Buyer's Guide to Boat Blocks

Boat blocks are essential for safe, efficient trips on the water. Without a quality boat block, you'll work harder than necessary when dealing with your rigging, and you might harm your boat. Use our expert boat block buying guide to help you learn all the basics of boat blocks and find the best system for your vessel. 

What Is a Boat Block?

Boat blocks are boat pulleys — "block" is a nautical term. These are essential components for any sailboat rigging system. Without them, it is much more challenging to control the sailboat while dealing with the heavy loads created by wind and waves. They provide a more straightforward method for changing the vessel's direction and multiplying the mechanical advantage of the lines, or ropes, used to control the sails. 

Sailboat blocks' core purpose is to provide smooth, efficient line movement, enabling sailors to trim the sails effectively. Boat pulleys help redirect the lines, reducing friction and redistributing the load so the sails are easier to handle and the boat's direction and speed are simpler to control. Boat blocks come in several sizes, materials and designs to accommodate all your sailing loads and needs. Finding the right one will help keep you safe on the water. 

Boat Block Components and Their Uses

While they might seem small and simple, boat blocks have several components that all help the pulley system work effectively. These pivotal pieces allow for efficient movement and connection of lines, mechanical advantage, ease of sail control and improved safety. 

• Sheave: Sheaves are critical components in a pulley system. The sheave is a wheel with a groove in the middle. The line sits in this groove, which guides the line as it moves through the pulley. The sheave creates the pulley system, allowing the line control to work with less friction and more smoothly. 
• Cheeks: Cheeks — or cleaves — are side plates that enclose the sheave. They stabilize the sheave and keep the lines in place as they move. Since cheeks sit against the sheave and also take wear from the outside, they consist of high-strength polymers or stainless steel. 
• Bearing: There are several bearing types, and each serves a slightly different purpose. Bearings are axles inside the sheave or pulley that minimize friction as the rope moves along the system. Plain bearing pulleys have a small steel pin the sheave rotates on. They're ideal for heavy loads and static purposes like masthead and mast foot blocks. Roller bearings have rollers instead of balls or pins. They can handle heavy loads for dynamic uses like main halyards. Ball bearings work well for low-load, active uses like spinnaker systems. 
• Shackle: Shackles are metal connecting devices that attach the block to other rigging components like the deck or mast. They simplify block installing, adjusting and removal. There are various shackle types for different situations, including snap and bow.
• Becket: Beckets are small metal loops or eyelets attached to the side of the block. Beckets make convenient attachment points for shackles, ropes and other essential hardware. They allow you to create multiple line configurations or secure lines easily. 

Types of Sailboat Blocks

Boat blocks come in several types, each with a unique function. Pulley blocks help make your rigging system safer and more efficient — investing in the right type for the job ensures your vessels work well on the water. Blocks can work in dynamic and fixed situations for all your rigging needs. Here are the primary block fitting types and their functions.

Single-Sheave Block

Single-sheave blocks are the simplest. They have only one sheave for the rope to pull along, changing the tension direction. All sheave blocks usually mount to the boom or deck. You'll see sheave blocks used with reef lines, the mast base and the foresheet. Additionally, the simplicity of single sheave blocks helps facilitate basic pulling and lifting tasks. 

Multi-Sheave and Fiddle Blocks

The more sheaves on a block, the better the mechanical advantage. Increasing sheave count allows you to handle larger forces with minimal strain. Multi-sheave blocks are also valuable for tasks like constructing a mainsheet jib. 

Fiddle blocks are a type of multi-sheave block. While most multi-sheave blocks feature sheaves connected side by side, fiddle blocks have sheaves stacked below each other. This configuration often resembles a fiddle, giving them their name. You'll usually see fiddle blocks on smaller boats as mainsheet foot blocks or boom vangs. 

Snatch Blocks

You'll use snatch blocks in temporary situations. Though most blocks have closed sides, requiring you to feed the line through the sheave, snatch blocks have a hinged side plate, allowing you to open and close the block around the line without threading it. With this convenient design, you can attach them to ropes under tension and remove them when there's no slack. You'll use snatch blocks in situations where you need to quickly attach or redirect a rope under tension — like rescue operations or rigging setups that need frequent changes.

Ratchet Blocks

Ratchet blocks use a locking mechanism to prevent the line from slipping backward. This system lets you hold the load in place with the block without continuous manual tension. Ratchet blocks work through an inner sheave that secures the line while a pawl stops the sheave from turning toward the load. Ratchet blocks are ideal for boating applications where you need to secure a load for hands-free operation or at a specific height. You'll mainly use ratchet blocks in sheet systems since they can hold loads in place.

Deck Organizers, Cheek Blocks and Stand-Up Blocks

Various deck organizers are available to divert and lead lines across your deck. While standard sheave blocks follow the pull direction, these organizers sit fixed to a service. Cheek blocks make excellent deck organizers — they guide lines parallel to a surface, fitting them as closely together as possible. Stand-up blocks are another helpful deck organizer block. They stand fixed vertically and work well for uses where you want to avoid having the block hitting the deck.

