Protecting Boats Deck and Cabin Protection
The interior of a boat can be protected with a magnetic contact in a simple alarm system. Protecting the hatches and companionway can be easily accomplished using recessed or small surface mount switches. Using open circuit switches, a relay, a shunt switch and horn, it is possible to use the boat battery with no power drain.
Install an Interlogix switch and magnet in hatch away from hinges. If hatch is plastic, use surface mount contacts. If wood, use recessed contacts.
Install switch and magnet in sliding companionway boards or door.
If using open contacts to drive horn, install a latching relay to handle current. Solder wire connection to prevent corrosion.
Caution: Magnets affect compass readings. Compass should be checked before and after you install magnetic switches.