Sherlock Ohms- The Electrically Challenged Sailboat

Voltaire experimented with frogs legs to demonstrate that nerves passed electrical currents causing a kick. Ohms law states the relationship between voltage, resistance and current. Design News relates problems that engineers face and how they approach finding a solution. They call this segment "Sherlock Ohms". It's in this blog because a) the problem happened on a sailboat and b) It is the nature of people to look at a system and identify how to analyze and improve it based on laws.

Here is the data: The Case of the Electrically Challenged Sailboat by Bob Humphreys
Over history, boat manufacturers, repairers and owners have used many inappropriate materials to conduct electricity. Finding those materials is often a challenge.
This particular one involved a 39′ sailboat made by a world renowned manufacturer. The retired owner was having difficulty starting the diesel engine in certain circumstances and was beginning to wonder if his choice for a retirement boat was a mistake.
This boat had two large 8D gel-cell batteries, a 150A 12V alternator and an aftermarket voltage regulator adjusted to prevent overcharging of the batteries. The batteries were connected to the engine through a ‘1, 2, both, off’ battery switch and when the engine was cold, it would not start using only one battery. When the battery switch had both batteries selected the engine would start without difficulty and the observed difference between single and dual battery cranking was a slight drop in cranking RPM.
The boat was two years old, and since new the starter had been rebuilt once and replaced, the positive cable from the battery switch to the starter had been replaced with one of significantly greater cross section, all with no change. My yard was storing this boat in anticipation of a sale in the spring because the owner just couldn’t rely on the engine.

This is also a great example as it shows how other people tried to identify and solve the problem. Philosophers state that that a problem can only be addressed from a consciousness (or understanding) that is larger than the original problem. The sleuth demonstrated that.

Click here for to find the solution:

And with this the case is closed.