Internal engine layout

It seems having an internal engine on a Vivacity 20 is very unusual. As such a number of people on the excellent Yahoo forum  have shown an interest in the layout.  I have tried to document in this post.

Engine Housed beneath hatch

Positioned beneath the entry hatch the engine does not intrude into the cabin too much but allows sufficient access for maintenance. This is balanced by lead ballast in bows for balance.

Engine in situ with cover removed

Arrangement of fuel line, exhaust & propeller shaft behind engine under cockpit

Batteries charged by engine

Fuel tank in port cockpit locker

All of this is then counterweighted with a load of old lead piping packed in the bows.

Stuart Turner Engine – part II


After advice from friends and forums it was time to head back and give everything a go. So armed with a new spark plug, a tin of 3-in-1 and a can of gypsy breath (easy start) I headed over to the boat yard to try getting the engine going again.

First off was a good glug of oil straight into the cylinder in case the seals had shrunk. After giving it a few cranks to give everything a nice coating I fitted the new spark plug.  Then it was back to cranking away. There was definitely some improvement. It was a lot easier and after a while a nice “shhh-ti-cop” noise began to come from the carb with each turn but it still wasn’t firing.

Next I tried adding a couple of drops of fuel straight into the cylinder.  After a few cranks there was a spark of life and the fly wheel turned a couple of times before dying. Enthused I tried again but nothing. Then took the spark plug out, dried it and replaced it. A few cranks and bingo. Another brief sign of life. I repeated the cycle a number of times, then the yard owner had a go. Strangely, the old spark plug seemed to work better. By now where getting three spins. Scratching our heads we checked everything to find the exhaust valve was not open. Remedying this and there was  a cough a splutter and then a shuddering build up as the engine kicked into life. Once up an running and it seemed hard to conceive of a more satisfying sound!

Since this time there have been a few breakdowns due to a variety of faults including the need to clean the carburettor and not having enough fuel in the tank. It was by no means empty, but being gravity fed needs the tank to be more than half-full to operate properly.

The Stuart Turner P5 Marine Engine

Diagram from the handbook

Well this was always going to be a big project. The sales literature suggested the engine had been running last year. However, I found an old log entry which suggested that it had last been used in October 2009 when it had broken down passing the London Eye on the way up from Essex. As such, my hopes of a quick and easy fix were not high.

The P5 has a crank start and has a little brass carburettor that need to be ‘tickled’ to fill it by pressing the pin on top up and down until the bowl fills and it floats.

On Wednesday evening myself and a friend who knows about motors headed over to see what state she was in. The good news was that the engine would at least turnover and amazingly the batteries still had a decent 12v charge. The compression was a passable 50, the plug had a spark and with a little ‘tickle’ the carb filled. Enthused, we began cranking away but to no avail.

Content of fuel tank

Next we decided to change the fuel. Unfortunately there was a nearly full tank of at least 10 litres. Luckily we were able to find an old petrol can knocking about and a five litre container. Draining from the bottom proved far too slow so we had to disconnect the whole tank and pour it out through a funnel. A good thing we did. What came out smelled like varnish and was a deep red colour and would probably put a fire out.

After flushing the fresh fuel through and adding some oil it was time to start cranking again. This was exhausting work. The engine seems to have an odd system whereby the crank will turn freely for a random number of turns before finally engaging with the flywheel to turn the engine over. As a result, it can often catch one unawares thereby missing the chance to give it a really hard spin when the right moment comes.

Despite checking the timing of the spark was okay (it was) and trying to get it going for another hour we had no luck. Not even a pop, and come nine o’clock when it started getting dark it was time to call it a day. This was not a very satisfying experience, but at least we had covered most of the basics and it was turning a bit easier when it engaged.

Stuart Turner P5 Marine engine beneath the hatch