http://www.tc.gc.ca/publications/en/tp1332/pdf/hr/tp1332e.pdf
This is the Canadian builders code for small crafts look at page 69 or 6.5 it has the regulation for all small crafts manufactured or custom built on battery ventilation.
Quoted "6.5 Battery Spaces
6.5.1 Spaces containing batteries shall provide for the overboard ventilation of hydrogen gas
released by the battery.
Information Note:
“Sealed”, “maintenance-free” batteries, or batteries with immobilized electrolyte (gel batteries) also need
to be vented outboard."
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