As Lou explained (as I sat in the land-rover feeling quite defeated) “It’s like when you built the racing bikes/cars – you can’t expect to show up at the circuit and have it all work perfectly the first time you race it. There is always going to be development work.”
…and I guess she is right!
This post firstly relates the trips we have made so far, and secondly attempts to provide a balanced view of the successes and failures to date – to help other builders.
Trials (and tribulations)
We have taken Befur out 3 times now and mastered the knack of getting to and from the moorings on the inflatable (including learning how to get the &^**^%$ Seagull to start, breaking its prop clutch (not enough water under the dingy), discovering how well the inflatable skims (sideways) across the water, having no keel, and how wet your bum gets when the inflatable is half full of rain water!!!).
Lou has demonstrated her helming skills, picking up the swinging mooring on the first attempt, and her line handling (and “avent-garde” knotting skills) casting off from and mooring onto the swinging mooring without losing the lines or dingy – well done!
First, here are two trip logs from Google Earth, (generated with an Android app “MadMutt 2 Navigation Software” – probably the best £2 I have spent in a good while! …) and a map of the whole lake to give you a perspective on things and then we will discuss what we have learnt!!!
…as you will see we have some more “development” work to do before we start a “scheduled service”. 🙂
– 24th July – testing tightened belt!
(a bit heart in the mouth, but ultimately successful)
– 12th July with John – investigating “the knock”
The whole lake – much more to explore!
The results of initial trials, issues discovered and successes witnessed
I have a strong/natural tendency to focus on the work still to be done and the issues that need “fixing”, but in this post I will try to provide a balanced view of what we have built and how it performs, hopefully this will help those who follow in our path, avoid some problems, and learn what actually works and doesn’t.
Hull & Fitout
The wooden bits
Actually this is all good news, thus far we have found no problems that need urgent attention.
The hull floats reasonably level, we have put two 25kg bags of sand in a port locker to even her athwartships, and probably need one more – these offset weight of the engine being offset to starboard, the weight of the hotwell and the heads; both also being on the starboard side.
With 3/4 of the 120litre fuel tank full she still is very stable and is still floats above the design waterline at the stern. We have 50 litres of water in the bow, and she rides perhaps 2-3 inches higher at the bow – so by the time we have added the sailing rig and further ballast, as suggested by Paul Fisher, we should be good.
The rudder works very efficiently ahead and astern. When moored shot-cord and webbing straps hold it in place to stop it wearing out the pintles.
The cabin works well and was a good decision (given the weather) and, baring a slow drip from the antenna cable in heavy rain, is water tight. (God how I wish I had paid more attention to this tell-tale. Over the following winter the water leaking here really got into the cabin roof and caused major de-lamination of the ply – and a lot of work to correct (patch up). Probably the ply was not as waterproof as it was meant to be, but this turned into a major pain).
The Airhead toilet is good, and doesn’t drain the battery or smell – a good decision.
The manual (diaphragm) bilge pump works well, but given the slight stern-down posture of the boat, the little water in the bilges tends to collect under the engine, rather than in the cabin where the strum-boxes for the pumps are located. I will add a steam ejector to drain these stern/end spaces, and permanently install the Whale stirrup pump to provide a manual option.
The automatic Whale bilge pump only operates when there is more than 2 or 3 inches of water in the bilge, so this is really only an item of last resort, to stop the sinking of the vessel.
We added a small internal ladder to allow easier access to the foredeck via the side decks, but actually the escape hatch in the front of the cabin provides really good access to the foredeck for mooring etc.
The transom ladder was a good decision and makes boarding to and from the inflatable slightly less hazardous, but still requires a certain degree of agility. However, the transom mounted rudder makes it harder to get the inflatable close to the stern.
The cover is brilliant! The “lift-the-dot” fasteners are very good – reliable and easy to fix/remove. The “ratchet strap” between the cabin and aft deck provides a good “ridge pole” for the cover, with enough springiness to keep the cover taught and stop it flogging. (We paid the price of cheap cloth, as it faded considerably in just a few weeks, but it works, so a job for another day).
We mounted the bow roller projecting well forward so that the anchor could be stored on it. But in reality this is where the mooring lines come aboard, so in the end we installed some anchor chocks on the foredeck and the anchor sits there. So, we might move the bow roller a few inches inboard over the winter as it would be stronger.
The Samson post was a very good (if late) decision. It provides a secure and easy to use strong point.
The rear deck cleats are just about big enough (200mm long), although the midship ones, at 150mm long, are a bit small, but will secure a pair of 12mm spring lines.
Similarly, the 150mm long foredeck fairleads are only just able to hold the backup mooring line and its anti-chafe hose, but are fine for dock lines.
This seems to be all good too.
