Watching them lower this cap make me think of a way to capture more of the oil.

[Statistical]

So they are going to put a cap on TOP of the BOP but it is going to leak right. How much remains to be determined but it will leak some. The reason is you don't have a tight seal.

So here is my idea. Design a tube that fits AROUND the entire BOP and at the top is a section of normal drilling pipe with threads.
So visualize a container which goes around the BOP, open on the bottom, and the top is welded a section of drilling pipe.

Now you lower this "collar" down around the BOP and let it settle to the ocean floor. Now well is still eaking out the top of the BOP. This is simply fitting over and around the BOP. Once it settles you fill the space around the BOP with concrete to hold it in place.

What you have you done. You have replaced the jagged BOP pipe with a new outer shell with some brand new shinny theads.
Lower a new riser pipe to the threads and couple them. Airtight seal and oil goes up to the ship.

Essentially instead of a cap you build a sleeve, anchor it in place and then attach that to the new riser. Of course same technology to prevent ice (heated salt water & methanol injection) can be used.

[BR_Parkway]

1. I can't figure out why they don't try a cover with a pipe leading to the surface to give the

oil a place to go where it could be captured by the tankers instead of trying to put a cap on it like they did before

[Statistical]

2. Actually that is exactly what they are doing.

The cap they are lowering is connected to a rigid pipe right to a drilling ship.

[Born_A_Truman]

3. Great idea ...

Or cover the entire BOP like you suggest and have rubber seals at the bottom, middle, etc that can be clamped down to secure it if they can't cement it on. Fit the top of the cover with redundant shutoff valves and threads to attach piping.