smileypete

Hi, You can work out the voltage drop as: 0.017V per amp per metre length of the cable divided by the mmsq CSA of the cable. I've just measured the resistance of a 100m reel of 1mm sq as 1.7ohms. Passing 1 amp through it would create a voltage drop of 1.7V, so the above checks out OK. This comes from the resistivity of copper, a cubic metre of copper has a resistance of 17 nano ohms from one side to the other! cheers, Pete. Edit: made slight mistake with formula...

Hi, I think my earlier message has been misinterpreted, so I'll reiterate and clarify some of it: In the last sentance I 'd better have said the amount of AC current and DC current conducted by the GI. It's not the voltage across the GI but any DC current flowing through it that's important. It's DC current flowing through the earth connection that contributes to galvanic corrosion. Without some measurement of this, there's no way of knowing if amount of corrosion caused is negligable or significant. This just doesn't look right to me, surely it depends on the source impedance of the AC voltage. cheers, Pete.

Hi, I'd wait and first see whether the default setup charges your domestic batteries adequately in normal use. If not then the next step is to see if the Sterling ABC would give a worthwhile improvement. If you can measure much voltage the alternators generate at typical cruising speed, that will greatly help others to give good advice on the above. cheers, Pete.

I think both Gibbo and chris w are missing the point...

OK, time for a little summary... the theory of the galvanic isolator (GI) RFI problem is as follows: You have a boat with hull-earth bonding, and a GI in the earth connection to the shore line. RFI generating equipment is plugged in on the boat, this causes the GI to conduct a small amount of AC, and a smaller amount of DC. The small amount of DC current is significant enough to cause corrosion to the hull. Now, at present this is just a theory. To prove this theory we now need a test method, and some results, in order to draw our conclusion. This approach is not degree level stuff, more pre O-level or GCSE!!! The results I would like to see is some real world measurement including: The type and size of boat. The type or design of the GI. The equipment used which generates RFI. The amount of AC and most importantly DC conducted by the GI. Without this there is not much point arguing the finer points of the theory itself! Blackrose has quoted some measurements done by the manufacturer of the GI he is using, but so far there is nothing better to go on... cheers, Pete.

You might as well check them all once in case of any wiring problems with the sockets. Thereafter any socket will do. cheers, Pete.

I think diode failure in a GI is far less likely than improper IT wiring. If an IT isn't wired properly the RCD after won't catch any dangerous faults. It is much easier for the average boatowner to connect any GI correctly than any IT. Just look at the questions on IT wiring both here and on u.r.w. Though working in the industry, you may still only appreciate one perspective of the problem. As an aside... This is one problem that safety commitees often suffer from. They have a lot of technical knowledge in particular areas, but aren't very good about taking a wider perspective and performing a proper risk analysis. cheers, Pete.

Your shorepower inlet should have an earth connection bonded to the hull. This will act in the same way as an earth spike, as called for by the website when there is a neutral-earth connection at the generator. For this scheme to work there needs to be an earth connection between generator and shorepower inlet. One of these would show up most shoreline/generator wiring faults: http://www.maplin.co.uk/Module.aspx?Module...#&doy=13m11 cheers, Pete.

Hi, Sounds good, I've got a 38' 'Springer' nb with cruiser stern so there's not a very long cabin space to say the least, though it's 8' wide which helps. There's a loo and shower at the back and a bit of corridor through to the rest, which is one space for galley, lounge, and sleeping bit. I've made some simple shelves to go under the gunnel at the sides, on which are stored all manner of things depending on where they are in the boat. Before those I had fitted cupboards down one side, but the doors opened outward, and the stuff that belonged in them would end up on the floor in the way of the doors Something that's really helped is getting a load of small and medium clear storage boxes from the local hardware shop. The medium ones are a bit bigger than A4 so ideal for papers. Being see-though it's easier to find things in them. I have a double 'metal action' futon which is brilliant for storing stuff under in the aforementioned boxes. The dreaded Ikea do a 2 draw square birch storage unit which fits quite neatly neatly underneath too. I doubt I'll post photos as it's usually a bit tooo untidy, but if there's anything you'd like to ask please do. cheers, Pete.

The switch on surge is caused by a 'degauss circuit', which keeps the tube demagnetised and so stops peoples faces eventually turning green or purple (on the TV that is!) Someone qualified to work on TVs could easily fit a switch to disable it when it's not needed/wanted. Indeed, and good connections are very important too. cheers, Pete.

