Indeed:
if (item_amount($item[dinghy plans]) < 1) buy($coinmaster[The Shore\, Inc. Gift Shop], 1, ($item[dinghy plans]));
if (item_amount($item[dingy planks]) < 1) buy(1, $item[dingy planks]);
use(1, $item[dinghy plans]);
if (item_amount($item[dingy dinghy]) ==...