Coastal boats traded stores for forward access

Italy's coastal boats were roughly half the submerged displacement of the large ocean-going types, but retained about eight knots of underwater speed. Their smaller stores suited shorter patrols from Mediterranean bases, including positions where larger boats would be harder to support. Even these boats were intended to pass submerged through Gibraltar and the Dardanelles, keeping access routes central to the design. The Suez Canal offered no comparable prospect of an undetected transit, limiting where these boats could move between theatres. Forward basing in riskier waters placed the boats closer to both targets and concentrated Allied countermeasures.