I quickly made the hull splitting tools today but whilst doing them, I tried to ask myself why the marking tool. If you align the two ends when setting the hull on the board, why have a line to follow when the whole idea of the splitting tool holder is to ensure a straight cut. I made one and will use it anyway.
I think I will split the hull at my factory during next week. There is much more room there and no wife to stop me doing the usual swearing.😁

I had a busy weekend planned. It was time to split the hull. It is fair to say that I had been looking forwards to having a go at this. I had made the special tools last week ready for the split.
The first job was to try to fix down the hull to a board perfectly level and rigid enough to ensure that it did not move during the cutting phase. The first thing was to find a suitable flat board, 12mm marine ply, and stick a 1” strip of sandpaper right down the middle to help to reduce the risk of the hull sliding. This done, I placed the hull roughly central on the board and marked out the positions for the anchor points for the elastic bands and screwed them in. I used standard hooks for this. The bands, two at each end, were fitted. It was surprising just how rigid this was but the hull could still slide. To stop this, I had bought some angle brackets. They were to be screwed onto the board, one each side at the centre of the hull. These proved top be very weak and I could still move the hull. A search of the garage followed to find something suitable and I came across two Krick motor mounts which were left over from the Dusseldorf motors. I screwed these to the board and the hull was rigid.
I fitted the Dremel to the special tool with four cable ties. These held it very well. I then set the height on the marker pen and tested it at each end of the weld line chosen as the split point. It was around 3mm out at one end so I placed two large washers at one end under the hull and this gave me level. I then checked to see if the hull was level across the width and twisted it until the pen made a mark at the same height on both sides using the weld line on the model as a point of reference. I them marked a cut line along both sides of the hull.
Next up was to set the height of the slitting saw using the previously drawn line. This done, I then very carefully cut the side walls taking care to only taking shallow cuts as the Polystyrene melts very easily if heated. I did this in stages leaving the hull connected at each end, behind the bands and about ½” in the centre to ensure stability when cutting the other side. I completed the cuts on both sides and then remove the hull from the board. The remaining sections still joined were then carefully cut with a 12” hacksaw blade. Success!! I had two pieces.
I then roughly cleaned up the cut joints and placed the two halves together. It was good.
Finally, for today, I made and fitted a support brace at the stern end of the deck piece as cutting into two had left this area weak.
Next time I will improve the cut surfaces, put locking devices on the deck half and location tabs to aid alignment.
Thanks for reading.
Peter.

Just a quick update today.
I have spent my available time during the past week measuring and drawing all of the parts I need to fit into the WTC tube. The main tube is 500mm long and I have drawn the ballast tube with endcaps inside. I can now arrange all of the required items into the available space so that I can determine the battery sizes. I think I might be able to reduce the length of the ballast tube by 40mm. This I have determined using the tube that Martin555 used with success. I can get even more water in my design if needed.
Tests will resume soon on the ballast system using Martin`s servo with mounted micro switch idea. I will fit two solenoid valves and possibly non return valves as well. The only real problem I would like to solve is regarding safety. I will look for a miniature pressure switch. They are around but choosing a suitable one is a little tricky.

