Water Tank Vents

[Driftwoods]

I was filling my water tank this weekend and heard the bilge pump running. A little investigation showed 2 openings in the forward water tank (under the V-berth). These openings appear to be designed; I assume as the tank vents but also serve as a bit of a overflow vent. However, they are all the way on the port and starboard side right next to the hull so it seems like they would leak into the bilge anytime we heel over enough and drain a little out of the tanks (probably not much).

So I'm looking for a sanity check. Are these just the tank vents and the overflow is working as designed?

[boatpoker]

Vents should be connected to throughulls well above the waterline, as close to the sheer as possible.

[Driftwoods]

That makes more sense to me than what I'm seeing. It's really strange ... it looks like these were intentionally made to vent the forward water tank. They are positioned symmetrically on the port and starboard sides, at the top of the tank. I have heard of some Morgan's being vented into the chain locker, I'll look there and see if there's a vent that is blocked.

[fryewe]

Originally Posted by boatpoker

Vents should be connected to throughulls well above the waterline, as close to the sheer as possible.

You may be right and I don't know if there are any specs that agree or disagree with your comment but...

I would never run my freshwater tank vents topside because saltwater or harbor water contamination may result. My vents are all loops of hose that run from the tank to very high under the deck then back down toward the bilge...ending well short of the bilge to allow drainage to it but prevent contamination if the bilge is full and the boat is heeled or suffers a knockdown.

Fresh water in the bilge hurts nothing. Harbor water or salt water in the tank can hurt your tummy.

[Hudson Force]

Except for bladder tanks I've never heard of a water tank that is not vented and I think this is best done with a through-hull. One vent would suit and you could plug the other or you could vent starbord to port & port to starboard if they might spill water at a heel. A loop in the vent hose can prevent contamination.

[Cheechako]

Originally Posted by fryewe

You may be right and I don't know if there are any specs that agree or disagree with your comment but...

I would never run my freshwater tank vents topside because saltwater or harbor water contamination may result. My vents are all loops of hose that run from the tank to very high under the deck then back down toward the bilge...ending well short of the bilge to allow drainage to it but prevent contamination if the bilge is full and the boat is heeled or suffers a knockdown.

Fresh water in the bilge hurts nothing. Harbor water or salt water in the tank can hurt your tummy.

I've never heard of your method, but it sounds good.... why do the vents have to go outside at all? Little Bees nested in the vents of my Passport and it was the pits to get them cleaned out... One thing about trrue outside vents is you can tell when the tank is full. Why not vent into the cockpit side wall?

[Driftwoods]

In my case, the openings don't seem quite big enough to handle the hose refilling at full speed when it get's pretty full so it runs up into the water fill hose and will overflow before it resettles. The first time that happens, it's as full as it should be.

I suppose I can just keep topping it off until I hear the bilge pump again. I get a full water tank and check my bilge pump is operating properly at the same time. Things could be worse.

[Vasco]

My port water tank (CS36M) is vented to the galley sink. The starboard tank is vented inside the boat, the line just runs up the inside of the hull. Any water from this vent would run into the bilge. I prefer this to venting outside the boat.

[fryewe]

Originally Posted by Cheechako

I've never heard of your method, but it sounds good.... why do the vents have to go outside at all? Little Bees nested in the vents of my Passport and it was the pits to get them cleaned out... One thing about trrue outside vents is you can tell when the tank is full. Why not vent into the cockpit side wall?

My vents discharge to the bilge adjacent to the fill line where I connect my hose. I can see when each tank is full when the tank overflows through the line to the bilge pocket and can shut off the fill supply.

Vents in the cockpit side wall on my boat would surely result in contamination due to seawater frequently entering the cockpit when seas are up a bit and I am heeled.

[Cheechako]

all vents should have a loop above the exit to prevent seawater entry.