Could you post a blueprint of your spar or just its dimensions and a description of it's features such as ballast and containment areas?
Also could you say what the spar is costing you to make and what source materials you are using to make it?
I am most interested in the construction of the spar because I do that sort of thing (metalwork, fabrication) and I think I might have a lot of 2nd hand source material perfect for making such a thing local to me that can be had very cheap and have all of the tools at my disposal..
I have even had a "real job" making similar contraptions from raw materials from rolling sheet metal to finished tanks including cutting and welding, installing fittings, pressure testing, you name it. From blueprint to finished product.
I also have experience pressure testing and pumping well over 10,000 psi.
I have plasma and oxyacetylene cutting tools available and many types of welding machines and very competent welders.
I might be able to make these things very competitively with logical delivery to the gulf of mexico or the Atlantic by New York..
Just to kick around ideas..
I have most of the specs here:
https://www.seasteadtalk.org/forum/engineering-discussion/51-xlii-specsThe spar is rolled steel tubes about 1.5 meters each welded together to get to the 20 meters. 14mm thick steel.
Ballast area on the bottom is about 1.5 meters walled off then filled with concrete. We also added about 10 tons of sand to the main area that became ballast when we flipped it.
Initial cost was around $30k but being a prototype and never having done this before we had to pay another $10k or so for incidentals.
Now that we have the process down we will likely be making mass steel purchases from China to bring that cost down for the production version, while ramping up the quality.
If you're up for seasteading we are hoping to move most of the metal and fiberglass work to the seastead so that we can grow the economy of the seastead by building seasteads.