According to TNA at http://www.nationalarchives.gov.uk/records/seamens-wills.htm the wills usually provide the following information:
- the man's name
- the date the will was made
- the man's rank
- the last ship he served on
- details of his effects
- the name (and sometimes the address) of the person who was to receive the effects in the event of his death (usually his next of kin)
These wills also hold details such as the name, address and occupation of the executor.