September 15, 2026

By John Gullick
 
“Boom, up she went.” 
 
This was a quote from a real-life incident where an East Coast boater was left with severe burns to much of his body that nearly resulted in his death. 
 
It all started on what was supposed to be a great day on the water but quickly ended with an explosion that showered burning bits of a small wooden cabin cruiser over the marina and left the operator in the water with those severe burns. 
 
Cause: One – the blower was probably not turned on for at least four minutes before the ignition was switched on and two, the use of a non-marine rated replacement alternator. 
 
Marine rated replacement parts like alternators, generators, ignition systems, blowers, pumps and carburetors with flame arrestors will not cause a spark when they are activated. This means that no fuel vapours caused by spilled or leaking fuel will be immediately ignited when the ignition is turned on.  
 
Most marine engines are located in enclosed spaces that will contain any dangerous vapours. This is why the blower should be turned on for at least four minutes before starting the engine(s). The blower will exhaust the vapours although will not remove any spilled or leaking fuel. To detect that problem, it is best to also lift the hatch for a visual inspection and use your nose, the least expensive and most effective fuel vapour detector. Fuel vapour detectors are also available and will help to detect leaking fuel while underway.

Ensure that the blower vent(s) are not blocked. 
 
The most common source of non-marine rated replacement parts are auto supply stores commonly used by the Do It Yourselfer. To get the right marine rated parts you must specifically ask for them and they can usually be found at most marinas and marine supply stores. When in doubt, ask your marine parts specialist. Most marine dealerships have years of practical experience on site and staff will be more than happy to answer your questions and ensure that you get the right parts for the job. 
 
While you are thinking about detecting fuel vapours give serious consideration to the detection of Carbon Monoxide. Carbon Monoxide detectors will quickly identify this odourless gas that is coming from engine and generator exhausts. A light breeze coming over the stern while the boat is moored, standing still or even moving forward at a slow speed, for example when trolling for fish, will quickly cause the cockpit and cabin to fill with deadly CO fumes. Many boating related deaths that were originally attributed to drowning are now being identified as having a root cause of Carbon Monoxide poisoning which can cause light headedness and drowsiness which in turn can result in falling overboard and/or death. 
 
Don’t take chances. Turn on your Blower for at least four minutes before starting the engine(s). Make a visual inspection of the engine compartment and use your nose to detect fumes. Leave the blower on when in a lock, standing still or even moving slowly. 
 
Consider the use of fuel vapour and Carbon Monoxide detectors. A safe boating experience is a more enjoyable boating experience. 
 
If you want to learn more about a boat maintenance CanBoat offers courses on Boat and Engine Maintenance and Electrical. Details HERE: https://www.canboat.ca/course-calendar/?course_category=51
 
John Gullick is currently CanBoat’s Manager of Government and Special Programs and has been an active recreational marine specialist and writer for over 50 years. 

All articles are free for use to promote boating and water safety. Credit must be provided to CanBoat / NautiSavoir and author John Gullick.