Ronstan RF573 – 25mm Series 25 Utility Block with Swivel Shackle HeadThe Ronstan RF573 Series 25 Utility Block is a lightweight, durable, and economical solution for various sailing applications. Featuring a 25mm sheave, stainless steel cheeks, and UV stabilised acetal sheaves, it ensures long service life with virtually no maintenance required. Ideal for vang, cunningham, and trapeze retriever systems on dinghies, as well as leech line tackles and bunk adjusters on larger yachts. The swivel shackle head design allows

offshore day passages

The Rotating Platform can be used as a flat surface to make many items StarPort compatible

Double rope clutch for two 6–12mm lines

So-Pac 40105 small marine access hatch

SeaTalk interface (SeaTalkng when used with SeaTalk converter)

it’s perfect for small to medium vessels and general onboard use

Full stainless steel swivel head for seamless rotation

it is an ideal base layer for painting systems where durability and adhesion are critical

and a 360° stainless swivel head for superior line alignment and twist prevention

Step spacings 260mm

A bilge pump is the only answer for a quick dry kayak that will be easy to paddle even after being completely full of water

Its recessed switch locks the sheave in place or frees it to swivel 360°