As rotational nuclear-powered submarines begin operating from Western Australia from 2027, sustainment demand will rise faster than dry-dock capacity can absorb it. With allied submarine sustainment now being delivered in-country, the requirement is now to draw on local suppliers, secure the supply chain and scale the model. This session will ask how the fleet stays available when a dock is not free and how far in-water techniques such as hull husbandry, biofouling management and underwater maintenance can close the gap. This session will also convey the importance of SMEs in allied submarine support and how that supply chain is built and qualified, a practical account of how sovereign industrial base behind AUKUS submarine sustainment is assembled.