The pair of 10W solar panels easily keep up with the load from the head extractor fan and recover any discharging of the batteries within 24hrs. (However, we discovered that in the autumn/winter they could not keep the battery full – so we will need to empty, clean and turn off the toilet fan over winter).
The alternator successfully keeps up with the 900W burner motor even at slow (about 200rpm) on the main engine, so the 12:1 gearing between engine and alternator must be about right. However, the “on-off” behaviour of the regulator means that one needs to juggle the throttle as it cuts in and out. It always seems that the battery winds up about 96% charged at the end of the run, and I think this is because the regulator tends to drop to a “trickle charge” quite quickly. A computerised smart regulator would probably improve this, but at ~£400 seems like an unwarranted expense
The 1600W inverter copes well. We changed from a “modified sine wave” to “pure sine wave” one as we had trouble getting the burner to start when the inverter was turned on. On reflection I think this is because the burner controller does not like the “soft-start” nature of inverter operation. Changing the arrangement so that the inverter is started and then the burner is switched on via a separate relay and switch from the driving position has provided a reliable approach. I might try changing back to the old inverter just to prove this theory.
The Danfoss RT5 pressure switch works reliably. We have it set to the maximum hysteresis, so it cuts out at about 225psi, and back in at 150psi.
The Battery Monitor, (similar to this one) is really good, giving information on battery state, charge and discharge rates, and a bargain at £15!!
The solar panel controller (similar to this one) is somewhat more suspect. Most commentators suggest that it does not really operate in MPPT mode, the day/night functionality on mine has never worked and I am not really sure that it dumps excess charge when the battery is full. But to be fair, all the displays work, and the battery voltage never seems too high, so maybe it is doing it’s job.
Well I think this counts as a success – perhaps due to the lack of moving parts!
The boiler certainly operates very well, raising steam is a matter of perhaps 5 to 6 minutes, and the boiler/burner controls do their job. (I actually manually cycle the burner during steam raising to reduce the thermal shock a little by slowing things down.)
Initially, with a 1.5GPH 60-degree jet in the burner, I could not get the burner to run smoke-free and start reliably (too much air needed). With the advice of my household boiler man we changed the jet to a 1.25GPH 45-degree one (less spread in the spray pattern), increased the fuel pressure to 12bar and it now starts reliably and burns cleanly (no smoke – not actually put a CO meter on it yet).
The burner seems to operate on about a 90% duty cycle, and I was thinking I would fit a larger jet to reduce this, but when watching the boiler pressure it is clear that (as we should expect) there is little thermal inertia in the boiler (being water tube design and all), so the pressure reduces from 225psi to 150psi in probably no more than 40 or 50 seconds when the burner stops.
This suggests that maybe the existing jet is fine. We are operating at a limited speed (for reasons discussed below), but we are also not getting a proper vacuum, so efficiency is below par. So, we will leave things as they are for now.
This all suggests that the boat will consume about 4.25 litres an hour in operation – about £5:50 per hour at current diesel prices. (maybe the tax man wouldn’t notice if we converted to heating oil – after all we are only doing heating 😉 …..)
The engine feed pumps seem well sized, they just exceed consumption when operating – if you recall we increased the feed pump bores to 1/2″ and reduced the pump speed to 53% of engine speed, and it seems our computations worked. We really need to fit an accumulator somewhere in the feed circuit as the feed clacks do complain a bit with the engine running above ~300rpm. Also we seem to have problems getting the air and feed pump glands to be properly water tight.
One unsuccessful feature has been the use of a commercial float valve (ball cock) to automatically control the bypass and hotwell level. This seems not to work, probably because 200psi+ is more than the valve can hold back – this is not a huge issue, but at some point I will make a better valve and try to get this working properly.
Well here lie the major issues still to be dealt with.
On the up-side the valve timing work seems to have paid off, so I would recommend the “practical” approach in that link to others building a similar (or other) engine. The engine starts and runs ahead and astern with no fuss – the Impulse Valve getting it going easily if it is stopped with the HP at TDC or BDC.
Similarly, the automated relief and drain cocks work well. After being stood for a couple of months, the small pistons which convert them between modes had stuck on two of them, but once freed they operate well. The only issue is that the o-rings I installed to “seal” the shrouds that are meant to direct the exhaust from the valves to the drainpipes blew out instantly. Over the winter I will fabricate some PTFE seals/gaskets to sort this out – for now you just need to mind your knees when warming through!
The lubricator pump seems to work well. We are still learning to operate the displacement lubricator – it is a bit “all or nothing” at the minute.
The vacuum/airpump assembly. When we first tested the engine on the bench we had good (20-inch) vacuum. Since it has been installed in the boat this has dropped away, starting at about 5-inches and dropping to almost nothing after 15 minutes. There is clearly a leak somewhere, or the o-ring sealing the air pump piston has worn – this will be dealt with in the next few weeks (see below)….
