VHF Power Supply - switchboard or independent?
- Thread starter Hardtack
- Start date
bedouin
Well-Known Member
I think it is wrong to regard your fixed VHF as so important for emergency use that an independent feed is essential. However you do it you can always dream up another scenario that renders it inoperable. I prefer the approach of having a hand-held and EPIRB which gives a much greater degree of resiliency.
For example in the OPs case I might choose to spend the time trying to fight the fire myself rather than transmitting a Mayday - by the time the fire was out of control it might be too late.
For example in the OPs case I might choose to spend the time trying to fight the fire myself rather than transmitting a Mayday - by the time the fire was out of control it might be too late.
lw395
Well-Known Member
On my first yacht, the VHF and Decca were powered from a small sealed battery, charged via some comedy diode/relay malarkey from the engine.
There was a switch to power it direct from the main batteries.
I'm not sure if this was derived from some racing requirement.
It's not completely stupid.
1) a fixed VHF with masthead antenna will give a high % coverage in the English Channel. Hand held more like 50% of the Solent?
2) starting the engine used to knock the Decca for six on the main battery, likewise the old GPS on my second yacht. Running it from the small battery stopped it going AWOl just when you want it.
I think it's the Buddhists that say 'there are many routes to serenity'?
One has to decide what might go wrong on a boat and be comfortable one has done the basics to live through that.
I've seen, and heard of, a lot of things failing on boats, but 'all the house and engine batteries flat' recurs.
I've also been in the situation of smoke coming from wiring, so we disconnected all the batteries and it stopped. Now what? We call Kev for a tow being the right answer.
An EPIRB is just the thing if you are in real trouble. Your fixed VHF enables you to actually talk to someone. That's good to have IME and IMHO.
Handhelds are good, better than they used to be, but still not immune from being flat when wanted.
There was a switch to power it direct from the main batteries.
I'm not sure if this was derived from some racing requirement.
It's not completely stupid.
1) a fixed VHF with masthead antenna will give a high % coverage in the English Channel. Hand held more like 50% of the Solent?
2) starting the engine used to knock the Decca for six on the main battery, likewise the old GPS on my second yacht. Running it from the small battery stopped it going AWOl just when you want it.
I think it's the Buddhists that say 'there are many routes to serenity'?
One has to decide what might go wrong on a boat and be comfortable one has done the basics to live through that.
I've seen, and heard of, a lot of things failing on boats, but 'all the house and engine batteries flat' recurs.
I've also been in the situation of smoke coming from wiring, so we disconnected all the batteries and it stopped. Now what? We call Kev for a tow being the right answer.
An EPIRB is just the thing if you are in real trouble. Your fixed VHF enables you to actually talk to someone. That's good to have IME and IMHO.
Handhelds are good, better than they used to be, but still not immune from being flat when wanted.
Hardtack
Member
"I think it is wrong to regard your fixed VHF as so important for emergency use that an independent feed is essential."
Be that as it may, whilst an independent power supply isn't compulsory on a large proportion of privately operated craft registered in the UK, in many countries such an arrangement is a statutory requirement.
Those regulations aren't unilaterally drafted by bored land-bound bureaucrats pushing pens in back offices - they're assembled in consultation with highly experienced professional mariners of many years experience.
A commercial vessel sailing under the UK flag will normally run its radio installation from the ship's house supply, but the radio must also have a back up battery supply reserved for the sole use of the transceiver.
To protect it from uncontrolled flooding for as long as possible, the emergency back up battery bank has to be high up in the vessel - typically adjacent to the radio room, which is generally on the bridge or directly abaft it. On some of my older commercial vessels the batteries were installed in weatherproof enclosures out on the bridge wings. Others have the dedicated back up battery bank inside, tucked safely away in a ventilated battery room.
Be that as it may, whilst an independent power supply isn't compulsory on a large proportion of privately operated craft registered in the UK, in many countries such an arrangement is a statutory requirement.
Those regulations aren't unilaterally drafted by bored land-bound bureaucrats pushing pens in back offices - they're assembled in consultation with highly experienced professional mariners of many years experience.
A commercial vessel sailing under the UK flag will normally run its radio installation from the ship's house supply, but the radio must also have a back up battery supply reserved for the sole use of the transceiver.
To protect it from uncontrolled flooding for as long as possible, the emergency back up battery bank has to be high up in the vessel - typically adjacent to the radio room, which is generally on the bridge or directly abaft it. On some of my older commercial vessels the batteries were installed in weatherproof enclosures out on the bridge wings. Others have the dedicated back up battery bank inside, tucked safely away in a ventilated battery room.
