{"id":2276,"date":"2008-06-10T00:00:00","date_gmt":"2008-06-10T00:00:00","guid":{"rendered":"https:\/\/setsail.com\/?p=2276"},"modified":"2009-04-15T08:52:16","modified_gmt":"2009-04-15T13:52:16","slug":"s_logs-dashew-dashew498","status":"publish","type":"post","link":"https:\/\/setsail.com\/s_logs-dashew-dashew498\/","title":{"rendered":"Open 40s"},"content":{"rendered":"
Checking out interesting design details on some Open 40s that just raced from Boston to Halifax.<\/div>\n

<\/p>\n

\"Open<\/div>\n<\/p>\n

We were fortunate to be in Halifax when a group of the new Open 40 class yachts finished a race from Boston (they had previously raced from Europe across the N. Atlantic). These are high-tech go-fast machines, intended to allow participation in the professional end of single handed racing with a more modest budget. There are a variety of rules in place to keep costs in check, although these look to be pretty expensive 40-footers!<\/p>\n

\"Boston<\/div>\n<\/p>\n

The hull shapes are beamy, in the fashion established by the open 60s. Rigs are enormous, and big bowsprits for downwind sailing are the norm.<\/p>\n

\"Open<\/div>\n<\/p>\n

An interesting dichotomy in hull design philosophy. The Open 40s are designed to a "box rule", so you trade stability for sail area. The boat on the left is in the vein currently popular in the Volvo 70 and IMOCA 60 classes. Wide beam truncated in a chine. The chine allows a more powerful hull shape and shears water off the back end of the boat (reducing drag).<\/p>\n

On the right is a Pogo 40, this with less stability, but more easily driven hull. The after sections on the Pogo are not that far off what we used for Beowulf<\/em> ten years ago. Note the slightly immersed sterns of both hull shapes.<\/p>\n

\"Outboard<\/div>\n<\/p>\n

Inboard rudders are more efficient than outboard rudders shown here. Inboard means they are endplated by the hull which effectively doubles aspect ratio. But you cannot repair inboard rudders, so some of the Open 40s had external kick up foils. The concept is these will release if something is kit, and in a worst case situation, you can replace a rudder.<\/p>\n

\"Open<\/div>\n<\/p>\n

Those flat plates at the hull level on the outboard rudders are an attempt at an end plate. This will help a little, but is not nearly as effective as a hull in terms of end plating. Note the complexity of the mechanisms.<\/p>\n

\"Open<\/div>\n<\/p>\n

Most of the boats have some form of hank on system for their jibs. These are soft hanks on an inner jib (really a big staysail or Solent jib). This is stored well aft, so the halyard, and stay are out of the way of the outer jib (the block on the lower left is used to tension the stay).<\/p>\n

\"Open<\/div>\n<\/p>\n

A different form of soft hanks here (made from high modulus rope).<\/p>\n

\"Open<\/div>\n<\/p>\n

There were a variety of bowsprit systems. <\/p>\n

\"Image\"<\/div>\n<\/p>\n

This one is housed J-Boat style inside of the hull. Clean, but that forward seal is going to leak.<\/p>\n

\"Image\"<\/div>\n<\/p>\n

We prefer the bowsprit on deck. Not as clean drag wise, but dry, and easier to execute.<\/p>\n

\"Open<\/div>\n<\/p>\n

These boats all have "fat head" mains, multihull style. This means they cannot have a fixed backstay, so they use a combination of swept spreader and masthead runners. Note how the cap shrouds intersect just above the headstay, but below the runner tangs. If you project these angles and their respective loads you will find the caps and runners are designed to induce a modest amount of rig bend to flatten the big mainsails when the breeze comes up.<\/p>\n

The Open 40 is a large enough design so much of what develops for sail handling and speed will be applicable to cruising yachts. It is going to be an interesting class to watch.<\/p>\n","protected":false},"excerpt":{"rendered":"

Checking out interesting design details on some Open 40s that just raced from Boston to Halifax.<\/p>\n","protected":false},"author":3,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[4],"tags":[],"class_list":["post-2276","post","type-post","status-publish","format-standard","hentry","category-dashew-blog"],"_links":{"self":[{"href":"https:\/\/setsail.com\/wp-json\/wp\/v2\/posts\/2276"}],"collection":[{"href":"https:\/\/setsail.com\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/setsail.com\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/setsail.com\/wp-json\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/setsail.com\/wp-json\/wp\/v2\/comments?post=2276"}],"version-history":[{"count":0,"href":"https:\/\/setsail.com\/wp-json\/wp\/v2\/posts\/2276\/revisions"}],"wp:attachment":[{"href":"https:\/\/setsail.com\/wp-json\/wp\/v2\/media?parent=2276"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/setsail.com\/wp-json\/wp\/v2\/categories?post=2276"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/setsail.com\/wp-json\/wp\/v2\/tags?post=2276"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}