Barton Marine Size 5 54mm Plain Bearing Block, Double Tang

Barton Marine's Size 5 block is one of those pieces of sailing hardware you rig once and stop thinking about. It's a 54mm plain bearing pulley with a single sheave and a double tang head, built for control lines and running rigging on larger cruising and racing yachts. Simple job, done right.

The heart of it is that 54mm (2 1/8") sheave. Barton molds it from acetal and runs it on a large-diameter bearing, so the line pays out smoothly under moderate loads without the cost or the fuss of a ball-bearing car. Plain bearing blocks like this one shine on control lines that get eased and trimmed rather than sheeted under constant heavy load. Think vang, outhaul, reefing lines, or a cabin-top lead where you want reliable, low-maintenance turning without a premium price tag.

Construction is where Barton earns its reputation. The load-carrying components and the interior frame are marine grade 316 stainless steel, and the side plates are high-grade molded and then through-bolted and riveted together. That combination is what lets a block this compact carry real load. Barton rates the Size 5 at a 750kg (1,650 lb) maximum working load with a 1,500kg (3,300 lb) breaking load. That's a serious margin for a block that weighs almost nothing and tucks into a tight spot on deck.

The double tang head is the detail worth understanding before you buy. Two tangs give you a fixed attachment that bolts or shackles straight to a deck eye, a boom bail, or a padeye without adding a swivel you don't need. On smaller boats and dinghies you can often mount it directly and skip an extra shackle. And because there are two tangs, you can stack blocks or lead a second line off the same fitting, which is handy on catamarans and trailer sailers where deck space is tight. One tip from the fleet: align the tang with your direction of pull and snug it down with locknuts, so the head can't twist under load.

Rope-wise, the Size 5 takes line up to 12mm (7/16"). It runs its cleanest with 8 to 10mm control lines, which is the sweet spot for most cruising rigs. If you're leading a larger diameter sheet at high sustained load, step up to a ball-bearing block from the same Barton range. And keep your lead angles gentle. A 54mm sheave doesn't love a sharp turn, and a hard lead will chafe polyester line over time no matter whose block you hang it on.

Maintenance is about as easy as it gets. Plain bearings don't have caged ball races to flush, but they do appreciate a rinse. Give the sheave a fresh-water rinse after salt exposure and a drop of light oil now and then, and it'll turn freely for years. That's really the whole routine.

This block is part of Barton's wider Size 5 family, so it plays nicely with their ball-bearing mainsheet traveler system and the rest of their control-line hardware. If you're building out a coordinated setup, you can mix plain-bearing turning blocks like this one with ball-bearing cars where the load justifies it. You'll find the Size 5 turning up all over a well-rigged deck, from kicker and vang leads to reefing systems and spinnaker control lines, wherever a compact fixed-head block makes sense. Over 95% of Barton's gear is still made in Whitstable, England, and the fit and finish shows it.

Who's it for? Cruisers and racers who want dependable, no-drama turning blocks for control lines and secondary leads. Who's it not for? If you need a low-friction, high-load block for a primary mainsheet or genoa sheet on a bigger boat, look at a ball-bearing option in this same size range instead. For everything else on deck, this is a clean, honest block that just works.