Thru Hull intakes

[Dave K]

Scenario: 24V
Brass mushroom thru-hull intake with strainer connected to emergency shut off value connected to a Tsunami 800gph pump.

When the boat is underway would there be any water forced through the pump, hose (even though shut off) and up to the ballast bags?

Thanks

[jason@wakemakers.com]

Yes, you can have passive filling with an aerator pump, as they do not impede the flow of water when off. More common is to have passive draining, where a siphon is established and the bag loses water.

In order to prevent that from happening you need to use an additional fitting between the pump and bag. The best option in our opinion is to use a vented loop, as it is completely passive, and will prevent both filling and draining from occuring.

Check out our blog for more information on Anti Siphon Vented Loops.

[Timmy!]

I have the setup you are talking about but only have the draining scenario, not the filling. Due to the sheer size of the sac (custom RZ2 sac), there isn't anywhere to put an anti-siphon loop so I just close the shutoff valve for now. I am going to put in a check valve on the fill sides shortly so I don't have to mess with the valve anymore.

[chpthril]

Yes, you can have passive filling with an aerator pump, as they do not impede the flow of water when off. More common is to have passive draining, where a siphon is established and the bag loses water.

In order to prevent that from happening you need to use an additional fitting between the pump and bag. The best option in our opinion is to use a vented loop, as it is completely passive, and will prevent both filling and draining from occurring.

Check out our blog for more information on Anti Siphon Vented Loops.

Hows it going Jason? I see you have had a change of heart and started selling the Rule pumps since my pump flow tests proved they were faster

Jason and I seem do differ on the use of the vented-loops. In a boat with as deep of a gunwale as Tige, a vented loop is not always needed. Hose routing and bag size (height) will have a bearing on whether they may be needed or not.

Brass mushroom thru-hull intake with strainer connected to emergency shut off value connected to a Tsunami 800gph pump.

When the boat is underway would there be any water forced through the pump, hose (even though shut off) and up to the ballast bags?

Are you talking about a scoop or a mushroom with a protective grate over it?

I dont like to use scoops because they do create the need to have a gate valve or manual-shutoff. When facing forward, they create positive flow though the pump. When turned backwards, they create a vacuum.

I prefer a mushroom, regardless of pump type used. With a shroom, I rarely experience any force-feeding or vacuum on the sacs. As noted, on most of the Tige boats, depending on what sacs are used, simple hose routing can eliminated the need for a pair of $47.95 (can be found for $40.00) vented-loops per sac.

In my experience, most of the self drain, or equalizing, comes on the drain and vent side of the plumbing. This a result of the filled height of the sac and location of the drain and vent thru-hull. If the height of the sac is above the thru-hull, the water level will drop, or equalize, down to the level of said thru-hull. Think of a bucket with a hole about 3/4 ways down. Fill it to the top and it will soon leak out till the level reaches the hole.

In this case, a vented loop can cure the issue and may be needed. If one is experiencing this with a surf setup, there is another option that only requires some additional hose and some time to reconfigure the drain/vent plumbing. All you need to do is route the port side sac's drain/vent over to the starboard sac's thru-hull and then do the same for the starboard sac. Once the sac is filled and the boat is listing to that side, the thru-hull is now higher then the sac because its on the opposite side of the filled sac.

Dave,

You basic layout is correct: Bronze pickup, covered with a screen if you feel your water is dirty enough, with a ball-valve for emergency shutoff and then the pump. Now, depending on where you locate the thru-hulls, you may need to add a 90* elbow in there.

[chpthril]

I have the setup you are talking about but only have the draining scenario, not the filling. Due to the sheer size of the sac (custom RZ2 sac), there isn't anywhere to put an anti-siphon loop so I just close the shutoff valve for now. I am going to put in a check valve on the fill sides shortly so I don't have to mess with the valve anymore.

Timmy,

We need to get you fixed up! Are you positive as to where the water is exiting the sac? The fill port is on the top of the sac, right?

If the water is exiting back out of the fill pump plumbing, then a good check valve will cure your issue and not have a dramatic impact on flow rate. If the water is leaving out the drain/vent plumbing, then swapping the hose side to side like i outlined above, may be the fix.

[jason@wakemakers.com]

I have the setup you are talking about but only have the draining scenario, not the filling. Due to the sheer size of the sac (custom RZ2 sac), there isn't anywhere to put an anti-siphon loop so I just close the shutoff valve for now. I am going to put in a check valve on the fill sides shortly so I don't have to mess with the valve anymore.

Check valves work 99% of the time in a bag that is in the rear half of the boat and above the floor, so that's usually a safe bet.

Hows it going Jason?

Hey, just enjoying our "off-season", and trying to get up to the mountain as much as possible, what about you?

I see you have had a change of heart and started selling the Rule pumps since my pump flow tests proved they were faster

Haha, yeah, your numbers were pretty persuasive! Actually we've carried the Rule product for a long time, but for some reason it was just never on our site.

Jason and I seem do differ on the use of the vented-loops. In a boat with as deep of a gunwale as Tige, a vented loop is not always needed. Hose routing and bag size (height) will have a bearing on whether they may be needed or not.

That's true, every situation will be a little different, and with a tall bag it can be difficult to get a large enough delta between the placement of the loop and the top of the bag. Like I said above, you can get away with a check valve almost all the time, but there are situations where you'll get passive filling in a rear bag when using a mushroom intake, and to solve that the only solution is a vented loop. Most of our customers just want the job down right the first time, so that's the easy way to be sure there won't be any problems.

I know you weren't advocating for this, but just to clarify in case any doing a DIY system reads this, just putting a loop in the fill hose between the pump and the bag is absolutely not sufficient, and you will absolutely end up with passive draining when a siphon gets established (see Timmy's post above, that's what he's experiencing).