Dripless shaft seals are designed to completely stop water from entering a boat’s hull via the stern tube. There are two main types of dripless seals known as face seals and lip seals which many boat manufacturers now fit to production boats.

One thing all rudders have in common is that they have three main parts that need to be checked: the rudder, or a steerable drive leg in the case of many power boats; the system that joins the rudder to the steering; the steering control itself.

Cutless bearings can last for many years but if the propeller shaft is out of alignment they will wear through more quickly. If you have noticed a clunking sound when motoring then it could be a worn cutless bearing that is causing the problem.

Irrespective of what kind of engine a boat is equipped with and who does the work, the regular care and maintenance of a marine engine is essential. The most common cause of marine engine failure is widely known to be lack of maintenance.

If engines are installed and serviced correctly then most marine engines are very reliable, but one of the most important parts of the engine to check and service is the fuel system.

Have a look around any boatyard and you will notice quite a variety of propellers – some have two blades, some have three and others have four or more. While most propellers are completely rigid some have blades that fold.

Under-sized battery banks are one of the key factors behind power failure at sea, as well as the premature failure of batteries, so make sure that your boat battery measures up to the use you want to put it to.

It is quite common to find cracks in the gelcoat when inspecting the deck and superstructure of a GRP boat. It is important to differentiate between a gelcoat crack and a scratch.

The basic principle of a diesel engine is less complex than that of a petrol engine. No spark plug or ignition system is needed, making the basic diesel engine a comparatively straightforward system that results in fewer faults and has lower maintenance costs than a petrol engine.

Leaking decks are perceived as a nuisance by some boat owners, but if leaks are ignored a much more serious situation may well be developing, especially in the case of boats with balsa or plywood deck cores. So deck leaks do need to be investigated and dealt with.

At the end of the sailing season sails should be washed and inspected carefully for damage, including small tears, stitching failure, ultraviolet damage, stains and mildew.