Diesel Cabin Heater - Portable
Diesel heaters (eg. Eberspacher, Espar or Webasto) have typically run about $2k +/- how much the extras cost to install. Chinese knock-off copies are coming in from $100-$200 USD complete with graphic displays and remote control, and a basic exhaust pipe/muffler setup.
I picked up and all-in-one 8 kilowatt unit (real world: 5k) complete with 5L tank and fuel pump that's about the size of a medium toolbox. The setup will be running on the deck midship outside an opening port and pump in fresh/dry/warmed air while keeping the exhaust & any noise outside.
While the actually heaters in these units seem very similar to the german made units the sellers often use lower quality accessories including stiff exhaust pipe and in my unit the fuel line needed to be upgraded as these unit are very sensitive to the proper fuel delivery setup. I wound up swapping out the 4mm ID flexible fuel hose as it caused the unit to burn with quite a bit of soot. The proper fuel line that I replaced it with was 2mm ID hard nylon line (4mm OD) joined with small sections of rubber fuel line as well as adding a fuel filter. (Why so critical? See YT expert John McK: https://www.youtube.com/watch?v=jCZhjGyR3bo)
I also added a 12 foot 14AWG extension coord w/ a cigarette lighter plug for power. The unit uses around 9 amps on startup/shutdown but only for maybe a minute or two and then backs off to < 1 amp on low maybe 2 amps on max.
It should easily fit into the cockpit locker and on medium to low I should be able to get at least two nights (24-30hrs on low, 12+hrs on high) from the 5L tank.
While there are many options out there the one I purchased came with a color remote that displays the battery voltage, altitude, ambient temperature (of the receiving unit - which I plan to drop into the cabin along side the vent duct. The remote also lets you manually control the fuel pump rate from 1.4hz to 5.5hz (each stroke of the pump delivers approx 0.00002 liters) or you can use it like a thermostat and let it automatically control the heat level.
Self contained, just add diesel and 12 volts: 10W x 15L x 12H
Fuel line required upgrading - key for a clean burn.
I had some trouble with the original glow plug but after replacing with a new $15 one from ebay it's been fine. For the price it's easy to handle a few bumps.
Once I get to see my boat again I'll test onboard and upload a few more photos but so far testing outside at night it's been great and with the new fuel hose it burns impressively clean once it's up to temperature, no smell of burnt diesel at all and little to no soot build up in the exhaust pipe. On that note I'm told that some people after running all night on low will run the unit on high for 5-10 minutes to clean/burn out any soot that might have built up.
You can also buy these units ready to install onboard but I would definitely order a proper exhaust and well sealed muffler and be prepared to spend another $100-$200 for thru hull fitting ($60), marine grade exhaust and ducting - imagining how nice it would be extending the sailing season with warm air pouring out of the cabin - it sure has been nice with my engine driven heater while motoring on those cold/foggy mornings.