Hello Jock.. I have a list of hobby sites I go to for my builds. Not sure I can attach them here. PM me if you like. I am in Victoria. And on your dream project. Buy yourself a good container of Famowood. Best ever wood putty to shape hulls etc. It does not shrink Crack or run. You can stain, resin or paint it. Sands like wood acts like wood. see my photo.

Hi Ron. Yes I am in Langley. The only other models in my attempts is the original Esso Deutschland from back in 1964 which never was completed in its details and the Billings Blue Nose which needs some of the rigging and sails.

Interesting read of your dream project. You are in Langley, B.C. correct? Do you have other models in your collection you would share with is?
Ron 🇨🇦

Hi Jock,
"Compressed air sounds complicated for a model unless you find a 12V compressor ..."
You'd need a pretty big sub/ship to fit a compressor in!
As far as I know folks who use compressed air only use the compressor to charge an on-board pressure vessel. Meaning of course a limited number of 'Surface, blow all tanks'.
Er was that the 5th or 6th dive?😮😭

Having investigated various methods for diving/surfacing I opted for the piston tank, which'll work until the batteries are flat!
So that's what I've bought for my Akula II sub, ca 1m, which I hope to finally get operational this winter.
Guess I'll have to build a vertical version of Martin's 'Big Blue' tank to test it 😉
A slower version using pumps should be adequate for a 'Heavy Lifter ship'.
Seen various docus about them and they don't seem to react too fast.
Especially when coming up with several thousand tons of load aboard.
My post was only 'tongue in cheek' anyway - unnecessarily complex just for removing ballast.
Would be fun though watching the ship rise.
Don't let the Coastguard see you though - they might think you are illegally flushing tanks at sea😁 Good luck with your dream👍
Cheers, Doug 😎

I see space every night Rick, WHEN it's not overcast 😁
😎

Where we boldly go. Shatner 90 years old sees space. How good is that
Rick

Just a standard fish tank air valve. As you are in Canada the suppliers in the UK would not be useful, but I'm sure you have suppliers in Canada. Try Googling "Air Line Control Valve Aquarium Fish Tank". You could use several on a larger model.

Wondering what kind of air valve you used? Is there the kind where a small float will seal the valve preventing water form exiting on top? Would be ideal as pitch could push water out fore or aft.

If its a choice between lead and water the logic is perhaps understandable. Large model hulls displace a great volume of water to carry essentially an open space full of air.
A fellow modeller had built the large Puffer I had and used exactly the same tank with a sealable air vent. My first attempt was to use a sealed container using a pump - bad idea the puffer listed badly when I used the rudder and would not self right.
I suppose you could emulate the real size and pump water into different tanks but using an open tank removes this problem and with two watertight compartments running fore and aft on port and starboard stability is not a problem.
Doug, the comments re the Starship Enterprise are classic and brought a smile. If we had their technology I doubt if slots in hulls would be required.
I'm off to "Boldly go"
Dave

Couldn't open video files. I got myself a new MacBook and having had only MS Laptops before not quite familiar with all download functions.
Compressed air sounds complicated for a model unless you find a 12V compressor with enough power to blow out the ballast tanks but 1 or 2 12V pumps should do the job.