PeterF

Check that your chimney is not between the ariel and signal as that can sometimes be an issue - which a pole resolves. Also are you re-using any of the same system for example on my boat I have an external socket and a wire from that to inside the boat so if I changed ariels I would still be using part of the same cabling which if it has a fault will affect all eariels. If you are using part of the existing ariel cable then try to run direct from the new ariel to the TV (both with and without the booster) to eliminate this. Aplogies if I am stating the bl**din obvious / teaching you to suck eggs etc. Peter.

Definitely the instability caused by having a large mass well above the centre of gravity (or equivalent boat location). Our CE plate states 8 people (55ft) but the RCD documentation from the builder states that at no point should more than 1/3rd of the people be on the roof and recommends less than this. This gives me the problem of which parts of my body I cut off before getting on the roof when my wife is the only other person on board.

Anyone remeber the episode of "The young ones" (the 1980's fly on the wall student household documentary) when the TV detector van called and Vivian ate the TV set before letting the inspector in. I think the trouble was he still had the power cord hanging out of his mouth like a string of spaghetti.

I can believe in the olden days steam powered TV sets generated RF noise that could be detected. What about modern TVs and more so LCD / Plasma screens, I have not heard of detector vans for years, do they still exist. I thought it used to be that when you bought a TV set the shop colelcted names and addresses and this was passed on to TVL. These days such information does not appear to be collected. Perhaps ths comes back to the earlier posting that all houses have TVs therefore those without licenses are de facto evaders.

The above only applies to semi permanent 2nd homes, you need to check the TVL site to see the clarification. I was thinking of asking the same question as we have just got our boat and bought a telly because my kids stay at home and will watch TV when I am on the boat. If the 2nd home is static or fairly immobile (mobile home) then you need a second license if someone else remains at your main home watching TV. If there is no one at home watching TV while you are in your 2nd home you need the declaration but only 1 license. However, if the 2nd home is mobile as in touring caravan or boat then you do not need a 2nd license at all and no declaration. Extracts from the TVL site are appended below. Peter. Do I need a licence for my mobile home or caravan? If you have a static caravan, mobile home or moveable chalet, and it has a TV which is used at the same time as a TV set is being used in your main licensed home - you'll need a separate licence to cover your second home. However, if the TV in your static caravan or mobile home is never in use at the same time as your TV at your main home, you don't need a separate licence. But you do need to complete a declaration form and return it to us so that we can update our records. Do I need a licence for any other type of home? If you watch or record TV programmes in a second home which is a touring caravan or vehicle, or a boat, you do not need a separate TV Licence; you will be covered by the TV Licence for your main residence. TVL 2nd home regs

The weight of an IT being in the megatonne range is one of the key downsides to their use. Therefore, has anybody any experience with this Mastervolt system that weighs only 6kg. Anybody know what it costs as I can not find it listed on a quick search. It seems in US with need for GIs to have self checking capability etc. that the cost of installed GI system is much more expensive than what can be installed in the EU and ITs may well be being seen as a cost viable option. Peter. Mastervolt lightweight IT

John and Chris, I take this to mean that the forces should be borne totally on the sides of the belt and the teeth should be kept clear of the pulley and they should not bear any load on their inner surfaces. The belt on the boat when we got it was quite narrow and I repleced it with like for like but from Halfords and it was sitting deeply in the pulleys - the new one is better but looking at the earlier link to an industrial supplier a wider belt may help to at lengthen belt lives by keeping the teeth away from the pulley but perhaps not cure the problem. Will see what sort of temperature develops in the engine bay on next lengthy cruise. Thanks, peter.

I knocked that one up on Excel, a lot of my job involves mathematical modelling of various chemical, thermal and mechanical processes and Excel can be used for rough and ready models. I am not volunteering to do any more stuff though. I only started this as a question around conductance in the water in a marina. What it has shown is as per GIbbo's earthing comments that potential differences can build up in the water between hulls with a raised voltage and local earthed surfaces be they other boats or the bed of the canal. I also have to state that I assumed no resistance between the hull and the water - the hull will be in some unkown oxide form rather than bright steel. Certainly in a shallow marina the most direct path is to earth - but what if the marina was lined with a membrane during construction, can the earth be taken as true ground in this case. In terms of current flowing then depending upon which way it is flowing and to / from what your boat could either be the the giving up its metal or your boat could be OK (or even being electro plated). In terms of adding anodes to this type of model, yes it can be done but it will be more complex and I am not going to do it. Cheers, Peter.

