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Written by Dave Dave
Category: What Works What Works
Published: 26 February 2017 26 February 2017
Hits: 212 212

After a long two days of sailing across Lake Ontario in our Tanzer 22 we deserved a respite and dinner ashore at Cape Vincent. A decent meal in a small town restaurant was a welcome alternative to putting together a meal in the nonexistent galley. Returning to the boat late in the evening after a relaxing meal and a few adult beverages we were greeted by the scent of rotting flesh. The first of many lessons about cruising on a small boat was about to be learned. 

Cleaning the bilge of any boat is not an enviable task, cleaning a bilge late at night, less so, and cleaning a bilge of the rotting remains of your icebox is one to be avoided. We persevered and in the morning assessed the problem.

At the heart of the problem was a poorly designed front opening icebox. Melt water from the ice drained through a tube and into a half-gallon jug in the bilge. The box was poorly insulated and with the front opening cold air leaked out and the box warmed quickly. Over the course of two days the temperature of the icebox had raised enough to set forth a veritable feast for the bacteria that had laid dormant over the past few days.

The ice melted, the packaging leaked, and the water and “juice” ran to the bilge that sat in 70-degree water. There was a bacterial population explosion, the byproducts of which greeted us at the companionway.

As a result of this experience, the icebox was relegated to dry storage, a portable chest cooler purchased, and packaging the perishables improved. This allowed us to avoid future putrid greetings, but seemed an incomplete response to keeping food cold.

Keeping food, especially uncooked food, below 40 degrees Fahrenheit is essential for food safety. As temperatures rise above 40 bacterial growth begins and accelerates with rising temperatures. Bacterial growth at low levels might not produce tell tale odors or a change in food texture indicating that it was about to go bad but might be sufficient to produce gastric distress or worse. Keeping food cold is essential.

While improved food storage and a better icebox reduced the risk of bacterial growth, it was essentially a brute force method, load the box with as much as ice as possible and hope for the best. For years this method kept us in reasonably cold food and sort of cold beverages. However, from time to time we were caught short and ice melted faster than expected. Over time we realized that monitoring the temperature of the icebox or cooler was necessary if we were to be assured of food safety.

The easy solution is to place a thermometer inside the cooler and check it periodically. A major drawback to this solution is that it is necessary to open the cooler to check the temperature allowing cold air to escape. An elegant solution would be to install a remote reading thermometer. One approach would be to hard wire a remote temperature sensor to a display, but that approach would entail piercing the icebox to run the sensor wire and then providing power to the display. Drilling a hole in the icebox runs counter to our goal of keeping cold in and heat out. Additionally it would be necessary to wire the display to the batteries; more work and expense. This would work, however, we sought a less expensive and more elegant, simpler solution.

The answer came in a battery operated indoor/outdoor remote thermometer, designed to read outdoor temperatures and wirelessly transmit the data to a receiver indoors. Ideal, no wires to run, no installation issues, just place a small transmitter in the icebox and locate the receiver in a convenient place on the boat. I found one at LL Bean for under $20.

Placing the transmitter in different parts of the cooler revealed large differences in temperature. On our last boat (Sabre30), with no refrigeration, temperature on the top shelf was near 50 degrees while the bottom of the icebox was still cold and filled with ice. Knowing about the temperature differential allows for safer food storage practices. Fruits and vegetables that need cool storage and food with a high acid content can tolerate warmer temperatures, while meats and easily spoiled foods need the colder temperatures for safe storage. Our current boat (Sabre 362) has dual cold plates in the refrigerator, the temperature next to the cold plates is often at or below freezing while the rest of the box is in the mid 30 degree range. Important knowledge to have if you want to avoid freezing the lettuce or tonight’s dinner!

For a very little cost and next to no effort food safety aboard has been markedly improved. Years ago had we known that the temperature in the icebox had risen to dangerous levels we would have returned to more pleasant conditions in our boat and avoided a midnight bilge cleaning.