Lochnevis

The fuse has been removed. Troubleshooting the alternator is going to have to wait for the weekend, but the new battery was given a good charge from the solar. Though if the alternator is broken in a way that is actually discharging the battery (is that possible?), I guess the battery voltage might now be low (it's had ~4 hours running since I changed the heater plugs). I'll check the resting voltage when I'm back on the boat.

Moving the boat today, it does seem to struggle to turn over, but then goes after a few seconds (<5 seconds). This applies even when warm - as the engine needs to be turned off in Thames locks, I had a chance to test a few times! The starting is now what I would consider absolutely fine, but as it didn't used to do this, I'm now a little worried that there's an underlying problem which I shouldn't ignore (or that I've knackered the starter motor a bit with the repeated long cranking attempts!). Does anyone have any words of wisdom?

Well, the new heater plugs turned up yesterday. I fitted them this morning, and it started! The starting isn't quite as good as it was when I got the boat (when it didn't need any time on the heater plugs, and fired straight away), but it only needed a couple of seconds (after ~15 seconds of the heater plugs). So, problem solved, thanks again all! I'll take Tony's advice and leave the rocker cover where it is, though I am tempted by the the idea of getting a compression tester, as suggested by Scholar Gypsy (mostly because I love a good gadget...). A very quick check of the battery voltage suggests that the alternator and/or wiring are in trouble, though (13V at the battery terminals, after giving the battery a good charge on solar charger), but further investigation of that will have to wait until the weekend.

I've taken out the heater plugs and tested them across a battery - and three of them seem to be dead. So hopefully I've finally gotten to the bottom of the problem, with lots of help from the forum! I've ordered replacements, and I'll report back once they're fitted. In the meantime, I'll get myself a feeler gauge to check the valve clearance, and enjoy the fact that there are many worse places to be broken down than the water meadow in Abingdon, especially in this weather! Then I may well be back with questions about how to troubleshoot my alternator, assuming the low charging voltage doesn't turn out to be a wiring issue, and if forum searches come up blank. Thanks all for the help and friendly advice; I'd have been utterly baffled without you. I will investigate if I've posted enough or whatever to sprinkle some greenies around.

Don't worry - no verbal slapping: been there, done that... Hand-hauling out of a Thames lock for 30 minutes of troubleshooting (with the lock keeper looking on), to eventually realise that my crew hadn't pushed the toggle back in, and I hadn't thought to check it, was a little embarrassing. [Forewarned by that experience, I checked the lever on the engine itself, in case of cable snags, as you suggest].

Plenty of fuel is definitely getting into the engine - clouds of diesel come out of the exhaust (very much "smoke" with inverted commas, as you put it - I can taste the diesel), though it does sound like Dr. Bob's engine was getting fuel too (he says that he checked "fuel being delivered"). I guess I'll give the fuel system a thorough check first (especially the new connections), as that should be fairly quick and easy - then I'll tackle the heater plugs (I don't expect removing them to be either quick or easy!). I have no idea how to go about checking valve clearances - any pointers/useful YouTube videos anyone could direct me to (I have a copy of the workshop manual somewhere) - or should I get in someone who knows what they're doing at that point?

Thanks Dr Bob. The symptoms sound remarkably similar, and I had a new fuel tank fitted in the spring, so maybe one of the new connections is dodgy. It would never have occurred to me that a cracked hose/union could result in a starting problem, but then the engine running fine, so I haven't looked nearly as hard as I would have if I wasn't sure that fuel was getting to the engine. I will now!

It was one of these, a Bussmann MRBF-150 (I hope the picture works - my first attempt at posting a picture here). I fitted it when rewiring my domestic system prior to boat safety. I had intended to fuse only the domestic battery, but I ended up with two of them when I stuffed up an order, so tried it out on the starter, and it worked (to my surprise - I'd assumed I'd need a larger fuse); then it worked for over a year, including the winter months. I've just looked at the datasheet, and it's interrupt time at 200% is 60 seconds, which may be why it was working.

@Boater Sam mentioned them, but I haven't checked them out. I'll make it the first thing I look at tomorrow. Is %0 amps a typo for 50 amps? What strikes me as odd if how suddenly this problem came on - it was starting fine, I didn't move the boat for 2 days, then it was very hard to start (blowing the 150A fuse I mentioned, and taking several attempts). And it's been like that ever since. The weather didn't change much in the 2 days I didn't move the boat, so I guess something else did...

