What did SpaceX change in the upgrade of the ASDS?

Question

The original ASDS (Autonomous Spaceport Drone Ship known as "Just Read The Instructions" (JRTI) was based on the Marmac 300 hull. It has been replaced with the Marmac 304 hull for use in the CRS-7 launch attempt of a first stage landing.

Marmac 303 has the wings from Marmac 300 and presumably will become the West Coast ASDS after a trip through the Panama Canal with the wings removed. Per Elon Musk, the West Coast ASDS will be named "Of Course I Still Love You" (OCISLY). Edit: In hindsight a few years later, OCISLY remained the East Coast/Atlantic barge, and JRTI moved over to the West Coast/Pacific.

What changes were made to the East Coast ASDS in the switch from Marmac 300 hull to the Marmac 304 hull?

Answer 1

Based on a rumour, who so far has been accurate the following is reported:

• The wings have been boxed in for added strength on both the original and new wing sets. They are attached by welding only; no hull penetrations needed.

• Only penetrations are through the barge decks, for fresh water ballast, which helps stabilize in towing. Ballast water is also used for flooding the decks during landing, which, along with heat resistant paint, protects the deck.

• Barge is unmanned during operations/landings, with no provisions for people, which helps keep USCG compliance as "unmanned vessels."

• No equipment located below decks.

• Thrusters are intended only for stationkeeping, not long-distance autonomous self-transport. They could do a full trip but would require larger fuel cells.

• Front wall is a breakwater, back wall is a blast shield, both to protect the containers, etc.

• In late 2016/early 2017 one of the cargo boxes was raised on stilts, and a garage door installed on the blast shield, as a garage for the "SpaceX Roomba" like robot designed to hold onto stages in bad weather. No official word on its name. (I like Xoomba, other like Attitude Adjuster).