Some like it HOT

The MOG is preparing for The Great Loop adventure. George McNeir, the designer, builder, and captain of the MOG is a member of the America's Great Loop Cruisers' Association (AGLCA). AGLCA is an organization of  "Loopers" that exchange ideas, experiences, and expertise to support each other. (More about The Great Loop in other posts.)
In a recent exchange on AGLCA's forum, George responded to a question that basically asked other members "What is the best method for a ready supply of hot water on a motor yacht? Would a Tankless heater work?"
We felt that the question and George's response would be useful information as to some specifics on the MOG and on options for hot water that may, or may not, not be so wise for boats. Response follows:

By: MOGelectric on February 28th, 2014, 1:35 pm

Electric 'flow through or instant' water heating is ok for on land but I would never recommend it for on board a boat. Too much additional testing is needed (in my opinion) to make it safe for on board a boat.
Corroding of key parts, water at high temperature, 40 to 80 amps at 240 VAC (wet & killer shock) and potential for grounding problems took it out of my book long ago.
Propane is better but still needs great consideration in the user's gas lines, venting, propane sensors, oxygen sensors, care and use. The units such as the Excel by ExcelAmerica http://excelamerica.com/ is what I use on the MOG solar electric yacht. http://www.mogcanalboat.com/ The unit is small and works. If you want a steaming hot robust, soaking, waterfall shower..... nope.
There are many other propane units out there in the RV and consumer world. Due diligence and in depth study on your own is key to creating the right system.
The MOG is not a commercial enterprise but is a floating/cruising test unit (for the last 25 years). It is not for sale. I am happy to answer questions here or at http://www.mognavy.blogspot.com/
Even with the current 'marine tank' water heaters there are problems. Tankless (flow through, instant, monotube and such) are compact and require fully reading their install and use manuals, reading customer reviews of Lowes, Home Depot, West Marine and online blogs/reviews.......... before purchase.

George aboard ALGEMAC II

PS: The MOG NAVY apparel nets enough income to just pay the local USA manufacturer here in Wilmington, NC . Some folks wanted to get items of the sort I wear, so I made it available. 

MOG's heat source. Note how close unit is to shower.