HMS Polyphemus (1881), Refit
A slight break whilst I concentrated on my newly acquired 1894 French cruiser and refurbishing HMS Skirmisher. I did not want to rush back into this, but give it loads of constructive thought.
Back to the Poly. Getting serious now. It only took one pneumatic joint failure to cause disaster.
Having come to a total impasse on my Engel 212A (aligning hull sections & sealing) I have been avidly following the 212 build log on Mayhem. He too has continuing O ring sealing problems, and had also suffered a pneumatic pressure pipe failure, so even quality kit subs can bite back. Poly at least is 90% scratch built.
So, progress to date. Removed Mister with 24V batteries, and closed off funnel lower air intake. Too many holes. Air pump moved back one compartment. Less joints, less compartments at risk of compromise.
Epoxied longer brass stubs into tops of ballast tanks. Heavy duty brass tees with barbed connections to allow wire-securing of flexible pipes. Air valve (ballast tanks vent) no longer vents into Mister compartment, now vents via tube to top of funnel. Air pump inlet also tees into this so sole air inlet is now way above waterline. If any ballast water gets past the air valve or pump its only route is up the funnel.
I spent ages trying to source suitable clamps for 5mm O/D flexible pipe, even bought some. All useless. So, I used plastic coated garden wire, twisted with pliers. The tubing has a high rating, and I reckon my revised connection scheme should withstand practical pressures.
With all the electrics fully functioning again I sealed the inter-compartment cable ducts (just under deck level) with silicone sealant. Even if one compartment fully floods it will limit overflow into the next. (Ref: 1912 'iceberg' bulkheads.)
Whilst refitting I replaced almost all of the M3 s/s blind nutserts, this time using 2 ton epoxy.
The MIL grade neoprene hatch gaskets were inspected, and are still in good condition. Just to be on the safe side I will be taping over the flush joints and fixings.
The bilge level warning system is to be upgraded to 10mm flashing LED’s. The ultrasonic alarm proved not loud enough inside the hull at even a moderate distance.
A full ‘watering can’ test in the bath will be necessary, aiming for full IP65 rating.
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Montgomery’s First Rule of War was “Do not march on Moscow”, based on the high historical failure rate. The First Rule of model Warship design should be “Avoid Semi Submersibles”.