Now that the hull is split in the right direction, it is time to locate the two halves and fix them in place. The first thing is to create fixing points for the two halves at each end. At the bow, two clips were built from the scrap pieces removed from the hull earlier. They were then positioned and glued into place. These spring on fitting so it shows just how strong super glue is. The rear fixing is a little more difficult. I had a bar of solid PEEK material which is a plastic which virtually nothing attacks. I cut a small piece off, roughed it up and did a glue stick test. It fixed well to my surprise. I made a plasticine cast of the area at the rear where the fixing point would be. I then formed, by milling and filing, an exact copy of the cast and then fettled it until the fit was good. I then measured and drilled a 5mm hole through so that I could insert a threaded bush which I would make next. First though, find a small piece of brass. I am a toolmaker with a small company but Brass?? None to be found. I then remembered an old toolbox that I had at my previous company some twenty years ago. Luck was with me. I found a small bent piece of brass I must have used as a drift at some time. I straightened it and turned the bush. I then pressed it into the PEEK block made earlier. I then measured and drilled a clearance hole through the deck to accept an M3 screw. I then glued the PEEK block in place. I have to drill the screw hole in the top deck next but that will wait until I am completely happy with the two halves joining together well.
There was a rather large gap where the deck fits to the lower hull vertically. It measured 3mm so I bought some 3mm black Plasticard. I cut out two strips, one for each side, and roughly shaped them. They were then glued in place and filed to match the hull shape. I think I will do the same thing to the main cuts along the length of the hull on both sides.
Next job was to add alignment pieces on both halves of the hull. These ensure that the sides are not flexible and retain the side wall shape. I measured regular distances, approximately 60mm each, along the cut length and glued 0.5mm Plasticard formers alternating between top and bottom to give a location for the two halves.
The final job for this phase of the build was to prepare and fix the two bulkheads. The original parts were marked to show where the WTC was going to fit and then I used my Dremel and files to create the round holes of 70mm diameter. I then placed the bulkheads in place in the hull and marked the split level on both halves. I then cut the bulkheads in half at about 1.5mm below the split on both halves. They were then glued into place.
This virtually concludes this part of the hull build. Later I will start on the superstructure and guns, but first, the ballast unit and the WTC.

I have started work on finalising the ballast system and then the WTC.
After the earlier failures, I decided to add a second solenoid valve to the output to try to eliminate the leakage. I also added a one-way valve to stop the back pressure on the input solenoid also. I took some advice from an expert in America regarding protecting myself against a possible tube blow out due to the internal pressure created. I have tapped a ¼ BSP hole into one of the end caps and fitted a pressure gauge to see what was happening. It would appear that a maximum of 3 bar of pressure will be required. I think this system will work with a lot less. I am restricting use to 2 bar until I get to testing the complete unit in a tank of water.
With these changes, I tested the system again. Once again it filled to 2 bar with ease but would not empty. The valves were all working without water but failed when water was present. I checked the specification of the valves and found them to be capable of working up to 0.05Mpa. 0,5 bar. Problem found. I need a minimum of 2 bar.
I searched everywhere for a valve that would withstand 0.3Mpa, 3 bar, which also had to be small. I finally found one on Amazon. It said it would work to 4 bar but on receipt I found that it was rated at 3 bar. That will be enough.
I constructed a wiring and plumbing diagram so that I have the basis for a design which I can now minimise to fit. I took the advice, eventually, of Doug and Martin to use the two microswitch operated by a servo option. This does not mean that I am going to drop the ESC route completely. I will, now that I have a working system, experiment further to see if I can get this to work. I have a variable voltage stable transformer so I can test to see what the minimum voltage that the solenoids need to throw is. I will try this soon but next I have to try to fit all of this into the main tube.

I have been continuing work on the WTC. This is going to be a long process.
I made the decision some time ago to fabricate all of the mounting plates from Aluminium. I have formed a few discs from 3mm section which will form the bulkheads for want of a better name. I have mounted the two motors to one plate and have made a frame assembly to hold all of the electronics. I am working to the 2d cad drawings I posted in an earlier entry. They are still being developed as I go.
As I have said before, I am lucky enough to have a good workshop full of useful machines. So that I could achieve a good and accurate fit for the servos, I decided to make an electrode and spark erode the rectangular holes. I also just happen to need to experiment programming my latest CNC machine.
I then added all of the fixing holes on a milling machine and assembled it. I have to make another one for the rear section which will have to hold a lot more items. Should be interesting.
Now that I have placed all of the parts in the front compartment, I might have a little extra space. I say spare with care as I have a lot more to fit into the rear. I will see if some of the electronics destined for the rear will fit into the front. Back to the 2d drawings I guess.
Now that I have my small lathe at home, I will start on the brass water tight fittings to seal the motor shafts and the control rods.