For the past hour, you've been towing your kids back and forth across the lake while your better half sits in the observer seat keeping an eye astern, when suddenly your engine makes a metallic grinding noise and stops. As you scan the instrument panel, you realize that the temperature gauge is so far off the scale that you can't even see the needle. This is why you need an engine alarm system. Airline pilots have an incredible number of instruments to scan, but because they're often busy handling radio or navigation tasks, the most important gauges all have warning buzzers and lights to alert them to possible problems. Why should you be any different aboard your boat?
The good news is that engine alarm systems are easy to install, and compared to the cost of a fried engine, very inexpensive. And while nothing takes the place of an alert skipper, there's no reason you can't use modern electronics to make your life easier. Ready-to-install alarm and safety systems are available at most marine hardware stores. Engine Alarm Systems
There are two parts to any engine alarm system: the control box and the remote sensors. The control box is usually mounted at the helm, and the best units have both visual indicators in the form of warning lights and audible alarms loud enough to override the normal noise level aboard your boat. The remote sensors are installed on your engine and also in potential trouble areas, such as a low point in your bilge for flooding protection, or under your engine hatch for fire warnings.

What sensors and warnings do you need? For your engine, two sensors are absolutely essential. The first is a high-engine-temperature detector indicating that your engine is overheating, which can lead to a cracked block or a seized motor. The second is a low-oil-pressure detector, which warns that your engine isn't getting enough oil for lubrication (with ruined bearings and a scored crankshaft a likely result). Both problems can lead to expensive repairs.
A third sensor is a cooling-water flow detector for freshwater-cooled engines that gives an early warning when the water flow is reduced. While most engines can run without coolant for several minutes without internal overheating, you may burn out the water pump in the process, which can lead to serious overheating. The exhaust system, which relies on water cooling, can also be damaged or even catch fire. For that reason, the flow detector is an important early warning that something is blocking your water intake.

In most cases, your alarm system will be used in addition to the engine instruments, which will require a bit of extra plumbing to accommodate both the alarm and gauge sensors. A simple tee fitting is commonly used so both sensors can still use the same engine aperture.

As an example of a simple system, Cole-Hersee makes a Marine Engine Warning Alarm Kit that monitors engine oil pressure and coolant temperature, and sounds an audible buzzer if either indicator reaches an unsafe level. The kit includes the oil and temperature switches, buzzer and instructions, and is available for about $35.

More Alarms
While you're in an alarming state of mind, consider fume detectors, more commonly called "sniffers," to detect the accumulation of dangerous gasoline fumes in the bilge of your boat. It's an unfortunate conundrum that because your hull and deck are designed to keep out water, they're also efficient at keeping in gases and fumes.

A fume detector will register fumes that are well below the explosive point, giving you a warning in time to correct the problem. Many alarms will sound a warning when the explosive fumes reach just 10 to 20 percent of the explosive level. Most sensors will warn of propane fumes as well as gasoline, providing a backup against leakage from your galley stove as well as from the fuel tank or engine.

Xintex is a well-known manufacturer of sniffers with several models ranging from a simple gasoline detector/alarm with a gauge that fits into a 2-inch hole in your instrument panel and a sensor for the engine compartment, to a more complicated sniffer that turns on your bilge blower and sounds an alarm when fumes are detected.

Another worthwhile alarm to consider is a carbon monoxide (CO) detector that sounds a warning when dangerous levels of this colorless, odorless byproduct of combustion is found. CO, which is always present in your engine exhaust, is deadly. It prevents your blood from carrying oxygen, resulting in dizziness, nausea and death in as little as a few minutes, depending on the concentration.

CO can enter your cabin through a leak in the exhaust system, from poor air circulation, or from the "station wagon" effect that uses the vacuum created by the moving boat to suck fumes in through open portholes.

The Xintex carbon monoxide detector uses a sophis-ticated sensor to duplicate the way your body is affected by CO. Since CO is normally present aboard a boat with an engine, the detector rejects low concentrations unless they are present over a long enough period to have a cumulative effect on your body. This detector has a suggested retail price of around $110, but can usually found for about $80. And it really is a valuable insurance policy for your family, especially when they are sleeping below during a cruise.

Mixmaster
Many boaters have moved up to larger boats not because they needed more cockpit space or more berths, but simply because they wanted a generator so they could run a blender to make slushy drinks onboard, far from the marina shorepower.

The Boatblender combines a 32-ounce screwtop bottle and a mixer blade unit just like the one on your home blender. But instead of a socket on the bottom of the mixer blades, it features a short bit that fits neatly into your cordless drill.

The bottles are molded from a flexible plastic and convert into drink canisters. And while you may not be able to back your trailer over them, they are reasonably indestructible.

The basic Boatblender kit includes two mixing bottles and the mixer blade attachment for $29, while the Party Boatblender kit has four bottles and the mixer for $37. Contact Boatblender, Dept. BW, 5300 Norwood Lane North, Plymouth, MN 55442; (763) 383-1933; www.boatblender.com.