akmext

To clarify how I have come to 8.5mm2 for the pump run: Two 12v pumps with a max combined draw of 8.7A over a total circuit length of 18m using 8.5mm2 gives a voltage drop of 2.9% - acceptable and negates the above mentioned problems eg burn out, no cut off. Reverse calculated using 6mm2 cable instead of 8.5 gives a voltage drop of 4.1% which is probably acceptable considering that both pumps are very unlikely to be running simultaneously? This would also make connecting 6mm2 to the 1.5mm2 less problematic than with the 8.5 to the 1.5. I may even add a switch prior to the second pump to ensure that they will not be in operation simultaneously as this pump will only be used when needed for a second water system. I would just prefer to over kill than to under do Also 100% agree - last thing I want to do is cause harm to me, anyone else or my beloved barge! However everyone has to start somewhere and no one was born with such knowledge. To simply say I don’t understand so I won’t do it seems like a cop out to me. Would rather spend the time trying to learn and plan so that I know the ins and outs of the system I’m going to be installing. It’s all in the planning and to clarify I know my limits so will be getting my plans looked at before I set to it. Would just rather present what I believe is right and learn from any corrections than pass the buck to someone else to do it and be clueless about a system I will be using and no doubt end up troubleshooting or modifying at some point.

No no it makes complete sense. I think I may have over complicated in my asking. Really the quandary was whether to account for the small gauge tails on loads when creating my circuits and considering fusing, or, whether they are by the by eg considered part of the load/equipment rather than the cable which is what we fuse to protect. To clarify any misunderstanding answers on the forum suggest this for my two earlier examples: Pumps: Fused switch panel to 8.5mm2 cable to connecting length of 2.5mm2 cable to 1.5mm2 tails (21A) to two water pumps (6A, 2.7A). With 15A fuse at panel. LED lights: Fused switch panel to 2.5mm2 cable to 0.5mm2 tails (11A) to LED lights (1.5A). With a 3A fuse at the panel. I’ve actually worked backwards from a list of equipment I require on the boat and have tried to divide my circuits sensibly in terms of load and layout. I’m still in the planning process but so far have the following circuits which will all be off a fused switch panel, returning to the negative feed: - bedroom + kitchen lights - living area lights - supplementary LED strip lights + 2x12v usb sockets - 2x water pumps - shower gulper pump + 12v extractor - 12v toilet flush + bathroom lights - wheelhouse lights + 1x12v usb socket Items such as nav lights, horn, bilge pump will have their own separate fuses/switches at the dash. I will also be running 240v - one radial to serve the kitchen area and a ring main serving the rest of the boat.

Thanks for everyone’s prompt replies. To clarify I meant 8.5mm2 and it’s yes, it’s available in tinned multi strand 👍 The use of 8.5mm2 to 0.5mm2 is just one example of a common situation when wiring a lengthy boat e.g. accounting for voltage drop over the length of the cable run results in a larger gague wire being linked to equipment with smaller gague tails. Two ‘real’ examples I'm dealing with: - Two water pumps with a max combined draw of 8.7A (unlikely to be running simultaneously but still allowing for max) with a total circuit length of 18m suggests 8.5mm2 cable to be suitable which will be linked to the 1.5mm2 tails of the pumps - 6x3w led lights two way switched with a combined draw of 1.5A over a total circuit length of 33m suggests 2.5mm2 to be suitable which will be linked to the 0.5mm2 tails of the lights The idea of fusing prior to the loads to account for the 0.5mm2 tails is logical but seems impractical as I understand this would mean having accessible fuses part way down the length of the boat? Also there will be several lights and therefore several 0.5mm2 tails to deal with eg the 6 lights in the above example have approx 1m lengths between them which, as they make up part of the total length of the circuit, I would assume should be 2.5mm2 - therefore meaning linking 2.5mm2 to 0.5mm2 tails multiple times. This seems like a good solution but also a significant extra step considering the total number of loads I will have this issue… which is why I’m wondering if I’m overthinking it and perhaps dmr’s comment is how this problem is approached by the majority with no ill effect..

I am mid renovation of a small Dutch barge and currently planning my electrical systems. Ive calculated voltage drop and cable size for all my circuits but one thing bothers me - many 12v loads have tails that are small in gauge eg 0.5mm - so I could be running a 8.5mm cable (in line with voltage drop calculations) and linking it up to the 0.5mm wiring on the load. I know I must fuse to protect the smallest cable in the circuit so any explaination/tips as to whether this is or isn’t an issue or how this works would be much appreciated.

Glad to hear it's all still in good nick after 7yrs. Mine will also be facing towards the bow so that's a good point you make. I'm renovating afloat but ballast/trim of the boat continually changing as thing are ripped out and replaced - think a deep shower tray is perhaps also useful for this reason.

Just wondering if anyone has any experience with Wesley Windows shower doors? I've seen good things about the windows they supply but not many reviews of the shower doors. If anyone knows of any alternative suppliers of reduced height shower doors that would be great too! Thanks!

I’m thinking you’re right - the vactan does need to be left longer... there doesn’t seem to be any instructions readily available about overcoating time though ? And floor paint due to cost - bilge paint isn’t cheap! As an overcoat to a vactan’d surface I thought the heavy duty floor paint would be a good option and have seen some other good reviews from use in bilges. It’s oil and chemical resistant and suitable for use on metal.

Thanks Dave In an ideal world that or owatrol is what I’d be using but it’s pricey stuff. I know in most cases you get what you pay for but with such a large area to eventually cover I opted to spend on the vactan and save using the floor paint which is less than half the price. Seems to have done the trick in most places so far ?

Without dedicating your whole life to it I think not ? Im a bit pedantic about most things I do on the boat but, unless you’re starting from brand new or totally gutting an old boat and spending a fortune and/or a lot of hours on it, I think it’s damage limitation!

Realistically I’m probably not going to grind it all back again - it’s taken a lot of work to get to this stage given the state it was in prior to any work - and I’m talking sodden with slabs of rust 5mm thick (don’t worry I’m overplated!) As it’s localised I was hoping to get away with wire brushing affected areas then spot treating with vactan (when conditions are ok) then more of the heavy duty paint over that.

Yes there has been angle grinding nearby since painting so it may well be that - guessing I would just wire brush back and treat again? Also the rusting specs are localised and not over the whole treated area. Was done end of Aug so warm enough - I’m all too aware of vactan being ineffective below 10 degrees! Didn’t realise 24-48hrs required prior to overcoating though - instructions don’t state anything about overcoating time but it would make sense to leave it to cure longer as you’ve said.

Hello! Just after some opinions or advice on why I might be seeing rust spots come trough my bilges treated as follows: 1. Significant chunks of rust removed 2. Wire brushed and scraped down clean as much as possible 3. Wiped down with white spirit, left to dry 4. One coat of vactan, left to cure for a few hours at least 5. One or two coats of leyland heavy duty floor paint All done a matter of months ago and now tiny speckles of rust have appeared through the paint. Any ideas why and what my next steps could be? Thanks in advance for any help!!