When I first posted a thread under ... a dreamproject.. I didn't realize it was the wrong forum category. So here is my built blog. I will spare you the original introduction as I have made progress which and most of you are already familiar with my project.
The hull was built merging 2 methods on a simple keel plate from plywood, bow and stern structure bread and butter and hull in between 3mm planks on frame.
The entire main deck is intended to be removable with a drainage irrigation system of plastic corner moulding (from a building supplier) along top of hull and flush at poop and back deck structure. The deck is made of 1/4" plywood skeletal structure incorporating midship deckhouse. Hull glassed with lightest cloth available after 2 coats 2-epoxy sealer and paint primer followed by final coat except top (above waterline) grey will be applied once I have finished doing any necessary adjustments. There have been a lot of them since I realized many inaccuracies in dims etc. I wasn't happy with.
Here are photos in the progress (some may have already been posted in the original post.
More a bit later next week.

The last months have been spent making sure everything is in line with Original and to scale.
I finally finished the removable main deck which was built as skeleton structure. For the deck material I went outside common practice and used melamine (the stuff for kitchen and bathroom counters). I always wondered about its use for decking and sofar my only issue is that paint doesn't hold very well and it takes several coats. I may even consider sanding it down slightly applying an appropriate undercoat. I just have to be careful to avoid sharp objects scratching it.
Next will see the aft superstructure taking shape.

Yes Alessandro. I thought about lead but concrete (cement) is cheaper and easier to handle. I just hope it will do the job. I will refrain from asking you for your scientific fancy drawing and calculation software to put to use to calculate how much concrete will fit in between the frames hahaha

Alessandro, thank you for your response and your welcoming comments. I think I will be ok
without immersing you in lengthy time consuming work on the computer. The ballast has to be removable therefore I will make forms to fit exactly the space between the frames and I don't have to resort to complicated transport and retrieval systems as luckyduck has been suggesting. I will pour the concrete and once cured remove the forms.

I agree with everything you brought up. I have to, however, consider practicality. While lead may be the best medium for its weight/volume density, not having any foundry facility, it also imposes inherent difficulties to achieve maximum space utilization.
Cement has specific weight of 3.16 to water, I could enhance this by adding gravel but with limited benefit.
Once I get to the point of putting my model to water, I will do some testing how much weight I really need. I can do some quick calculations how much I will need and have the option with the smaller compartments to achieve ideal balance.
When running 'in ballast' I will have a small acid/lead battery (those for motor bikes) in the aft section to get proper draft (I hope).
I surely let you know once I get there.

Alessandro, if I will sail the model how have I intended it remains to be seen. Definitely I'll start in Ballast condition, then try loaded as planned. If everything goes as hoped I will subject it to water dousing. If it proves to keep the water out I will go further. One tiny step at a time

Since my Summer break, I have been working on the aft superstructure. Before I can proceed I have to finalize the porthole. I was unable to find anything I could use on the model supply market suitable as the port holes on the original are flush with the hull and just the window recession. To simulate I thought to drill the holes in the 1mm siding with the acrylic glued in place. This imposed problems as I found out as there is not much space to properly place the acrylic and secure in place. Next option was to construct port holes from alu tubing, filed and sanded to 1mm thickness. I used a tool to cut 3mm holes in leather belts to cut out the acrylic windows which I superglued to the back of the port hole frames. As some drill holes were not quite properly aligned, I had to drill them I bit larger to adjust position and for that expanded the porthole frames with a larger ring of aluminum tubing into which the smaller ring with the acrylic window would fit. A tedious operation with many duds redoing numerous pieces. I had to strengthen some of the siding when the larger port holes didn't leave much material in between. After many attempts, failures and frustration I managed to get them to the point I was finally able to move on to the next stage.
More to come shortly

Thank you Alessandro.
Having advanced to the first Deck structure I had already cut out the deck material from Arborite. For you Modellers a very unusual choice but I like its finish, hardness
and virtually indestructibity. When I did the back (foc'sal), midships, main and poop (aft) decks the Tamiya paint, I had chosen for colour preference, not adhering and easily chipping off. I then painted all decks with standard Hardware shop spray paint first and second the Tamiya on top which worked great.
I tried the same when finishing the styrene deck walls for the first deck (white) but noticed the regular spray paint seems to react with the styrene giving it a rubbery feel
and in some places. After sanding it and reapplying I wasn't at all satisfied with the result. As I couldn't get Tamiya white in the rattle can bought Revell acrylic with disastrous effect. The paint's texture seem to become mottled although I had sanded all surfaces. Does anybody have any experience with painting Styrene. I also can't find Tamiya white at my local stores and I am not sure using the Revell. I could resand everything and try the Revell again since I already have otherwise I need to find Tamiya
somewhere else around town.

I have seen Krylon in the stores and certainly will give it a try. I have to give it a rest for a few days as I have to into surgery tomorrow.

I had to have a cancerous kidney removed. Surgeon is confident he got it all and I should be able to finish the model 🤔 which requires at least another 5 years.