At the battery terminals. I'll post the voltage direct from the alternator tomorrow (if I can start the engine!).

Update: I went and bought a new starter battery this morning (same size as before, a 644). The starter battery was definitely knackered, but it seems that there's an underlying problem. I'm now back to where I was a couple of weeks ago - it takes several attempts to start: four times cranking ~30 seconds. After a while (on the 4th attempt, for most of the time) the engine sounds like it's about to fire, but keeps not quite managing it. I couldn't swear that the starter is turning over as fast as it used to, but it doesn't sound unusually slow or otherwise wrong (and it's turning over much faster than it was yesterday, with the old battery). It looks like there is definitely something up with either the alternator or some related piece of wiring, as the charging voltage from the alternator was still very low (12.6V, not the 12.7V I said above). Unfortunately I didn't have time to move the boat today (so I've left the starter hooked up to the solar charger+domestics to make sure it gets a proper recharge.

The starter battery isn't monitored (except when it stops working and I stick a multimeter on it!). The domestics (2* T105 Trojans) are on a Smartgauge. According to the Smartgauge, the batteries generally cycle between around 70 and 100%. From November-January, they start to drop below 70%, and generally at around 60% I start to panic, and stop using anything apart from pumps and lights. I may well spend more time in the pub in winter... I don't think they've ever shown below 50%. As for voltage, I can't remember what the lower end is, but they are usually around 12.9-12.95V fully charged under light load (just after dark at the end of a sunny day, with a few LED lights on, in other words). Mind you, I might have jinxed myself saying they were in good condition - I just checked the water, and they were very, very low indeed. Which is odd, because in the last 4 years, they've needed only very occasional and slight topping up. I don't think it's longer than usual since they were checked, but maybe I've got a bit careless with them. Or maybe something else has changed (I do have a new fridge, but the batteries didn't seem to be discharging quicker, so I don't think it's drawing anything crazy.

I turn the fridge off when the solar can't keep up, usually around the end of October. Other than that, LED lights, and all 12v (no inverter) - so pretty low power usage.

The Trojans charge from an MPPT solar charger, and aren't connected to the alternator - I've got 500W of solar panels, so have never needed to connect them to the alternator charging circuit (or at least not often enough to have actually got around to it!). There is indeed - I changed it, too, though. It's an awkward sod to change, as it's been mounted vertically, cap end down (do these things need to be a particular way up?!) No, the problem started a few weeks ago, in that it was suddenly much harder to start the boat, but it was only today it completely refused. The filters were changed when the problem started, and the engine has been running fine (once going). So I hope it's just the one (probably battery) problem. Thanks everyone for all of the help! I'll try jump starting from the domestics in the morning, and assuming that does the trick, I'll go and get myself a new starter battery. Then I suppose I'll start trying to troubleshoot the low charging voltage (assuming it is still low, rather than being caused by a problem with the battery)...

I'll give it a shot when I'm back at the boat. I hadn't because I wasn't sure if doing so would knacker my domestics (which are Trojans in very good nick, so I was being ultra-cautious). I assume that just doing this once or twice won't do them much/any harm, then?

For pretty much the first time, I've hit a problem where mining the forum for info from past threads hasn't provided the answer (or rather, it's provided several possible answers, and I've no idea where to start!) So, here goes: My boat's engine (Thornycroft 80 = Mitsubishi K4D, keel cooled) has always started pretty well, either in a couple of seconds in warm weather, or after 10-15 seconds cranking in the cold, but a few weeks ago it suddenly became much harder to start, usually need two or three attempts of ~ 30 seconds cranking. But it was still starting, so I (stupidly...) put off solving the problem until I could get to a spot where I could moor up for a couple of weeks (I'm currently on the Thames, but was planning to move on to the canal in Oxford in a few days). And then this morning it didn't. So I'm currently a bit stuck, and in desperate need of the forum's collective wisdom (and hoping that Abingdon council are going to be understanding about me breaking their brand-new 3 day mooring limit!) Some more info: The engine turns over, but not fast enough. Fuel is getting through (lots of vapour when I crank). I changed the fuel filters just in case when the starting became more difficult, but it made no difference. I don't have a clamp-meter, but I think the starter is drawing more current than it used to: I've had a 150A fuse on the starter battery for the last year, and it's always worked fine, but the first sign of the starting problem was the fuse blowing (and the replacement went straight away too, so I've removed the fuse block for now). The starter battery is fairly elderly, and the alternator doesn't produce a great charging voltage (~12.7V, from memory). My domestics charge from solar, but the starter charges only from the alternator. The voltage on the battery after four attempts at starting this morning is 12.2V. I've just hooked the starter up to the solar to give it a good charge. The engine has been running fine once it started, and would restart pretty easily when warm (though still only after a couple of seconds cranking). From reading everything I can find here and elsewhere, the possibilities seem to be (a) a starter motor problem, (b) a battery problem - but I don't see why this would have come on suddenly, (c) poor compression, (d) the injectors need servicing. Is there anything I'm missing - and how should I go about working out where the problem lies? Thanks everyone!

