BEngo

A decent hole saw is no problem in vertical 5mm steel using a slow enough drill- get a squirt bottle and regularly hose the saw over with paraffin ( or cutting fluid if you can find it)to wash the swarf out. Horizontal steel is a pain because the swarf clogs the teeth and is hard to get out of the groove. Drill the pilot hole first then go back and cut the main hole with the saw fitted. I've never used Machine Mart's holesaws but I have used Starret and Irwin HSS Bi-metal holesaws. You get what you pay for! Two new ones would be about 25 the pair from Screwfix and I'd be a little surprised if they don't fit the arbors in the MM set. A 19 mm drill is a big ask for a portable tool- the professionals would use a magnetic drill and a rotabroach type cutter but you might get away withdrilling the hole with a series of smaller drills then finishing it with a 19mm drill. The big hole is just too big for any hand-held drill. N

Take a straight one, warm it up a lot (good red hot but not yellow). Bend to suit. Allow to cool gently. This will work with mild steel and most alloy steels as they don't change properties much until they get yellow. It won't work with ordinary high-carbon steels where heating will take the temper out. N

If the alternator is doing 16 V it's probably OK and it has a new regulator then I expect it's being over driven by the Sterling or a fault in the Sterling wiring. What sort of Alternator is it? Step 1 Check all the joints and connections between the alternator and the battery particularly round the relay. Fix as required and re-test. If not then OK Step 2 Disable the sterling box- disconnect its power wire and the wire to the alternator regulator. Step 3 Start engine. Tell us what the voltages are at the alternator, the relay input, relay output and both batteries. N

You have sanded all the oak veneer off the ply in places- it's only about 0.4mm thick. Whatever you do now it will look like you sanded the veneer off. You will have to paint it (or renew the ply) if you can't put up with it. For corner work you want a detail sander- a roughly 50mm per side triangular thing, or a B&D mouse sander. Looks like http://www.diyshop.com/detail-sander-180w-81-p.asp N

Get em close by eye. Then run with the belt fairly tight. Look for black dust and polishing on one side of the belt- adjust accordingly. For twist eye up two straight edges stuck across the pulleys- first horizontally and then vertically. Blu tak is good for sticking small steel rulers on. N

My Waeco 25 amp works happily on my cheap Italian genny. Hasn't got an equalisation setting tho. N

I think that layer of ice on the top is not a problem, but freezing solid might be, especially if the ends froze solid before the middle (highly unlikely.). The other factor is the continuous flow of water from Horseshoe falls will tend to reduce the tendency to freeze. N

Are you sure it's not really called a handbowl? N

The Stability of floating docks can be a naval architects nightmare. The Admiralty had several in sizes fro 250 tons to battleship size, strategically sited, and there were a very specialist group of Dockmasters who not only could run the repair operations but knew how to get HM's war canoes and submarines in and out without turning the whole kit and caboodle over. The key was getting the dock to sink on an even keel and without any list. N

Indeed. It does require more Ah to get a diesel going than a similar petrol engine- remember the technique for hand-starting a petrol? You only have to push it over compression and, provided the sparks and mixture are good, away it goes. For a diesel it usually means getting a heavy flywheel going round fairly well, then dropping the compression in. This is much more like work! Add in some heaters and the energy needed goes up again. It still doesn't add up to much though- say 50A for the heaters for 30secs and 1000A for the starter for 15 Sec (both probably over estimates but they are easy numbers to multiply). That's a total of 16500 Amp seconds or all of 4.58 Ah- about half the capacity of an alarm back-up battery! The petrol numbers are even lower -say 600A for 10 secs. So the diesel starter has to provide more energy but it also needs a much higher level of torque to accelerate the heavier flywheel and get the engine over a higher compression pressure 16:1 or more compression as oppose to about 10:1 for a petrol. Torque to an electric motor means amps so you will find that not only is the battery bigger in Ah but it's bigger in CCA too. I did say that generally bigger Ah = bigger CCA. N

The size in Ah of the start battery is not really what you need to worry about. It requires surprisingly few Ah to get a diesel going, but it does require them very quickly. When dealing with a start battery the rating to look at is the CCA or cold cranking amps. This has to be large enough to turn the engine over quickly enough on a frosty morning. Vetus should be able to tell you what the minimum required CCA is for your engine. Generally, bigger (more Ah) batteries have bigger CCA's but CCA rating can also be increased without enlarging the battery by using thin plates, fancy additions to the lead and lead sulphate mixtures in the plates, and other clever techniques. N

The Aylesbury Arm was never closed and was designated a Cruiseway in the 1968 Transport Act. The Wendover Arm was never really fully open due to leaks- GJCC tried all sorts of things and eventually piped a large section to preserve the water supply from Wendover and protect the summmit. The present restoration is more like a renewal and WAT are doing a really good job. Aylesbury basin has been dredged at least twice since 1980- that is right into the corners. The major part of the arm (from below Lock 4 or possibly 5) right to the basin was dredged (for some value of the word 'dredged') in late 2011. This enlarged the infamous reed corridor in the 2-mile pound but did not go into the corners of the basin. The basin itself is supposed to be being done as part of the Aylesbury Waterside development. I doubt that being navigable for only 3 months out of the last 12 has done it much good though. N

