On this day I also tested the ballast tank and did a very brief full submergence dive, in the limited light I could not see below the surface and lost sight of the sub right away.

这一天，我也测试了压载水舱，并没有一个非常简短的充分淹没下潜，在有限的轻，我不能见下文表面和抛诸脑后小组的权利。

youdao

Lower turbines should, together with clever design and material selection, help reduce the turbines' weight, and thus their need for ballast, which in turn should reduce sub-sea costs.

BBC: Floating challenge for offshore wind turbine