Those of our readers with small boats will be well aware of the need for fenders – air filled cushions, usually sausage-shaped, which are hung over the side to prevent damage either when encountering other boats, or more commonly, harbour walls, jetties and dock sides.
These devices are normally tied to the side of the boat, often to rails running round the sides to help prevent users falling in when performing necessary tasks. Boating on the open sea or river, whether powered by sails or engine, is relatively easy compared to coming in with one's white painted, fragile hull to moor to a hard jetty against the effects of wind, tide and current. Jetties often have projecting iron work and one of the tasks of whoever is on the bows of the boat is make sure that the fenders are at the right height to absorb an impact.
This height is often hard to judge until very shortly before impact. Most pleasure boats are navigated by husbands and wives, and divorce is a distinct possibility if a row results as to whose fault it was if the precious vessel makes a direct crunch against a hard object.
The usual solution is to undo the ropes on at least two fenders, and hold them by hand so they can be lowered to the right position as impact occurs, and then tie them back in place. This requires rapid dexterity, never an easy task on rough water in windy weather.
The alternative is to have rather a lot of fenders at different heights, but this not only looks unsightly but invites ridicule from other boaters.
The Challenge
Our challenge this month is to come up with a method of making sure that fenders are at the right height when a boat is brought into moor. It would in theory be possible to devise something based on laser stripe sensing to determine the profile of the approaching dockside, coupled to a suitable programmed microcontroller and electric winches on the ropes supporting the fenders. Apart from being expensive, the chances of such a system continuing to work in a marine situation, particularly on a boat used only for occasional weekend trips is low.
The solution we offer in the January edition of our magazine has to be a preferred solution because it is so much simpler, cheaper and more reliable.
See if you can come up with something better.