Hardtack
Member
"I've also been in the situation of smoke coming from wiring, so we disconnected all the batteries and it stopped. Now what? We call Kev for a tow being the right answer."
Hurrah!
At last!
From the surrounding vortex of entropy, misunderstanding and general chaos, a still, small voice of reason has emerged!
Hurrah!
At last!
From the surrounding vortex of entropy, misunderstanding and general chaos, a still, small voice of reason has emerged!
Hardtack
Member
"For example in the OPs case I might choose to spend the time trying to fight the fire myself rather than transmitting a Mayday - by the time the fire was out of control it might be too late."
Thanks for your input on this and yes - I think you're quite right. Although, as one necessarily needs to organise and adapt one's priorities to fit the circumstances of an emergency, it obviously isn't possible to be precise about the details of the modus operandi before the event.
Fortunately, in 32 years at sea professionally, I've only had to deal with two fires at sea. One was in the engine room of a minesweeper, the other occurred in the engine room of a Saudi Arabian flagged motor yacht. Neither of those conflagrations affected my radio equipment.
I've yet to have a fire on any boat that I've owned, so statistically speaking it's becoming more likely as time passes! Ready for it when it happens though...
Thanks for your input on this and yes - I think you're quite right. Although, as one necessarily needs to organise and adapt one's priorities to fit the circumstances of an emergency, it obviously isn't possible to be precise about the details of the modus operandi before the event.
Fortunately, in 32 years at sea professionally, I've only had to deal with two fires at sea. One was in the engine room of a minesweeper, the other occurred in the engine room of a Saudi Arabian flagged motor yacht. Neither of those conflagrations affected my radio equipment.
I've yet to have a fire on any boat that I've owned, so statistically speaking it's becoming more likely as time passes! Ready for it when it happens though...
lw395
Well-Known Member
Years back I had a handheld VHF with a BNC socket for the antenna. I could connect that to my masthead antenna, which was nice.
PaulRainbow
Well-Known Member
Anyway, if i don't get the fire under control i won't need the VHF, the smoke will be visible for miles 
Lon nan Gruagach
Well-Known Member
You know, every time something like that is said a statisticians' puppy dies.
Hardtack
Member
"Years back I had a handheld VHF with a BNC socket for the antenna. I could connect that to my masthead antenna, which was nice."
That's an elegant solution.
Looking at the problem from the other end, for the price of a couple of beers you can also make an emergency VHF antenna that coils up and stows away in a locker.
You need good quality 50 ohm screened cable. Remove about 18" of the outer sheathing from one end and throw it away. Now roll the screen (braid) back over itself and pull it down over the top of the outer sheathing. Now put a 50 ohm BNC connector on the other end. You've now got a 1/4 wave antenna that resonates at the marine VHF frequencies, works very well, and you can hoist it with a halyard.
Before you rush off and make one, best to Google and check the 18" figure that I've given you. I think it's 18 point something inches, that resonates on the Channel 16 frequency, and it also covers the surrounding marine band VHF frequencies. The closer you can get the stripped length to the ideal length for optimum resonance, the better it will work.
That's an elegant solution.
Looking at the problem from the other end, for the price of a couple of beers you can also make an emergency VHF antenna that coils up and stows away in a locker.
You need good quality 50 ohm screened cable. Remove about 18" of the outer sheathing from one end and throw it away. Now roll the screen (braid) back over itself and pull it down over the top of the outer sheathing. Now put a 50 ohm BNC connector on the other end. You've now got a 1/4 wave antenna that resonates at the marine VHF frequencies, works very well, and you can hoist it with a halyard.
Before you rush off and make one, best to Google and check the 18" figure that I've given you. I think it's 18 point something inches, that resonates on the Channel 16 frequency, and it also covers the surrounding marine band VHF frequencies. The closer you can get the stripped length to the ideal length for optimum resonance, the better it will work.
PaulRainbow
Well-Known Member
As i already have a backup masthead and another at the pushpit, can i skip this one please ?
Hardtack
Member
"As i already have a backup masthead and another at the pushpit, can i skip this one please ?"
Okay. Just wish my boat was as comprehensively equipped as yours.
Damn...
I was hoping you'd ask me what to do with it if the mast collapsed, leaving you with no radio and a halyard deficiency.
Okay. Just wish my boat was as comprehensively equipped as yours.
Damn...
