Mastbase and Cabintop Blocks

Mastbase and cabintop blocks allow crew to raise, lower and trim sails from the cockpit. A variety of specialized blocks have evolved for routing lines aft.

Typical Boat Length:
Small Boat: 22' - 28' (6.7 - 8.5 m)
Midrange: 29' - 34' (8.8 - 10.4 m)
Big Boat: 35' - 42' (10.7 - 12.8 m)

1 Halyard

This simple system leads principle halyards aft. Used by boats under 9 m (30 ft).

DiagramRef.	Description	Small Boat Part No.	Midrange Part No.	Big Boat Part No.
A	Mastbase block	222	1986	1990
B	Cheek	2644	2606	3220
C	Single	2652	—	—
D	Flip-flop	2142	3122	1987

3 Halyards

Larger boats use special mastbase halyard lead blocks. Lines are routed out to deck organizers then aft to stoppers and winches. Stand-up blocks on a base are sometimes preferred for their complete articulation, but they hold halyards higher off the deck than specialized mastbase blocks.

DiagramRef.	Description	Small Boat Part No.	Midrange Part No.	Big Boat Part No.
A	Mastbase block	222	1986	1990
B	Deck organizer	9001	9001	9006
C	Winch	20.2PTP	35.2PTP	40.2PTP
D	Single	2636	2660	1540
E	Stand-up spring	097	071	1634
F	Stand-up	2652	3227	3244

6 Halyards

Modern race boats lead halyards and control lines straight aft through deck organizers so they can be used on either cabintop winch.

DiagramRef.	Description	Small Boat Part No.	Midrange Part No.	Big Boat Part No.
A	Mastbase block	1986	1988	1990
B	Deck organizer	9001	9006	9006
C	Winch	20.2PTP	35.2PTP	40.2PTP
D	Crossover block	—	1984	1981

Over the Top

Special “over-the-top” blocks are required to route lines over an outside corner like the front of a doghouse or coaming.

DiagramRef.	Description	Small Boat Part No.	Midrange Part No.	Big Boat Part No.
A	Mastbase block	1986	1988	1990
B	Mastbase block	1986	1988	1990
C	Over-the-top block	3002	3002	3002