Cross venting?

[Palle Man]

i see a lot of comments about cross venting. Not to sound dumb, but what is the advantage of this? Will this stop the water from draining out of the bag after its full? I still have not figured out where I'm losing so much water so fast. I know some is coming out of the overflow and vent, but it doesn't seem like that much. I open up the locker, after just a short time, and I've already lost a lot of water.

[JohnnieMo]

There are usually two reasons why this happens.

You nailed the first one. You fill the bags and list the boat. But the act of listing causes the water to slosh out , especially with bigger ballast. It scan come out the vent AND the drain. Cross venting and draining means you plumb those lines to the other side of the boat. That way, at list, gravity prevents it from coming out.

The other way is through 'back-draining' out through the fill pumps in the bottom of the boat. This is corrected by installing one way check valves in the fill lines.



Sent from my Passport

[Palle Man]

Ok. Thanks. I did try closing the valve after filling the bag and it helped, but it's a pain in the ***! Guess I'll chock up another winter project. Not like I have much better to do. Stupid winter!

[chpthril]

We find that the 2 biggest offenders for passive draining are the fill line and the drain line. This is due to the fact the source for those two line, is lower then the filled sac. Gravity will just allow the water to flow down hill out of the sac. A check valve in the fill line will cure it, but in some case, the fill line routing can be adjusted. Routing the hose so there is a loop thats higher than the sac. This breaks the gravity siphon. In the case of the drain, not only do you have the weight of the water pushing through the drain pump, but the thru-hull is below the level of the filled sac. This makes the passive draining much easier. Crossing the drain line to the other side, creates some up hill travel for the drain flow, reducing the passive draining. For the vent line, its probably the least of the 3 and crossing will it as well will take cure of any passive draining.

[JohnnieMo]

I'm planning on doing this mod in the winter too. So far I've got it mostly pulled apart. I'll post the results in my "Winter Projects" thread.

[Palle Man]

Cool. Thanks for the feedback.

[.JOSEPH14]

All new 2015 Model Tiges will now come with cross venting from the factory!

[baileytench]

Naturally occuring ventilation of building is considered as cross venting. It is like pulling cool air inside house and removing hot warm air. Advantages of cross ventis ventilation is that this ventilation process does not require energy.