Water ballast vent

[Retcoastie]

Oh, Boat, you must do things differently than I do. I agree a vent is needed when filling. I usually pull the plug, then the gate valve, and then just sit around enjoying life until I see water flowing in and then out of the gate valve. At that point, I feel the ballast is full and water is just sloshing in and out of the tank, so I close the gate and then the vent. No hassles.

Emptying, I think we are talking apples and oranges. I suspect you are talking about how long it takes to empty the ballast. I'm talking about how long it takes for water to get below the top of the gate valve allowing air to enter the ballast tank. Agreed, it it takes awhile to empty underway, but that is not the question here. I'm only talking about how long it takes for the water level to get below the top of the gate valve, allowing air to enter thru the gate valve, and rendering a vent useless, not emptying the entire tank. Not very long no our boat.

[dlandersson]

On my 98, on the ramp, my ballast tank empties faster with the vent open than with the vent closed. Just sayn'.

Oh, Boat, you must do things differently than I do. I agree a vent is needed when filling. I usually pull the plug, then the gate valve, and then just sit around enjoying life until I see water flowing in and then out of the gate valve. At that point, I feel the ballast is full and water is just sloshing in and out of the tank, so I close the gate and then the vent. No hassles.

Emptying, I think we are talking apples and oranges. I suspect you are talking about how long it takes to empty the ballast. I'm talking about how long it takes for water to get below the top of the gate valve allowing air to enter the ballast tank. Agreed, it it takes awhile to empty underway, but that is not the question here. I'm only talking about how long it takes for the water level to get below the top of the gate valve, allowing air to enter and rendering a vent useless, not emptying the entire tank. Not very long no our boat.

[Retcoastie]

On my 98, on the ramp, my ballast tank empties faster with the vent open than with the vent closed. Just sayn'.

Agreed, if you have time to stay on the steep part of the ramp where the ballast water is mostly trapped high above the gate valve. Here they want you to move off quickly. On the near flat parking lot, I would wager a precious 12 pak, there would be little difference, vent open or vent closed, even in a 98.

[BOAT]

It may be the model year - my 98 takes far more than 45 seconds to empty with the vent closed.

Mine too! and it's a 2013!

[Sea Wind]

One of the main reasons i put the forward vent on an electric valve was so I could just drop the motor, pull the handle and go

couldn't you accomplish that by just rerouting the vent to the anchor locker?
I haven't done that mod yet, but wondering what is gained with the switch.

[Tomfoolery]

On my 98, on the ramp, my ballast tank empties faster with the vent open than with the vent closed. Just sayn'.

Agreed, if you have time to stay on the steep part of the ramp where the ballast water is mostly trapped high above the gate valve. Here they want you to move off quickly.

Just for another data point, though I haven't timed the draining of ballast, I open the vent and gate valve before I hit the trailer. Ballast is draining as soon as the bow is elevated even the slightest. By the time it's winched, pulled up the ramp a little, winched again, and so on, it's nearly empty. I pull it completely out and there's not much left to come out, so a little vamping to look busy 'inspecting', and it's empty. But even if it wasn't completely empty because there is a line waiting, there wouldn't be enough in it to worry about.

[Retcoastie]

Ah, crap. I might as well go cut the grass. I can see I'm making no progress here.

You guys keep talking about "empty" and "empties". I'm not talking about the last pint of water in the ballast tank. This post is about how and why to have a ballast vent and if it needs to be modified. I agree a vent is necessary to fill the ballast tank efficiently. It is a minor inconvenience to inset the plug into the vent hole after a fill, IMHO. My contention is that a vent makes little difference during the dumping of the ballast. Removing the plug or some other method of allowing air into the ballast tank is not necessary and is therefore a non-event and is not a legitimate reason to modify what is there now. Dumping with the plug in place takes only a few additional seconds verses the hassle of going into the cabin and removing the plug, underway or on the hard. The dumping operation does not justify effort or cost to accomplish the desired effect.

