There are facts from which we can ascertain the minimum number of men
 in five of the boats: those bearing Mawney, Bowen, Brown, Potter, and Ormsby.

Number in Mawney's boat. Consider the Statement of Dr. John Mawney (see Staples, p15-16). [After hearing the drum beat, he went to Sabin's tavern, where he learned the object of the meeting; and was asked to accompany them, as surgeon.] "To this, I readily consented, and went to Corlis' wharf, with Capt. Joseph Tillinghast, who commanded the barge, it being the last boat that put off     . ..  I was then sitting with Capt. Tillinghast, in the stern of the barge.,

Note Mawney's reference to "barge". A "barge" in the 1700's was a large longboat used for transportation of large amounts of materials and men to and from ship and shore at the various ports. "Barges"  were used by the English navy for the landing of the royal marines to fight.  In New England a "barge" was built to hold many more than eight or 10 men.  Likewise, English navy midshipman Dickinson referred to the attacking boats as including launches. A "launch" was a defined term in the English navy, which used "launches" placed on large English warships for the landing of marines for amphibious warfare .  If an English royal navy midshipman used the term "launch", it would mean a large boat, capable of being sloop-rigged, and -- importantly as part of the naval definition -- capable of carrying at least 20 fully armed men, plus a small crew to get the launch back to the warship. 

Further, Mawney stated he and Tillinghast were not rowing. At least in their boat for the six mile rowing trip to attack the Gaspee, the ten oars were completely crewed.  We conclude there were 12 men at least in Capt Tillinghast's longboat.  And still the Tillinghast boat had more room --- the entire Gaspee crew of 20 men (hands bound behind them) was carried off  the Gaspee in only Tillinghast's longboat  plus one other of the attacking longboats.  It was a large boat, not easily handled by a crew of only a half dozen intending to row six miles --- against the tide --- to attack the Gaspee.

Number in Bowen's boat. Bowen tells in his account of Joseph Bucklin not being in a rowing position as they approached the Gaspee.  Brown had ordered "eight of the largest longboats" available, with  five sets of oars This would indicate at least 12 men in Bowen's boat. 

Number in Brown's boat. John Brown was not the sort of man to be rowing.  First of all, because of his gentleman station in life; second, according to estimates of the Rhode Island Historical Society based on his clothing, John Brown weighed about 250 pounds. With some confidence we can say he was not rowing the boat the six miles needed for the attack.  That indicates at least 12 men in his boat.

Number in Potter's boat. Potter's boat was described by informant Arron Briggs as: "....he was in a boat which was rowing with eight oars; that the time . . . Potter was about five miles from Bristol; that there were eleven men in said boat."  Briggs was impressed by the Potter group to aid in the rowing.  That indicates with the eleven men in the boat plus Briggs there were 12 men in Potter's boat.  [Note how this fits the facts. With a "five oared boat", which really means in today's language, "ten single oars", one way to have a boat rowed an 11 mile distance, as Potter was doing coming from Bristol, is to have two men rest (leaving eight oars being used) and rotate the resting among the rowers.]

Number in Ormsby's boat.  Ezra Ormsby, in his statement said his boat from Warren had: "Capt John Greenwood, James Smith, Abner Luther, Abel Easterbrooks, Nathaniel Easterbrooks, Hezekiah Kinnicut and myself".   That would be seven men.  Ormsby specifically described his boat as a "whaleboat".  A whaleboat was a particular kind of boat,  usually carrying a crew of five men.  Using a whaleboat to row to Namquid point from Warren would be logical, because of its design for fast and easy rowing in the about 12 mile row to the attack site. However, the small size of the whaleboat and its peculiar oar configuration would only allow the town of Warren to supply Brown's raiding force with a ship captain and six other men.

Thus, in the five longboats of which we have rather firm conservative estimates, there were 55 men.  We do not have firm information on the remaining five longboats, all of which were longboats from Providence, but we can strike a probable average. To extended discussion of how many boats and of the total of men were in the attacking force.