Most of the time, the owner of a seagoing boat or ship would prefer to keep their craft in dry moorings, but having even the smallest craft dry-docked for any significant length of time is often prohibitively expensive. As such, the majority of seagoing craft are moored at sea when not in use, either secured to a sturdy mooring or pontoon or anchored in a safe anchorage spot.
Of course, seagoing craft are designed to shrug off almost anything the wind and waves can throw at them, and mooring or anchoring your craft at sea for extended periods does not usually cause problems. However, certain components of your craft are more vulnerable than others, and if your craft is fitted with a sterndrive to provide power you should take particular care to inspect and maintain it while your craft is moored and inactive.
The following problems can badly damage even the most robust sterndrive if neglected, and should be checked for regularly:
Corrosion
Naturally, the greatest enemy of any seagoing craft is corrosion caused by saltwater, and your ship's sterndrive is no less vulnerable to the ravages of rust. Even if your sterndrive is made predominantly from stainless steel or aluminium, it will still have some vulnerable ferrous components (such as prop bearings), and must not be allowed to become corroded between uses.
To prevent corrosion from damaging your sterndrive, your first task should be to inspect the sacrificial anodes fitted to the hull of your ship. These anodes are deliberately designed to corrode in place of more important components of your ship and sterndrive, and generally will not look in the best of shape; however, badly deformed or pitted anodes are reaching the end of their useful lives, and should be replaced as soon as possible.
If your anodes have already corroded severely by the time you inspect them, you cannot be reasonably sure that internal components of our sterndrive haven't been allowed to rust. You can try and detect this damage yourself, but taking your engine to a specialised sterndrive repair service is a much easier and safer option.
Fishing wire
Problems with fishing wire and loose netting are particularly dangerous if your craft is moored in a busy port servicing commercial fishing craft, or at popular tourist locations where marginally-skilled fishermen abound. Though modern fishing wires can be incredibly thin, they are also incredibly strong, and a wire or piece of netting that becomes looped around your propeller shaft can cause catastrophic damage very rapidly.
Consequently, the propellor and prop shaft of your sterndrive should be checked for wires and lines even after brief periods of storage, and must be thoroughly removed before the sterndrive can be safely activated. If you suspect that fishing wire has infiltrated your engine more deeply, or if your propeller cannot turn smoothly due to tangled lines, seek professional assistance and repairs immediately before the damage is worsened.
Rubber components
While sterndrives have a number of attractive advantages over more commonly used outboard engines, one of their few drawbacks is that several perishable rubber components must be positioned below water level. The fuel lines, oil lines and air hoses of a sterndrive may or may not be submerged at any given time, so checking them for damage and leaks caused by constant exposure to saltwater is a routine task. Damaged lines and hoses should be replaced immediately.
However, the most vulnerable rubber component of your sterndrive is probably the bellows hoses, which expands and contracts to prevent water from entering the driveshaft and other important components of your sterndrive. These components are particularly vulnerable to saltwater damage, and should be inspected regularly for any signs of decay. These specialised hoses are also more difficult to fit than regular hoses, so having damaged bellows replaced professionally is never a bad idea.
Work with a marine shop near you to get more information about protecting your boat's mechanics and what kind of sterndrive repairs you might need.
