Hi Nigel,
That will be a huge build!!!
Have you made any calculations at all for how much water you'll need to get her to the lifting waterline?
I say this because I know there is a stretch of hull in the middle, about 5-8m wide, housing all the pumps, all extra hull width is ballast tank top to bottom.
There is a reason for that: when the ship is at normal waterline it has reached maximum waterline surface area, this means that for every meter extra depth you'll need to add more and more weight.
This ship is even worse in this sort of situation because of the overhanging ballast tanks, but this extra width is very needed for extra stability when lifting, along with the added weight of the ballast.
In short, I think it's safe to say that Engel tanks are not going to be enough, not 4, and quite possibly not even when you fill the entire hull with these tanks because of the moving bulkhead mechanism.
Add to this that a hull this size in itself is way to lightweight to reach the waterline so you'll need to have quite a bit of ballast in there for the normal waterline alone.
It would be really great to bring this project to that level but I strongly recommend making some calculations before you start building.
I calculated the weight, both at normal waterline and at lifting waterline, the difference is bizar:
Normal waterline: 22,77kg
Lifting waterline : 92.89kg
You'll need to be able to pump 70kg's of water in the hull to get her from normal waterline to lifting waterline, adding over 3 times the normal weight to get there.
This calculation is based on fresh water, should you want to sail in seawater you'd need to multiply this numbers by 1,025.
Greetings Josse