how many bilge pumps?

[ghostlymoron]

Not true unfortunately.
Diaphragm bilge pumps often pump air at a very low efficiency especially when dry.
Some will completely fail to prime with the slightest bit of dust in the valves.
Even if they work perfectly, to reduce the amount of gas below the explosive limit you would have to pump an enormous amount of air out of the bilge, like emptying the cabin several times over.

The best way to remove gas from a confined space is with a bucket - although it looks strange to say the least to see someone lifting apparently empty buckets from the space and emptying them outside!

 

[onesea]

Was pumping some Rain out of the Bilges this morning. Pump was not working well checked suction was clear...

Crawled into corner pump is hidden in, opened pump and removed... The compression sack for my daughter sleeping bag .

Seriously impressed with that pump Henderson Mk5... Also must clean bilges more often .

 

[Tidewaiter2]

Was pumping some Rain out of the Bilges this morning. Pump was not working well checked suction was clear...

Crawled into corner pump is hidden in, opened pump and removed... The compression sack for my daughter sleeping bag .

Seriously impressed with that pump Henderson Mk5... Also must clean bilges more often .

Just fit a strum box

 

[Graham_Wright]

Not true unfortunately.
Diaphragm bilge pumps often pump air at a very low efficiency especially when dry.
Some will completely fail to prime with the slightest bit of dust in the valves.
Even if they work perfectly, to reduce the amount of gas below the explosive limit you would have to pump an enormous amount of air out of the bilge, like emptying the cabin several times over.

It may be a centrifugal one which does blow out a fair draught. But I have a bilge blower anyway (which is reversible by polarity change).

 

[jwilson]

It may be a centrifugal one which does blow out a fair draught. But I have a bilge blower anyway (which is reversible by polarity change).

Having once had gas inside a hull, I would not touch anything electrical at all. Open every hatch and use buckets to empty air at bottom of bilge to over the side. This was on a cruising cat dried out on a beach in Salcombe - the holidaymakers around thought we were crazy at first, but once I'd moved my own small kids who were making sandcastles next to the boat well away some at least understood after asking what we were doing.

I have seen two boats that had gas explosions: one was a 45 ft motorboat - ended up in two halves some distance apart. Other a sailing yacht where most of the deck blew off. Both cases had fatalities, but in one case the person who lit the match below survived, presumably everything exploded away from him.

 

[fisherman]

It may be a centrifugal one which does blow out a fair draught. But I have a bilge blower anyway (which is reversible by polarity change).

Nooooo!
Firemen use water powered fans for this.

 

[KellysEye]

We had two hand pumps, one in the cockpit and one in the toilet with a two way switch so they could pump three bilges between them. We also had an electric sump pump.