The data from members of the EEC and the Far East shows that outboard engine motor theft is continuing to be the most destructive manmade threat to both leisure and commercial boats. To combat this increasing trend, a number of companies have designed solutions that fall into three main categories. The locks should be purpose made which is the usual requirement for most insurance companies.

SLOT LOCKS

These are lengths of tube of either square or round section that have a slot cut into them. They are designed to fit over the clamping screw toggles once the engine is secured to its fastening surface. The cheaper versions have one size that fit all locks. As clamping screws vary in diameter from 8 -16mm it can be assumed that a 16mm slot on a 8mm screw thread is very loose and can be levered unless spacers or padding is provided. The advantage of the slot lock is that it can be quickly and easily fitted and removed needing the minimum of knowledge. Its disadvantage is that additional protection is required to safeguard attacks against the exposed threaded portion of the clamping screw. Further it may be used as a surface face to lever the outboard engine off using the top of the transom as the other fulcrum. 

BOLT or NUT LOCKS

These devices are usually built around a small shell like cartridge, the bottom of which has a hole in it and acts as a washer in the common bolt, nut and washer assembly. The top of the shell has a specially designed locking cap. Some preferred models are made of marine grade stainless steel that is either machined or cast. The outboatd lock is attached on the inside of the transom by one of the hexagonal bolts supplied in the engine rigging kit. The nut used, must be a STIFF/NYLOC type, otherwise the outboard engine lock can be used to undo the assembly. This type of lock can be successfully used on most motors of 8hp and above and is the most cost effective and secure of the three types of designs. A few tools are required to fit the shell of the lock and cut the rigging bolt to the correct length, so this is best carried out by your engine dealer as part of the engine service

CLAMP LOCKS

The clamp outboard engine lock was created to eliminate attacks to the one or both sides of the clamping assembly. They are usually considerably larger and more agricultural in their construction and hence cost nearly twice as much as the other designs. Shape wise they mostly resemble rectangles or squares.

Recently their popularity has increased because a number of engine manufacturers have increased their toggle size resulting in the fact that some slot locks no longer are large enough in cross section area to accommodate the toggles, hence useless.

All the designs necessitate that part of the lock remains fixed to the transom. This could result in it going missing if the owner does not remove it with the engine. As these locks are substantial structures the only area where additional protection can be achieved is if the bolt/screw that is provided to fix the body to the transom be made of 6mm diameter material and be captive as an integral part of the transom.

ADDITIONAL PROTECTIVE MEASURES FOR SLOT LOCKS

Slot locks by their very design offer a thief a lever point for a crowbar between the lock and the transom to lift off the motor. To overcome this a dormer drill can be used to countersink the washer area on the transom to a depth of 5mm. An alternative is to get a 4mm thick steel plate made that picks up on the clamping washers and cut two large holes in it, then bolt or screw the plate to the transom.

IDEAS FOR BOLT LOCK INSTALLATION IMPROVEMENTS

Most manufacturers rigging kits are supplied with hexagonal headed bolts. Some have stiff nuts and previously stated bolt/nut locks must be secured with a stiff or nyloc nut. Further, it is desirable to protect the exposed bolt head on the outside of the transom as these can be ground off by modern tools. It is suggested that other types of bolts be used as once the hexagonal head has been ground away, the attacker has simply to punch the shaft of the bolt through its hole with the lock still attached to the other end. The deterrent is to use a coach bolt, step bolt or countersunk bolt.

TRANSOM REINFORCEMENT

Much has been written about how good or bad various locks are. Little if nothing has been suggested for transom protection. A few instances have occurred where transoms have been chain sawed, or the rubber structure of inflatable dinghy has been cut with a shape knife for the removal of the outboard mounted there upon. The author prefers a clandestine approach by the boatbuilder. During moulding/ laminating they should insert strands of piano wire across the transom to form a grid. Once finished the boatbuilder should ensue a notice is placed on the transom Armed Transom to cover any liability. Another solution that is more common is to bend a U channel made of 3mm stainless steel plate and place it across the top of the transom. Ensure that it is bolted and the bolts are countersunk and welded.