One Engine or Two?

What are the advantages of having one engine or two?

Single Engine

Pros

• Cheaper purchase/installation costs
• Less maintenance
• More efficient
• Propeller and rudder usually better protected by keel

Cons

• No back up against engine failure
• Less low speed manoeuvrability

Twin Engines

Pros

• Spare engine if one fails
• More manoeuvrable at low speeds

Cons

• Expensive purchase/installation costs
• More expensive maintenance
• More expensive to run
• Props and rudders more exposed

Summary

To sum it up, a single engine boat will be cheaper to buy, maintain and run whilst a twin engine boat will be more manoeuvrable at low speeds and has some redundancy in the event of one engine failing.

It seems the commercial market generally favours single engines and the pleasure market has tended toward twin engines. The commercial market favours low running costs and this has been less significant to the pleasure market.

With rising fuel costs and the increasing use of bow thrusters and, more recently, stern thrusters to aid manoeuvring it will be interesting to see if this changes.

Also having two large engines for backup in the case of one failing seems flawed in some
cases. Some twin engined planing hulls may not be able to maintain a course in rough windy conditions under one engine.

For the majority of well maintained boats being used in sheltered waterways in populated areas the money saved on the extra engine and fuel for a twin engine set up seems
unwarranted. The money saved would be better spent on preventative maintenance.

Also for peace of mind a subscription to one of the commercial emergency towing services that are springing up might be considered so that in the unlikely event of an engine problem at least you get back home.

Let me know your thoughts and experiences.