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about 10 percent from one cylinder to the next. Variations greater than 10 percent indicate a cylinder that is not fully combusting the fuel. It is also possible to detect a cylinder that runs at a higher temperature than the others, though this condition occurs more rarely.
Moving off the engine, we can turn our attention to a conventional shaft gland, or stuffing box. In an effort to reduce the drip rate, many cruisers overtighten the adjusting nuts, creating excessive friction and heat. The increased heat and friction will gradually wear grooves into the shaft, creating an area that will never seat properly with the packing even if new packing has been installed.
Water-injected boxes can also overheat if the cooling flow is reduced for some reason. When functioning properly, the metal housing temperature should not exceed the ambient seawater temperature by more than 20 degrees. Additionally, under normal conditions, the housing temperature should not exceed 120°F. Depending on the brand and type of packing material used, higher temperatures might melt the tallow and wax in the material, rendering the packing material useless even when new.
The infrared pyrometer provides valuable information, easily gathered, at a very low cost. Consistency is the key— perform the checks under comparable conditions (e.g., same cruising rpm). Some variables, such as seawater temperature, cannot be controlled and should be taken into consideration. Incorporating regular temperature checks into your cruising regimen will help you identify maintenance needs to be performed dockside before they become repair needs under way.
TRAWLER THERMOMETER
I’m looking for an add-on product that includes a number of temperature sensors (20 or 30) that can be attached in various engine room locations and that includes an intelligent monitor and display.
With the system, I want to attach temperature sensors to critical engine room items and have the monitoring/ display system track readings from each sensor, and based upon historical averages and allowable deviations, present an alert.
For example, I would like to attach sensors to the engine raw-water inlet, engine cooling water outlet, engine wet exhaust mixer, transmission oil, transmission heat exchanger, prop shaft seal and engine room ambient air temp, to name a few. Are there some costeffective products out there?
—Leonard Landon 45’ DeFever Pilothouse
Seattle, Washington
Leonard, monitoring temperature will be the easier part of your plan— crunching that information against historical averages and allowable deviations will present the challenge.
Maretron offers a system that will enable you to monitor temperatures at multiple locations and to set alerts. They also have a “black box” that will record readings over time. You would have to study that data and then establish your own alert thresholds.—
SULFATION FRUSTRATION
My question is in regard to the article, “Shock & Awful” by Nigel Calder in the July/August 2014 issue of PassageMaker.
A number of times in the article Mr. Calder states that the state of charge of batteries should frequently be brought to 100 percent. He does not indicate how often he means by “frequently” to reduce sulfation.
In our situation, we cruise the entire summer in the North Channel/ Georgian Bay area of Ontario, Canada. We primarily anchor out for 8–10 days, only going into marinas to provision and pump out. Sometimes we do not even stay in the marina overnight.
We use a 5.5kW generator to charge the house batteries to an 80–85-percent state of charge. This is done in the morning and evening. Our house batteries consist of two 8D AGMs. We seldom get above 85-percent charge unless we spend a couple of days in a marina. Then we are able to get to a 100-percent charge, but this may happen only two to three times during the summer.
Are we reaching 100 percent often enough for these batteries? Do you have any suggestions on what we should be doing differently?
—Bob D’Alcorn
WINGS
35’ Nordhavn Coastal Cruiser
Charlevoix, Michigan
Bob, as with most things to do with batteries, there is no absolute answer to this question. It depends on such things as the depth of discharge at each cycle (are you going below 50-percent state of charge?), the level of recharge during non-full-charge cycles (80–85 percent in your case), how long in a partially discharged state (it sounds like it could be weeks at times), and the temperature of the batteries (reasonably cool where you are).
My experience with AGM batteries in moderately aggressive cycling applications such as this suggests that if a slow decline in capacity is to be avoided, the batteries should be brought to a full state of charge as often as once a week.
However, this would require unacceptably long generator run hours and is obviously not occurring in your situation. You may be suffering from incipient sulfation at times. Incipient sulfation can be recovered by an extended charge. I suspect those times when you stay in a marina at least overnight, and preferably for at least 24 hours and maybe 48 hours, is providing that charge.