BEngo

Since the heater to tank joint is a screw joint you will need some sealant on the new immersion- Boss White and hemp for the traditionalist, heavy gauge (yellow) PTFE tape for the easy but not always reliable solution, or Fernox LS1 for the bodger! The current flexible cable appears top be a piece of Arctic blue. It really should be a 3183 heat-resistant flexible cable: www.screwfix.com/p/heat-resistant-flexible-cable-3183tq-3-core-2-5mm-x-1m-white/71940 N

The short answer is " With difficulty". The long answer is : You need to work out the angle of the chord of the blades at a convenient diameter. This is the helix angle, the tangent of which is the pitch divided by the circumference of the circle of your chosen diameter. The angle can be measured by putting the prop on a flat surface, drawing the chosen circle onto each blade and calculating the difference between the height of the leading edge off the surface and the height of the trailing edge off the flat surface. You then measure the straight-line distance between the two points at which your chosen circle crosses the edges of the blades/. The sine of the helix angle is then the height difference divided by the straight line distance. Alternatively, measure the height difference as above and also the angle subtended by the two points at which your chosen circle crosses the edges of the blades, where you measured the height difference. If you work in degrees the pitch is then ( 360/angle of bats) x height difference across the bats. Either way it's difficult to get accurate measurements because of the thickness and curvature of the blades. N

My J2 has a 21 in dia 13 in pitch blade in a 60ft boat. This gets to about 650rpm in open water (Thames or Severn), so is a bit too big, but the boat goes well enough and stops beautifully. I would replace it with a 20x13 if I ever needed a new blade. The standard Kelvin prop for a J2 was 19 in dia 13 in pitch, though the bats were narrow and almost scimitar like. Are you getting black smoke when you open up? If so that will also contribute to the overheating problem- The cooling depends on the engine speed increasing for the pump to push enough water through the heads. If the pipework is badly scaled the heads and cylinders are also going to be scaled up. Circulate some descaler through them - brick cleaner ( aka brick acid or more accurately dilute hydrochloric acid) is very effective, but if you use that follow it with a strong solution of washing soda. N N

On the Thames expect to pay everywhere, especially down stream of Osney Bridge. Most riparian landowners with a mooring have worked out that they can charge (sometimes like a wounded rhinoceros) and will come and collect. a few pubs will refund/not collect a fee if you go in for a meal/beer. That said, there are a few free spots. Good luck in finding them! N

This filter is there as a final line of defence for the injector moving parts lest a piece of crud get into the pipe between the pump and the injector. Edge filter is a description of the way it works. If there is no crud then everything will work fine without it. Just be careful to keep that injector pipe really clean if removed, stop the ends against dirt and blow it out well before refitting, though you should do that with all the injector pipes. N

The handle is held in by and pivots on a roll-pin. Lift the door off, put it on blankets on a firm surface and look at the side- you will see the hole for the pin. Drift this in toward the centre of the door and the handle will lift out. The knob unscrews and will screw onto the new handle. Fit the new handle and tap the pin back in till it's nearly flush with the outside of the door. Be careful not to break the door glass! Same for the handle on the bottom door. The hook of the handle fits over a roll pin in the body of the stove. That may also need replacing. In this case it is drifted out from the inside of the stove. If it is badly worn you could, as a temporary measure, turn it so the worn side is to the front and then re-fit it. N

Bugger all, IME, but it does make it easier to just hold one straight spare pipe on board and bend it to fit when needed. Bizzard is right that they njeed to be restrained from vibrating or they will break. Had that happen once on a Foden FD4 off the Needles at night in a SW gale. Diesel everywhere. Squeaky bum moment! Fortunately the other FD4 was OK and kept going. N N

Not that uncommon- they sometimes rot from the joints where the gate is fitted. The beam at Lock 2 on the Aylesbury Arm broke last month. It's a fairly quick job once the new beam is on-site. Presumably one for Rushall could/would come from Bradley workshops. N

The mooring rings are indeed dangerous. CART and the Local council have plans for a restaurant boat (which would collect the overnight mooring fees,) and a trip boat. Since Aylesbury as a town has pretty well never been able to support a conventional independent restaurant (not a Pizza/pasta/continental cuisine chain) and the trip boat would run through the back of a light industrial estata and Tesco's car parks I rather doubt the commercial viability of either. As well as the Waitrose at the end there is a Tesco Extar just above the bottom lock. Mooring rings provided ACS will welcome you at Circus Field, with free moorings available for one or two weeks and longer term temporary ones by arrangement. Contacts as in the linky above. The new clubhouse has not yet been handed over by the builders ( it is imminent,) but there are still laundry facilities and showers for those who need them. N N

The Halfords 12V one is less use than a chocolate teapot. DAMHIKT. Makita make a good variable speed polisher, but they ain't cheap. Axminster used to do a Chinese copy much less expensively. If it's a 240 V one Farecla do some good compounds for elderly and well oxidised paintwork; these need to be followed by a wax, or any automotive polish for not too bad paintwork. T-Cut and similar are best avoided. Use good quality bonnets N

