Webasto forced air
We have a forced-air diesel Webasto unit. We really like that it runs off the diesel, reducing the number of fuel sources we have to worry about. Power consumption seems to be quite small. And, it runs off the main diesel tank, saving space. There is no noticeable diesel smell to the heated air. It works very well on the hook as long as you keep the boat mostly closed up. The minute you open the hatch, all the heat goes out of the boat. If we were to do it again, we might look for some diesel-fueled option that created more of a radiant heat source so that there would be warmth from the source even if the hatch is opened. Kind of like the difference between a wood stove and a forced air furnace. But given the options, we'd likely end up with the forced air system anyway. It does distribute the air throughout the boat. The exhaust is at the rear side of the boat - we only use the diesel heat on the hook or under way, but never in the marina unless a good wind is blowing to clear the exhaust away. At the dock, we usually use an electric heater to reduce the chance of carbon monoxide poisoning from the exhaust. It looks like you could install it if you are handy with electrics. The instructions call for it to bypass the battery switch so it isn't accidentally turned off before it cools off - it has a separate battery toggle switch that you turn off after you switch the thermostat off, allowing it some time to cool down.I would check with the retailer or supplier to make sure the warranty is valid if you self install.