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Big Boat Blocks Q&A


Harken offers a variety of Big Boat blocks that stand up to sun, salt and impact. These are common questions we are asked about our high-strength, smooth and efficient variety of blocks for big boat sailing.

Element Blocks

6260What is the bearing system of the Element block?
Element blocks use simple and reliable journal wheel and axle style bearings.

Do Element blocks have aluminum or plastic sideplates?
The sideplates are forged aluminum for strength, sheave protection and corrosion resistance.

Can I double stack my single cheek Element blocks?
The Element blocks are not designed to be stacked but Harken does offer double blocks.

Black Magic Air Blocks

How do Black Magic Air blocks stand up to sun, salt and time?
Black Magic Block - disassembledThe sideplates and sheaves are Hard-Lube anodized aluminum for maximum UV protection and a smooth surface. Dissimilar metals are isolated to prevent corrosion. To keep blocks in good working order, all blocks should be regularly cleaned with water and dish soap.

Should any parts of the blocks be replaced over time?
Sometimes side load bearings need to be replaced because they have been continually pressed into the side of the sheave or roller cages. Shackles should also be replaced if they are showing signs of wear.

What sizes do Black Magic Air blocks come in?
They are available in 57 mm, 75 mm, 100 mm, 125 mm and 150 mm.

Black Magic block - low-load isolatorWhat does the red isolator mean on the 57 mm and 75 mm blocks?
The red isolator means the block is a low-load option.

Black Magic Runner Blocks

How do Black Magic Air Runner blocks dampen load vibration?
The blocks include captive Delrin ball bearings and a sideload strip between the inside of sheave and sideplate to dampen rig vibration.

Black Magic Footblocks

Can I use the Footblocks lockoff feature in place of the rope clutch?
No, the lockoffs are only for holding a line temporarily, usually while a winch is being used for something else. Lockoff part #: 3236, 3237.

Stainless Steel Cruising Blocks

What is unique about the stainless steel blocks?
They are an elegant and high-quality option with the stainless look, complementing Harken's existing blocks and functions.

Megayacht Blocks

What does the Megayacht block's ultralight composite bearing system (ULC) do?
The blocks' ULC rides on a heat-treated stainless-steel inner race to handle extremely high loads.

Mastbase Halyard Lead Blocks

Can I use Mastbase Halyard Lead blocks for reefing line on my mainsail?
Yes, they work great for reef lines because they do not use a shackle for attachment to the sail which keeps the block tight to the sail and boom.

Flip-Flop Blocks

What makes Flip-Flop blocks so versatile?
Flip-Flop blockThey are lightweight and pivot around the line axis to keep line close to the deck allowing crew to trim from more places on the boat. These blocks can be used for various leads including halyard leads, mainsheet leads and spinnaker sheet leads.

What are the Flip-Flop blocks sideplates and sheaves made of?
The sideplates are aluminum hardcoat-anodized and sheaves are Hard Lube-anodized aluminum for strength and corrosion resistance.

High-Load Snatch Blocks

High-load snatch blockWhat makes the high-load snatch block high in demand for racing yachts?
These are a must-have on racing yachts because they can be virtually attached any place, for a wide range of use. Opening sideplates make them easy to deploy, allowing crew to quickly fasten them. This makes them perfect for temporary leads, line deflection and static line functions requiring small adjustments.

V Blocks

What makes V blocks efficient at very high loads?
V block - disassembledThe mechanics are simplified, combining the axial and thrust bearings into a single bearing set of V-shaped titanium rollers. This offers strong, lightweight blocks that have unmatched efficiency at high loads, while spinning freely at low loads for smooth easing in light air. V blocks are standard with 3D-molded carbon sideplates, a titanium sheave, and captive titanium roller bearings but are also available in anodized aluminum.

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