Cool Man Cool! (Engine Cooling)

“ Does yours run hot?” is a question often heard between Piper owners and it refers to the tendency of older boats to overheat when running at higher than usual power levels when on bigger, deeper waterways such as rivers.

The answer for me was “No, yes and no”. As built (in 1980) and for many years thereafter, the cooling system on Owlet was adequate, but only just. At that time only one keel tank was connected into the water cooling circuit but gradually, as the internal surfaces ‘furred up’ and externally some of the surfaces received layers of ‘blacking’, the overall efficiency of the system deteriorated.

This first became a problem for me while punching the tide from Teddington to Brentford and Owlet was unable to keep up with the flotilla as the temperature gauge approached 100 degrees! (The correct temperature for our diesel is about 80 degrees) The situation was temporarily saved by running off the domestic hot water and by searching for slack water on the bends - and we made it to Brentford Locks in time.

A long term cure has been achieved by Tony Perry, as shown in the diagram below, by connecting the spare tank on the other side of the engine so that they are in series. However, this is very difficult to do unless the engine is removed and so was done when other work was needed. Before the sloping plate was welded in place a hole was cut into each tank near the back corner. Where the old connection was capped off, a small tap was fitted to bleed off any trapped air.

Since this modification the engine has run at 80 degrees under all conditions, including a good thrash against the tide on the Trent. We recently discovered that when new, Owlet had been taken from Keadby to Cromwell Lock against the tide, at full throttle, in 12 hours 40 minutes by the original owners and their friend Harry Arnold without any problems!

PGM.

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