MoominPapa

Yes, don't connect neutral and earth of a shore supply. Apart from anything else, you'll trip the RCD in the shore supply post. This is one reason why inverter/shore changeover switches have to be double pole, switching both live and neutral. That way the earth-neutral bond gets removed when switching to shore supply. I wish there was an easy way to include a sketch circuit diagram here - it would make explanations so much simpler. Anyway the main point remains: bond the neutral terminal of the inverter directly to the Hull earthing point. MP.

I've read Gibbo's document, and in my opinion, it's correct and well argued. That's one more vote for Gibbo. MP.

Agree completely to here. Disagree with this; I think the exact opposite is true. Consider the following scenario. Boat supplied from inverter through RCD, human touches hull and live conductor simutaneously. Firstly without the neutral to earth bond: If all is absolutely fine, nothing will happen: the hull will float to the 240v output of the invertor, but no significant current will flow since there's no circuit back from the hull to the neutral terminal on the invertor. The RCD will not trip. BUT, if there's already any connection from neutral to the hull, from any means (damp, cut insulation....), then the human will get a shock via the circuit invertor live -> human -> hull -> accidental neutral connection -> invertor neutral. The RCD will not trip. Before the live-touch, there will be no way to tell that the neutral to hull leak exists, everything will be working fine, such a fault could persist for years. Now bond the neutral terminal on the invertor to the hull and try the same thought experiment: firstly there cannot be an accidental neutral to hull connection, it will trip the RCD because some neutral current will take the path via the hull and neutral terminal bond, bypassing the RCD and unbalancing it. Second, the live touch will also send some current live -> human -> hull -> bond -> neutral, unbalancing the RCD, which will again trip, before the current reaches a harmful level. Even without an accidental neutral to hull connection, the bonded system is safer. Without a bond, a human touching the hull and live and neutral simultaneously will get a shock and not trip the RCD. With the bond, the RCD will trip, since some current will take the live -> human -> hull -> bond -> neutral route and unbalance the RCD. To be clear, the Hull bond has to go to the neutral terminal of the inverter, the one that is connected to the RCD input. It should NOT go to the neutral output terminal of the RCD. In effect, this is the same as the electricity supplier does on land. The neutral terminal of the substation transformer is always very firmly earthed. That's true, for the in-building wiring. The difference on a boat with an inverter is that you have to worry about the equivalent of the substation. As I said substation neutral is always earthed, and inverter neutral should be also, for the same reason. Oh yes! Sorry it hijack your thread with more geekery, PB. Cheers, MP

Congrats. Looks like a nice boat. Hope to see you around when you make it to the flat, Eastern bits. Have you sorted a mooring? Cheers, MP.

In the situation you're describing, the engine, and therefore propshaft and prop are at the same potential as the battery negative, but the hull is floating somewhere between battery positive and battery negative, exactly where depending on the stray resistances between the boat wiring and the hull. You will therefore have a current between the prop shaft and the stern tube. This is Not Good. One of the reasons for all this stuff is to ensure that every conducting part of the boat that's in the water is, as close as possible, at the same potential. That ensures that you don't get currents through the water and all the associated ionic chemistry and corrosion. It's for the same reason that the hull is not used as the earth return. Even big lumps of steel have some resistance, so if you're pushing large currents through them, you'll get some potential difference, and some current will pass through the water surrounding the hull, rather than through the hull itself. A small proportion, to be sure, but a small proportion of the current flowing through a starter or inverter or alternator is enough to corrode the hull.

"Bond" means electrically bond, which means "connect together electrically with a secure, low resistance connection." Practically, it also implies some amount of mechanical strength, so that normal wear and knocks can't accidentally break the connection, and a connection with high current-carrying capacity which will withstand potentially large fault currents. on a boat, it means the hull. The hull of a boat should also be connected to the wider mass of the earth through the earth conductor of the hook-up lead when you are using shore power. More or less. One conductor for each system is enough, and it has to be secure (protected from corrosion, locknuts or other locking devices.) One other thing to check is that the neutral (blue wire) terminal of your inverter has to be connected to earth too. Some do this internaly, some don't. The inverter on Melaleuca doesn't, and the is high on my list of jobs to do, It should have a fuse, in the positive wire, as close to the batteries as possible. Cheers, MP.