I was hoping you'd ask me what to do with it if the mast collapsed, leaving you with no radio and a halyard deficiency.
duncan99210
Well-Known Member
Whilst I fully understand the OP thinking about a dedicated, hardwired feed to the fixed VHF he has yet to step into the real world of the UK leisure boater. Most VHFs are fitted somewhere in the vicinity of the chart table/navigation station, both for ease of access and proximity to the NEMA feed from the GPS/chart plotter. This will likely be in the area of the bus bars and switch panel, probably with the antenna routed through the area as well. A fire in this area here will likely take out the wiring to the VHF as well as disabling the GPS/chartplotter, thus rendering the DSC functions of the VHF useless even if the radio were still functioning. So, unless you site your VHF with its independent connections to the battery plus an independent NEMA source and its antenna routed away from any other wiring, it seems to me that there is little point for most of us in having a dedicated supply with its other inherent weaknesses.
It has to be bourne in mind that we are, for the most part, not dealing with large vessels needing to comply with complex regulations and with the space available for redundant additional wiring runs. As I said in an earlier post, I struggle to see how I could reposition my radio and provide a NEMA signal to it in a manner which would remove the risk of the radio being lost due to fire.
Since this thread emerged, I've given thought to what, if anything, I could do to improve the "survivability" of my fixed radio installation. I could power it from yet another battery, charged from the main bank via a relay, so even if I inadvertently left it switched on it wouldn't flatten the main bank. I could buy a new set incorporating a GPS receiver. I could re-site the set so as to minimise the chances of it becoming involved in any putative event which disabled the remaining instruments. I could re-route the antenna cable, perhaps placing it in a fire resistant conduit to enhance or prolong its survival time in the event of a fire. It'd cost me a couple of thousand quid and a a couple of weeks work. And I'd end up with a radio that I still couldn't reach after an engine fire, because that'd deny me access to the saloon.
Clearly, wiring the radio directly to the battery wasn't considered necessary by the writes of the RCD (otherwise all recent yachts would have been wired that way and we wouldn't be having this discussion). I suspect that this is because someone sat down and thought through what would be involved in imposing this on to leisure boaters and decided that, whilst it has some merit in larger commercial vessels, it has no place in the leisure market because the risk of failure is comparatively low whilst the cost of compliance would be relatively significant.
It has to be bourne in mind that we are, for the most part, not dealing with large vessels needing to comply with complex regulations and with the space available for redundant additional wiring runs. As I said in an earlier post, I struggle to see how I could reposition my radio and provide a NEMA signal to it in a manner which would remove the risk of the radio being lost due to fire.
Since this thread emerged, I've given thought to what, if anything, I could do to improve the "survivability" of my fixed radio installation. I could power it from yet another battery, charged from the main bank via a relay, so even if I inadvertently left it switched on it wouldn't flatten the main bank. I could buy a new set incorporating a GPS receiver. I could re-site the set so as to minimise the chances of it becoming involved in any putative event which disabled the remaining instruments. I could re-route the antenna cable, perhaps placing it in a fire resistant conduit to enhance or prolong its survival time in the event of a fire. It'd cost me a couple of thousand quid and a a couple of weeks work. And I'd end up with a radio that I still couldn't reach after an engine fire, because that'd deny me access to the saloon.
Clearly, wiring the radio directly to the battery wasn't considered necessary by the writes of the RCD (otherwise all recent yachts would have been wired that way and we wouldn't be having this discussion). I suspect that this is because someone sat down and thought through what would be involved in imposing this on to leisure boaters and decided that, whilst it has some merit in larger commercial vessels, it has no place in the leisure market because the risk of failure is comparatively low whilst the cost of compliance would be relatively significant.
Hardtack
Member
"You know, every time something like that is said a statisticians' puppy dies."
Well having read that, I'm now bent double with remorse.
But on the other hand, if the statistician's any good he'll know in advance that his puppy's in big trouble.
Well having read that, I'm now bent double with remorse.
But on the other hand, if the statistician's any good he'll know in advance that his puppy's in big trouble.
Hardtack
Member
"Whilst I fully understand the OP thinking about a dedicated, hardwired feed to the fixed VHF he has yet to step into the real world of the UK leisure boater."
I thoroughly enjoyed reading your offering.
Just want to correct one point. Although I've been a professional mariner for most of my working life, I come from seafaring stock and most of my spare time over the past 50 years has been absorbed by sailing and maintaining my own boats and those of others.
My favourite was a 49 foot timber ketch (built in Gosport in 1946) which I owned for many years and lived aboard for much of the time when I was on leave from the Merchant Navy. Also owned one of Van de Stadt's lovely old Excaliburs - very pretty boat with a nice long keel, and in contrast, a Contessa 32 which, although not one of my favourites, was surprisingly quick for such a short waterline. Since I've retired I've downsized a tad but still spend much of my time afloat
So a more accurate statement would be that I "stepped into the real world of the UK leisure boater" in 1964 (which is when I was first ordered to get into a sailing dinghy and figure it out) and I've yet to find a satisfactory way of stepping out of it! (The world of the UK leisure boater I mean - not the dinghy).
