fill lines, but no check valve.