Yes there are still visitor moorings in Aylesbury. They are unfortunately opposite a building site, so aren't pretty, but they are fairly secure with Residential boats still in the towpath side near the moorings. Last time I looked they were also piling the edges of the basin, so don't expect a quiet start to the day as builders seem to like an early start. They knock off at dusk or earlier though. The basin is convenient for a few pubs, several take-aways and a (new) Waitrose. You pass a Tesco on the way in above Lock 16. Aylesbury town centre is about 10 mins from the visitor moorings and is IMHO not exactly an exciting place, but it does have at least two quaint pubs, chain restaurants and some of the usual high-street names. There's a good train service to London via Ricky too. When you pass do call in on ACS and say hello. It's not as convenient as the town centre and there are more, but much less noisy, amusing builders to watch but I'm sure that you will find it worthwhile. Not sure what the current visitor moorings arrangements are at Circus Field, but someone will know when you call. On the way down the arm the main attraction is the scenery, though the HUGE new Arla dairy is notable. Wilstone is a typical dormitory village but may have a store and the Half-Moon was a decent pub. I don't know if either are still open. Allow about 4-5 hours two-handed from Maffers to the town basin. The Red Lion just north of Marsworth junction and the Anglers Retreat 100 yds east along the road from lock 39 are both good pubs at the top. N

I agree an explosion would probably have popped off the side door(s) but if the case is painted someone might just have replaced the nuts/studs and fitted it back again, especially if it still ran OK. I've seen a few fatigue cracks over the years and, given an initiator, I would not be surprised to see one on one side of a crankcase, especially an Al or Mg alloy one, but I would be very surprised to see two cracks fairly neatly opposite each other. Stranger things have happened though. Some pictures of the fracture surface might be interesting. N

Baldwin PA3419 £4-60 from In-line Filters. N

Crankcase explosion? N

Stray potentials from shore power continue to be a corrosion driver. How fast depends on how well the boat is protected. It is extremely unlikely that a complete hull would last less than 18 months, unless there is a significant shore-power fault or it's never been properly painted and is in brackish or salt water. Areas of localised loss of steel can happen in that time, if the conditions happen to be right. Explaining what the 'right' conditions might be is a whole corrosion text book! Pitting of unprotected steel, or of an area less well protected than those around it, can certainly happen in 6 months, whether or no there is a shore power fault. A galvanic isolator (or an isolation transformer) is just an additional item in the protection armoury. The most important continues to be ensuring that the steel is protected from contact with any electrolyte that can complete a corrosion cell. Once that barrier is broken corrosion will occur at the point of failure unless something else (like an anode) prevents it. Stray voltages from shore power will speed it up, but they don't 'cause' the corrosion. N

I am also a satisfied customer of Oxon boat painters at Brinklow (Kitman on this forum). N

I have a 24 year old RW Davis hull. It has poured concrete ballast which I put in myself when it was new, straight onto the fabrication primed steel, and, last time I looked, it was fine. I know of other, much older, boats with poured concrete ballast and they are fine too. It's a bugger to get the quantity right, it's even harder to adjust and it doesn't like riveted hulls, perhaps because the riveted structure moves a little or moisture gets in between the plates. Concrete needs to be put in properly, with lots of vibration using a concrete poker to get a good seal to the steel and the steel to concrete joint should also be sealed against moisture- mine is covered by the sprayfoam. I've not needed to overplate, but have welded anodes to the concreted areas without trouble. Someone mentioned the Ark (Royal) earlier I think- both the proper carrier Ark and Hermes had very large quantities of concrete in the bottom, but they were both delayed in build for years, old, riveted and had spent their life in sea water. N

Worth having a spare on board IMHO- it could just be a right-sized piece of 3 or 4 mm MS plate. N

Almost all non-inverter generators have an awful wave-form. It's not so much the fundamental at 50Hz (or 60 Hz) that's the problem but the large number of additional harmonics that you get whether you like it or not. It's not confined to single phase generators as I know of a big 3-phase site generator which is acceptable to some washing machines, but not all of them. It might be worth checking the genny speed- frequency is speed dependent and if it's out the washing machine may not like it- if the machine rating plate says 50-60Hz then setting it a bit higher than 50Hz on load might help. The trouble is that generator governors suffer from inherent droop and are usually pretty crap too, so as load falls the speed rises. Finally, check the voltage on-load and off. Cheap generator regulation is as bad as the waveform so the voltage is rarely constant with load, and probably is not easily adjustable either! Otherwise the only easy way round it is to find a big battery charger that the genny will drive and use this to power the w/m through the inverter. The hard solution is to fit a big 12V alternator for the genny engine and use that to drive the inverter.

There are two big backnuts on the boiler pipes, as well as the pipe fittings. N

It just sits on some lugs on the back/front pieces of the fire. No bolts. It will come out of the door, diagonally, if you can get it and the boiler in the right place, which is not where the boiler normally belongs IIRC, so it will help to undo the boiler securing nuts and get the boiler free. The plate will probably be well stuck up with ash so be careful as they are cast iron and not all that strong. You need to free the boiler off to get at the back two top plate bolts if you decide to go that way at it. N

Unless you have some ancient lump with gauze filters only (which probably would not use 10W40 anyway) then the API specs exceeed the required levels so you won't do any harm except perhaps if you are prone to leaving the engine ticking over for hours or run it a lot on light loads battery charging when bore-glazing might be an outcome. N

It's the Lucas/CAV distributor-type diesel fuel injection pump as used on BMC 1.5 1.8 2.2 etc. and I think the Perkins 4.107/8. Two main internal parts- a high pressure fuel pump with opposed pistons and a distributor function, all inside one rotor. Everything you need to know and maybe more, here: http://www.bluemoment.com/manuals/Lucas%20CAV%20DPA%20injection%20pump%20instruction%20book.pdf If one of the seals has gone it's a specialist job- take (or Get Jonno to take) the pump off and have it away to a diesel injection company. Getting it to bits is reasonably easy, but finding somewhere clean enough to do the job, getting the parts, re-building it and setting it up are sadly not. N