The impact of COVID on costs occurs in two ways in a shipyard.
One, it has affected the production hours that it has taken to complete the ship. That would be due to the disruption caused by not having all of the workers we needed on any particular day and in any particular week. There were periods of time, even when the shipyard was open, that we suffered 30% absenteeism. We've gone through a very detailed analysis of the additional costs associated with the production inefficiency. It was a study that was conducted by a third party, and that is under review with Canada right now. There was certainly an impact on the production side.
Also, on the materials side, the impacts have been significant. I mentioned the skyrocketing price of steel. That has certainly affected us. The price of steel has gone up by over 150% since April of 2021. The price of copper has gone up by over 100%. Those increases in prices affect not only the commodities—the raw material we use—but also the finished products, because all the suppliers are using them. The shipping costs have also been significant for us.
All of these costs are on the order of millions of dollars per ship, because the increases have been so significant and so sudden.
In terms of what options we have to reduce those costs, on the materials side, I'm open to ideas on that. It is extremely difficult. We are dependent on our suppliers. All of our suppliers on AOPS at this point are single source. I'm not in a position to change suppliers in most cases. We always do that as part of our process anyway, to try to get the cost of material down, but it's not something that I can just instantly do. The material we buy is very highly specialized. It requires engineering approvals and it has to be approved by Canada, so we're in a tight position there.
Regarding the productivity—