The name of the boat is a Russian word Чайка (modern transliteration Chaika) that means "Gull". The name was used as a generic for any small sea going vessels deplyed by cossacks. The boat didn't have a deck, was capable to move either by rowing or under sail. Large boats could be armed with light artillery. The boats were widely used in XVIII century Russo-Turkish wars, for example at Izmail.

As for the crews it very much depends on particular situation. If it was an action where Russians could take part the crew was probably raised from cossacks. In particular those of Ukraine or Black sea.

English language article in Wiki:
http://en.wikipedia.org/wiki/Chaika_(boat)
The Russian language article contains several interesting links.