46 C.F.R. § 76.23-5 – Zoning.

(a) Separate zones may be used for each deck, and on any particular deck, spaces separated by “A” or “B” Class bulkheads may be separately zoned.
(b) On any particular deck, large common areas may be zoned in accordance with table 76.23-5(b). All such zones within one common area shall be of approximately the same size. Zones of this type shall overlap in such a manner that the end sprinkler heads of both adjoining zones will cover the identical area.
Table 76.23-5(b)
Square feet of common deck area Maximum number of zones
Over Not over
800 1
800 1,800 2
1,800 3,000 3
3,000 5,000 4
5,000 9,000 5
9,000 16,000 6
16,000 30,000 7
30,000 8

Square feet of common deck area	Maximum number of zones
Over	Not over
	800	1
800	1,800	2
1,800	3,000	3
3,000	5,000	4
5,000	9,000	5
9,000	16,000	6
16,000	30,000	7
30,000		8