Thinking more, I should have known that it was possible. In the past I have owned several 70s era Fiats which had Magnetti Marelli alternators with external "vibrating contact" regulators. Electrical, rather than electronic, PWM! MP.

Oh, I didn't know that alternator regulators are PWM. Makes sense, I suppose, to reduce power dissipation in the regulator. Do they have suitable circuit arrangements to allow the rotor inductance to smooth out the current waveform? If not I imagine the rotor will produce fairly high back-EMF as the current is chopped. Is the whine you get from a heavily loaded alternator related to the regulator frequency? I had always assumed it was rotation speed x number of poles, but maybe not....... MP.

IF (big if) the boat regulations are the same as for domestic gas work, then the definition of "competent" is not formalised. It certainly doesn't imply CORGI. In theory, you can fit gas appliances yourself (for you own use, not for other people and for money) and if it conforms to the makers specs, works well, and doesn't blow you up or gas you then you are, by definition, competent. OTOH if it does blow you up, then you've broken the law, as well as being exploded. More practically for DIY, if you can read, understand and follow the manufacturers installation manual and know how to do gas-tighness testing then there's really no magic. Since soldered joints in gas pipework are verboten by the BSS, you don't even need to be able to make those reliably. I'm not advocating that just anybody should be doing gas work willy-nilly, but just because your local Corgi won't do it doesn't mean it can't be done. MP.

I've had problems with "that toasty alternator smell" from my A127 when it's working hard. It's in an engine room and therefore should be well cooled, but on dismantling it, I found large amounts of fluff and crud blocking the airways. Hopefully with that cleared it will cool OK. Hobson's choice: cook the alternator in an engine compartment and keep it in an engineroom and have it collect hair, fluff and dust from the domestic activites aboard. MP.

I find it difficult to image how it would be possible to get enough force to change Melaleuca's Lister-Blackstone box with a wheel. It would have to be well geared down, in which case it would take even longer to engage emergency stop mode. (Oh look we're going backwards! Not because we're in reverse, just because we bounced off the target.) The alignment on the linkage is all wrong at the moment: when I've fettled it the forces should be easier. The speed control is a wheel, and well geared down. It uses the Stanley drill technique to take the rotation through 90 degrees and the vertical shaft has a square-cut thread on the end on which runs a nut which is pinned to the engine speed control lever. The main thing I would like to change it to provide a positive stop at the idle end of the travel. At the moment it's too easy to repeatedly give the wheel another half-turn "down" to make sure its in tickover and then when you need to go it's an unknown number of rotations before anything happens. MP.

Ah, OK. Does anybody know if it's possible to do the same thing on an Adverc? The 70A Lucas alternator fitted to the FR2 is driven by a belt which wraps around the flywheel, so the pulley ratio is very high - I'd guess 8:1 or 9:1 from memory and without measuring it. That means that the Adverc can wind the alternator up almost to maximum output even when the engine is at idle. This is good for charging, but I think it may be overloading the engine. The governor opens the fuel-racks quite wide and the exhaust tends to smoke. If I could find a way of limiting the current that the adverc demands, that may be more healthy for the engine.

They could look at Bill Fen Marina, Ramsey, NE of Huntingdon. I don't know of there are available spaces ATM, but I've heard whispers of an extension, so there may be a chance for the future, even if there's nothing now. MoominPapa (Happy Bill Fen moorer, no other connection.)

What sort is it? Are they still available? MP.

The plan was to loose the header/day tank, and feed the engine injection pumps directly from the lift pump. I guess using a float valve and keeping the tank would be a possible alternative. MP.

