Bilge ventilation

Sorry if I have caused some confusion. Let me describe my set up.

1) Under the lazarrette port side hatch is the Hurricane hydronic heater. The exhaust is piped to a port side through the hull. I am not sure but there may be a tube within a tube for this introducing combustion air. Up to now, I have never owned a diesel heater and this one does not work yet, so I have a lot to learn. There is still enough room in here for two good size Rubbermaid storage boxes.
2) Under the lazarrette center hatch is the gen set. It takes up most of the space.
3) Under the starboard lazarrette hatch are (2) 8D start batteries for the main engines and (1) group 27 start battery for the gen set. There is still enough room for two good size Rubbermaid storage boxes.
The above is what I meant by saying many 47's have a similar setup.

The swim step hull extention has (4) GC batteries for the house back. This is where they were located when I bought the boat last August. There are no other systems or permanently mounted things in here. I have installed a whale bilge pump. The rest of the hull extention is just storage. I am thinking of adding some additional potable water storage tanks in the neighborhood of 100 gallons but that is another topic.
Here is the short list of what is stored in the hull extension now:
2props, 1 strut, big coil of stern tie line, extra 100' chain, 15-20 gal of engine oil and misc fluids, to big plastic boxes of lines, 2 crab traps, floats, lines, four big fenders, three good size Rubbermaid boxes of misc stuff. This is after I threw away ?? Dock cart loads of stuff.

I though about relocating the (4)GC house batteries to somewhere in the lazarrette. There is pretty good room for service access in the lazarrette now but putting the GC's in there would reduce that. Besides, my hope is to make the hull extension more "pleasant" to store things in takes care of the battery gassing issue.

Hopefully this clarifies what I have at present and what I hope to accomplish. Thanks for all the input!

OK, Thanks for the clairification.

To solve the problem I would move your house bank back into the lazerette.

There is plenty of room to service the batteries. This also solves any hydrogen issues.

Then you can just store misc stuff in your hull extension.

I dream of adding your extension with a 5KW generator for night use in the hot summer nights.

Pura Vida said:

I dream of adding your extension with a 5KW generator for night use in the hot summer nights.

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????? You already have a generator, or you did

Is it too loud?

ksanders said:

????? You already have a generator, or you did



Is it too loud?

Click to expand...

Kevin, I think he means a cruise genny.

N4712 said:

Kevin, I think he means a cruise genny.

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I am not a big believer in cruse generators, at least for our size boat.

In a larger boat maybe, since it supplies redundancy.

If I had too light of a load on my generator, say while sleeping, I'd move the load to the inverter.

Then to insure the batteries don't go flat overnight I'd use an autostart controller on my generator. This would be tied to a battery State of Charge meter.

When the batteries dipped to 50% the generator would start. When they reached say 90% the generator would shut down.

I would caution you in adding 100 gallons of water, that's 800 lbs far back on the boat, in addition I would do as recommended and put the extra extra batteries back in the main part of the boat.

Really nice platform setup, but I'd use it for fenders, lines and hose storage and all systems stay simple, that's a good thing on a boat! All the best.

I would not penetrate the lower hull period.


Consider running some flat tubes up the transom to vent scoops or just grills. a fan could be located there way above the deck.