Rated 4.9 out of 5 by our customers
Rated 4.9 out of 5 by our customers
90 Day Risk Free Returns
Price Match Promise
5 Star Rated by Sailors
Over 70,000+ Orders Shipped
The 40mm block from Harken comes in two formats, the Carbo and then the ratchet Carbo. The ratchet version of the 40mm Harken block comes either with on/off switches or as an automatic ratchet.
Harken 40mm blocks are lightweight, strong and reliable with a fibre-reinforced composite construction meaning they have a great strength to weight ratio.
You can expect breaking loads of up to 1,383kg.
Explore other Harken block and pulley sizes on our Harken blocks page.
Some frequently asked questions that other customers have asked us about Harken 40mm Blocks.
What are Harken 40mm blocks used for?
Harken 40mm blocks are used for sheet systems and higher load controls. On dinghies and small keelboats you will find them in mainsheet, jib sheet and spinnaker sheet systems, and in kicker systems on larger boats. They are made from fibre reinforced composite, which gives a strong, light block with breaking loads of up to 1,383kg.
Should I choose a Harken 29mm or 40mm block?
Choose a Harken 40mm block when your rope is thicker than 8mm or the load is too high for a 29mm block. The larger sheave gives the rope an easier turn, which reduces friction, and the 40mm range carries breaking loads of up to 1,383kg against 907kg for the 29mm. For control ropes of 8mm and under, the 29mm block saves weight.
Do I need a ratchet block?
A ratchet block is worth fitting on any sheet you hold by hand for long periods. It grips the rope under load, so you hold a fraction of the strain, while still letting the sheet run out when you ease. The Harken 40mm Carbo ratchet is a popular choice for jib and spinnaker sheets, and for the mainsheet on smaller dinghies.
What is the difference between a switchable and an automatic ratchet block?
A switchable ratchet has an on/off switch, so you choose when the ratchet grips. An automatic ratchet engages by itself as the load on the sheet builds and releases when the load comes off. That means the sheet runs freely in light winds and through gybes, then holds when you need it, with no switch to reach for.
What size rope fits a Harken 40mm block?
Harken 40mm blocks take rope up to a maximum of 8mm in diameter, and work best with 6mm to 10mm sheets. For a ratchet block, the right match matters more than usual, as a rope that is too thin won’t grip the sheave properly. Check the maximum rope diameter on the product page before you buy.