I thoroughly enjoyed reading your offering.
Just want to correct one point. Although I've been a professional mariner for most of my working life, I come from seafaring stock and most of my spare time over the past 50 years has been absorbed by sailing and maintaining my own boats and those of others.
My favourite was a 49 foot timber ketch (built in Gosport in 1946) which I owned for many years and lived aboard for much of the time when I was on leave from the Merchant Navy. Also owned one of Van de Stadt's lovely old Excaliburs - very pretty boat with a nice long keel, and in contrast, a Contessa 32 which, although not one of my favourites, was surprisingly quick for such a short waterline. Since I've retired I've downsized a tad but still spend much of my time afloat
So a more accurate statement would be that I "stepped into the real world of the UK leisure boater" in 1964 (which is when I was first ordered to get into a sailing dinghy and figure it out) and I've yet to find a satisfactory way of stepping out of it! (The world of the UK leisure boater I mean - not the dinghy).
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grumpy_o_g
Well-Known Member
The only reason I'd not use the switched busbar is if I thought the quality of the power supply might be affected by something else connected to it - fairly unlikely on a DC battery system and with today's kit. If I was out of range of VHF or had no battery then I'd reach for the epirb/plb if it was a mayday situation. Purely a personal opinion though.
I would use the adapter to connect my DSC equipped handheld to the ship's aerial if a) I could remember where the adapter is and b) I knew where the end of antenna cable was and and could actually get at it without dismantling the nav station. I reckon a DSC call from a masthead antenna might just reach 50 miles on a good day, even from my handheld.
I would use the adapter to connect my DSC equipped handheld to the ship's aerial if a) I could remember where the adapter is and b) I knew where the end of antenna cable was and and could actually get at it without dismantling the nav station. I reckon a DSC call from a masthead antenna might just reach 50 miles on a good day, even from my handheld.
JumbleDuck
Well-Known Member
If you believe that I have some good gambling games we could play.
PaulRainbow
Well-Known Member
My boat came with two masthead antennas, for some odd reason. It also had one on the pushpit that was wired to the FM radio, i've replaced that one as it was a bit iffy and routed the cable to the black box VHF. It's fitted with a PL259. I have a patch lead with a PL259 on one end and the FM connector on the other, screwed onto a female/female PL259 connector and clipped beside the VHF. In the event of a dismasting i'd unscrew it from the connector and connect it to the VHF.
The black box VHF is installed beneath one of the saloon sofas, along with the batteries and a few other items. It has a handset at the chart table and another in the cockpit. Besides the FM radio there are no other fixed electrics at the chart table. The switch/breaker panel is on the side of the companionway and the VHF is switched from here. It needs a switch because it's a black box unit.
The GPS receiver is mounted in a ceiling space above one of the aft cabin wardrobes. It is connected to a small NMEA 2000 network which lives under the chart table seat. The antenna cables are all routed well clear of the switch panel, but terminate in the battery compartment.
So, a fire at the switch panel would indeed take the VHF out as the switch wiring would be burned. However, if i can put the fire out it's an easy fix as the black box and antenna cables will have survived. I just need to open the battery compartment and connect the VHF to a battery. I can connect the N2K supply while i'm in there and i still have GPS/DSC.
As for GPS, i have my phone, tablet, N2K GPS, laptop with a USB dongle and of course my handheld is a DSC model.
I have given some thought to what's been said and i think i'm almost as covered for emergencies as i can. But, it might be worth considering an emergency switch fitted in the battery compartment, which would bypass the switch/breaker panel.
I was hoping you'd ask me what to do with it if the mast collapsed, leaving you with no radio and a halyard deficiency.[/QUOTE]
What would i do with a coiled up emergency antenna in the event of a dismasting (just in case the mast falls backwards and takes the pushpit antenna out and the handheld battery is flat
) ?Hardtack
Member
“I have given some thought to what's been said and i think i'm almost as covered for emergencies as i can. But, it might be worth considering an emergency switch fitted in the battery compartment, which would bypass the switch/breaker panel...”
Yes indeed! I think yours is an excellent idea and a thoroughly seamanlike belt ‘n braces approach. I reckon your emergency switch proposal might be the nearest we’ll get to a complete solution to the perceived problem of helping to maintain battery power on a fixed station VHF.
