JUN 2014 TECHNICAL MEETING

NO JUNK ABOUT THIS !

Our speaker for the June Technical Meeting was Roselt Croeser who addressed us on the conversion of his 18 ft Spacesailer ‘Squirt’ to junk rig and on his subsequent sailing experiences in the boat. I’m sure many of those present were quite surprised at the amount of detail required to successfully complete such a project and the extensive advantages that this junk rig offers in practice – perhaps a reason why there is a substantial following for this rig across the cruising world at least.

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The first point of detail that Roselt explained to us was that the junk rig has a whole vocabulary of its own. Understanding the concepts (and conflicting stories) of the junk rig is assisted by a library of material available around the world including an article titled ‘Junk Rig for Beginners’ by Arne Kverneland which is accessible via the following link;

http://www.junkrigassociation.org/Resources/Documents/Arne%20Kverneland’s%20files/Junk%20Rig%20for%20Beginners.pdf

Whilst there are no fixed rules for the junk rig and everyone tends to do their own thing, there are some common components and Roselt explained the main ones to us. These include the following;

  • Batten parrels are lines that hold the battens loosely to mast. They enable the skipper to adjust the fore and aft position of the sail under way.
  • Hong Kong parrels are lines that support the sail panels diagonally and prevent diagonal creases forming. They are entirely on the sail side of the mast.
  • the luff parrel runs around the mast to each batten front end in turn and is used to fix the sail’s position when it is hoisted
  • lazyjacks serve the same purpose as on a sloop rig to keep the sail constrained on the boom as it is reefed or lowered completely.
  • a number of sail shapes and batten configurations which have been developed and used by cruising sailors are recorded in the literature.
  • junk rig generally uses multiple sheet attachment positions on the batten aft ends and the running sheet is combined via small blocks into a single sheet at the cockpit.

So……why bother with the junk rig. The main incentives for conversion to junk rig are around the simplicity of the rig and the relative absence of complicated and expensive equipment. Because of the sheeting arrangements, the loads on each component are much smaller than traditional rigs and therefore the rig is not only less expensive but also less prone to breakage. The junk rig can be fully controlled from the cockpit and does not require any ventures to the foredeck. The rig can also be much more easily reefed than a traditional rig and hence in the first instance a larger sail area can be set in favourable conditions. Roselt referred here to the junk rigged folkboat Jester which Blondie Hasler sailed, largely from the cabin, without venturing outside.

With this back ground summary, Roselt explained his Spacesailer 18 junk rig conversion project in detail.

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The Design

He commenced with a standard sloop rigged Spacesailer 18. The first step was to draw a scaled elevation of the existing boat including the sail plan and find the centre of area of the sloop rig. Roselt then developed the design for his junk rig sail using a Vincent Reddish modified version of the Blondie Hasler design and locating the centre of area in the same place as the original sloop sail. The area of the junk sail was approximately equal to the combined mainsail and jib area of the sloop rig. The aspect ratio was 1:1 (ie the sail was approximately square) and the objective was to have 10% balance. These criteria required the mast to be relocated further forward on the hull.

The Mast

The junk rig has a free standing and unstayed mast which is stepped on the keel and well supported at the deck. As there appears to be nobody in Perth who is a specialist in this field, Roselt and Harry Speight developed the mast design from cantilever calculations themselves. Roselt researched the use of aluminium but ultimately built a three piece wooden mast using recycled oregon on the outside with a radiata pine lamination in the centre – all glued together using the WEST system, epoxy coated and then painted with SolaGuard house paint. The completed mast was 6.8 metres long and weighed 29 Kg. It was supported by an additional beam across the boat inside and boxed in at deck level where it passed through the forward face of the cabin trunk.

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The Sails

The sails were 13 m2 in area and made up in five panels of heavy Dacron by North Sails. They were made with minimal camber but were not flat. They were supported initially by fibreglass battens but these proved ineffective and were soon replaced with polypipe. Similarly, the wooden boom was fairly quickly replaced with a large diameter polypipe.

Rigging

Roselt rigged the Spacesailer with a two part halyard and sheeting along the lines of the Hasler rig using the main sheet block from the original sloop rig. Initially he tried batten parrels but found by experience that they were not very useful and in the longer term used just luff parrels and down hauls to adjust the sail position on the mast. The sheeting was attached to the boom end and battens on the leach end of the sail; and lazy jacks constrained the sail to lie along the boom when the sail was reefed or completely lowered.

 Performance

In practice, the junk rig tacked through the same 110 degree angle made good over the ground that the sloop rig had achieved. But the big up side was the ease with which the rig could be handled and the boat sailed. In particular, sailing on and off moorings was easier and reefing was very simple. In fact, the boat could be sailed off the mooring with the sail reefed and the full sail could then be easily hoisted when outside the mooring area. This was in addition to the rig allowing everything to be done without leaving the cockpit.

The mast performed satisfactorily even in knockdown conditions and the boat sailed well on all points of sailing and all wind strengths except in light airs.  Croselt indicated that the rig was not as good in light winds of less than 5 knots. A wind vane that Croselt built also sailed the boat well in upwind and reaching conditions. The rig produced little or no wind noise and the configuration allowed good visibility under the sail at all times.

Conclusions

In closing, Croselt spoke of his main conclusions in regard to the junk rig based on his experience over the two years that he sailed ‘Squirt’,

  • For a cruising boat, the junk rig performance is comparable with a casually sailed jib and main rig for the same hull. He found that this performance was better on the port tack when the sail was against the mast and was also improved when the luff parrels were tight.
  • The ease of use of a junk rig is way ahead of the sloop rig.
  • The junk rig benefits by its simplicity. There is no need for any winches, there are only a few blocks, only one sail, no mast track and overall one feels much more in control of the rig.
  • The free standing mast reduces the complexities and worry of multiple fittings and their associated breakage risk on a stayed mast, there is minimum noise and the rig is more resilient to shock loading.
  • The keel stepped mast option is difficult to get up and down and presents challenges in achieving secure bracing.
  • The rig has somewhat of a “messy” look which may not be to everyone’s liking.

However, the junk rig can be adapted easily to fit most needs and you can design your own and make it yourself.

If Roselt was doing this again he said he would

  • develop a tabernacle style of mast step.
  • use softer sail material which would accommodate a neater reefed sail bundle. Experience showed that the sail material does not work hard.
  • consider building more shape and camber into the sail
  • consider having a larger sail area specifically for use on light wind days.

For those that may wish to study this form of rig further there is a very large amount of material available on the web. Roselt referred us to the following references;

‘Practical Junk Rig’ by HG Hasler and JK Mcleod

‘Voyaging On A Small Income’ by Annie Hill

http://cruisingashiki.blogspot.com.au/

http://speedwelladventures.com/blog/

http://www.junkrigassociation.org/

https://groups.yahoo.com/neo/groups/junkrig/info

This was a fascinating presentation on an innovative and intriguing subject and we thank Roselt for sharing his journey with us.