So, from my seat, just inserting the plug, maybe once a trip, is such a little thing it does not require additional effort to modify.

[BOAT]

Ah, crap. I might as well go cut the grass. I can see I'm making no progress here.

You guys keep talking about "empty" and "empties". I'm not talking about the last pint of water in the ballast tank. This post is about how and why to have a ballast vent and if it needs to be modified. I agree a vent is necessary to fill the ballast tank efficiently. It is a minor inconvenience to inset the plug into the vent hole after a fill, IMHO. My contention is that a vent makes little difference during the dumping of the ballast. Removing the plug or some other method of allowing air into the ballast tank is not necessary and is therefore a non-event and is not a legitimate reason to modify what is there now. Dumping with the plug in place takes only a few additional seconds verses the hassle of going into the cabin and removing the plug, underway or on the hard. The dumping operation does not justify effort or cost to accomplish the desired effect.

So, from my seat, just inserting the plug, maybe once a trip, is such a little thing it does not require additional effort to modify.

Why plug it at all? Why even have a vent??

Look, the boats come with a bow vent. We like to yak yak all day about weather or not the boat needs a plug in the vent. It's a great discussion:

Some guys think the vent does not need a plug - so they just vent the ballast out to the chain locker permanent - they don't even have a plug.

Other guys think the vent is not even necessary so why not just leave the plug in all the time? I agree, if the vent is not needed why bother to vent it, right?

The salient fact here is: the boat comes from the factory with a bow vent.

Now, we can all decide on our own if the bow vent or the vent plug is needed and all call Roger and tell him what a mistake he made by bothering to put in a bow vent and a plug. I'm sure he would love your opinions, but, as long as MY boat came from the factory with a bow vent AND a plug - I will be using the bow vent and I will be plugging it.

There are many reasons why the vent should be sealed when underway, and many more reasons why the vent should be unplugged when emptying the ballast tank and they have been discussed at length on this very website, but for me I figure Roger knows more about water ballast than I do (after all, he invented it) so I think if Roger says to plug and unplug the ballast vent in the owners manual I'm gonna do it.

That's good enough for me.

[Doug W]

That is really cool engineering! A neat project in itself just solving a way to do everything from the helm. Very impressive.

I old school it even when solo which is now nearly every time at this stage-- now that the Admiral can bring the trailer around and back it somewhere near and occasionally onto the ramp!
1. I open the rear valve, lift the fins and rocket the 3/4 mile to the ramp.
2. As I approach the no wake, I drop to idle speed. stiffen the steering with the thumbscrew on my steering collar,
3. close the aft valve
4. hop below and pull the vent plug - I added a hatch on the bulkhead so that it's fast to flip the door up and reach in to pull the plug--no mussing with the cushion/sheets/blankets which could invoke the Admiral's Angst
5. pop back on deck to verify course into the no wake zone and look for surrounding boats then go forward to
...... 5a. hang my fenders on the appropriate side,
...... 5b. run my forward dockline aft to the helm
...... 5c. drop the daggerboard a foot if needed
...... 5d. drop one of the rudders
6. Then I prep the aft dock line on the correct side (I can do all of the preceding steps very quickly due to practice and routine...)
7. Afterwards, I get to hold water, wait my turn at the ramp and enjoy the living heck out of the "Ramp Show" that is always good entertainment!

I assume that most of you have similar steps or a process for preparing to pull out? (um, at the ramp...ya filthy minded rascals!)

Doug
2010 MacGregor 26M; hull# 2569
sv Galactica

[yukonbob]

I think the important reason for venting when filling is to ensure the tank is full and not air locked and keeping the properly design amount of water from getting in. As for emptying it’s a little faster, but I rarely empty the tank anyways and when I do I almost never pull the vent plug as I’m usually on a long trip and the extra 3 min it might take is insignificant, and when loading on the trailer it’s too much a pain to climb back on board and vent. By the time I got in there it’d be close to empty anyways.

