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FLY 29 mm single block

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Harken Fly Blocks with through-sheave lashing stand out for their high strength and light weight.

Specifically designed for technical ropes, these high-performance blocks boast an exceptional working load for their compact size. Fly Blocks are ideal for sport boats and foiling dinghies, as well as for cascaded vang systems and backstay tackles on Grand Prix racing yachts.

The 29 mm versions feature stainless steel ball bearings with a stainless steel inner race and a one-piece titanium outer race. They also feature fiber-reinforced composite side plates.

The lashing line is not included.


SKU: 2171  |  Barcode: 85016376
Regular price €18400 EUR

Length (mm) 44 mm
Length (in) 1 3/4 in
Weight (g) 26 g
Weight (oz) .92 oz
Maximum working load (kg) 350 kg
Maximum working load (lb) 770 lb
Breaking load (kg) 700 kg
Breaking load (lb) 1540 lb
Sheave Ø (mm) 29 mm
Sheave Ø (in) 1 1/8 in
Max rope Ø (mm) 7 mm
Max rope Ø (in) 9/32 in

Our tips for choosing

Workload and breaking load

Workload and breaking load

Choose your pulley based on the workload it will have to handle and the desired gear ratio. The orders of magnitude vary depending on the support: 400 to 500kg for the mainsheet or cunningham of an 18-foot catamaran, 100 to 200kg for the mainsheet or downhaul of a 420 dinghy for example.
Coefficient of friction

Coefficient of friction

Modern ball bearing pulleys offer a much lower coefficient of friction than those without balls and are recommended for maneuvers that require constant adjustment (mainsail sheet, downhaul, cunningham, spinnaker essentially).
Restraining force

Restraining force

For the mainsheet which is not always fully tightened, or even never on some boats which require constant adjustment (29er, 49er, Class A,...) as for the spinnaker sheet, favor automatic or non-automatic winch pulleys, which considerably save muscles and gloves thanks to a retention that can go up to 70% of the workload.
Sheave diameter

Sheave diameter

Choose the diameter of the pulley according to the diameter of the rope it will guide. For example, depending on the support and workload, a 40 or 57 sheave is very suitable for a 6 to 10mm mainsail sheet. For Cunningham or downhaul type maneuvers, 16 or 22 sheaves are suitable.
Material

Material

Stainless steel, carbon, composite, it's essentially a matter of weight, with an impact on the price: it all depends on the importance you attach to it. If the pulley is to guide a cable, use aluminum sheaves which will be much more resistant than composite materials.