An update, it took awhile, bought WEST system epoxy ready to use as in Peters deck repair method.
Then bought an Air compressor (from "Supercheap Auto", a BR3000, 25%off) with beginners 5-pack of Ozito tools and 30m of ozito airhoses (preparing for the "drying out" phase). It's running well, 190 litres per minute, direct drive, 40L tank.
However it's a very wet wet season now. The new tarp is working well keeping her bone dry, however it's not high enough to work on deck. (slowly working on that issue, have 100m coil of 50mm HDuty poly pipe - arch shelter in mind) oh for a decent cyclone-proof shed.
This year i've looked into all other possible repair methods online. However reckon Peters is the best/"easy" method, it surely will last for decades. (most other permanent WEST epoxy methods are more complex, require one side of deck to be cut off, brand new ply core laid in then biaxial glass skin recovering..allot of work/cost)
Expanding Foaming with Australian available products was looked into. But suitable high density 2 pack injectable foams are hard to get up here. Mitre 10 had Soudal products. I online ordered Soudal "Fill and Fix" foam (36kg/m3) for fastening window and door frames, harder stuff but they sent ordinary "Gap filling and expanding foam" (25kg/m3) the stuff for around pipes through wall openings, which was on the shelves already. Both were one part, moisture curing types (ok if its a wet space to fill) It's the expanding foam found in most hardware stores. It's partially open celled, so can take up sea water (bad).
Sikaflex has "Sika156 2C" a 2-part in one-can product which could be better. But can't obtain any of this stuff, or get spec's on it online. It might be ok for repairing lower stress areas of decks? Only some of the 2 part epoxy expanding foams are closed cell and can be rigid enough, but their delivery is to just pour the cup pre-mix into a large hole, (only Injectadeck has developed a dual-syringe & mix delivery, its expensive)
My guess is that building codes must be stricter overseas, so the top shelf foams like Sika156 2C aren't used downunder much, if at all? A "structural foam" is what is required, maybe some aircraft engineers etc who use these specialist materials out there? There must be tons of glass old boats around requiring rotten core repairs.