Thursday, 31 March 2011

Stern Tube

Happy that the drive shaft was perfectly in line and the engine was set square I welded in the engine mounts.  This was pretty straight forward once I wriggled into position to see what I was doing.

Next job was to weld in the stern tube.  This is a bit tricky and its easy to get wrong if you don't understand the forces involved when you weld 2 pieces of metal together.  What happens is at the spot of the welding there is a small but none the less significant distortion, first expansion, then contraction.  This would be fine and would cancel its self out if no additional metal was put in, but thats exactly what happens when you weld, you add metal.  This small amount of local distortion can have a big effect on something even as short as the stern tube which is about 250mm long.

To counter this distortion its vital that the job is set up with a number of strong tack welds and that the shaft is checked after each one.  The first few are the worst, but as more are added the movement becomes less.  Its also important that the tacks are done in opposite sides, a but like when you do wheels up on a car. Once a reasonable amount of tack welds are in place longer stitch welds can be applied.

Another factor that needed consideration was that the cutlass bearing is a rubber / plastic compound and therefore would melt if too much heat was applied.  To counter this each weld was quenched immediately.

It is also very important to ensure that the drive shaft still turns easily before proceeding with the next weld.  Its a slow gentle process but its the only way to do it.  If the weld was just blatted in all sorts of nasty things could happen.

Once I was happy with the positioning of the stern tube I removed the drive shaft and the cutlass bearing, and set to with welding it all properly.



The extra plate seen here was on the hull when I bought it.  There was evidence it had been afloat at some point and that these had been welded on to close up the hole for the stern tube.  This hole would have been cut as part of the original laser cut kit.  I decided it was beneficial to leave these plates on.

Stern Tube with the cutlass bearing removed

Tuesday, 29 March 2011

Drive Shaft Fitting Time

I have been waiting for an engineer to fix a date to come and fit the drive train. Despite several calls it was, clear I was getting nowhere so as usual its back to self reliance.  I do get fed up with this culture that seems to prevail these days where instead of saying straight out no I don't want the job, or even I can't be bothered, people just string you along in the hope you will get fed up.  I never run my business like that.  Its a waste of everyones time and effort. Rant over :-)

I never really had any problem with the task. It's simple engineering which I am experienced in.  My main concern was doing the work myself and invalidating the warranty.  I have sorted this issue now.

So today I picked up my key piece of kit for the job.  A turned collar made by a local engineering firm.

The shaft, the collar and the gearbox to flex drive adapter

Here's what the collar does.

The collar centers the shaft on the adapter plate

The fit is a tight one or an "interference fit" to give it its correct term.  With that done I was able to to bolt the adapter plate to the gearbox flange and have the shaft now perpendicular to the thrust line.

Although the shaft will have a flexible coupling its important that the shaft is set without relying on the flex to take up any inaccuracies.  With the shaft set right "solid" the flex coupling will work a lot better and a lot less hard.


This is the stern tube

I had done my calculations when I made the engine mounts and provisionally adjusted the engine mounts I had no idea I had got it so near.

See the tiny gap at the bottom?

I put two bolts in the top at 10 and 2 o'clock only finger tight this was how near my calcs were.   Don't you just love trig?

A few turns down on the front engine mounts and this gap closed up and a third bolt was put in finger tight at 6 o'clock.  I then rotated it by hand to feel for any tight spots, but all was smooth.

video

All that remained was to make sure the engine was set square on the engine mounts and the shaft was central to the boat.

 Starboard 203mm

 Port 203mm

 Zoom this picture up

Next job is to weld it all in position.

In preparation for work on the stern tube and later the rudder I had to have a space excavated under the back of the boat.  Frank and his trusty mini-digger once again obliged.


Thursday, 24 March 2011

Fuel Plumbing Kitchen Sneak Peak

The plumbing is done for the fuel system for both the generator and the main engine flows and returns. All that's needed now are the flexible parts that connect to the engine and the genny.

15mm copper tube and compression fittings 

I have put in isolators for the main engine flow and return near to the tank, and a more convenient one for the flow only near to the filters.  The reason for the isolators is some inspectors like isolators as near to the tank as possible and on the return side my fuel level can be higher than the return inlet so if I need to do something on this line I can stop any back flow.  Both engines share the same return pipe.  The generator feed isolator will be in the final 8mm copper section

And now a sneak peak at the kitchen layout.
All base units in approximate positions


Monday, 21 March 2011

Central Heating Works

I reconnected the radiators, charged the system with water and combined inhibitor / antifreeze, put diesel in the tank connected the temporary battery, hit the switch and after a bit of priming off it went.

I'm pleased to say it all seems to work.  After about 40 minutes the radiators were piping hot, and no leaks.

I need to alter a couple of bits of plumbing but otherwise its all systems go.  :-)

Quite ironic really that I fired it up on the warmest day of the year so far.

Sunday, 20 March 2011

It's Been a Plumbing And Painting Week

The internal finish I wanted in the boat was the same as I'd seen on several of the nicer manufacturers boats.  It's essentially a painted finish, however after much trialling with different paints I could not reproduce the finish.  I asked a couple of the manufacturers using this finish but my emails were not replied to.  Not surprising really.  Then in a post one of the CWF members told me what it was.  It is a 2pac pigmented lacquer.  Product Link


While I got on with the plumbing a friend and very good decorator did the painting.  This involved 3 coats applied very carefully with a roller.  The ply surface first needed hand rubbing down with 320 grit then between coats a 400 grit.  This product is primarily formulated for spraying but with care an excellent finish can be achieved with a roller.

This is the soft sheen a 20% gloss produces
and the wood grain is still visible as I wanted
The light colour has made the boat seem even bigger now.