Thanks all! I am indeed talking about the diamond-shaped lock before Nell Bridge (if heading north). The woodwork sounds very reassuring - I had vaguely remembered there being some, but not if it was in good enough condition to hold me off the weir, should the worst happen (e.g. something around the prop at the worst possible moment...).

Thanks Nightwatch. What's it like crossing with a decent flow? I've only been through in dry weather before (and I wouldn't want to end up pinned to the weir...).

I'm moving north up the southern Oxford at the moment, and was planning on Heyford - Banbury tomorrow. But the Cherwell is very high... Is anyone up Aynho way at the moment, and if so, how does it look where the canal crosses the Cherwell? I'll go as far as Aynho in any case, but it'd be good to know now if there was no chance of getting any further than that!

Thanks to everyone who responded. We didn't have a problem in the event: the only substantial ice was on a few of the pounds on the Hatton flight, and it wasn't a problem to break, no more than perhaps half a cm at its thickest.

Thanks everyone, I think we'll chance it! I had visions of half-inch thick ice... I think the weather station data I looked at must have been on top of a hill or something (it reported -5 last night)

A little bit of on-the-ground info would be much appreciated: I was planning in moving a boat from Lapworth over to Warwick tomorrow, but I'm traveling most of the day, and won't get there until late. From the forecast, it looks like it froze very hard down there last night, so I'm now wondering whether to write off tomorrow entirely. In which case, there's no point in me turning up at midnight to thaw out a boat which is currently heated only by a catalytic gas heater! So, can anyone help me out with an eyes-on-the-ice report? And/or a bit of local knowledge on how quickly that stretch freezes and then thaws? Thanks! edited: to fix autocorrect nonsense.

I've just ordered one of the post-in lab kits (for about £25), for a similar reason: a 1987 boat, with the paloma attached to a fireboard (white, in this case). The problem being that the paloma is knackered, and attempts at repair haven't been hugely successful. Anyway, I was surprised to find that the sample required is actually an inch square piece. In my case, this means that taking a sample is likely to pose a higher contamination risk than just removing the thing would, so I think I'll have to take it off (FFP3 mask, plastic sheeting on carpet, much wetting down, etc., etc...), then cut off a piece once it's off the boat, to work out how I need to dispose of it. So to the OP: don't go ordering a test kit assuming that you'll just need to scratch a tiny piece off - maybe the amounts vary between labs, but it's worth checking first.

ditchcrawler: In theory, yes - at the moment it looks like there'll be a week's slack in the schedule, but various bits of work keep being delayed, so I suspect it'd actually be a case of turning up in a Monday morning, and really needing it all to be done by the Friday afternoon. So people/boatyards en route who are good at timekeeping would suit well (people with what may well be my usual approach, less well...) Richard: thanks, I'll drop him a line.

My girlfriend is in the process of buying a boat in Droitwich, and we're hoping/planning to move it to Oxford during the break in the stoppages over Christmas (ice permitting!). She's getting as much work as possible done on it in the meantime (it's currently out of the water, awaiting new anodes and a little more paint, so now's a good time to get work done), and one of the most urgent jobs is to rip out the existing gas space heater and fit a shiny new Refleks diesel stove. So: can anyone out there recommend people for the job either near Droitwich, or on the way from the there to Oxford (the obvious route being the Worcester & Birmingham as far as Kings Norton, then the North Stratford, and then the GU from Kingswood to Napton)? As well as the stove installation (including cutting a hole for the flue), it will need a hole tapped in the diesel tank and pipes laid to the stove. And the heat-proofing will have to be taken very seriously - there's no obvious way to reroute a gas pipe which goes down that side of the boat. I'll be calling all of the boatyards on the route, but I'm hoping the collected wisdom of the forum can direct me towards the best options, and let me know if there are any independent contractors in that neck of the woods who would be worth calling.