Tuesday, 10 April 2012

Boat Engines

These thoughts will be few because I am incapable of more! I don’t understand engines but I do appreciate them when they work. 

Engines? Don't understand Ok with rope though

Petrol or diesel?

Well, the received wisdom seems to be that diesel is best for boats and petrol is simply dangerous. I’m ignorant but unconvinced. Firstly, because I’ve heard of plenty of incidents where boats have exploded but the culprit was gas for the cooking stove not petrol. Secondly, because diesel engine reputations were built on marinised versions of heavy duty lorry (truck) engines. They had the reputation of running forever on a relatively inexpensive fuel. The reputation for reliability however, was based on a huge heavy engine block (a requirement of the time) to cope with the extreme compression needed to get the diesel to ignite.
But in recent years diesel engine manufacturers have progressively lightened the size of the engine block to improve fuel efficiency. A modern diesel is much lighter than its ancestors and so, potentially, its longevity has been compromised. Bear in mind also, that an engine which is kept running will suffer less wear and tear, than one used only occasionally. A truck engine used everyday will probably outlive a boat engine used only once a week in season. Running keeps and engine lubricated, stagnation invites condensation and corrosion. Just to rub salt in the wound, UK sailors will have noticed that in recent years diesel is no longer the cheaper fuel.
Inboards are good if you can maintain them

So, in my search for the perfect low budget cruiser what is it to be petrol or diesel? In truth, I don’t mind so long as the engine is reliable and not too big.

Outboard or inboard?

Well, an inboard puts the propeller where it needs to be, protected by the keel and rudder, well below the waterline, to keep it below the surface in a running sea. Inboards can charge batteries too but access can be difficult and, if like me, you intend to rely on an engineer to complete the annual service and checks, then his visits to your inboard commits you to some expense.   Add to that the constant danger in these waters of tangling pot ropes or netting and an inboard could require you to drop over the side with a knife between your teeth now and again.

So, it’s an outboard then? Maybe, but they have their downsides too. Firstly I have to admit a prejudice.I don’t like outboards slung on a bracket on the transom. They are as ugly as sin and not only that - they don’t perform well except in very calm water. In anything of a ‘sea’ they seem to spend half their time churning air. To be fair though, they are relatively light and they can be removed for servicing so maintenance costs can be lower (no call outs).
Beautiful boat - spoiled by the hunk of metal on the stern - nope won't have it!


Ideally then, would an outboard in a well, offer the best of all worlds? Yes, I think that might do nicely – providing I can find one that has a starter switch like an inboard and that will add a charge to the battery when running.