{"title":"Sheave Boxes for Dinghy Masts","description":"\u003cp\u003eSeldén composite and stainless steel sheave boxes for dinghy mast halyard exits, available in 21mm and 35mm sheave sizes with plain bearing, ball bearing and XSM bearing options for halyard turning, jib halyards and spinnaker halyards.\u003c\/p\u003e\n\u003ch2\u003eHow to choose\u003c\/h2\u003e\n\u003cp\u003eSheave box selection depends on three things: the application, the halyard type and the rig load. Start with the sheave diameter. The 21mm sheave boxes suit lower-load applications such as halyard turning points and boom outhauls. The 35mm sheave boxes are rated for wire and HMPE jib halyards and higher-load applications where a larger sheave reduces halyard wear and friction.\u003c\/p\u003e\n\u003cp\u003eWithin the 35mm jib halyard range, three bearing options are available. The plain bearing composite sheave is the standard option for most dinghy jib halyards. The plain bearing aluminium sheave improves wear resistance and increases the safe working load, the correct upgrade if you are replacing a worn composite sheave. The stainless steel ball bearing sheave is the highest performance option, suited to classes where rig tension is high and the halyard is adjusted while sailing, reducing friction at peak loads.\u003c\/p\u003e\n\u003cp\u003eThe stainless XSM bearing jib halyard sheave box (505-092-23) is in a separate category. It uses a solid XSM bearing rather than conventional ball bearings, developed specifically for the Fireball, 505 and Flying 15 where extremely high halyard tensions are standard. It is not a general-purpose upgrade, choose it only for these classes or equivalent high-tension applications.\u003c\/p\u003e\n\u003cp\u003eThe stainless spinnaker halyard sheave box (505-079) is a low-profile fitting for high line-speed applications such as spinnaker halyards and pole lifts, where a compact box with minimal friction is needed.\u003c\/p\u003e\n\u003cp\u003eThe wear guard (505-075) is a stainless steel insert that fits all 505-071 sheave boxes to protect the mast and box from halyard wear. It is recommended for any installation where the halyard runs over the top of the box.\u003c\/p\u003e\n\u003ch2\u003eDinghy class applications\u003c\/h2\u003e\n\u003cp\u003eThe \u003cstrong\u003eXSM bearing sheave box\u003c\/strong\u003e (505-092-23) is specifically referenced for the \u003cstrong\u003eFireball\u003c\/strong\u003e, \u003cstrong\u003e505\u003c\/strong\u003e and \u003cstrong\u003eFlying 15\u003c\/strong\u003e classes where 1:1 jib halyards are used at exceptionally high tensions.\u003c\/p\u003e","products":[{"product_id":"angled-through-deck-fitting-1","title":"Angled Exit Bush \/ Through Deck Lead","description":"\u003cp\u003eAngled nylon bush to lead lines through mast and boom walls. Can also be used at a through deck lead. Normally used to lead the pole downhole internally at deck in classes such as 420.\u003c\/p\u003e\u003cp\u003e\u003c\/p\u003e","brand":"Selden Dinghy Store","offers":[{"title":"Default Title","offer_id":52143057469778,"sku":"319-792","price":6.3,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0993\/1325\/4738\/files\/index_12d893c3-b54a-4be7-82d9-b71cf9be0119.jpg?v=1769092266"},{"product_id":"composite-sheave-box-21mm-plain-bearing-composite-sheave","title":"Composite Sheave Box, 21mm Plain Bearing, Composite Sheave","description":"\u003cp\u003eComposite sheave box with a 21mm x 9mm composite sheave. Plain bearing with a stainless steel pin. Commonly used for lower load applications such as halyard turning and boom outhauls.\u003c\/p\u003e\u003cp\u003e\u003cb\u003eHeight\u003c\/b\u003e: 76 \u003cem\u003emm\u003c\/em\u003e\u003cbr\u003e\u003cb\u003eD1\u003c\/b\u003e: 21 \u003cem\u003emm\u003c\/em\u003e\u003cbr\u003e\u003cb\u003eD2\u003c\/b\u003e: 18.00 \u003cem\u003emm\u003c\/em\u003e\u003cbr\u003e\u003cb\u003eWidth\u003c\/b\u003e: 20 \u003cem\u003emm\u003c\/em\u003e\u003cbr\u003e\u003c\/p\u003e","brand":"Selden Dinghy Store","offers":[{"title":"Default Title","offer_id":52143091745106,"sku":"505-069-21","price":42.18,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0993\/1325\/4738\/files\/index_e4be2235-00b2-4672-93e1-86664205b1c0.jpg?v=1765189018"},{"product_id":"composite-sheave-box-21mm-ball-bearing-stainless-steel-sheave","title":"Composite Sheave Box, 21mm Ball Bearing, Stainless Steel Sheave","description":"\u003cp\u003eComposite sheave box with a 21mm x 9mm stainless steel ball bearing sheave. Commonly used for lower load applications such as halyard turning and boom outhauls. Ideal as an upgrade from the 505-069-21 plain