In this Hearts of Iron IV campaign, moving Sweden's capital from Stockholm to Visby makes convoys essential for delivering resources to the island. A shortage can interrupt supply as soon as the capital moves. The advice is to start convoy production beforehand and keep some yards assigned to it. Buying additional convoys offers another way to cover the immediate shortage.
Notable Point · 2:16-3:35
Why an island capital makes convoys indispensable
Sweden needs convoy production in place before a move to Visby makes the island capital dependent on maritime resource deliveries.