electrician says vhf should go straight to battery

[Ubergeekian]

electrician says vhf should go straight to battery but i think i should wire it to the blue sea breaker panel what do you guys think ?

My personal preference is that the VHF should be switchable on as easily as possible by someone who doesn't know the boat and that all wiring should be protected by switch.

When I wired the Jouster, therefore, the VHF was wired directly to the master switch, so the emergency instructions could say

• Make sure the master switch is on.
• Turn the radio off and on with the top right hand switch (thus ensuring Channel 16, high power).

On the new boat it's wired through a fairly inaccessible 1-2-both switch and a master switch and a circuit breaker. That, to me, is too many and I'm pondering what to do. The logical thing would be to take it from the switched side of 1-2-both, but that's a sod to find if you don't know it. I'm therefore thinking of having a "Radio Emergency Supply" switch which bypasses everything and connects a battery to the radio ... possibly a couple of Duracell 6V lantern batteries in series. Or perhaps, if the radio can take 0.6V less at input (I must check) it will connect 1, 2 and the alkalines through three diodes, so whichever is perkiest can take the strain.

Sorry, I have digressed slightly. I would avoid unswitched supplies wherever possible, if I were you.

 

[Channel Ribs]

... possibly a couple of Duracell 6V lantern batteries in series.

I had something similar on a boat prior to a rewire, though everything on board seemed to take an AA so I got an 8 cell holder and put the right connectors on it so that it could live next to the VHF. Never needed it, but it was there as were lots of spare batts.

 

[oldharry]

VHF straight to battery - always. How else do you call for help if the electrics fail? Except flattening the battery of course. Also, as the prime mans of distress calling it should always be immediately available to any user who does not know the boat.

No other safe way.

 

[elton]

Good practice to wire it straight to the battery. Fit an inline fuse as close as possible to the connection to the battery, then even if you get a short (anywhere beyond the fuse), you won't get a fire.

 

[Ubergeekian]

VHF straight to battery - always. How else do you call for help if the electrics fail? Except flattening the battery of course. Also, as the prime mans of distress calling it should always be immediately available to any user who does not know the boat.

No other safe way.

I don't like leaving live circuits when I'm away from the boat, so while I agree with you that direct to the battery has its advantages, I like the added electrical security of a switch. As long as it's easy to switch on, I don't see any major safety issues - particularly since it will normally be on while under way anyway.

 

[cimo]

the electrician said if there was a fire you would always have your radio my concern is that it might cause the fire

you would also "always" have heat, fumes and the possibility of toast!
Seriously though - I always felt a fire on board to be the worst senario.

nothing new to add. I connect at the fused distribution panel, and I think a continous watch on 16 is good practise. (It's what everyone esle is expecting you to be doing).

I beleive a dedicate radio emergency battery is required on commerical vessels >12m but I could be wrong on that. It seems like a good idea, but not an overhead I'm willing to absorb, prefering instead to run a handheld backup.

PS - electrical fires are a result of a poor electrical installation. Circuit protection (fuses & breakers) is important.

rgds
c

 

[TradewindSailor]

I can find no such requirement in the MCA or RCD documentation. Perhaps you should ask your electrician if this is an official requirement and if so for a copy, or just his preference. I'd like to know too.

Personally I would attach it above the battery isolator switch ...... and, provided it was convenient, to the main switchboard.

If you do connect it directly to the battery, you will need to size the cables correctly and to fuse it on the positive (and I prefer in addition: to the negative) as NEAR AS POSSIBLE to the battery.

It must be fused or protected with a properly sized circuit-breaker as close to the 'supply' anyway.

 

[Tranona]

I can find no such requirement in the MCA or RCD documentation. Perhaps you should ask your electrician if this is an official requirement and if so for a copy, or just his preference. I'd like to know too.

Suggest you read 16.2.5 of MGN 280 (M) Second paragraph on security of power supply to VHF. That is most easily met by an independent supply direct from the battery.

As I said in my first post, the Greek authorities go one stage further and now specify a completely independent supply with the same objective. Overkill perhaps. My boat in fact has a dual supply - works through the switchboard or the dedicated battery - the GPS is on the same circuit to make the DSC bit also independent of the service battery.

 

[Neil_Y]

Spot on Tranoma, direct independant supply fused of course.