Considerations When Choosing Boat Blocks

It's essential to consider all factors when deciding what sailboat block you need. Boat blocks perform vital functions on your vessel — getting the right block for the job enables you to safely and smoothly operate your raft on the water. When buying your boat blocks, you should evaluate the expected forces, rope diameter and brand. Examine these factors to help you find the best block for your needs.

Expected Forces and Breaking Loads

While you might think you need a block based solely on boat size, you must also calculate the expected forces and breaking loads you'll be dealing with. The larger your rig — the halyard and sheets — the more forces your vessel will deal with as they catch wind. Larger rigs typically have correspondingly larger lines, so a too-small block will break under sudden, strong tensile forces caused by rough seas. Selecting the correct block from the get-go is even more crucial, since damage will not be immediately apparent. Instead, it will seem fine, only failing the next time it's under load. 

What loads will your blocks deal with? Determine each block's required maximum load capacity and select blocks that can surpass it. Exceeding the expected forces ensures your blocks can handle potential shock loads and all expected forces. All manufacturers state the maximum tensile force each block can handle without damage. 

Rope Diameter

If you choose a block with a higher load-bearing capacity than your line, the rope material is not an essential detail for selecting a block. The rope diameter is much more critical to the block you choose. The rope's cross-section must match the block sheave's width to prevent early material wear. A too-small block will increase friction, causing decreased efficiency and possible damage. If the line is too thin, it will slip out of the sheave and affect performance. 

Only wire rope blocks are an exception for this factor. Since their sheaves deal with extremely high demands, you'll want to get blocks made for use with wire ropes to ensure the best performance and minimal wear. 

Type

Getting the appropriate block type is essential for maintaining boat safety and efficiency. Otherwise, your block will not perform correctly. Checking your block location and usage on the boat will help you match the hardware to the job. If you need help choosing a block type, consult your boat supplies retailer for assistance. Their experts can help direct you to the correct block for your needs, ensuring you get a trustworthy system for your boat. 

Brand

Various hardware brands have different pricing and performance. Going with a higher-priced manufacturer like Harken, Lewmar or Schaefer will increase your expenses but provide you with a lasting piece of hardware. Other brands like Ronstan offer excellent quality at a lower price, though you might need to replace their products sooner. Choosing a reputable brand ensures you get a reliable product. Whatever brand you select, ensure its quality so you can trust it to support you on the water. 

Boat Block Maintenance

Once you install your boat blocks, you must keep them in top shape. Otherwise, you'll have to replace them much earlier than necessary, compromising safety when they fail and increasing your expenses. Taking time to perform regular maintenance helps reduce friction, prevent failures and avoid premature wear. Remember these best practices to protect your boat hardware.

• Inspect: You should regularly inspect your boat blocks and other hardware for signs of corrosion, wear or damage. Closely check cheeks, sheaves and other components for deformations, cracks and excessive wear. Inspect attachment points like shackles and mounting hardware to ensure they have secure connections. Inspections allow you to proactively catch problems. The faster you can detect and address any issues, the better you'll be at preventing further damage and accidents. 
• Clean: Clean boat blocks to remove debris, dirt, salt and other contaminants. Buildup can affect block performance, reducing efficiency and leading to accelerated wear. Use a specialized marine cleaner or a mild soap combined with a soft cloth or brush to clean the hardware. After gently cleaning the blocks, rinse thoroughly with fresh water to remove all residue. Never use harsh chemicals when cleaning, as they could damage the block's materials or functionality. 
• Lubricate: Proper lubrication is essential for reducing friction and maintaining a smooth operation. Apply the correct marine lubricant to the block's sheaves, bearings or brushings according to the manufacturer's instructions. Lubrication helps minimize wear and maintains efficient block rotation. Always use lubricants specifically designed for marine use, with formulations that prevent corrosion. 
• Check ropes: Check ropes used with boat blocks for wear and fraying. Clean your ropes regularly to shield them from damage. You should also store them properly to prevent UV damage and entanglement. Finally, consider rotating your ropes so they wear evenly. 
• Replace: Regularly monitor your boat blocks and replace them if they start showing signs of severe wear and tear or as they reach the end of their recommended life span. 
• Professional help: If you have a complex or critical rigging system, consider getting a professional rigger to inspect your setup. Periodic professional inspections provide a thorough breakdown of your system's condition and allow you to get expert recommendations on repairs or replacements. 

High-Quality Boat Blocks From Fawcett Boat Supplies

Boat blocks are critical for ensuring your boat's enjoyment and safety. Investing in high-quality boat supplies helps protect you and your vessel whenever you want to enjoy some time on the water. Fawcett Boat Supplies provides you with an unmatched selection, enabling you to maximize your boating experience. We've offered exceptional products to our customers since 1948, making us an industry leader in supplies and expertise. You can trust us for all your boating needs. 

From an extensive array of boating supplies to expert boating services, Fawcett has everything you need for safe, efficient boating. Contact us online today to learn more about our product selection!