HTML 4.0 Transitional//EN"> On my hobbyhorse about weight

On my hobbyhorse about weight
by Jim Murrant


I couldn't believe my ears. And you won't believe this either unless I can convince you. This story, told me by a friend who is also a respected ocean racing sailor, made me wonder just how much of the basic, basic, basic forces involved in sailing some sailors understand.

My friend was telling me about the crew of a veteran yacht who were trying to work out the best place to put the liferaft they had bought to meet the new regulations.

The liferaft weighed about 60 kilos and they discovered that it fitted neatly between the steering post and stern of the boat. My friend suggested that this would create a great deal of hobbyhorsing, especially in any seaway. But the crew had the answer. They would move one of the two regulation anchors further forward in the boat to "counterbalance the weight in the stern."

My friend was speechless but tried to explain this would make the problem worse. "No way," said the crew man. "You have heard of a seesaw averaging weights and settling in a straight line, haven't you?"

My friend gave up at this point.

For this reason I have decided to write a rather simplistic view of the forces that control a yacht and of the structures and systems that control the forces. I'm afraid it will offend those who will see this as suitable only for beginners, but to find two highly experienced people with such unbelievably wrong attitudes shows there is a need.

To believe that the function of the seesaw is to remain in balance is ludicrous. How on earth is it going to balance when there is the slightest motion of a sea? The seesaw is a simple fulcrum (a plank on a pivot) which means that each side from the fulcrum becomes a lever. If one side lifts with more force than the other tries not to, it will lift and force the other side down. That is precisely what happens with weight in a boat which is taken into the stern or bow. Somewhere in the middle of the boat is the centre of effort, which we will come to later, and that becomes the fulcrum for these two weights.

If the liferaft and the anchors were to be brought together at the centre of effort they would become the fulcrum and there would be no hobbyhorsing. That is the ideal, but all weight can't be on one spot. So therefore what happens from now on is compromise. Certainly the closer together two weights can be brought the less problem they would be in terms of pitching.