The Ship Model Forum

Hi all

These pictures show me returning to work on the already completed hull plug halves. The upper hull has been given a thin coat of silicon rubber (red arrow) and when it had set I have filled some of the larger detail and sharp corners with thicker (more viscose) white silicon (blue arrow).

Hi all

Here are a series of pictures which show the final stages of the hull mould manufacture.

This includes the addition of two more coats of silicon rubber and finally the covering of the whole lot with two layers of chopped strand mat GRP. When this had set the real nerve racking bit was getting the whole lot to come off the hull plug without damage. A bit of gentle levering and both the upper and lower hull moulds did come off OK.

Each half was then mounted in a lightweight wooden cradle which holds the mould steady while it is being used. I usually clamp this cradle to the work bench to stop it wandering about when the GRP is being laid up.

Awesome Scratch building work mate. I cant wait to see the end result.

Thanks Haratio

Here are a few more pictures of both finished hull half moulds. I'm pleased with how they came out. The real proof however will be when I take the first hull moulding out of them which could be next week if I get the time.

The hull plugs were fine after the moulds were removed. One little bit of hull plating (aluminium foil tape) lifted a bit but soon pushed back into place. This means I have both plugs if I need them for the future.

Hi all

Well this is the point where we see if all this effort is wasted or not.

The silicon lined moulds were cleaned with solvent and lightly sprayed with release agent. A layer of pigmented Gelcoat was applied and left to cure. This first layer was worked into the detail well using a 25mm wide stiff artist brush. Next a layer of surface tissue was applied to both moulds followed by two layers of lightweight chopped strand mat. A small piece of fine glassfibre cloth was also applied to the extreme bow and stern to give a little extra rigidity. Again the moulds were left to cure before a palette knife was used to ease up the edge. The glassfibre edge of the mould had previously been covered with masking tape before "laying up" the hull and I was able to peal this up to help get the hull out. The upper hull was a little bit more difficult (as it has a few more undercuts and detail) but it came away in the end. I will use a bit more release agent next time.

The hull halves look pretty good. The upper hull in the pictures still needs to be trimmed and both are covered with dust and finger prints but the detail was all there. Some minor cleaning and prep work is needed before they can be used. Disappointingly there was a couple of "drop outs" in the bilge keels caused by trapped air bubbles but I know how to cure this on the next hull. These gaps (arrowed) can be easily filled so the hull can still be used.

With these hull halves and the cast resin components I now have about 85% of the model. A photo etched set would be great for the fine detail but time will tell if I can get this designed as I have no Autocad skills.

At the moment I'm cheerfully relaxing with a large single malt knowing that all the months of work has paid off and actually produced a decent hull. Now the model making can start.

Coming along nicely, the hull has a pseudo realistic appearance like weathering right out of the mold. Cant wait to see the finished

Mick

Hi all and thanks Sandy and Mick

The removal of the waste material around the edge of the GRP mouldings has to be undertaken with care. One slip and and the whole job is ruined.

Some of you might find this little invention useful. It can also be used to cut down plastic hulls to waterline and fantastic for removing vac formed mouldings from their plastic base. Take care as despite its small blade it will take the end off your finger.

Take a bolt (with a suitable shank size to fit the mini circular saw blade) and slide on the chosen blade. Then fit a small steel plain washer followed by a ball race and then a nut which should be tightened down. The drill press should be at a reasonable fast speed. You can experiment with this and the diameter of the saw blade. If you are cutting through thin material it's often better to run the blade backwards as it has less bite and is less likely to grab the material and cause damage. The ball race follows the hull and causes no damage.

I cut the waste off the two hull halves but left about 2mm which will be removed by sanding down to the register line in the GRP moulding.

Looking very good Steve, you deserve that malt!

Hi all, hi Doug

Well the first task in actually building the model, now that I have the components, is to chop up that beautiful GRP hull . All that effort and time and now I chop it into three! This was always going to be a working model so the upper hull mould has to be divided, the centre section being removable to gain access to the internal water tight compartment (WTC). I used a fine blade saw to cut the hull. The cuts were made where they least impinge on external hull detail. I hope to make the cuts as neat as possible so that the "break line" is not too visible on the completed model.

