It is Reliable. Yes.
For you, I and a small boat engine, reliability probably centres around three issues.
Will it start, does it break down, and if I stop it, will it start again.

One of my friends had trouble with that last one. Locks were a problem. When the petrol engine was stopped in the lock, it could not be restarted. Despite all efforts, the problem was never solved. The outcome was that the essential boating kit included cakes (and beer) as a "thank you" to lock keepers to let her keep the engine running in the lock!

At the extreme end of engine reliability is the situation of a Moon base – or even men on Mars.
If the power supply fails – it’s mission over. Electricity is essential to keep the habitat warm and the electronics working. The generator has to run continuously for years – without fault. Maintenance free.
NASA’s answer to this crucial reliability issue is to use a Stirling engine to generate enough electricity reliably enough. Have a look at the NASA "KRUSTY" video above.

Yes – that stuff is “out of this world”. But the Stirling engine in my little boat has the same basic elements as theirs. For me, the starting power comes from the heat of a gas hob.
No reliance on charged batteries and dry circuits to create a spark and ignite the petrol/air mix. The fuel/air mix needs to be correct in a petrol engine. Don't flood it.
When the weather is cold – the Stirling actually starts quicker. Its all about the hot end being hot and the cold end being cold – the colder the better.
Small boat engines suffer from neglect – especially during the winter months. Stirlings don’t have carburettors or injectors. The boats in the Stirling fleet do not need starter motors or batteries to drive them.
The “average” petrol engine has more than one hundred parts. The Stirling has less than ten moving parts. Far fewer parts to go wrong or wear out.
Too many times I have walked down to the mooring, petrol can in one hand, tool box in the other, glancing at my watch thinking,
“Ok I’ve got an hour before the family turn up with the picnic. I hope I can get it started by then”. .......BACK