This is what I have always fitted and as was required by MCA coded boats I've sorted for coding inspection.
http://www.mcga.gov.uk/c4mca/blue.pdf
16.1.5 supply should not be interupted, ie you can isolate everything else in the event of an electrical fire and still use the radio.

 

[fireball]

so you turn off the bilge pump too

Er yes - but then my bilges are dry ... aren't yours perhaps you'd be better off with a Bav ...

 

[TradewindSailor]

Suggest you read 16.2.5 of MGN 280 (M) Second paragraph on security of power supply to VHF. That is most easily met by an independent supply direct from the battery.

As I said in my first post, the Greek authorities go one stage further and now specify a completely independent supply with the same objective. Overkill perhaps. My boat in fact has a dual supply - works through the switchboard or the dedicated battery - the GPS is on the same circuit to make the DSC bit also independent of the service battery.

I hadn't realised we were discussing commercial vessels. As for the MGM :
"
16.2.5 When batteries are used for the electrical supply to radio equipment, the batteries, when fully charged, should provide sufficient hours of operation to ensure effective use of the GMDSS installation bearing in mind the distance from shore that the vessel can operate.
Appropriate charging facilities or a duplicate battery of capacity sufficient for the voyage
shall be provided.

The battery electrical supply (reference should be made to Section 8) to the radio equipment should be protected against flooding/swamping as far as practicable and arranged so that radio communications are not interrupted in adverse conditions."
"

I can find no mention of an "independent supply direct from the battery".

 

[TradewindSailor]

Spot on Tranoma, direct independant supply fused of course.

This is what I have always fitted and as was required by MCA coded boats I've sorted for coding inspection.
http://www.mcga.gov.uk/c4mca/blue.pdf
16.1.5 supply should not be interupted, ie you can isolate everything else in the event of an electrical fire and still use the radio.

Your quote is incorrect :

"16.1.5 When the electrical supply to radio equipment is from a battery, charging facilities, or a duplicate battery of capacity sufficient for the voyage, should be provided. Battery electrical supply to radio equipment should be arranged such that radio communications should not be interrupted."

The i.e. is not there. The "i.e." is your interpretation.

 

[William_H]

VHF power

So to the OP you have a lot of opinions and reasons. It is up to you to decide priorities assuming you are not trying to meet a specific code.
Most boats I know just feed the VHF like any other service via a switchboard with fuse and a main switch.

If you are concerned to have someone able to operate VHF without knowledge of the power supply switch(s) then connect direct. However you then run the risk of inadvertently leaving it on when you leave the boat. There should always be a fuse or circuit breaker somewhere in the supply to minimise risk of electrical fire in case of short circuit.

Perhaps a normal sytem with clear instructions on how to get power to the radio.

depending on boat complexity for a simple boat electrics a connection via switchg board should be OK.
For complex systems then perhaps there is merit in a separate reliable supply. Up to you olewill

 

[Neil_Y]

You're right in what you say, however much of the advice and code details are open to interpretation.

Saying that radio communications should not be interupted means that in the event of an electrical short and subsequent need for assistance the radio should be available. Many boats that I have worked on and one that I had the need to call for the RNLI on after an electrical failure, have a messy often added to wiring mess behind the switch panels that grows with age. In the event of an electrical burning smell would you want to leave the main supply to this area behind the switches live whilst you put out a mayday? I interpret and this was approved by the MCA surveyor that protecting the supply means I could isolate evrything from the batteries quickly with one switch leaving the bilge pump and radio available for emmediate use.

Trust me when you have a sinking boat with a potential fire starting up you switch off the batteries quickly and then grab the vhf.

My own boat also had a back up sealed 12v next to the vhf available incase the main batteries were emmersed, but this was following my near sinking experience.

The code wording has to cover many different installations and boat uses and as such can be a bit vague, but on safety grounds I believe this is the meaning intended.

 

[fisherman]

I believe it was a conventional fitting.

There have been instances when the inline fuse to a VHF has got a bit green, the set receives OK, you think it's OK, only about 0.5 amp draw, but to transmit takes possibly 7 amps at 12 volts, then the connection breaks down and the transmission is broken, so as few connections as possible is favourite.
I would prefer to connect to the battery but have no delusions about my memory and switching off, so it goes to a main battery switch, and has its own inline fuse. Perhaps the answer is to connect to the battery, with the inline fuse at the battery terminal to protect the wire, but always hang the boat key on the VHF, so you switch off as you leave.

