A cheek block is a fixed pulley that bolts flat to a deck, spar, or bulkhead through a base plate — called the "cheek" — to redirect a line without adding a swiveling shackle or eye strap. MAURIPRO stocks cheek blocks from Ronstan, Selden, Schaefer, and Lewmar in sheave sizes from 20 mm to 100 mm, so you can match the block to your line diameter and load exactly.
If you've ever needed to lead a halyard down a mast, route a reef line back to the cockpit, or organize sheets across a deck without a swiveling block flopping around, a cheek block is usually the answer. Its flat base plate holds it in one fixed plane, which is exactly what you want for a lead that doesn't change direction.
On a mid-size cruiser in the 30–45 ft range, cheek blocks show up most often at the base of the mast (turning halyards and reef lines aft), along the boom (leading outhaul or reefing lines), and as deck organizers ahead of a clutch bank. This guide covers what makes a cheek block different from a turning block or snatch block, where to use one, and how to size the right model to your line and load.
Cheek blocks at a glance
| Model | Sheave Ø | Max line Ø | Safe working load | Shop at MAURIPRO |
|---|---|---|---|---|
| Ronstan Series 20 BB Block, Single Cheek | 20 mm | 6 mm | 250 kg (551 lb) | Shop RONRF20151 — $17.99 |
| Selden 20 Ball Bearing Block, Single Cheek | 20 mm | 8 mm | 100 kg (220 lb) | Shop SEL40210113R — $24.99 |
| Lewmar 40mm SC Cheekblock | 40 mm | — | 240 kg (530 lb) | Shop LEW29901460BK — $28.99 |
| Ronstan Series 40 AP Block, Single Cheek | 40 mm | 10 mm | 400 kg (882 lb) | Shop RONRF41151 — $35.99 |
| Schaefer Flat Base Aluminum Cheek Block, 2 in. sheave | 51 mm | 11 mm | 795 kg (1,750 lb) | Shop SCH50411 — $100.95 |
| Schaefer Flat Base Aluminum Cheek Block, 2 3/8 in. sheave | 60 mm | 13 mm | 1,020 kg (2,250 lb) | Shop SCH70411 — $144.00 |
| Selden 100 Plain Bearing Block, Double Cheek | — | — | 4,000 kg lower / 2,000 kg upper | Shop SEL41000116R — $570.00 |
For light control lines and reef lines under about 400 kg, the 20–40 mm single-cheek blocks cover most mid-size cruisers. Step up to the Schaefer 51–60 mm range for halyards and heavier sheet leads, and reserve a double-cheek block like the Selden 100 for a genoa sheet lead feeding two winches or a load that needs splitting across two sheaves.
What is a cheek block, and how is it different from a turning block or snatch block?
A cheek block is a specific type of turning block — "turning block" is the general term for any block that redirects a line, while a cheek block is the version that bolts flat through a base plate rather than hanging from a shackle or swiveling eye strap. Because the base plate is fixed, the block can't rotate to follow a shifting lead the way a swivel block can, so it's built for a lead that runs in one consistent direction.
Riggers sometimes use "cheek block" and "foot block" interchangeably, but per Rig-Rite's own block glossary, foot blocks are generally the larger, higher-load versions mounted on deck, while cheek blocks are the smaller sizes bolted to a mast or boom — both are fixed in place with through-bolts rather than a shackle. A snatch block is different again: it has one hinged cheek that swings open so you can clip it onto a line that's already rigged and loaded, which a fixed cheek block can't do — you thread the line through a cheek block before it's under load.
Where on a sailboat do you actually use a cheek block?
Cheek blocks earn their keep wherever a line needs to change direction along a fixed path:
- Mast base halyard and reef-line turns — redirecting a halyard or reef line down the mast and aft toward the cockpit.
- Boom-mounted outhaul and reefing leads — guiding a line along the boom to a cheek block near the mast end before it drops to deck level.
- Deck organizers ahead of a clutch bank — lining up multiple halyards and control lines so they run parallel into a row of rope clutches.
- Sheet and control-line leads on deck or cabin top — any fixed run where the line's direction of pull doesn't change.
Because the base plate is bolted flat, a cheek block also spreads load across a wider mounting footprint than a single shackle point — Schaefer's own spec sheet for its flat-base aluminum cheek blocks notes the plate distributes load "to a larger surface area than other designs that place loads on mounting bolts only," which is why the flat-base design is common for higher-load spar and deck applications.
How do you size a cheek block to your line and load?
Start with your line's actual diameter, not the block's maximum rating. Every model above lists a maximum line diameter — 6 mm for the Ronstan 20 mm block up to 13 mm for the Schaefer 60 mm block — and a line running at the very top of that range sits stiffer in the sheave than one sized closer to the middle.
