Ship vouchers are crafting items obtained via purchase at Premium Merchant NPCs, either through mystery crates or direct purchase. Some are used in crafting the ship itself, others are directly redeemed at Premium Merchants to award the ship to the player. There are several different types of Ship Vouchers which will be covered here with the exception of Ghost Ship Vouchers, which are explained in the page on Ghost Ships.
Super Steamfish Vouchers first went on sale in 2015 and can be redeemed for a Super Steamfish (1 voucher) and a Partyfish (10 vouchers) at Premium Merchant NPCs.
Minnowclad Vouchers first went on sale in early 2016 and can be redeemed for a Minnowclad (1 voucher), RIOT Minnow (3 vouchers), and Steamclad Minnowfish (3 vouchers) at Premium Merchant NPCs.
The Empty Barrel was a crate-exclusive item from 2016 mystery crates, and is used to craft the Titan at Shipwright NPCs.
The Mark of the Nahrluminati was originally added in 2016, and is obtained at the mysterious merchant known as "Brek Brekerson" when on sale. It is used to craft the Combat Log at Shipwright NPCs.
Mortar Platform Vouchers went on-sale for a short period in mid-late 2018, and are used to craft the Mortar Platform (1 voucher) and War Koi (2 vouchers) at Shipwright NPCs.
Steam Goose Vouchers went on sale for a short time in late 2018 not too long after the Mortar Platform Vouchers, and are used to craft the Steam Goose at Shipwright NPCs.