[BOAT]

There are many more reasons - when the boat is in heavy seas the water can pound the rear gate valve and the seal in the vent helps prevent that - there are other reasons too. Mastreb made a long list of reasons why the vent it there and why it is plugged.

All I know is that after consulting with all the people I could find about the subject I was instructed that there are two ways to vent the thing with a valve - the wrong way and the right way.

Here is the wrong way:



And here is the right way:

[kurz]

Well I think one of the reason Roger put the vent is the following:
In the manual he sais before closing the vent you have to check the water level with you fingers or seeing the water coming out of the vent.

If you vent it directly to the anchor locker you have no control.

Becouse of this I installed the ballast check LED that shows if the tank is full. So I think its quite save. Worked quite well in the Tyrrhenian sea the last two weeks, even so the gimbal origo 3000 installation

[BOAT]

Well I think one of the reason Roger put the vent is the following:
In the manual he sais before closing the vent you have to check the water level with you fingers or seeing the water coming out of the vent.

If you vent it directly to the anchor locker you have no control.

Becouse of this I installed the ballast check LED that shows if the tank is full. So I think its quite save. Worked quite well in the Tyrrhenian sea the last two weeks, even so the gimbal origo 3000 installation

Yes, that is what they told me at the factory too kurz - they wanted to make sure I could see water in the bowl or in the hole so that I could confirm the tank was full and that is exactly why I removed the hose from the vent hole and put a clear plastic cover on it - so I could SEE it. The next best thing would be an indicator light like you have.

[sailboatmike]

Am I missing something here, the whole vent thing is basic science, year 7 stuff.

Why vent when filling, - Vessel has a limited capacity, when the tank is empty that is full of air, so if we want to replace the air with water we must provide somewhere for the air to go, if we dont the tank will never completely fill, during the initial period of filling as the water level rises the air can escape from gap between the the actual water line and the top of the inlet valve, once the water line rises to the top of the inlet valve unless there is a vent for the air to escape the water level in the tank wont rise because the tank is full to the waterline of the inlet valve, the rest of the tank is full of air. unless there is a way for the air to escape the water level will never rise because the tank is full (with a mix of water and air), to allow the tank to completely fill you must allow the air to escape to give room for the water in the tank.

Same when emptying except we have a helping hand from gravity or venturi effect , basicly the water can only escape from the tank at the rate that air can enter remember our tank is always full, of course that can be with water, air or a combination of water and air.

In its simplest form, we open the gate valve on the ramp, water will still come out even if we dont have the air valve open, but slowly, thats our dear friend gravity helping out, water will continue to flow until the vacuum created in the tank by gravity allowing the water to flow is actually stronger than the gravity allowing it to flow out, at this point the vacuum takes over and draws air into the tank and you will see the water sort of gulp as the vacuum draws air into the tank, the flow will then continue until once again the vacuum takes over and draws more air, as the water level drops in the tank there is more room for air so its longer between gulps,

If the system was open (air valve open) the water can continue to flow out of the gate valve at the rate that the inlet of the air valve allow water in, limited by the diameter of the gate valve, of course because the diameter of the gate valve is larger than the air inlet the air cant keep up with the water flow out so you will still get some gulping as the tank empties through the gate vale.

There it is simple You can try this with a soft drink bottle in your sink at home, take the lid off and lat the bottle on its side and push it down, without a vent the water can only fill the bottle until the volume of air wont let any more water in, now put a hole in the top of the bottle, the water will now completely fill the bottle, put you finger over the hole you just put in the bottle and hold the bottle out of the water, the water will flow out very slowly, noe take you finger off the hole, the water will flow out much faster as the air fill the space the water once filled.

Remember your ballast tanks are always full, just full of air, water or a combination of water and air

[yukonbob]

I don't think anyone arguing your point. The LED indicator is just to know when to shut both valve and gate when ballast is full of water.