Should I install a dedicated boat heater on my yacht?
I've got a 34-foot sailing yacht that I want to use more in the shoulder seasons and over winter. I currently just use a plug-in fan heater on shore power, but I'm thinking about a proper installed system. Should I install a dedicated boat heater, and what type is best?
Answer
Installing a dedicated marine heater is the best upgrade for extending your cruising season and protecting your interior woodwork from damp. For a typical 34-foot yacht, a 4kW forced-air diesel heater is the most practical choice, drawing from your main fuel tank and running off your 12V house bank.
Limitations of Plug-in Heaters
Plug-in 240V fan heaters or oil-filled radiators work fine on a marina pontoon. However, they restrict you entirely to shore power. They also fail to circulate warm air through the cabins and lockers. This circulation prevents the winter damp and mould that ruins marine upholstery. A dedicated blown-air system pushes dry heat through the length of the boat, driving out moisture and protecting the hull interior.
Forced-Air Diesel Heaters
For a 30 to 40-foot yacht, a 4kW forced-air diesel heater is the industry standard. Eberspächer (specifically the Airtronic M2 D4L) and Webasto (Air Top Evo 40) are the premium choices. These typically cost £1,500 to £1,800 for a marine kit. The Autoterm (formerly Planar) 44D has taken over the market in recent years. It uses identical mounting footprints and costs around £600 for a full marine kit.
These units tee into your main diesel tank or use a small dedicated day tank. They burn between 0.12 and 0.4 litres of fuel per hour depending on the heat setting. Electrically, they need a healthy 12V battery bank. The start-up sequence draws about 15 amps for a few minutes to heat the internal glow plug. This draw drops to a steady 1 to 3 amps once the fan reaches cruising speed.
Hydronic Heating Systems
Hydronic heating uses a diesel boiler to pump hot water through a loop of radiators or matrix fan heaters. Brands like Kabola or the Webasto Thermo Top suit liveaboards perfectly. They provide even, silent heat and can be plumbed into your calorifier to generate domestic hot water.
Hydronic systems are heavier and more expensive. They also draw significantly more battery power to run the circulating pumps. For a 34-foot boat used for weekend cruising and shoulder-season sailing, a hydronic system is expensive overkill. Stick to blown air.