The warning is worth a read. Inductive loads (motors) at only 30%, so not more than 600W/1200W depending on what you want to read the rating as. No information on N/E bonding. N

The balance beam one one of the gates at Lock 2 is reported damaged and has been removed by C&RT. The Arm is shut till Monday when CRT will staff the lock three times a day until tghe beam can be replaced- possibly by Wednesday 23rd. N

Your Skoda and its service interval is ( like all the mass-market motors) designed to last about 7 years, having cost the lease company nowt at all during the first 3 years. After that they don't care as they will have flogged it, possibly to you.. N

There would have been a pair for somewhere else in construction, so not too hard to adjust the size - providing you know what size is needed, of course. Still, BW were always pretty good once the blokes on the ground (were allowed to) got going CART seem to be much the same. N

No, it's the term for what happens between elections when Parliament needs a break. The monarch ( at whose whim parliaments exist, technically) tells a parliament to knock-off, by proroguing it, then re-opens it after the break. www.parliament.uk/about/how/occasions/prorogation/ N

Dave, There is not a snowball's chance in a bonfire that C&RT will ever get Government parliamentary time for legislation on this in the next two Governments, unless C&RT go belly-up. They asked for legislative changes as part of the Bill which transferred BW to CART and were politely but firmly told to go away. Any C&RT Bill now would either have to be a private Bill (as the 1995 BW Act started out) or remotely possibly a hybrid Bill. Either and both are subject to the whims and arcane processes of Parliament and cannot be driven through by the Government of the day. The outcome is thus very uncertain. The changes wrought between the BW Bill introduced in ( IIRC) 1994 and the 1995 Act which eventually emerged were significant, but essential to enable the Bill to proceed at all. Much the same tactics are available today should a new C&RT Bill be introduced (and will no doubt be seen in action against the HS2 Bill currently before Parliament.) About the only advantage a Hybrid or Private Bill has is that it does not fail when Parliament is prorogued. N

The thing with the sink is that it is the level of the top that matters, provided the pipe to the side outlet is intact. If the outlet goes below water all that happens is that the sink starts to fill with cut water, until the level in the sink is the same as the level outside. Until there is cut water above the top rim of the sink no water will enter the boat and once you raise the outlet above water the sink will drain back. Not necessarily recommended as a way of washing the dishes though! N

Get a bigger 'ammer- and make sure the tips of your pins are forged to a squarish point. This seems to work better than a round one. Tarmac is easier tho. N

The return (blue) from the gravity rad will need to be connected on the other side of the pump (suction side). As shown there will be a tendency for water to try to circulate backwards through the rad and hinder the pumped flow through the boiler. CH pumps are centrifugal types, usually so there will be little resistance to gravity flow through the rad when the pump is OFF. N

The large, spoked wheel on the right is the gear wheel. It looks very similar to a decent-sized lathe's carriage handwheel, though no doubt Yarwood's (or H&W's) own foundry and machine shop were quite capable of making them as needed. The speed wheel was on the left, and if a fancy one, usually the boatman's own, like the decorative cabin brass work and knobs. I think it can just be seen as a dark blob on the plate. N

Try the manuals page on Internal Fire site. www.internalfire.com/index.php?loadf=93&sid=56bf48118f48fbc8443dff57ffc6526a They have the RN Dx and the National D Need to register, but it is free and access to manuals is also free, though a donation would be appreciated no doubt. N

Arthur, An alternator will come to no harm if it is spun up without all the connections, even if it is excited. The internal voltage regulator will cope with that because the voltage and magnetic flux rise quite slowly in electrical/electronic terms. The regulator cannot cope with the output being disconnected once the machine has excited because the pre-existing flux and the inductance in the windings which works for you on start-up works against you on disconnection and causes the output voltage to go up far too fast for the regulator to be able to do anything and the diodes ususally go 'pfft' Ditchcrawler , If you connect the two ind terminals, once excited, the 12V terminal will see ~24V less whatever the voltage drop in the lamp between them is. It might not like that. I would include a decent sized diode as well as the lamp so that current only flows into the 24V machine. Arthur's alternative is a good one. N

Metric threads into cast iron or aluminium tend to give very poor performance, because the thread is too fine. The door comes off regularly which means the fine threads wear very fast. Helicoil type solution at the original coarse thread is much the best way forward. N Beaten by Tim.

Mooring first, especially in the current climate. N

Not sure what your boat actually is- I would guess perhaps an older pleasure hull with a timber top. Repeated hard bashing of the bows against gates etc can cause a spread because the U shape of the hull is not stiff enough to resist outward flexing. It is not likely to have spread because the insides are being pushed out by a load as with carrying craft. The problem is not pulling the hull in- that can be done with a temporary chain and Weston hoist used horizontally or a turnbuckle as found in most historic working boats. The problem is how to hold it in (oo er missus) if the top is not rigid enough to do this. Extra knee plates can be fitted but they get in the way inside. N