A Skipjack in Ireland

[The Boattrainman]

Hi John,

Nice to hear from you.

I'm afraid Railway Modelling is in the past, I sold my OO Scale Railway to fund other hobbies, but I did try a small layout in N Gauge at one stage. Had to give up, as I simply couldn't see the small parts, though I appreciate you can make a wonderful layout especially on the scenic side.

I swore I would never make another model below around 1/40 ratio, my Ben Ain is 1/32 and was a joy to work on, but I couldn't resist this sub as it's a reasonable size in 1/72 and it was a bargain.

I've actually come up with my first problem with the Skipjack, more later.

Rob

[The Boattrainman]

On to the sail planes and their mechanism. I glued a piece of 1mm Plasticard on the inside, square to the holes for the dive planes, when hardened the Caswell bushes are pushed into the holes from the outside and then sanded flat. The hole is then re-drilled to the new diameter.






So why the inner piece. This appalling drawing will explain, the Caswell dive plane fitting has to fit into an odd shaped sail, not only is it slanting inwards towards the bow at this point, but also slanting inwards going upwards. The fitting will have a slight gap where it meets the hull (see the arrows in the drawing). Now the fitting does have rounded ends, but I want there to be as little friction at this point as possible, so by sanding the piece of card using a small piece of sandpaper and by hand (no files or tools), it can be made easily to this rounded shape (the black parts in the second drawing) to match the rounded end of the fitting, which I have further rounded.




Now this is where it all went wrong!

I couldn't align the larger Caswell resin ring fittings for the second lower toothed part-wheel that takes the movement into the hull, plus I've a big problem gluing resin parts to polystyrene. No amount of jigging and re-fitting could get it aligned, so I gave up. For me the area is too restricted, visibility poor, along with my eyesight!!!!




So I ditched the rounded resin bushes and made two larger square Plasticard fittings from 2mm stockwith the same diameter hole and glued them to approximately where the brass bar should sit. I united both sides and then inserted the bar and fittings and moved the square pieces around before the Polystyrene cement set (around 30 seconds, plus two hours to totally cure).



Now to snag number two, when united, both parts of the sail are pushed apart by this piece of the sail on both sides which affects the tension on the lower moving fittings. I cut these off both sides (just the shaded bit), but having aligned the fittings with the piece on, now there was binding of the parts. I had to quickly re-set the lower larger plastic bushes before total glue set had occurred. The top of the sail with the mast bases sits better on top with these pieces removed.

[The Boattrainman]

The sail lights get their 1mm Plasticard supports plus the resistor to drop the 12v down.

[The Boattrainman]

Here is the inside with all the mods, everything is in line (now!).




I've put four pieces for strengthening of 2mm Plasticard at the screw points and one other, three screws will come up through the hull to hold the sail, two as per David's instructions and the one in the end of the exhaust will receive a new hole in the hull and a very small screw.

I'm not using the beautifully machined Caswell resin blocks as I may have to drill out the front thick screw holder to get the wires from the sail lights down into the hull.




Here is how they will go into the opposite sail sides, two each are currently glued to one side only and will be liberally covered in Polystyrene cement when the two sides are finally united for good. If the Caswell blocks are used you will need two types of glue to get the two halves permanently together (CA and Polystyrene Cement), now only PC will be needed.




A side effect of all this work and fettling is the two sail sides go together much better and are here resting on the hull without needing tape to force them together a good sign.




I learned a lot during this two night build:-

1. I should have made a small plastic jjg to set the lower Caswell fitting, if I had, I wouldn't have wasted so much time fiddling with the resin bushes.

2. I'm not good at gluing resin to styrene/plastic parts.

3. Always, always make sure you can see it if you are doing it, especially parts that have to index together in some way.

Finally, these are my problems, it's perfectly possible to follow David's directions and get it right.

The Boattrainman


.Go to Page 7 of this thread to see a fool proof method of setting these parts! Rob

[The Boattrainman]

If anyone is in the mood for a nautical movie based on real events, this just arrived in cinemas:-



I just saw this on the web, and while it's not the greatest movie ever made (not even the best sea disaster movie ever made), the true story of what happened in 1952 to the Tanker Pendelton and the efforts to rescue the survivors is incredible...............can't say any more..............don't want to spoil it.

Apparently to give the viewer the sensation of what they went through there are over 1000 effect shots (mostly CGI), and it took a year in post production to get the movie together, visually it's amazing.

The Boattrainman

[The Boattrainman]

To finalise the sail light installation, a surround of L-shaped Plasticard is made with a gap to the let the wires out. Two pieces of square tube are used as cable guides to keep the wiring away from the dive plane yoke fittings.





The square is flooded with epoxy, a fair bit is allowed to flow out to ensure the wires are totally encased.



