Be aware that Crew Agreements at NMM Greenwich do not begin until 1861.
You say he was Crew member of MAYNARDS prior to sailing on GOLCONDA in 1859/60. So it may pay you to look at the 1857 Crew Agreements of MAYNARDS.as well as 1858
I would try this first, if you find nothing, then it's off to NMM.
You can short circit this by filling in the following form. A bit long winded but easier than visiting.
Keep going. You will find him!