How many protected lead ships would a Dardanelles assault need?

Would three minesweeping pre-dreadnoughts have been enough for the Dardanelles assault?

The suggested minimum is six, with two protected ships at the head of each of three columns.

The proposed formation has three columns, each led by a pair of protected ships. A second vessel provides continuity if the first is knocked out. False hulls are preferred for those leading pairs because they offer the more secure protection. Following ships could receive a quicker arrangement of netting held away from the hull on poles.