The wiring is led down and will exit through an off-set hole in the Plasticard fitting in the left side of the sail (right in photo), and the through the hull. Both sets of wire will exit the same hole, but that can't be sorted till the sides are united for good. the exit hole will be off-set to one side to let the wiring pass the snorkel inlet fitting under the hull and unite with the rear light wiring. Coming up from the back of the Subdriver are an air line, a linkage to the sail dive plane fitting and this wiring, they all can't go up the middle top of the Subdriver, I'm working on how this will all fit/work on paper at the moment.

The Boattrainman

[The Boattrainman]

I'm only going to use one KlikOn magnet, it will be on the linkage to the sail planes, not sure which end of the linkage yet, but I want a quick break as the clevis linkages are hard to open.




However, I want security, so this has been achieved with a small washer, soldered to a short brass wire, plus two very small split pins which have been pushed through holes in the plastic housing and glued in place and the ends opened and spread around the housing. The brass wire is pushed through the two holes in the split pins and soldered, all brass parts that won't rot in water and very strong, but will pull off.

[The Boattrainman]

Here is finally how the sail light wiring exits the sail through the hull, I drilled two holes off-set to left and right and went for the left hole to take the wires. It would be better to unite the four wires into two (+ and -), however I need the sail in two parts for a while to do other work, as it is I can remove the sail and wiring and may need to for maintenance when complete and in service.




The wiring going to the right works with the KlikOn connection and safety loop on the left, leaving the centre free for the snorkel and the through hull fitting.




The lights working correctly with the wires exiting the hull for the moment, Green/Starboard, Red/Port.




The Boattrainman

[The Boattrainman]

Some of the Photo-etched (PE) parts are now attached, the ballast tank surrounds are slid down a cocktail stick jammed in the hole so that they centre correctly.




The two deck hatches have their indents accentuated by using a small drill bit in a pin vice.




I'm not going to use all the PE parts, just where I think they make a visible improvement, the quality of the Revell kit is good enough for some hatches etc.

There is a series of indents along the spine of the exhaust aft of the sail, these are drilled all the way through (72 thou bit), to accentuate the feature and more importantly to let the air out when filling with water when submerging. That seam will eventually be filled and sanded which will fill some of those holes, they will be re-drilled from the inside, their position is set by drilling through now.



The Boattrainman

[trout]

In our mind, it would make sense those tiny holes would let air out, but they won't work much on the first time diving. Once water gets to them, the surface tension of water is too great. The effective hole needs to be 3-4mm (1/8 inch) or larger. The best thing you can do is grind out a path on the underside of the exhaust so the air will travel to the sail.
Your whole sub will need to be inspected to see if there are areas that will prevent air from leaving. Those pockets of air will make it very difficult to trim or if trimmed with the air pockets, in the wild can cause your boat to run incorrectly. So removing mold marks, ribs, and other obstacles is important. You may know and have done this, if so I apologize for being redundant.

[The Boattrainman]

Roger that.

I've ground out a path in the ribbing under the exhaust as per other threads, plus I've not used the rear resin screw holder in the sail, as the top has to be ground out anyway as an air path.

Would really prefer to not have to put a 3mm hole (scale 21cm/9 inch) in here, would look bad, so hopefully the air path will work.

Rob

[trout]

You will not need to in the exhaust with a good path for air to escape, the only place you may need to is at the aft end of the sub. As the Skipjack initially dives the air gets pushed to the rear. Once under, the leveler allows air to once again travel out the sail. I am really excited for you, it is a fun sub to run!

[The Boattrainman]

I've been scratching my head about the rear section.

For a full 12 inches to the prop, there is no flood/drain/air route out of the top of the hull, and given it's going to pitch forward I can see what you have explained happening.

I've holes in the rear dive plane supports, but I was considering a 2/3mm hole very tight to the pivot point under the top rudder, between the the rudder and the prop, it will be hidden as long as the rudder doesn't swing more than around 35/40 degrees each side.

Rob

[trout]

Being hidden means being restricted. You may want to reconsider that. If it is under your rudder, is it getting the 3mm space to allow the air out or water in?

[The Boattrainman]

Here is a partial solution.

The two holes are 2.5mm wide, and under the upper rudder, when heeled over to 40 degrees they are still hidden, at least some air will escape at these holes as the rudder is held off the hull by 0.3mm and I have sanded a concave shape in the rudder base at the hole points to give more room. Other than a great big un-prototypical hole in the upper hull, that's the best I can come up with.




Ok, so I cheated a bit with the deck mounted PE parts (ballast vents etc.), I sanded the mounting points down a bit and then hard sanded the metal parts when glued on to get them (almost) flush. I can't use that dodge on the sail PE parts.




Instead, the locations are completely drilled out, and a backing of 0.5mm Plasticard is stuck inside the hull, and disc of 1mm card drop into the hole, which brings the depth back to just under the lip, with the PE part pushed into the shallow hole.




The two vents on either side of the sail get the same treatment, they will have their edges filled with putty and sanded into the hull.

The Boattrainman