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News Latest News 2011 Designer's Report

2011 Designer's Report

Designer’s Report to World Tasar Council,   Torquay,   Sept 2011

Since the WTC meeting in Wakayama, the re-imaged Tasar has continued to grow strongly.   It is interesting to review what we have learned about the life cycles of different classes, and the effects of different design changes.

At the long-life end of the spectrum, the hull of the 1908 Star has changed from timber planks, to marine ply, to uncored “Fiberglass”, to foam sandwich  -  four changes in 100 years.   Each update brought significant advantage  -  plywood simplified construction, “Fibreglass” was cheap but heavy, foam sandwich is lighter, stiffer, faster, durable.

The Star thrives.

The lesson here seems to be “For a long life, periodically update with new technology which gives significant advantage, but hold steady to the ethos”.

At the short-life end of the spectrum, almost all of the OD classes which were popular when we were developing the Tasar have chosen to change nothing.   They all lived their 25 to 30 year product life.   All then withered and vanished.

The lesson here seems to be “For a short life, change nothing”.

The 1995 49er has taken a different approach.   The class decided to have a hard look at itself every third Olympiad, i.e. every 12 years.   In Higher Performance Sailing I comment on some of the detail and highlights of the 2006 update work.   The end result is impressive.   In winds where the 49er used to sail to windward at 12 knots, it now sails at 14 knots.

With this sort of approach, the 49er is unlikely to wither and vanish any time soon.

The re-imaging of the Tasar was due to the vision of the Future Directions committee.   The time from recognition of the problem about 2000, to decision to re-image, to implementation, to renewed sustained class growth has been of the order of five to ten years.   The present strength of the class is due to the recognition of the problem by the committee and the work initiated by them many years ago, and they deserve the Class’ profound thanks.

Suggested Next Step

Now, nearly twelve years later, the rising cost of alloy and the falling cost of carbon fibre offer an opportunity to update Tasar spar technology with a change which will give significant advantages  -  lower cost, lighter (half the weight), nicer handling, and higher performance.   Along the way we see opportunity to simplify the rig and simplify the mast rotation.   All these proposed improvements strongly support the class’ ethos.

The work that we have completed to date, and what we propose to do if the class approves the next three phases, is summarised in App 1.

If the class approves, the next steps and broad timetable would be –

1 Oct to Dec 2011                    Aerodynamic R and D re section of FRP mast.
This will provide the shape to be trialled.

2 Jan 2012 to Mar 2013          Construction and modification and adjustment of full-size prototype spar(s) and automatic rotation system(s). with trialling by class.
This will provide the spec to be costed.

3 Apr to Jun 2013                   Assembly of cost data prior to Cascade Locks worlds.

At Cascade Locks worlds       Vote by class whether or not to adopt, and If yes, introduction program, i.e. when initially available, and when class-legal for world
championships.

2013, 2014                              Commercial arrangements re production, construction of mandrels, trials to confirm dynamics of trial production masts, distribution, and
implementation of introduction program.

I encourage the class to approve in principle the start of a three to four year program to change from the present alloy mast and boom to spars made primarily of carbon fibre.

(The whisker pole, which needs to crumple before it breaks the mast, would probably be a thin-wall glass tube).

For interest, App 1 lists the work completed to date, and the objects and steps presently envisaged in Phases 1, 2 and 3.

Frank Bethwaite,   Designer

App 1

Objects            At a Future Directions committee workshop in Feb 2011 the objects were defined as –

CF spars must be robust and of long life

Two piece mast

No diamond stays.

CF spars must be free from electrolysis issues

Performance must be at least equal to or better than the present mast

Cost must be less than alloy spars

Mast must not favour heavier or lighter crews

The spars must suit the existing Mylar sails.

Simplify the mast rotation (should be automatic, or as automatic as possible).

Work completed to date -

Exchange of ideas has led to the formation of an ad hoc “CF Spars subcommittee” of Frank B designer, Julian B facilitator, Chris Parkinson exec sec, Graham Hanna chief measurer and with experience in trialling the Mylar sails, Richard Spencer immediate past exec sec who brings to the group a professor of engineering’s knowledge, and Jamie Waters, a Southern Spars engineer.

Liaison with Southern Spars, who make the high-tech 49er mast, has clarified what can be done, and who should do what.

In an unexpected development over the past few days, Jamie Waters advises that Southern Spars have made two test samples to a notional section we suggested.   Their properties –

Appearance          Pic refers

Size                       63mm x 46mm

Weight                   465 and 525g/m          (Lower mast alloy 1300g/m)

Strength    One slightly stronger than, one slightly weaker than, the present alloy lower.

This initiative has greatly increased our confidence that a CF spar to an aerodynamically efficient section can be made by an economical process, and that with such a spar we can satisfy the design objects.

If the class approves the project –

Phase 1 – Aerodynamic R and D      October to Dec 2011

Aerodynamic R and D to develop “FRP section plus turbulator” shapes which will equal or better the Tasar’s present outstanding reaching performance.

For interest, this work would involve duplicating the test rig shown in High Performance Sailing p 213, or Higher Performance Sailing p180, and would start with a half size model of the present alloy mast, with the expectation of repeating Fig 17.33 p 215 in HPS-1 or Fig 13.18 on p190 of HPS-2.   This will provide the benchmark.

5 UNLESS THIS BENCHMARK CAN BE MATCHED OR EXCEEDED, THE CF SPAR PROJECT WILL PROCEED NO FURTHER.        (Object 5)

6          Re object 9, this will be easier to achieve if 4 above can be achieved over a wider range of rotation angle

Phase 2 -  On-the-Water Trialling

If we can develop a practical mast section plus turbulators which will do the aerodynamic job, the next step will be to -

7          Hand make a prototype of the same stiffness butt to hounds as the present mast in the plane of the major axis, and strong enough in the plane of the minor axis to stand without diamond stays, and otherwise slightly softer in the topmast than I think we will need.   This should match the present sail butt to hounds.   This will be rigged and trialled.

8          Trialling would be by a “volunteer sailor or sailors plus designer” test group.

9          Object 8 will be approached by progressive and judicious stiffening of the topmast, but not to duplicate the present alloy topmast. This operates with an “over-centre lock” dynamic which was the best I could do with the alloy section.   This was never a feature of my earlier timber spars, which were more pleasant to handle, and, I think, faster.   The object will be to duplicate the properties of the earlier timber spars..

10        Before long I would expect to have a mast which would match the mylar sail, and be well-mannered both to handle and to rotate, and which would be faster.   It would then be up to the trialling sailors to determine or judge whether the new mast favoured lighter crews, and if so for the class’ elders to decide what should be done about it.   There would be two optional approaches –

Further stiffen the topmast.   This would make the boat more “wooden” and less pleasant to handle, and a little slower.

Use the crew rule at club level.   This is what I wrote it for in 1972.   It worked.

11        Re object 9 - Work to make the rotation either fully automatic, or as automatic as possible, would be ongoing.

Reports of the trialling will be published on the class website.

Overseas visitors to Sydney will be welcome to participate.

I would hope that this approach would lead to a product with which both the test sailors, the class’ officers, and I as designer, will be happy.

Two of the key players who have helped bring the project to its present stage – Chris Parkinson, Exec Sec; and Graham Hanna, Chief Measurer, will be at Torquay.   I will leave it to them to respond to your questions.

Frank Bethwaite,      Designer.

Ref      Tasar.org>WTCA>Agenda>2011Worlds>other business> CF spars

Posted by Chris Parkinson

Sep 05, 2011

Last Updated:
Sep 05, 2011

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