Systems Thinking – as a Sailor

I have a passion for sailing. I got the bug when I was learning how to be a Surface Warfare Officer in the Navy over 30 years ago. Recently, I crewed on a sailboat participating in the St. Petersburg to Habana offshore race. Habana, as in Havana, Cuba. A unique circumstance immediately prior to leaving the dock for the race reminded me of how systems engineering and sailing have a lot in common. Had the crew not taken an overall systems perspective, we may have never left the dock and started the race.

Early in the morning on the day of the race, the entire crew (nine of us in total) were stowing last minute items and getting the boat ready to sail. As I was stacking some of the final stores in a cabinet above the combined freezer-refrigerator cabinet, I glanced at the LED temperature panel and noticed that the refrigerator was at 48o Fahrenheit and the freezer at 38o Fahrenheit – much too warm for a boat at the dock on a shore power connection over the weekend. The value of these two LED indicators meant that we potentially had a serious problem.

The boat had been moved to the St. Petersburg Yacht Basin three days prior to the race and was connected to shore power. In that state, the batteries and the refrigeration system should have been powered by 120VAC shore power provided from the pier. However, based on the temperature of the refrigeration units, the refrigeration system did not have enough power to operate properly. What was wrong, and how were we going to fix it in short order to start the race?

To solve the problem we had to think about both the sailboat as a system and the context in which we were going to operate the sailboat – namely a three-day offshore race.

First, the sailboat system. We knew that the refrigeration unit was not operating properly. This would be a lengthy race, and we needed the refrigeration system to keep our perishable food stores from spoiling. Moreover, we need plenty of electric power to use our navigation, communication, and safety systems. Our knowledge of the sailboat and the electrical subsystem in particular were key to figuring our way out of this predicament.

Anyone who has done cruiser sailing has to have fundamental knowledge of sailboat electrical systems, which are all basically configured as follows:

Sailboats operate off a 12 VDC system, much like your automobile, but with much larger capacity. There are generally two sets of house batteries (bank A and bank B) and a diesel engine starting battery. When at sea, the sailboat gets power from the house battery banks to run things like radios, navigation equipment, lights, water pumps, etc.

Each house battery bank consists of more than one 12 VDC battery operating in parallel. A check of the voltage on each bank revealed that the voltage was 12.0 VDC – not a good sign. Voltage on a 12 VDC system should be higher than 12.5, and the reading we got showed that the batteries had been discharged. That also explained why refrigeration was not operating well, hence the higher than usual temperatures in the units. And, this told us that the batteries were not charging off of shore power.

Again, armed with system knowledge, we knew we had other ways to charge the batteries – the alternator on the diesel and the solar panels on the deck. The solar panels, with sufficient incident sunlight, were capable of running the refrigeration system during the day but did not have the capacity needed to recharge the batteries.

So, how were we going to participate in the race? We knew that the racing rules said that we could run the engine with the transmission system disengaged to charge sailboat batteries. So, if we could start the diesel engine and then check to see if the house batteries were getting charged off the alternator, we were capable of completing the race.

Starting the diesel engine, however, did not happen easily. The starter battery also had low voltage. We ultimately reconnected to shore power and then started the engine. A quick check of voltage on the electric panel revealed voltage of 14.2 VDC – meaning that the batteries would charge up and we could continue in the race. The likely culprit in this scenario was the shore power charging unit which we could examine while underway after the start of the race.

In the end, running the engine for four hours at the beginning of the race charged the batteries sufficiently to last more than 24 hours. We found a tripped ground fault switch on the shore power charger well after the race start. With the shore power charger reset, we were able to use shore power while alongside the pier in Havana, Cuba.

Had we not taken a systems view to examine our sailboat and how we needed to operate in the racing environment, we may have spent an inordinate amount of time troubleshooting at the dock and missed the race start. In the end, the boat (and crew) performed well and took second in our division, but the actual race is a sailing tale best left to another article.

From my perspective, applying systems thinking helps to keep you in “fair winds and following seas” on a sailboat – not to mention good advice when designing your system.

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