Dehumidifiers and bilge switches

[Guest]

Just went down to the boat on Sunday, having decided on the advice of the board to turn the battery charger off. The dehumidifier had been working a treat, but you guessed it, the float switch had stuck, leaving the pump running to the point where it was almost too hot to touch... It was only the fact that the charger was on that saved me from trashing the domestic batteries.

So I did some experimenting. Under way, any water in the bilge will slop around, making movements of the switch quite rapid, and under these conditions, it works a treat. But at rest, the water is calm and as the pump comes on, the level falls smoothly. At the bottom of the travel, the float sticks as the slow fall is not sufficient to overcome the spring in the switch...

I have now glued two washers to the top of the float, and the extra weight is enough to ensure that the switch always turns off. I took some experimenting, since too much weight means that the switch won't turn on.

There MUST be a better way, surely, than relying on these crappy float switches?

 

[JerryHawkins]

There is! There is a device called a 'Bilge Buddy' (I think) which is a solid-state switch. It relies on the change in resistance between two electrical contacts when they are either in or out of water. Can't remember where I saw it - may have been Cruisermart, but ask your chandler.

Cheers,

Jerry

 

[Guest]

Re: Solid state switches

You have to be careful as to the height you mount these as they are quite sensitive and as most pumps don't lift the last inch or two of bilge water, if set too low these switches will drive the pump permanently.

Interestingly, some years ago there was an article in PBO about using a domestic smoke alarm as a bilge water alarm. Basically you solder some coax cable to the output from the smoke sensor (the main cable) and the shielding to an earth somewhere in the alarm. The other end of the coax is led to the bilges with the cable and shielding exposed (but not touching) If these are immersed, they set the alarm off.

I remember thinking that this was to easy to be true but I did try it and it works.

Nick

 

[Guest]

Re: Solid state switches

I seem to remember reading about pressure switches, using plastic tubing in the water, too. Anyone have any info?

 

[jfm]

Re: Woooah, barking up wrong tree mate

Hang on Graham. The dehum should cut in/out on a humidistat. The float switch only is only last resort in case tub fills up. It's much better to let it drain down the sink anyway, then the float switch is history. But what I'm saying is, is your humidistat set too dry? If not you have a lot of moisture to suck out of the air in your boat (surely new f'line not that damp??) . And if you do indeed have that much moisture to suck out, then you should be sucking it out not letting your dehumid cut out on the float switch just cuz the blimmin tub has filled up. In other words you need a more industrial strength dehumid unit. But bottom line always, is the float switch is a last resort, not an important bit of kit

Re batteries going flat, isn't the dehumid mains powered? If not sugget you get a mains one

JFM

 

[Guest]

Re: Woooah, barking up wrong tree mate

Sorry for confusion. DH is mains powered, drains into the bilge, not the sink, as it's sat on the floor (see previous thread about density of humid air etc). So actually, it drains into the shower tray in the heads, which drains into a shower sump with a float switch and bilge pump.

The batteries would only have gone flat cos the bilge pump was running continuously (it draws about 4A, I think, so would kill a big domestic in a day or two)

 

[longjohnsilver]

Fire!

If the bilge pump was running continuously dry you're lucky it didn't catch fire - if it had done you would have had a very dry boat!!!!
Get yourself a decent float switch, The Yank ones seem the best.

 

[Guest]

Re: crppy fline shower pumps

Youy have a Targa yes, GW? If outlet to shower tray then than goes to naff shower pump assy, no? Our had a lousy awful rubbish etc always flooding showr tray pump. Eventually I disconnected the shower waste and redirected to the much bigger and beefier "real" bilge pumps in fwd bilge.

 

[Guest]

Re: Fire!

T'was as hot as hell. It was only stopped from melting by the inch of water in the bottom that it couldn't pick up, I guess.

 

[Guest]

Re: crppy fline shower pumps

Same thing. It's a crappy plastic box with a pump and switch inside.

Now to the real problem. The engine bilge is separated from the rest of the bilge (which is good), but the forward bilge (as distinct to the bit with the shower sump in it) has no pump in it. It all runs back under the shower pump (which is next to the seacocks for the bog), and under the midships cabin, where it hits the bulkhead in front of the doemstic water tank. From there, it's got nowhere to go. Daft, or what.

 

[Guest]

Re: crppy fline shower pumps

But under the cushions in midcabin/den and under a poxy sq bit of wood somehwere right at the back will be a mid bilge, I bet. Which will be much bigger than the shower thing. At the dashboard, there will be the same number of bilge override swiches as there are bilge pumps. Sounds as tho the 29 has two. This no bad thing as massive water intake at front is shielded from engine, and stinky diesely bilges in engine don't sloosh under the nice carpety bit.

 

[Guest]

Re: crppy fline shower pumps

I wish! Under the cushions are two big bits of wood, and under those is a 42 gal water tank. There's a full height (up to the sole) bulkhead foward of this, and that's where the water stops, on it's journey aft from the bows (assuming we've been holed forward). There is no pump in this section. About a foot up from the keel, there is a hole in the bulkhead, but I'd have to remove the water tank to see where this hole leads, besides, I wouldn't want a foot of water down there before it starts to drain back to the engine bilge.

 

[Guest]

Re: Solid state switches

Graham

I have on my desk a leaflet that I picked up at SBS. It is for a 'Water Witch' electronic bilge pump switch.

I can fax it to you or they have a web site: www.penguingeng.com

Neil

 

[Guest]

Re: really?

Really really? but but ...ok what about on the dash - there's only one switch that when you press it the red light goes an eventually it beeps becos pullingh no water? Or two? There just must be two?

Cos otherwise if a bog seacock fails....then there's no bilge pump anywhere near?

 

[Guest]

Re: really?

Nope, just the one. If the bog seacock fails, the water pressure will blow the hatch out of the floor, the water fills the cabin sole, over the step to the heads, down the shower tray, into the crappy little box and gets pumped out. Except the pump couldn't handle that volume, and anyway, you'd have six inches of water everywhere.

Now you know why, unlike you, I keep the bloody seacocks closed unless soemone's using the bog.

Unsurprisingly, this is a situation I am keen to rectify...

 

[Guest]

Re: Solid state switches

Thanks, I'll take a look...

 

[Guest]

Re: Hunt the bilge pump

http://www.fairline.com/targa/targa_frameset.htm

says that the targa 30 has one bilge fwd and one in the engine. That's two. They don't call the shower pump a bilge pump.

 

[Guest]

Re: Solid state switches

Neil,

The website's knackered, could you fax, pse. I'll send you the fax no as a private msg...

 

[Guest]

Re: Lies, Damn Lies, and Sales Brochures

OUrs is the T29, not the 30, but the spec sheet is the same. The handbook shows an extrahatch in the sole, four engines, torpedo tubes and an anti aircraft gun, so I'm inclined not to believe it.

I'v hunted and hunted, but I can find no forward bilge pump. Now if I had a flock of Bilge Fairies, I could force them down there with mops and buckets, or even rig something up to the raw water pump...

 

[Guest]

Re: don\'t believe it

There are two switches on the dash, so two bilge pumps.

The brochure says two bilge pumps.

That size of boat I Bet isn't allowed to have just one bilge pump.

A fairliney bloke I called says there are two bilge pumps: it is either the cushions mid cabin OR under the carpet at the bottom of the stairs, under a hatch.

So, in summary I ask the court to judge in favour of there being two bilge pumps, one of which is hiding in a teehee hidden fairliney sort of place. Not just one in the engineroom.