Pressure Testing for Leaks

You may have found like me that locating the source of deck leaks on the Hunter 19 / Europa can be a real headache. There are so many possible sources and it is not clear where water may be coming through.  Short of re-sealing absolutely every fitting how can you find out what really leaks and what does not?  I managed to resolve this problem with the use a vacuum cleaner a lot of sticky tape, a spare board, soapy water, a sponge and a manometer.

The thinking behind this solution was based on citadel pressure testing carried out by the Navy in order to ensure that the ships citadel can be sealed off in event of a chemical or biological attack.  The air pressure on the inside of the ship is increased; the crew can then go round checking for escaping currents of air.

To achieve a similar solution on a Hunter Europa, meant that our first challenge was to seal off all known holes (e.g. the main hatch and vents).  We simply used sticky tape (duck tape and parcel tape) to cover any joins between the hatch boards and the boat.  We also substituted the normal hatch board with a purpose cut board of the same size in to which we drilled some carefully measured holes.

Before completely sealing the cabin, the vacuum cleaner had been placed inside the boat and the hose connected up to one of the drilled holes in the hatch board so that it would suck air into the enclosed hull.  A second hole enabled us to pass a power cable into the boat for the vacuum cleaner.  The third was to connect up the manometer which is basically a glass `U' tube containing water which would enable us to monitor the pressure difference between inside and outside.  Having connected everything up, the hatch board was finally sealed into place.

At this point I was still quite sceptical of how well this was going to work.  I started the vacuum cleaner by connecting up the power and the change in pressure was immediate and dramatic and the manometer went completely off the scale.  We realised that the boat was too air tight and we had no way of controlling the level of pressure.  The vacuum cleaner was inside and we couldn't turn it down!  We would assume that the pressure would build up until the weakest seal broke (like an over inflated balloon).  The problem was resolved by opening the small round hatch into the cabin and placing a large sponge in the hole which was enough to maintain a level of pressure (see photo in archive).

By going around potential sources of leakage with soapy water on a paint brush the actual leaks could be easy detected by the appearance of bubbles (Some very large… see photos).  This technique worked amazingly well and surpassed my expectations.  I can now target my repairs at specific locations and will rerun the test to prove they've been fixed. 

 In order to do the same test for the stern locker, the bilge pump pipe going through to the main saloon was disconnected to allow the air to flow freely through from the pressurised area.  The locker lid was then sealed and the locker then came part of the pressurised area.

Places that I have found with leaks are:

§         Shroud plates

§         Both stantions

§         Starboard window ( I resealed the port one in 2005)

§         Under the rubbing strip in a few places around the boat

§         Small round window in the aft of the cabin

§         Lower rudder pintal

§         Point at which the bilge pump pipe goes through to the aft locker

§         Port halyard winch