One of the most important safety devices you can add to your boat is a fuel vapor detector. For the low cost of these detectors, its a wonder why they are not standard equipment. I chose the Safe-T-Alert SA10XL multi-sensor detector from Marine Technologies, Inc. , because it monitors fuel vapors, high temperature (fire), and high bilge water conditions.
A remote SA10XL-R monitor is also optionally available so that you can monitor the boat's condition from two locations.
I have a fly-bridge style of boat, and way up there on the bridge, conditions in the engine room may not become apparent until well into a catastrophe. This multiple-sensor unit with remote monitor is just the thing for a fly-bridge style boat.
I plan on mounting the primary display unit in the salon and the remote on the bridge. The manufacturer's instructions for connecting the remote are not very clear, so after discussion with the manufacturer, I made this schematic.
Even after following the manufacturer's recommendation on where to place the sensors, I was able to centerally install all of the sensors in the engine room.
It is fairly typical for manufacturers to not include a suitable mounting method for the sensors, so you should think about how to best install them so that they are secure and protected. For the heat sensor, I was able to use a standard electrical box typically found at Lowe's. I also added a Heyco CordGrip style cable feedthrough to maintain some degree of water-tightness. Install the heat sensor as high as possible in the engine room.
One exception is that the Fuel Vapor sensor was already in its own enclosure; I guess it is a bit more sensitive. This sensor should be in the forward part of the engine room, about 8" above the bottom of the bilge. Note that althought I did not purchase it, an optional second sensor can be added to the system, which is useful if you have two areas on the boat that need monitoring.
The bilge float-switch was borderline downright cheap. I again made a custom mount with a few PVC electrical box components and the all important Heyco CordGrips. One word on the CordGrips; they are about $10 each at boating stores, such as West Marine, or less than $1 at traditional electronic supply houses, such as Mouser Electronics. I have included references for both Heyco and Mouser Electronics at the end of this project page.
Install the bilge float-switch about 4" above the lowest point of the bilge. The mounting bracket is such that the mounting screws go into the electrical box, and the float-switch just hangs in the desired location.
The remote panel is mounted at the helm. The primary and remote panels are identical, so you can select either panel for the primary monitor. The sensor and 12VDC power connections go to the primary monitor only, so by choosing the lower salon for the primary location, the cabling is minimized. When mounting the remote panel, the 6 wires coming out of the panel are unused, so they can be cut-off. The only connection to the remote is the cable and y-adapter.
To check the system out, depress the ON switch on the primary panel. The WAIT LED should be on for about 1 minute, then the ON LED should be lit. When depressing the TEST switch, all LEDs should come on, as well as the buzzer.
To check out the remote monitor, depress the TEST switch on that unit and ensure the LEDs and buzzer work. The remote has limited functionality, and you cannot turn the system on or off from there. Otherwise, the remote will provide the same alarm indication as the primary.