bearing version,\u003c\/p\u003e\u003cp\u003e\u003cb\u003eHeight\u003c\/b\u003e: 76 \u003cem\u003emm\u003c\/em\u003e\u003cbr\u003e\u003cb\u003eD1\u003c\/b\u003e: 21 \u003cem\u003emm\u003c\/em\u003e\u003cbr\u003e\u003cb\u003eD2\u003c\/b\u003e: 18.00 \u003cem\u003emm\u003c\/em\u003e\u003cbr\u003e\u003cb\u003eWidth\u003c\/b\u003e: 20 \u003cem\u003emm\u003c\/em\u003e\u003cbr\u003e\u003c\/p\u003e","brand":"Selden Dinghy Store","offers":[{"title":"Default Title","offer_id":52143091777874,"sku":"505-069-22","price":22.46,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0993\/1325\/4738\/files\/index_da19cc3e-f7f6-4f93-b1a4-45b4317ab277.jpg?v=1765189020"},{"product_id":"composite-jib-halyard-sheave-box-35mm-plain-bearing-composite-sheave","title":"Composite Jib Halyard Sheave Box, 35mm Plain Bearing, Composite Sheave","description":"\u003cp\u003eComposite sheave box with a 35mm x 7mm composite sheave. Plain bearing with a stainless steel pin. Used for wire and HMPE jib halyards, and other higher load applications.\u003c\/p\u003e\u003cp\u003e\u003cb\u003eHeight\u003c\/b\u003e: 86 \u003cem\u003emm\u003c\/em\u003e\u003cbr\u003e\u003cb\u003eD1\u003c\/b\u003e: 35 \u003cem\u003emm\u003c\/em\u003e\u003cbr\u003e\u003cb\u003eD2\u003c\/b\u003e: 23.00 \u003cem\u003emm\u003c\/em\u003e\u003cbr\u003e\u003cb\u003eWidth\u003c\/b\u003e: 18 \u003cem\u003emm\u003c\/em\u003e\u003cbr\u003e\u003c\/p\u003e","brand":"Selden Dinghy Store","offers":[{"title":"Default Title","offer_id":52143093645650,"sku":"505-071-21","price":39.66,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0993\/1325\/4738\/files\/index_73e302ef-2fcf-48ce-ae94-30e2e6a68abb.jpg?v=1765189023"},{"product_id":"wear-guard-for-505-071-sheave-boxes","title":"Wear Guard For 505-071 Sheave Boxes","description":"\u003cp\u003eStainless Steel wear guard guides halyards on to the sheave reducing wear to the halyard box and mast. Fits all 505-071 sheave boxes.\u003c\/p\u003e\u003cp\u003e\u003c\/p\u003e","brand":"Selden Dinghy Store","offers":[{"title":"Default Title","offer_id":52143094497618,"sku":"505-075","price":4.32,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0993\/1325\/4738\/files\/index_f0b80205-4cc3-4bed-a02b-12ede213db7f.jpg?v=1764240570"},{"product_id":"stainless-steel-spinnaker-halyard-sheave-box-35mm-ball-bearing-stainless-steel-sheave","title":"Stainless Steel Spinnaker Halyard Sheave Box, 35mm Ball Bearing, Stainless Steel Sheave","description":"\u003cp\u003eLow profile, stainless steel sheave box with a 35mm x 4mm stainless steel, ball bearing sheave. Used for spinnaker halyards and pole lifts where a compact, low friction sheave box is required that can manage high line speeds.\u003c\/p\u003e\u003cp\u003e\u003cb\u003eHeight\u003c\/b\u003e: 57 \u003cem\u003emm\u003c\/em\u003e\u003cbr\u003e\u003cb\u003eD1\u003c\/b\u003e: 25 \u003cem\u003emm\u003c\/em\u003e\u003cbr\u003e\u003cb\u003eD2\u003c\/b\u003e: 28.50 \u003cem\u003emm\u003c\/em\u003e\u003cbr\u003e\u003cb\u003eWidth\u003c\/b\u003e: 9 \u003cem\u003emm\u003c\/em\u003e\u003cbr\u003e\u003c\/p\u003e","brand":"Selden Dinghy Store","offers":[{"title":"Default Title","offer_id":52143094563154,"sku":"505-079","price":34.8,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0993\/1325\/4738\/files\/index_50d2306a-439a-448b-842e-eac4cc067b53.jpg?v=1765190766"},{"product_id":"stainless-steel-jib-halyard-sheave-box-35mm-xsm-bearing-stainless-steel-sheave","title":"Stainless Steel Jib Halyard Sheave Box, 35mm Xsm Bearing, Stainless Steel Sheave","description":"\u003cp\u003eStainless steel sheave box with a 35mm x 4mm aluminium sheave. The sheave runs on a solid XSM bearing that delivers low friction even with extreme rig tension loads. Developed specifically for 1:1 jib halyards in Fireball and 505 where exceptionally high halyard loads are used, and for small keelboats such as Flying 15.\u003c\/p\u003e\u003cp\u003e\u003cb\u003eHeight\u003c\/b\u003e: 86 \u003cem\u003emm\u003c\/em\u003e\u003cbr\u003e\u003cb\u003eD1\u003c\/b\u003e: 35 \u003cem\u003emm\u003c\/em\u003e\u003cbr\u003e\u003cb\u003eD2\u003c\/b\u003e: 23.00 \u003cem\u003emm\u003c\/em\u003e\u003cbr\u003e\u003cb\u003eWidth\u003c\/b\u003e: 18 \u003cem\u003emm\u003c\/em\u003e\u003cbr\u003e\u003c\/p\u003e","brand":"Selden Dinghy Store","offers":[{"title":"Default Title","offer_id":52143094890834,"sku":"505-092-23","price":77.42,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0993\/1325\/4738\/files\/index_deacb4ea-a5a6-4229-bdc1-e99dafbc6ce6.jpg?v=1765193170"}],"url":"https:\/\/dinghy.seldenmast.com\/collections\/sheave-boxes.oembed","provider":"Seldén Dinghy Store","version":"1.0","type":"link"}