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davisr

Member III
I'm thinking of using my starboard side cockpit locker as a compartment for two 6V golf-cart batteries wired in a series. Knowing that these flooded cells will release hydrogen during charging, I want to provide some passive ventilation for this locker so as to avoid the build up of this potentially explosive gas. I have read in various places that only a small hole is needed in a battery compartment and that it should be placed as high as possible in the compartment, since hydrogen is lighter than air.

A local West Marine employee (who is also a liveaboard) suggested that I install a clamshell vent or possibly even a cowl vent on the cockpit coaming. I told him my only worry was that this would provide a point of entry for water into the cockpit locker in the event that the cockpit itself took on some water in a following sea, etc. Told him I'd like to consult the Forum.

Would be grateful for some voices of experience on how I should approach this ventilation issue.

Thanks,
Roscoe

E25, cb, Hull 226
 

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sleather

Sustaining Member
I've got twin 12V wet cell batteries mounted in the stbd. locker just behind the cabin and she hasn't blown up in 24 years, although I usually prop open the hatch covers during charging. :cool: Unless your locker hatch covers are gasketed(something I plan on doing) there's more than enough ventilation from the clearances around the hatches IMHO.
 

davisr

Member III
Thanks Steve. That's reassuring to know that you've stayed safe and sound with this set-up for 24 years. Is your locker sealed in every other place except in the place you mention - around your hatch covers? I ask this question because this afternoon I looked closely at the interior of the locker. I discovered that at both ends of the locker there are plywood bulkheads of sorts. These bulkheads are glassed-in to the base of the locker, but are open at the top. In other words, there are openings above the plywood (in the space behind the coamings) that permit any fumes, gasses, etc. to flow up and over them. Where do these openings lead? Into the lazarette (or what some would call the engine compartment) beneath the cockpit. This was one of the reasons why I wanted to get the portable fuel containers out of this cockpit locker (as I describe in the thread, "E23-27 fuel tank ventilation"). Gasoline fumes, being heavier than air, take the low road. This was why I smelled gas and the surveyor smelled gas in the main salon during the survey. The fumes were travelling down from the interior gaps in the starboard cockpit locker bulkheads - down into the lazarette, and from there into the bilge. The surveyor said that he was surprised the boat had never been blown to pieces. With flooded batteries in the cockpit locker, the issue of hydrogen gas seems less benign, if only because the gasses, being lighter than air, take the high road, rather than the low. Thus, the gaps around the hatches in the cockpit locker provide a means of escape.

Does this sound right?

Best,
Roscoe
 
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