Sentence:  "They know our boats will stand up to their work," said Willison, "and that counts for a good deal. A low <WSD>estimate</WSD> from us doesn't mean scamped work, but just that we want to keep the yard busy over a slack time." 
Meaning of the word marked with <WSD> tags:  A document (or verbal notification) specifying how much a job is likely to cost.