Ballast vent thread

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lee.mcintyre
Ballast vent thread

Hello

I have had a scan through, but not seen the answer to this listed. Does anyone know the thread of the ballast vent plug? I want to extend the vent 50mm or so higher, but don't live where I store the boat so can't just measure it. It is a 1991 C.

Cheers

Lee

quentin.sands
quentin.sands's picture
Hi Lee, don't know when you

Hi Lee, don't know when you are next at your boat but I will be at mine sometime next week and can take measurement, if that helps. Why would you raise it? Q

Quentin Sands

Mrs MacGregor 26C

lee.mcintyre
Hello Quentin

Hello Quentin

Mine has a fair bit of kit in it, and a 20hp on the back, so the vent sits pretty much at the water line when fully loaded. I want to raise the vent level a small amount so that it remains above the waterline at rest. Seems to be quite a common modification on the net.

If you do get chance to measure it that would be great. Also if you can take a photo of the plug lying on a tape measure so I can approximate the pitch please.

Cheers

Lee

quentin.sands
quentin.sands's picture
Is this the vent plug you

Is this the vent plug you want measuring? If so will find a tape measure

Quentin Sands

Mrs MacGregor 26C

quentin.sands
quentin.sands's picture
Pics attached I hope

Pics attached I hope

Quentin Sands

Mrs MacGregor 26C

jonathan.fox
Vent system modification

Vent system modification

I hope this might be of interest. When I bought my 26M I wanted to bypass the whole business of opening and closing the vent and copied an idea from someone in the States. The vent plug is removed and one half of a suitable tube connector permanently fitted to the opening. The other half is fitted to a flexible pipe (similar to a plastic hose pipe) which allows a secure connection to be made. The pipe is then fed under the forward berth and upwards in the bow to join the drain pipe from the anchor locker. This means the vent is permanently open but high enough for this not to be a problem in terms of any ballast water escaping while well healed. the reason for having the connection at the original opening is so that it is possible to re-assure oneself that the tank is full. I suppose if the pipe was transparent this might not be necessary (a further mod?). This has worked very well for me and saves having to access the vent plug all the time. It assumes a good fitting gate valve in the stern but I have not found a problem there.

Regards,

Jonathan

Jon Fox

rick.jones
rick.jones's picture
I tried something similar on

I tried something similar on my former 26X. Following an idea I found online, I fitted a tube from the ballast tank (separately from the vent plug) to the top of the centre board trunk - which is above the water line. The concept kinda worked, but filling and emptying was very slow unless the vent plug was removed. This is because the diameter of the tube was too small to allow air to flow fast enough.

My conclusion was that if doing any kind of mod like this, make sure to use tube the diameter of the vent plug - about 1" (25mm) - if you want to be able to fill and empty as quickly as normal.

Rick Jones (Treasurer) 1994 Mac 19 "White Lightning", Isle of Wight