Index | Use chart | 57 mm | 75 mm | 100 mm | 125 mm & 150 mm | Teardrop | Crossover | Mastbase Halyard Lead & Flip-Flop | Footblocks | AirRunners | Stainless Steel Runners | Opening Foot Blocks | Snatch | ESP Blocks | Stainless Steel ESP | Stainless Steel Blocks | Specifications
Big Boat blocks > Mastbase Halyard Lead & Flip-Flop
Low profile mast base halyard lead blocks are lightweight and can be grouped in a small area at the mast base. Flaired cheeks prevent chafe on the halyards.
Over the top blocks lead lines aft over cabin houses, coamings and splashguards. They feature hi-load sheaves and come in single, double and triple configurations.
The high-load flip-flop blocks pivot around the line axis to keep line close to the deck. Hinged construction allows variable leads. Lockoff provides a temporary stop to free up winches.
 1986 |
 1988 1990 3053 |
 |
 3003 |
 3004 |
 1987 |
 1989 |
 3002 |
| Part No. | Description | Sheave |
Width | Length | Height | Max line |
Weight | Safe working load | Breaking strength | ||||||||
| in | mm | in | mm | in | mm | in | mm | in | mm | oz | g | Ib | kg | Ib | kg | ||
| 1986 | Halyard lead block** | 13/4 | 44 | 7/8 | 22 | 313/16 | 97 | 21/4 | 57 | 3/8 | 10 | 3.36 | 95 | 750 | 340 | 1500 | 680 |
| 1987 | Flip-flop block±±± | 3 | 76 | 27/8 | 72 | 6 | 152 | 4 | 100 | 1/2 | 12 | 17.37 | 493 | 5000 | 2273 | 10000 | 4545 |
| 1988 | Mastbase block/fixed*** | 21/4 | 57 | 13/8 | 35 | 33/16 | 81 | 27/8 | 73 | 3/8 | 10 | 6.2 | 175 | 2500 | 1136 | 5000 | 2273 |
| 1989 | Flip-flop block/lockoff±±± | 3 | 76 | 27/8 | 72 | 6 | 152 | 4 | 100 | 1/2 | 12 | 21.1 | 598 | 5000 | 2273 | 10000 | 4545 |
| 1990 | Mastbase block/fixed± | 3 | 76 | 15/8 | 41 | 45/8 | 117 | 33/4 | 95 | 1/2 | 12 | 11.5 | 326 | 5000 | 2273 | 10000 | 4545 |
| 3002 | Single over-the-top block*** | 21/4 | 57 | 13/8 | 35 | 31/4 | 83 | 31/4 | 83 | 3/8 | 10 | 6.4 | 181 | 2500 | 1136 | 5000 | 2273 |
| 3003 | Double over-the-top block*** | 21/4 | 57 | 27/16 | 62 | 31/4 | 83 | 31/4 | 83 | 3/8 | 10 | 12.2 | 346 | 2500 | 1136 | 5000 | 2273 |
| 3004 | Triple over-the-top block*** | 21/4 | 57 | 31/2 | 89 | 31/4 | 83 | 31/4 | 83 | 3/8 | 10 | 18.1 | 513 | 2500 | 1136 | 5000 | 2273 |
| 3053 | Mastbase block±± | 4 | 102 | 17/8 | 48 | 413/16 | 122 | 415/16 | 125 | 5/8 | 16 | 22.4 | 635 | 7500 | 3402 | 15000 | 6804 |
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** - 1/4" (6 mm) RH
*** - 1/4" (6 mm) FH
± - 5/16" (8 mm) FH
±± - 1/2" (12 mm) HH
±±± - 5/16" (8 mm) SH
Index | Use chart | 57 mm | 75 mm | 100 mm | 125 mm & 150 mm | Teardrop | Crossover | Mastbase Halyard Lead & Flip-Flop | Footblocks | AirRunners | Stainless Steel Runners | Opening Foot Blocks | Snatch | ESP Blocks | Stainless Steel ESP | Stainless Steel Blocks | Specifications