While Matt was painting I got on with some plumbing.  All the heating plumbing is now done and as soon as the walls have hardened off I will be putting the radiators back and commissioning the central heating. 
 Final bit of C/H plumbing

I have put isolators in the heating and water circulation systems so they can be turned off or balanced  with the seasons.  I have incorporated a filling loop and a pressure vessel as this is a sealed system.

Other plumbing jobs done are the water and exhaust seperator for the generator.

Not easy to see what goes where but it all goes where it should

The self pump out.  

This will be used to discharge our black tank where its permissible to do so.

The fuel tank balance pipe.
This is to ensure the fuel is used from both tanks at the same time. The return fuel from the engine will be put back into the port tank and new fuel will be drawn off the starboard ensuring the fuel is being mixed about and used.  The new types of diesel coming on stream has a reduced shelf life due to is Bio content we are told.  The 2 stop cocks will enable each tank to be isolated for drainage or maintenance purposes and the fuel contents gage will fit in the vertical stub just above the drain off cock.





Tuesday, 8 March 2011

You Live And Learn

Well, I thought I'd made a good and well thought out solution to the switching of my generator and shore power.  I even went the extra mile and doubled up on the relays to provide a large (so I thought) redundancy.

I sought advice from a national electrical component tech. dept. explaining what I needed to do and how much current was being handled.  Based on this advice I purchased the replays in the previous blog.

On posting the blog one of my readers pointed out that should one of the relays become stuck it would be possible for either to back feed the shore power or permit the genny and the shore power to both be supplying at the same time, which is exactly what is trying to be avoided with the relays.

I posted this on CWF and if you follow the thread you will see there were other concerns.  One member went through the relay spec. and spotted that the relays weren't even up to the un-switched load.  Combined they amounted to 6 amp, not the 60amp I had discussed with the supplier.  60amp is way over what I needed but remember I had doubled up everything.

It was decided on the forum that what was needed to do the job was a contactor not a relay.  Think of it as a industrial heavy duty relay.

So this is what it looks like now..

On the right

The black box on the left is a Galvonic Isolator.  I'm not even going to try and explain what this does, but you can see here.

It really goes to show how combined knowledge can prevent a problem later on.  I am very grateful to all contributors on this issue.

Thursday, 3 March 2011

Power Input Relays

The 240v power input to the inverter will be delivered by 2 means.  Primary will shore power, the other will be from the on board generator.  Some models of inverter will deal with this internally and even combine the power sources. This on the face of it seems fine, accept of course that 240v is AC or alternating current.  This means that in the case of UK and European power 50 times a second or 50Hz the current alternates between positive and negative.  This is fine if you are lucky enough to get both in sync.  Chances are very high that if you do it won't stay that way for long as they will drift slightly, especially the generator.  More on AC here.  

I am sure if I searched around I could find a device that could combine the power inputs but if I needed that amount of amperage on the boat I would have bought one of the inverters that can do this.

So to avoid the 2 sources being on together a control has to be in place.  This could be a selector switch or a relay or even as basic as unplugging the shore power and plugging in the generator.  I have chosen a relay because:-

If the shore power is on power flows through the relay when it is in the un-energised position this is the default setting and essentially the relays are doing nothing or switched off.

If the shore power goes out the generator can be switched on buy the remote panel I have.  By so doing the relay becomes energised and the contacts inside moved to allow power from the generator only.

Now, if the power should come back on say after a power cut, I don't want this to flow in as well.  This is where the auto function of the relays come in to its own.  Because the relay is now energised the power now coming from the shore power can only get as far as the relay and so can't 'mix' with the generator power.  Once the generator is turned off the relay will revert to closed and let the shore power back in.

 
Like so

The actual unit

I have used 2 relays in parallel to offer some redundancy and to spread the load although each relay can handle more than is required.  I plan to limit the power input 25amps.  This is done on the inverter.   More on that later.

The finished (accept the Cat 5E) power cupboard.



Wednesday, 2 March 2011

Consumer Units In

After seemingly adding another wire then thinking of something else needing one about half a dozen times I eventually put in all the wires I could think of.  I know there will some I've missed but I can still run them safely if I need to.

The electric cupboard is part of the kitchen units.  Initially I was going to use standard units and cut them in as required, but the owner of the kitchen manufacturing company is also a keen boater and when he heard it was going into a boat he came and had a look.  He said as they manufactured the units they could make them to fit the boat and save me having to hack the units about.  I made him a template and this is the result.

More on this as I fit the kitchen

Once the cupboard was sited I fitted the consumer units and cut the holes and run the cables through.

Top CU is 240v Middle is 12v Bottom is 240v as well

The reason for 2 x 240v CU's is that the way the inverter handles power means that if the boat is on shore power or generator it will pass mains through AC out 2.  If the inverter is generating its own 240v from the batteries it will drop out the AC out 2.  This enables automatic AC management for heavy items like Air Con, or in my case immersion heater.  Neither of these would last long on battery power. 

The mid unit is dedicated to 12v systems only and the top one is dedicated to 240v systems that I want through AC out 1 even if the 240v is coming from inverted power.

The white wire is a CAT5E cable for inverter / PC interface

All the connecting up took about 3 hours, and was jolly hard work.  The cupboard is only 265mm wide inside and it did nothing for the arther in my hands.

The mains into the inverter needs to be split as it will be powered by shore or generator.  To ensure that only 1 source can input at a time it needs a selector switch, or so I initially thought.  On thinking about it a bit more I decided an auto switching power relay would do the job better.  So thats on the list to be made very soon.  Watch this space.