Hi, You could try asking Rinnai UK, I'd be interested to hear what they say: http://www.rinnaiuk.com/ BTW there's a service manual here which might be useful sometime: www.rinnaisales.co.nz/tradesmart/rinnai2/pdfs/service_info/21.pdf cheers, Pete

Hi, A length of stainless chimney/flue/liner with a slit down the side should do, it can be rolled smaller then pushed down into the inner chimney and will spring apart to hold itself in place. The above should be available from a good stove/fireplace shop, not some arty farty showroom but a place that sells fire cement, firebricks, glass rope etc etc. With a bit of luck they might even have a n offcut/old/used bit for a good price. Failing that try a chandlers that sell stoves. cheers, Pete.

Google might be a bit of help here: http://www.google.co.uk/search?q=dickinson...en&safe=off HTH, Pete.

Is there a spec? Out of interest, what is the power rating, efficiency, and power consumption when idle? cheers, Pete.

The switching current in the earth connection are very very brief in duration, in no way is it constant! Also even if the GI is biased into conduction when this happens, the current involved is not large. Averaged out over time it's almost certainly vanishingly small. Not quite, see above... Anything switches of the mains current as part of it's operation, dimmers, computer power supplies, some battery chargers. I posted about this on another thread here. As I said in the above post, I'd like to see some real world measurements in order to decide if there really is a problem or not. cheers, Pete.

Trojan T105's are worth a look, eg: http://www.trojan-battery.com/Products/Marine.aspx http://www.batmanuk.com/trojan.htm cheers, Pete.

I've got something like this, which is a little cheaper: http://www.screwfix.com/app/sfd/cat/pro.js...48&ts=38871 I only use the 16A breaker and not the 6A as well, to ensure the shore line is not overloaded. Some people wire the boat with a 'ring main' where the cable goes from the consumer unit (CU) round all the sockets in a loop and back to the CU. I think this is a little OTT for a 16A supply, and just have a 'spur' running down each side of the boat back to the 16A breaker in the CU. Something like this is handy to help check the sockets are wired OK: http://www.maplin.co.uk/Module.aspx?Module...er&doy=6m11 Using stranded cable is recommended by the BSS, for a 16A supply 2.5mm2 stuff is fine. If buying cable for the shoreline too it might work out cheapest to get a big reel of 2.5mm2 blue 'Arctic' cable for everything. If the marina supply is RCD protected that gives an extra level of protection. cheers, Pete.

Hi, I'd love to see a useful real world measurement of this condition. Something like 'ABC charger will cause a GI to conduct X milliamps AC and Y milliamps DC.' OK it won't represent all possible circumstances but will give some idea of what may happen. Otherwise the 'problem' could well turn out to be a non-problem after all, who knows??? cheers, Pete.

Hi Jill, How do you find your trad stern boat for living on? cheers, Pete.

Hi, I doubt a 2" tube would make a lot of difference. You could try making a 6-8" tube of thin dust sheet plastic, and put a 12v 'dashboard fan' for a car at one end. If the other end is narrowed, the fan should inflate it. Don't let the tube get near the fire whatever you do!!! cheers, Pete.

Hi, Larger users may get a preferential rate that is cheaper than domestic. I wonder what BW and marinas actually pay? cheers, Pete.

Hi all, How much does spray foam cost for a given size narrowboat? Has anyone considered or used 'multi-foil' insulation? cheers, Pete.

Something similar to this will pump down to 1/8": http://shopping.lycos.co.uk/9428en570100.html After that see the other thread for ideas, I've also found sawdust can be good for soaking up oil, if a little messy. Wet or dry vac and pressure washer would be the best way to go IMO. cheers, Pete.

Hi, IMO if your 240v AC is RCD protected, there's not much benefit on a narrowboat for running cables separately. Without an RCD I see some benefit in doing so; if the cables are together and get damaged then theres a greater chance the +12v could become a shock hazard. With a lot of these standards they try and harmonise which is good up to a point, but what's appropriate for a cross channel ferry might not be for a narrowboat. cheers, Pete.

Hi, I have one of these: http://www.concept-wohnen-gmbh.de/england/...ll-viskose.html They sell on Ebay.UK and .DE, it's best to bid on the german .DE site. They can make them smaller to spec, mine cost ~155 GBP incl delivery. They're a medium firm mattresses IMO, anything that can take a 25st person isn't going to be that soft! I've also had a 3" memory topper that I found tooo soft. I wonder if a sprung mattress could be a little cold in deepest darkest winter because of the free air around the springs. cheers, Pete.