The “Knock”. The engine has a persistent knock, it is not clear what this is, but the prime suspect is a failure of one of the joints on the crank – but the fact that after 3 or 4 hours of running it has not seemingly got any worse is surprising – it may yet prove to be something else. I have managed to source a pattern for a crank for a Leak compound, so we might try to cast and grind a replacement over the winter. (It had broken! Don’t use Loctite to fabricate cranks!)
Leaks in the block. There is a quite significant leak on the mating faces between the HP valve chest and the HP cylinder casting. This joint is only secured with 4 bolts, and strikes me as a weak point in the design. When the engine is removed for a major overhaul I will look at this again – I think a better sealing agent (Steamseal?) and further attention to the flatness of the sealing faces might improve this – a gasket seems the wrong approach, given the structural nature of this joint.
The pump/alternator drive. You may recall that we had a failure of the bearings on the scotch cranks when we were testing on the bench. replacing the miniature ball races with needle roller bearings seems to have fixed this problem – although we will give them a close inspection in the next few weeks.
However, the big issue on this topic is the failure of the jack-shaft drive while on the water a few days back – this is discussed below.
Propshaft & drive.
The timing belt approach to driving the propeller shaft seems to work well – and we are achieving 4 to 5 knots even at quite modest (~250) engine RPM, so SBA member John King’s computations on prop-size and gearing have proved spot on – thank you John.
We have discovered that you need to try to get all of the slack out of the drive belt to avoid problems – see below.
The cutless bearing in the stern tube is clearly suffering – see discussion below.
Conclusions to date.
Not all of the decisions we made in the design phase have worked well, and there is more to be done. But so far we have gotten home each time, so not a complete disaster! I think we need to get the sailing rig installed ASAP as the ultimate solution to mechanical difficulty.
Results from July 23rd trip.
What follows are my notes from our last trip out, following some changes.
Well after a couple of days work on components, and some further trips on Befur we have learnt some stuff – and broken some stuff!
1 – the knock: still no worse but defiantly happens at TDC on the HP cylinder, I am pretty sure it was BDC when John and I looked at it two weeks ago, so still a bit of a mystery! Sticking stuffing box glands? (it was traced to a broken crank in the end)
2 – vacuum leak: there is certainly a leak on the lower joint on the air pump body, but it is too inaccessible to check tightness of bolts etc. So I was wondering what to do about it – but the last trip resolved that uncertainty…. (investigation later showed this was due to a gasket blowing out, probably because I had failed to open the ball valve on the pressure release line).
3 – the nasty intermittent “banging noise” at speed: I finally listened to Lou who kept saying “it’s the drive belt” and managed to reduce the noise by further tightening of the belt tensioner, as we felt it was probably slipping a tooth now and again causing the bang. As this was then at its limit of adjustment I fetched it home, lengthened the adjusting slots and refitted it much tighter – now it does not bang at all! Fixed 🙂
4 – the “whining/squeak” from the propshaft that starts after 30 minutes: Having refilling the stern gland greaser, thinking this was the issue, I concluded this was not the culprit. But on opening the bleed cock to the stern tube we got hot/steaming water out, and after a minute/pint or two the water got colder and the squeaking stopped. So it’s clearly the mid-shaft cutless bearing overheating and complaining. Really not sure how to fix this “properly”, moving the cock to a more accessible location would allow us to “bleed it occasionally on the run”, but this seems fraught with opportunities to leave it open and sink the boat on the mooring! Adding another pump to force water down the stern tube feels like overkill. – Any ideas are welcome!
5 – sticking, non-whistling whistle: fixed sticking whistle valve, and adjusted bell to get best sound I could. I know why this whistle was in the auction, it’s feeble!
6 – new stuff: Yesterday we took a trip down east side of lake to the 2nd reach, and as we turned round I saw that the pumps (air and water) and the alternator had stopped!!! So we started home hoping the battery would get us there and hand pumping like mad!!! After 10 minutes there was a pronounced CLUNK and it all started working again – amazing! I had guessed that the pin holding the chain-wheel to the jack-shaft driving the worm-box running the pumps and pulley driving the alternator must have sheared. On making it back to the mooring, sure enough the offending pin was in the sump, with one end missing. So not really sure how it fixed itself, I guess it either seized on the shaft or a bit of the pin still in the shaft dropped into the hole in the chain-wheel and remade the drive. Either way we were happy not to have to call for a tow, or row home!! So, this solves my problem WRT the air-pump, I am in the process of stripping the pump/alternator drive off the engine and will fetch it back here for remedial surgery! (and fix the air pump at the same time.)… Subsequent investigation showed that the taper pin fixing the chain-wheel had fallen out, and then the chain-wheel had seized onto shaft – hence the drive re-starting. Re-fixed the chain-wheel with Loctite and two grub-screws, as shown in this picture…
So not sure this boating lark feels like fun yet!!!