Installed suppression systems come in three types -- manual, automatic, and a combination of the two. The best? A fully automatic system. If you're not onboard or if a fire starts in the engine room, a manual system can't work. Also, an overly excited owner or crewman might be too quick to activate a combo unit, instead of putting out the fire by simply shutting down the engine or using a well-aimed blast from a handheld extinguisher. An installed automatic (bottle) fire suppression system is always ready to go off when the engine room temps rise above a specified level. Prices vary with the size of the engine room and the type of extinguishing agent (HFC-227ea for use around people, or FE-241 in unoccupied areas only) -- figure on a modest $200 to $300 for a 25-cubic-foot compartment, going up to thousands for your 100' megayacht. Longtime established suppliers of these systems are Sea-Fire and Fireboy (www.fireboy-xintex.com).