Then check the safe working load against what the line will actually see in use, not its breaking strength. A reef line or control line rarely approaches a genoa sheet's peak load, so a 20–40 mm single-cheek block (100–400 kg SWL) covers most control-line duty on a 30–45 ft cruiser. Reserve the Schaefer 51–60 mm range, or a double-cheek block, for halyards and sheet leads closer to your rig's real working loads.
Single vs double cheek blocks: when do you need two sheaves in one base?
A single-cheek block turns one line. A double-cheek block, like the Selden 100 Plain Bearing Block above, stacks two independent sheaves on one base plate — each line runs through its own sheave rather than sharing one, and the two sheaves usually carry different rated loads (4,000 kg on the lower sheave, 2,000 kg on the upper, on that Selden model). That's different from a compound block-and-tackle setup, where multiple sheaves work together to multiply mechanical advantage on a single line; for that kind of purchase system, see our guide to single vs double vs triple blocks. Reach for a double-cheek block when two separate lines — say, a genoa sheet lead and a reef line — need to turn at the same point on deck without stacking two single blocks and doubling your mounting footprint.
Which should I choose?
For reef lines and light control lines on a 30–45 ft cruiser, a 20–40 mm single-cheek block from Ronstan, Selden, or Lewmar covers the job. Step up to Schaefer's 51–60 mm flat-base aluminum cheek blocks for halyards and heavier sheet leads, and choose a double-cheek block only when you genuinely need two independent lines turning at the same mounting point.
Expert notes from the rigging bench
We size cheek blocks to the line first, every time — a 6 mm reef line loaded into a block rated for 13 mm line just adds unnecessary friction and a sloppy lead; it isn't a safety issue, just a wasted upgrade.
On mast-base organizers with several cheek blocks side by side, we check that the base plates are backed the same way as any other high-cycle deck hardware — the block itself rarely fails first, but an unbacked plate on a cored deck will work loose over a season of halyard loads.
Common mistakes to avoid
- Choosing a swiveling or snatch block where a fixed cheek block would do. If the lead never changes direction, a fixed cheek block is simpler, lighter, and has one less moving part to maintain.
- Sizing to the block's maximum line diameter instead of your actual line. A line at the top of the stated range runs stiffer through the sheave and wears faster.
- Mounting a load-bearing cheek block without a backing plate. The safe working load figure assumes the mounting surface itself doesn't fail first.
- Using one double-cheek block as if it were two single blocks sharing a rating. The two sheaves on a double-cheek block are independently rated — check both figures, not just the higher one.
Frequently asked questions
What is a cheek block used for on a sailboat?
A cheek block redirects a line — a halyard, reef line, outhaul, or sheet — along a fixed path at the mast base, on the boom, or on deck. Its flat base plate bolts through the mounting surface, so it holds one fixed lead rather than swiveling to follow a shifting line of pull.
What's the difference between a cheek block and a foot block?
The terms overlap, but riggers generally reserve "foot block" for the larger, higher-load deck-mounted versions and "cheek block" for the smaller sizes bolted to a mast or boom. Both mount flat with through-bolts rather than a shackle.
What's the difference between a cheek block and a snatch block?
A cheek block is fixed — you thread the line through it before it's under load. A snatch block has one hinged cheek that swings open, so you can clip it onto a line that's already rigged and loaded.
What size cheek block do I need?
Match your line's actual diameter to the block's max-line rating first, then confirm the safe working load covers your line's real working load, not its breaking strength. Most 30–45 ft cruisers run reef and control lines through a 20–40 mm cheek block and halyards through a 51–60 mm block.
Do cheek blocks need a backing plate?
For any load-bearing installation on a cored deck or thin laminate, yes. The block's safe working load rating assumes the mounting point itself doesn't fail first.
Recommended gear
Ronstan Series 20 BB Block, Single Cheek, RONRF20151 — a low-friction ball-bearing cheek block for control lines up to 6 mm.
Ronstan Series 40 AP Block, Single Cheek, RONRF41151 — a self-lubricating all-purpose cheek block rated to 400 kg for sheets and control lines.
Schaefer Flat Base Aluminum Cheek Block, SCH50411 — a flat stainless-base cheek block rated to 795 kg for halyards and heavier leads.
Selden 100 Plain Bearing Block, Double Cheek, SEL41000116R — a heavy-duty double-cheek block for two independent lines at one mounting point.
You may also be interested in
- What Is an Antal Snatch Block, and When Do You Need One?
- Ball-Bearing vs Plain-Bearing Blocks: Friction, Load & Longevity
- Single vs Double vs Triple Blocks: Building the Right Purchase System
About the author: Written by the MAURIPRO Rigging Team — MAURIPRO Sailing has outfitted cruisers and racers since 2003, and our rigging specialists spec and maintain deck hardware, including blocks, clutches, and cleats, on boats in the 30–45 ft range. Facts in this guide are drawn from MAURIPRO's own live product listings for the cheek blocks shown and from Rig-Rite's and Schaefer's own published block documentation for the mounting and load-distribution principles.
Last updated: August 31, 2026.