Essentially a secondary supply line in case a problem arises at the switchboard. No unnecessary connections or other (potentially faulty) circuits borrowing (i.e. loading) the backup supply cable. I seriously applaud your idea. So taken with it that I’m highly likely to implement it on my own boat when I visit her later this week.
The only addition I’d make to your circuit would be to include a 10A fuse or circuit breaker between the battery positive and your battery compartment emergency switch, to protect the proposed emergency supply cable. So in the event of the emergency cable becoming damaged (perhaps through chafing) and shorting to ground, the circuit protection adjacent to the battery would isolate the entire length of cable from the positive terminal. From the tone of your post, which suggests you know exactly what you’re doing, I’d guess that you’re technically savvy enough to take that addition as a given, so didn’t bother mentioning it.
Although the direct VHF / battery supply question seems to cause a lot of hand-wringing and vociferous comment in the UK, it’s a mandatory requirement in the USA, Canada, Greece, and quite possibly other countries that I haven’t been involved with (other than as a leisure visitor) in a marine context. That’s not to say that they’ve got it right - but those nations nonetheless consider the direct route best practice to the point where they’ve seen fit to support the method with legislation.
Icom and Garmin also support the direct connection method for marine VHF, as indicated by many of their installation diagrams. That said, Garmin is an American company, and as a large sector of Icom’s market is the USA then installation literature generated by those manufacturers might well be biased towards USA installation requirements.
Be that as it may, I believe your own solution covers all bases plus a bit more - and it’s a notable improvement on both the “power via switchboard” method and the “direct to battery” method.
Moving on...
“What would i do with a coiled up emergency antenna in the event of a dismasting (just in case the mast falls backwards and takes the pushpit antenna out and the handheld battery is flat...”
I’ve abandoned my original solution to that one. Just post it to me when you get home and I’ll send you a refund for the capital expenditure! Or, if you’re determined to use it in anger, once you’ve got your departed mast under control so that it won’t puncture your yacht, you could lash a spinnaker pole (or whatever’s available) to a stanchion - assuming you still have a stanchion - and hang your bendy antenna from that.
Yes indeed! I think yours is an excellent idea and a thoroughly seamanlike belt ‘n braces approach. I reckon your emergency switch proposal might be the nearest we’ll get to a complete solution to the perceived problem of helping to maintain battery power on a fixed station VHF.
Essentially a secondary supply line in case a problem arises at the switchboard. No unnecessary connections or other (potentially faulty) circuits borrowing (i.e. loading) the backup supply cable. I seriously applaud your idea. So taken with it that I’m highly likely to implement it on my own boat when I visit her later this week.
The only addition I’d make to your circuit would be to include a 10A fuse or circuit breaker between the battery positive and your battery compartment emergency switch, to protect the proposed emergency supply cable. So in the event of the emergency cable becoming damaged (perhaps through chafing) and shorting to ground, the circuit protection adjacent to the battery would isolate the entire length of cable from the positive terminal. From the tone of your post, which suggests you know exactly what you’re doing, I’d guess that you’re technically savvy enough to take that addition as a given, so didn’t bother mentioning it.
Although the direct VHF / battery supply question seems to cause a lot of hand-wringing and vociferous comment in the UK, it’s a mandatory requirement in the USA, Canada, Greece, and quite possibly other countries that I haven’t been involved with (other than as a leisure visitor) in a marine context. That’s not to say that they’ve got it right - but those nations nonetheless consider the direct route best practice to the point where they’ve seen fit to support the method with legislation.
Icom and Garmin also support the direct connection method for marine VHF, as indicated by many of their installation diagrams. That said, Garmin is an American company, and as a large sector of Icom’s market is the USA then installation literature generated by those manufacturers might well be biased towards USA installation requirements.
Be that as it may, I believe your own solution covers all bases plus a bit more - and it’s a notable improvement on both the “power via switchboard” method and the “direct to battery” method.
Moving on...
“What would i do with a coiled up emergency antenna in the event of a dismasting (just in case the mast falls backwards and takes the pushpit antenna out and the handheld battery is flat...”
I’ve abandoned my original solution to that one. Just post it to me when you get home and I’ll send you a refund for the capital expenditure! Or, if you’re determined to use it in anger, once you’ve got your departed mast under control so that it won’t puncture your yacht, you could lash a spinnaker pole (or whatever’s available) to a stanchion - assuming you still have a stanchion - and hang your bendy antenna from that.
Hardtack
Member
I'm okay with blackjack, if that's on the menu.
I reckon that most gamblers bet on chance and lose, whereas the intellectually well equipped gambler employs statistical probability - and still loses but in a cleverer way.