Hi all

The separate bow and stern section were now attached to the lower hull. The joint created between these sections and the lower hull was quite neat with just a fine crack visible. The bow was dealt with first being held in place "dry" with masking tape, before medium grade CA glue was applied (where arrowed) and allowed to run down the joint. The hull was stood upright while the glue ran down wards and allowed to set. I then removed the tape. CA glue sticks very very well to well sanded glass fibre and sets very quickly.

A strip of chopped strand matt was positioned dry over the inside of each joint and using an old paint brush glass fibre resin was stippled through this creating a very strong joint. The same process was used on the stern section. The ferrule of the paint brush can be bent to make it easier to use.

The stern section was positioned, prior to glueing, using the removed centre section as a spacer, again helping creating a barely visible joint.

Hi all

The glass fibre joint strengthening was trimmed after it had set. Two acrylic bulkheads were cut and installed under the edge of the upper bow and stern. These were thick enough to partly protrude and thus give a register for the removable upper deck to sit on. They each had a cut out to allow air bubbles to rise to the highest point within the hull and escape. These are arrowed. An arrow also indicates where the bow diving plane activating rod will run.
A plastic card strip was added to the horizontal joint to seal the gap and again to help locate the removable upper hull section.

Hi all

The upper hull section has to be able to allow trapped air to escape as the hull floods.

On the prototype vessel there appears to be venting holes along the deck to allow air to escape from under the raised "walk on deck". There were also numerous hinged access panels to allow torpedoes and stores to be loaded through the top of the pressure hull. These where moulded into the GRP hull, but I now drilled these vent holes right though the hull. The holes were slightly countersunk on the underside.

The anchor chain hawser holes were also opened up and just aft of this a slot was also drilled out. This contained the hidden capstan. On the prototype the panel hinged up to give full access to the capstan. The lower part of the capstan would have just been visible through the slot and this will be reproduced later.

Looks a little messy, but totally worth it...

Hi Goodwood

You're right these GRP scratch builds can be unbelievably messy and not the sort of thing to attempt on the kitchen table. That's why all the images so far have been in my (already messy) workshop. Having got through the initial very messy bit it becomes more like a kit build and I am even allowed to undertake some of the assembly in the house! The latter part of the build is more enjoyable too. Keep watching because the next post should carry images of something which is actually recognisable as a submarine!

Looking forward to it then, PIGBOAT!

Hi all

The conning tower resin casting was drilled out with a tapered cone shaped ream, on the drill press, to render it hollow. This will hopefully add a little extra buoyancy at the top of the model. The stern casting was also drilled through to carry the prop shaft.

The lower hull moulding had the, as yet, unidentified square apertures. These were cut out and will have a grating fitted over them eventually.

I also cut out two slim cradle bulkheads from aluminium/plastic laminate (strong waterproof and easy to work). These will be fitted into the lower hull half and will act as cradles for the water tight compartment. The small holes will contain stainless wire clips to hold the WTC in place.

Lord Pickering of Chyldshall has returned

Sorry I missed seeing the C-boat when you visited the club, Steve.

Hi all

Thanks Sandy for your comment regarding the picture circulated by Messrs Haigh !

The assembled hull shell can finally be seen here.

The capstan shaft was drilled from below and inserted upwards. The capstan itself would not normally be visible as it was behind hinged steel panels.
The two slim bulkheads/cradles for the watertight compartment were glued in place inside the lower hull moulding.
The 2mm stainless threaded shaft which will carry the forward diving planes was temporarily fitted and this incorporated an activating arm from a mini servo. This was just the right size and will eventually be well secured, as once the bow is fitted access will be very difficult.
I made up a simple cradle to hold the model as it was always rolling about and very difficult to work on.

Looking good, PIGBOAT! Can't wait to see it all come together...