My bilge alarm is straight to the battery, I leave a phone number in the window, has saved a lot of grief when someone has phoned to say "Your boat's beeping".

 

[Pye_End]

electrician says vhf should go straight to battery but i think i should wire it to the blue sea breaker panel what do you guys think ?

I'm trying to imagine circumstances where long range VHF is critical in the event of electrical failure.

Since batteries tend to be the lowest part of an electrical system, an ingress of water will probably submerge these first. If the VHF is wired, directly or indirectly, will it still work under these circumstances?

If the wiring is fried due to a failure, presumably there is only a need for an emergancy VHF if there is an uncontrollable fire? Otherwise a wiring failure can always be re-jigged if time was not of the essence.

In the days of mobile VHF radios; mobile phones and PLB's just how critical is a fixed VHF?

 

[boatmike]

electrician says vhf should go straight to battery but i think i should wire it to the blue sea breaker panel what do you guys think ?

Having fitted out many ferries and commercial vessels needing Lloyds and MCA certification I think the definition of the subject under discussion needs to be clarified. For “straight to the battery” please read “straight to the battery isolating switch” No battery should have wiring direct to it without the facility to isolate the battery and isolating switches should always be as near to the battery as possible. The requirement to wire VHF radio and indeed other safety related items direct rather than through a general service panel is to ensure that a short circuit or failure in the domestic circuits does not interfere with the “safety” circuits. Fire is not the only issue. Flooding, or other damage may also require that all other circuits are isolated ASAP. In the case of ferries the usual preference is for a separate battery for safety related supplies that is not in the machinery space. The normal requirement however is for a supply independent of other general house supplies. For small yachts like ours it is sensible to apply the principle as far as possible. This may mean taking the VHF from the battery isolating switch or indeed the feed in to the main service panel. Obviously the first is preferable, but if, like my boat, the battery bank is some way away from the VHF and distribution panel and there is a very large heavy cable feeding the latter, it is in my opinion acceptable to use that same feed and connect to the input terminal to avoid the need for a duplicate heavy cable to avoid voltage drop. Either way the issue of bilge pumps is an “owner issue” frankly there is nothing in the code to say you should leave a feed to these when the ship is docked and passengers disembarked as there is no MCA related safety issue when the passengers are ashore. Under no circumstances however should anything at all be wired directly to a battery terminal without the facility to switch it out of circuit before connecting or disconnecting batteries.

 

[Tranona]

I hadn't realised we were discussing commercial vessels. As for the MGM :
"
16.2.5 When batteries are used for the electrical supply to radio equipment, the batteries, when fully charged, should provide sufficient hours of operation to ensure effective use of the GMDSS installation bearing in mind the distance from shore that the vessel can operate.
Appropriate charging facilities or a duplicate battery of capacity sufficient for the voyage
shall be provided.

The battery electrical supply (reference should be made to Section 8) to the radio equipment should be protected against flooding/swamping as far as practicable and arranged so that radio communications are not interrupted in adverse conditions."
"

I can find no mention of an "independent supply direct from the battery".

As coding only applies to vessels used commercially...... The quote is taken from the standards that would apply to a charter yacht.

I did not say it specifically requires direct wiring as the requirement is about function and not means of achieving it. Difficult to see how the requirement could be met without an independent supply.

 

[Neil_Y]

I forgot one important point I install an earth isolator as well which is always on and not emediately accessable to guests/passengers (the key is hanging nearby but not inserted)

This gives you the possibility to isolate if needed.

 

[gasdave]

the "hanging key"

Perhaps the answer is to connect to the battery, with the inline fuse at the battery terminal to protect the wire, but always hang the boat key on the VHF, so you switch off as you leave.
My bilge alarm is straight to the battery, I leave a phone number in the window, has saved a lot of grief when someone has phoned to say "Your boat's beeping".

As an "aide memoir", the hanging key is not without it's drawbacks either - what do you hang on the gas supply?

My fixed VHF is wired separately from the main switch, through it's own switch and fuse to the battery. However I also carry a handheld.