My Lister FR2 has a day tank, filled by a rotary hand pump. Whilst this is all nice and trad, it has some disadvantages. The pump leaks, it's a pain to use and the only way to check the level in the tank is with a dipstick which is even more of a pain to use. So, I'm wondering about solving the entire problem by ripping it out and replacing it with something like Clicky The current arrangement down stream of the day tank is a fuel cock on the tank outlet, then to a filter/water separator, then a flexible pipe to the engine inlet. The engine has a second (wick type) filter. Injector overspill goes into the filter/water sep via a non-return valve. Questions. 1) What pressure should the pump delivery be? The static head from the current day tank calculates to 1-2PSI. Facet make pumps which go that low, but commonly available ones are maybe 5-10PSI. Will it matter if I use one of those? 2) Apart from the injector overspill, there's currently no recirculation. The filter has two blanked-off spare ports, one marked as an inlet and one as an outlet. Can I use the outlet as a recirculate line back to the main tank, to avoid the need to bleed the pump and suction line from the tank? 3) Any BSS gotchas? I know that I need all metal pipes and connections, and no soldered joints. 4) The main diesel tank arrangment is odd: there's both a tank at the stern and one a bilge level. When both are full, the diesel level is about the same height as the engine injectors, when the tank is nearly empty, the lift pump will be lifting from almost base-plate level. Is that likely to cause any problems? Thanks in advance for any suggestions or advice. MP.

I really wouldn't fancy doing that single-handed. I've prefected a technique with rope for these locks, as on-board steerer, but it has been interesting getting in to the downstream landing to pick up the shore-crew on occasion. The boat gets flushed out of the lock like a cork from a bottle and it can be difficult not to shoot straight past! Indeed, today's most difficult problem has been stopping. We've made good progress though! Can't beat Chevetter, but Melalueca is moored for the night on the pontoon on the lake at Ferry Meadows, within easy reach of Stanground for out appointment tomorrow with Tina the lock-keeper. MP.

Update from Melaleuca: we set off from Gayton at 10am this morning, and we're moored for the night just above Cogenhoe lock. We pulled some more crap out of lock 17, and got briefly stuck in lock 16 because of stuff jammed behind the gate. We were followed down the arm by another boat, so traffic is increasing. Cheers, MP.

Go for it! I just spoke to Roy Smith the inpector. Lower Barnwell lock is now passable, but you need to use a windlass to raise the guilotine: the electrics are still broken. I'll be setting off from Blisworth early on Sunday. MP.

Thanks, Chevetter. Please continue to keep us all informed. How are river flows looking, at the moment? Cheers, MP.

We fought rain, snow, hail, etc, etc and made it to Blisworth by Thursday mid-afternoon. I didn't know about Barnwell lock at that point, but decided anyway to take a break. I talked to Andy Hall, the inspector for the upper Nene, who confirmed that it was open and off SSA, but still quite high, and likely to go straight up again with any significant rain. Since significant rain has not been exactly unknown recently, I decided that I didn't want to fight marginal stream conditions and marginal weather for my very first Nene trip, with the added risk of getting stuck half-way down. Given the announcement about Barnwell, that looks like a good move. (What were the EA doing between the 20th when it was supposed to reopen and the 28th when they anounced it's still closed?) So, Melaleuca is moored towpath side at Blisworth opposite Blisworth Tunnel Boats, That feels to me like a safe location, talking to locals seemed to confirm that, and there were at least two other private boats left unattended at the same place. Anyone who passes, please take a look and make sure it's all OK. If Barnwell opens when EA says it might, and the weather is good this week, we may be moving again by next weekend. If we miss that, it may be towards the end of the month before we can get the people together again and time off. I'm hoping I can stretch my 14 days towpath mooring in that case. I'll try and write up a trip report and some photos soon. (PB, WW should have something in her work email-box.) We passed "Keeping up..." going the other way in the middle of Stoke Bruerne flight MP - who really should have had a nice meal of pine-needles and hibernated 'till spring finally arrives........