The boat we have just bought has a 4yr old Barrus Shire (Yanmar) 2000 40hp engine using a single drive belt with 50Amp + 80Amp alternators. When I inspected the boat before purchase the belt on the drive had no teeth left and there was loads of rubber powder around the alternators. I thought what a shoddy owner leaving the belt to get into that state but reading this it could easily have caught someone unawares with rapid wear. I am now forwarned and will watch this routinely. Has anybody tried to remedy this at all although as one alternator has no adjustment it would be more difficult to change to 2 indepedent belts - suppose could try and add 2nd pulleys. Joining this forum is reaping benefits, glad I found it. Peter. The boat we have just bought has a 4yr old Barrus Shire (Yanmar) 2000 40hp engine using a single drive belt with 50Amp + 80Amp alternators. When I inspected the boat before purchase the belt on the drive had no teeth left and there was loads of rubber powder around the alternators. I thought what a shoddy owner leaving the belt to get into that state but reading this it could easily have caught someone unawares with rapid wear. I am now forwarned and will watch this routinely. Has anybody tried to remedy this at all although as one alternator has no adjustment it would be more difficult to change to 2 indepedent belts - suppose could try and add 2nd pulleys. Joining this forum is reaping benefits, glad I found it. Peter.

Chris, Oh you meant do the FE cal now, I obviously thought "it" meant something else. Anyway I put together a model and the result is below. I know this has lost its place as the discussion has moved on quite interestingly. This is to scale and shows quite wide current lines. The model was of 2 boats sat on the surface of the water to simplify model. Base plates were 2m wide. The model was done as 2D ignoring end effects. The boats were spaced 2m apart, hence mid points of the base plates were 4m apart. The water was 4m deep. I could be accused of being disengenious here (if only I could spell it) as water is not normally that deep. I have also assume the water is conatined in an insulated container so there are no grounding effects. The water is 200µS/cm, the boat on the left is at +1V, the boat on the right at 0V. The coloured areas are contours of constant voltage, the bright red from 0.9 to 1.0V, the dark blue from 0 to 0.1V and each one representing a 0.1V range. The black arrows represent current stream lines, the area below the first line has 10% of the current flow, the area below the uppermost line has 100% of the current flow with the space between pairs of lines containing 10% of the current flow. The current streamlines are orthogonal to the contours of constant potential as they should be. The model predicts a total current flow of 0.185A for a 15m long boat giving a resistance of 5.4 Ohms. I ran the model with 2 flat plates 4m apart 2m wide and 15m long and this gave 6.7 Ohms as had already been established and hence 0.15 Amps. I agree if I had restricted the water depth to say 0.5m below the hull then the resistance would have been higher and the contours shallower. The effect would also have been different had the surroundings benen modelled as earthed at 0V. However, to say the surrent only flows in a direct thin strip is wrongbecause if no current was flowing from the bottom of the left hand boat downwards this would mean that there was no voltage differential, hence the water under the left hand boat would be at 1V. The same goes for the ater under the right hand boat which would have been at 0V. therefore you would have 2 volumes of water from boat to bottom of container at different voltages, which would not be sustainable, thus the current can flow in arcs between point sources in a large volume. Peter.

Electricity does not travel in straight lines it travels at 90° to contours of equal electrical potential. The only time you get planes of equivalent electrical potential is from an infinitely large flat plate. Otherewise most everyday 3D objects create 3D shaped fields. On an infitesimally small scale electricity does flow in straigh lines, like water does down a slope, but if the lines of equivalent potential are uneven then on a global scale the current can flow round corners as does a stream down anything other than a conical hill. If you had a plastic pipe full of salt water with a U bend in it and an electrode at the end of each leg of the U bend you could still flow electricity through that pipe. A conductive fluid can be considered as a matrix of resistors and you could solve the problem by finite element methods. This tries to show 2 boats with a matrix of resitors connecting the boats together. Given this nature of the water to transport current in 2D the current has multiple paths to traverse between the edges of the 2 baseplates AND between the two baseplates themselves. Now in my original post I did say there were geomtric factors, i.e. the actual area through which the current flows is smaller than that of the base plates. But some current will flow outside of the direct line. The current outside of the direct line will be lower per square cm as it has furtehr to flow and hence a higher resistance but it will augment the main flow wihtout a doubt. If you took your analogy to its extreme, then if the two baseplates were coated on the cut edges as well as the boat sides leaving only the horizontal surface bare then no current would flow between them. This despite having 2 large plates plates suspended in a conductive fluid. Peter.

