Maintained supply I'm confused

[JamesDavis]

Maintained supply I\'m confused

I am in the process of rewiring my boat (Rival 32) and designing a switch panel. I am trying to keep things very simple but also give myself the ability to add futher items later. I am finding the whole subject of having a maintained supply to various items, which is independent of the battery selector switch , rather confusing. As far as I can see, books I have read advise, the bilge pump, the VHF and the diesel heater to be on a maintained supply. It seems my instruments would benefit from a maintained supply. A call to Raymarine also advised a dedicated battery connection for my ancient Autohelm instruments . These are directly connected to the service batteries, at the moment, and I do remember loosing my log data when inadvertidely starting using the service batteries, so I can see the theory of their advice.
My gut feelings are these. When I leave my boat I always switch isolate both battery banks and therefore leave the boat "dead". I am lucky to have a very dry bilge. Therefore no need for a maintained bilge supply.
I can't see the point of a maintained supply to the VHF and I can see disadvantages as you could'nt switch it's supply in the event of a run down battery. Therefore there is no advantage of a maintained supply to the VHF.
I hav'ent got a heater yet so I would invite any advice.
I can see the point of a maintained supply to the instruments to avoid a zeroing the log when I start the engine. But this begs the question Should all sensitive equipment be on a maintained supply? Radar,Navtex,GPS etc etc?
As You can see I am a little confused and would invite clarification. My main criteria for design are to keep it simple and allow flexibility in it's operation.
Many thanks for any replies James Davis.

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[LadyInBed]

Re: Maintained supply I\'m confused

It’s a recommendation, you don’t HAVE to follow it to the letter.

I would always wire an automatic bilge pump and a sump frost heater ‘direct’ to a battery, but the rest of the instruments go through an isolator and battery switch.

You pays your money and takes your choice!


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[hlb]

Re: Maintained supply I\'m confused

You want everything to turn off with the master switch. Thats what it's for. Except anything that has to come on automaticly when you are away like bilge pump.

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Haydn

 

[colvic]

Re: Maintained supply I\'m confused

Why not split your switch panel into two halves, one for items than can be isolated when away from the boat and the second for those you may or may not want to isolate; You just need to split the common feed to the switches on the panel and use two isolating switches.

I've always had a dry bilge but when a leak starts it's surprising just how much water comes in over a period of time when you are away from the boat. It's always recomended to have an auto bilge pump if you can and then you can relax.

Phil

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[tr7v8]

Re: Maintained supply I\'m confused

It's a condition of my insurance to have a continuos live Auto bilge pump.
Reason for wiring the VHF direct is that in the event of a fire you'll have isolated the batteries via master switch and you just might need to call for help via the VHF!
I'd always wire VHF, Auto bilge pump and if you have one a heater direct to the batteries via their individual fuses.

<hr width=100% size=1>Jim

Draco 2500

 

[colvic]

Re: Maintained supply I\'m confused

I agree; since our little incident, we now have a battery up forward, just beneath the deck that is connected to JUST VHF and BILGE PUMP as we found out that as soon as water covers the batteries and gets into the wireing you loose the lot.

Didn't have to put very large wireing in, as the draw is minimal, and an isolating switch cuts it from the charging system in case of emergency. It's only when you need a fixed VHF that you realise how little power, and therefore range, a handheld has.


Phil

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[dickh]

Re: Maintained supply I\'m confused

Interesting that Raymarine say you should have a dedicated maintained supply for the instruments, I always switch off cpmpletely and all my instruments still work OK.

<hr width=100% size=1>dickh
I'd rather be sailing... /forums/images/icons/smile.gif