Ballast tank airvent

[Colin Lawson]

Hi, does anyone have any advice on position of an airvent for ballast tank as recommended by Claus.  He put his immediately behind the centre board case below his GPS. But if your GPS is on top of the centre board case as mine is, an air vent in front of the CB case would be in the way and liable to be damaged by feet looking for something to brace against.  Has anyone tried putting the vent in front of the centre board case.  I know the battery usually goes there but re siting the battery off the deck might be a good idea anyway.Where does the air collect/get trapped? At the front of the ballast tank or at the back.

Thanks in advance for any words of wisdom.

Colin (looking forward to taking his BR20 to Falmouth first week in June and then again at the beginning of July)

[Colin Lawson]

Thanks Claus - I think I will go with your advice, seeing when the tank is full sounds like the deciding factor.

Colin

[Graham W]

I installed a lean-to piece of wood astern of my centreboard case to hang instruments off, in this case a Tackticks wind indicator (see photo). My ballast tank vent is hidden and protected in the triangular shaped void between the case and the instrument board. 

As an additional source of information about what is happening in the ballast tank, a transparent watertight inspection hatch cover is available to replace the Henderson TCL4 red and black one that is fitted as standard equipment.  Seamark Nunn sell it http://www.seamarknunn.com/acatalog/info_MTLD4002.html

I found my watertight hatches increasingly difficult to open as the threads became crusted up with salt and general muck.  As well as cleaning them up,  I coated the threads with silicone grease and now they are much easier to open and close.  Same thing with my ballast tank bungs.

[John Davis]

Claus and all,

I've just read this string and wondering why an airvent is a must.  I have not put one in yet and have had no problems filling or exhausting the tank.  Under what circumstances do you find it to be particularly useful?

Thanks, in advance, for your advice.

John

[Matthew P]

Rather than make another hole in my BR20 I have fitted (screwed and Sika-flexed) a small drain plug into one of the forward hatch covers, which seems to work well and has so far has stood up to my large feet.  It is surprising how much faster water floods out of the tank from the other end when the vent is opened.

Following Clause s lead I have fitted a drain plug into the sump from which I can pump it out with a Whale Titan pump. I will post a picture of this under a new string; Sump Pump.

Matthew

[Simon Knight]

Hi,

I have my drill out ready and wonder now that three years has passed how well the bung in the hatch has stood against the test of time and big feet.

best wishes

Simon

[Graham W]

I recently re-did my airvent, which is hidden away between the aft end of the centreboard case and a lean-to piece of wood that I use as an instrument panel.  It's basically a plastic through-hull fitting with hosetail, allied to a jiggle syphon.  The idea is that the jiggle syphon lets air in when the tank is being emptied (so that a vacuum can't form so easily) but closes up in the very unlikely event of being inverted with a full ballast tank. For fast filling and emptying of the tank, you still need to undo one of the inspection hatches to equalise the air pressure but this apparatus at least prevents a vacuum from jamming the inspection hatch so that it can't be undone.  I'm thinking of putting another one in at the forward end of the centreboard case, in front of the battery.

[Simon Knight]

Thanks for the information and photo.  I was not familiar with "jiggle syphon" but I guess that there is a ball inside that blocks the opening when inverted.

Simon

[Graham W]

Exactly.