Ohhh B****r I see my error now. I am now eating a large portion of humble pie and aplogise to Chris, it is only me that needs to go back to school for getting cm conversions mixed up. So 7 ohms is the answer. Thus with low resistance currents can readily flow between boats even with small voltage differences. Peter.

Chris, ooooh - its back to school for the both of us I am afraid. I scribbled some sums on a piece of paper based on tapwater giving 0.75S (100µS/cm) and then wrote the note on river water. The correct answer for river water is 0.2S/m (200mS/m or 200µS/cm) x 30m² / 4m = 1.5S which is 0.67Ohms. For this reason I suggest safety regs are ammended to suggest you do not bath in Perrier water whilst carrying out DIY electrics!!! Peter.

Some figures I have for water conductivity are 100 µS/cm for tap water, 200 for river water and 500 for mineral water. Heaven knows what some of the canal water is because it has a long residence time to collect agricultural run off / grey water from boats etc. Taking 200µS/cm as a good value, this should be through of a 200µS.cm/cm², i.e. it depends upon both distance through which the current flows and area through which it flows. If we correct this to a length scale of metres then it becomes 200mS.m/m². If we assume the narrowboats have unpainted baseplates of 2m x 15m (area = 30m²) and the boats are 4m apart then the conductance is 0.75S which is 1.33 Ohms. This is simplified as the two baseplates are not parallel plates and there will need to be some geometry in there to account for this and if the canal is shallower than 4m then the point of maximum resistance will be dictated by that. However, as an order of magnitude calculation it illustrates that the resistance values should be quite low, mainly because of the large areas involved. Peter

Chris, Mine were on the boat when I bought it last month but I have bought them before from RS. They are called spanner locks. Go to RS website www.rswww.com and enter spanner lock into the search. The stock number is 451-1469, you could search on that also. Peter

My covers are split about 20%:80%, both are anti slip steel plate with gas lift struts on the larger forward cover which is hinged with stainless hinges by the cabin entrance doors. Both covers have the low security cabinet type locaks you see on electrical type cabinets that engage in the support channels. I know these are not very secure, use a very large screwdriver to open them. My philosophy however is that they are there for protction against the opportunist thief, vandal or drunk on the way home who finds it amusing to void himself in your engine bay and they will stop this sort of thing. If somewant wants to knick bits and comes tooled up appropriately then there is little that can be done to stop them. These days with portable battery powered equipment you can make short work of many padlocks. Peter.

Richard, Thanks for that, will give it a try. First attempts worried me because I was bending down or squatting and I kept thinking my head was the closet part to the top of the spike if I got things wrong. But then that is the hardest part of me and I did not want to break the spike. Peter.

Travelled part way up Calder & Hebble for the first time at the weekend. I had no trouble using the spike to open paddles, the trouble was lowering them which seemed to need 3 arms and if not careful worried me about getting bodily bits in the way if the spike whipped round whilst lowering the paddle and holding the ratchet clear. When lowering them I inserted spike, took pressure off the ratchet (or pawl or whatever it is called), lifted the ratchet by hand, rotated the spike 90°, put the ratchet back in and moved the spike round one slot and continued. Is this the right way to do it or is there an easier way. Peter.

Hello there, I have only recently found this forum and been reading old posts etc. very inetresting and something I will keep coming back to and hopefully contributing to. I am not new to boating, first experience was as an 18year old on the Llangollen many years ago on a schoolmate's dad's boat. I also married into a boating family, with my father in law having a cruiser then a narrowboat in the 1980s we we made use of, always wanting to have our own boat. Since he sold that in 1990 or so we have had several hire boat holidays culminating on the Llangollen this August. I made the mistake of buying Waterways world in Ellesmere - with the result that 2 months later we have an empty bank account (we downsized house last year) and a 2nd hand 55ft cruiser stern Narrowboat - bought as Shirley Lousie but being renamed to Kingfisher. We have just completed our first run taking the boat from Thorne to Shepley Bridge on the Calder and Hebble to beat the Woodnook stoppage this month. All of our previous boating has been done in the East and West Midlands, this was our first trip on the North East waterways, we both some from the midlands but now work in the North East, hence the choice of location. My wife was a little aprehensive about the commercial traffic on the Aire and Calder but this turned out to be less of a problem when we met Rix Eagle one of the petroleum barges at Pollington. I suppose it was a case of the unkown, but the midlands canals are more intimate. We are looking forward to tidying the boat up over the winter and then exploring the pennine canals next year as these are terra incognito for us.