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blaze720 View Drop Down
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Posts: 1635 		Post Options Post Options   Quote blaze720 Quote  Post ReplyReply Direct Link To This Post Topic: Cirrus Icon Development
    Posted: 12 Mar 10 at 10:14am
This aspect of the debate seems to be getting bogged down a bit now.  The acid test is and will remain 'on the water'.  I read the theoretical stuff as well but my maths is now too poor to follow every detail  (use it or lose it).... therefore I read the descriptions and quickly move to conclusions and summaries more often than not now.  I've used many carbon masts, wing masts, including the square back Tasar ones, camber inducers and a whole variety of 'stick' masts over the years. 

Modern over-rotational wing masts are in fact light, simple to use and effective.  They add a little complication but some cost and have been largely ignored on monohulls here as 'stick' evolution has been very fast in recent years.  In parallel though wing masts have also been refined and developed but many builders and classes have not recently explored the benefits and implications yet.  Sometimes our accepted views need to be challenged and if the case is proven can become more mainstream.

In relation to Icon, as with the NSs, the wing mast works.  It works very well with these rigs and appears to offer a worthwhile advantage in Oz and here in our initial tests.  If it did not well then it would be changed to a slimline stick for Icon  - but this obvious alternative does not look favoured by testing so far.   The only very clear non-cost advantage of 'stick' I can see would be if we were to put a third sail on the boat as the arrangements for 'stick' + asymetric are then much simpler.  Our plan for Icon however is to keep close to the NS 2-sail model for sound commercial reasons.   

Personally I'm not going to defend 'wing' over 'stick'  or even vice versa - we'll let other testers have their say first.  To my more simple mind the case is simply one of seeing if the benefits of 'wing' clearly outweight the extra cost in a production boat.   Sails ? - we we can tweak them in all sorts of ways and will continue to do so .... probably well beyond the production of hull tooling.

Mike L.



Mike L   
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Post Options Post Options   Quote Guests Quote  Post ReplyReply Direct Link To This Post Posted: 12 Mar 10 at 6:54am
Well obviously it's always the sail and mast together, but I think it's
fairly well understood that the square head can twist open more
easily?
I can't think of (m)any successful applications of an ICON style square
head on a fixed mast without going beyond the simple staying
system? I'm sure I'll be proved wrong though!
Interesting stuff...
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JimC View Drop Down
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Posts: 6662 		Post Options Post Options   Quote JimC Quote  Post ReplyReply Direct Link To This Post Posted: 12 Mar 10 at 12:32am
Originally posted by Peaky

It is the sail rather than the mast that does the gust response, but it is just as effective.
I must say I find that quite a suprising statement!


Originally posted by Peaky

I do not believe you could put such a square head on a fixed mast without much more complex rigging a la 14s, 49ers etc, but maybe you could.

I can't imagine why not, goodness knows enough people have...
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Post Options Post Options   Quote Guests Quote  Post ReplyReply Direct Link To This Post Posted: 11 Mar 10 at 9:34pm

Just a couple of other points, and then I promise to shut up!  Personally I like the square head on the ICON, because a. it looks good and b. it works.  It is the sail rather than the mast that does the gust response, but it is just as effective.  I do not believe you could put such a square head on a fixed mast without much more complex rigging a la 14s, 49ers etc, but maybe you could.  I think it would be real shame to  lose this visually striking part of the design.

How a boat behaves in gusts is also a function of more than just the rig.  How light and easily driven the hull is, and the quality of the foils also play an important role.  If the hull accelerates quickly, gusts will just make the boat go faster.  If it is a draggy hull, it will stagger. 

In fact, more completely, the hull and rig have to match, to have similar/complimentary responses to gusts. The ICON hull is based upon a successful NS hull form, and the one that carries weight best out of all the modern designs.  It is also one of the best in the light/moderate winds we get more of here, whereas some other NS hulls are perhaps more optimised to the fresher breezes the Aussies enjoy. 

By way of comparison, the hull is about 6 stone lighter than a Merlin hull.  To put that in perspective, for every hull length the boat travels forward it has to push aside about 80 pints less water than a Merlin Rocket does.  So the different hull has a different rig.

As someone who spends his working day creating fluid dynamic models of underwater bodies, and has sailed the protoype ICON for the last two years, I am convinced in both a theoretical and real way that the ICON is a step change in two-sail boat design.  But as Mike says, 30 mins on the water is the best proof.
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Slippery Jim View Drop Down
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Posts: 586 		Post Options Post Options   Quote Slippery Jim Quote  Post ReplyReply Direct Link To This Post Posted: 11 Mar 10 at 8:45pm
Originally posted by blaze720

Slippery ...Good to meet you at the show etc ...BTW
no pontificating here ... the options are lined up ready for testing and we
already have a choice of rigs in place.  But we are interested to see the
full variety of views out there.I've got my favorite configuration written up
already but proper trials are the real decider and that involves a number
of other testers as well.  The programme is set already.  In due course a
boat or possibly two will be used to get a few of you in them and giving
us your 'post Icon' views.  30 minutes on the water is easily worth 30
hours on a keyboard.Mike L.
Ok. Now I understand. BTW, I enjoyed meeting you at the show
too. My thoughts are merely that if you want to have an automatic rig,
make sure itīs carbon or similar and avoid trying to do it with a wing
mast, cos itīl cost you... There are only a few people who can really
calculate what sort of change in laminate thickness you need with height
increase in a wing mast designed to automatically flex with the gusts.

As for just having a "normal" wing mast it would only be truly good in a
steady wind. In gusty conditions and/or in chop itīd lose out against
boats with more flexible masts. Thatīs why I say stick with "conventional"
automatic masts, or the ones Rick mentioned - profiled I think he wrote.
Good luck!

Edited by Slippery Jim
Pass the skiff, man!
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Post Options Post Options   Quote Guests Quote  Post ReplyReply Direct Link To This Post Posted: 11 Mar 10 at 8:02pm

Hi Mike,

Saw you at the show but didnt want to interupt....and I didnt have long while searching for the best cover maker for my 400.

Um.... really like the Icon....

Bearing in mind all your previous remarks about masts etc, I would just like to say the first thing that came to mind (honestly) was...."oh carbon mast where is it?"

How shallow of me i guess

Lovely boat....good luck

Timg

 
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blaze720 View Drop Down
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Posts: 1635 		Post Options Post Options   Quote blaze720 Quote  Post ReplyReply Direct Link To This Post Posted: 11 Mar 10 at 7:48pm
Slippery ...

Good to meet you at the show etc ...

BTW no pontificating here ... the options are lined up ready for testing and we already have a choice of rigs in place.  But we are interested to see the full variety of views out there.

I've got my favorite configuration written up already but proper trials are the real decider and that involves a number of other testers as well.  The programme is set already.  In due course a boat or possibly two will be used to get a few of you in them and giving us your 'post Icon' views. 

30 minutes on the water is easily worth 30 hours on a keyboard.

Mike L.
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Slippery Jim View Drop Down
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Posts: 586 		Post Options Post Options   Quote Slippery Jim Quote  Post ReplyReply Direct Link To This Post Posted: 11 Mar 10 at 7:38pm
Originally posted by blaze720

  If you go the 'stick' route you need more area for the
same performance in our experience.Mike L.  
Then go for it - itīs cheaper and you can make the mast much
more gust responsive. Otherwise youīll spend too much time on mast
development.
Time which you honestly havenīt got. I personally was not impressed with
that Tornado - type elipsoid mast at the DS.
Get as much sail area up above
as possible, which would be good for restricted and obstructed waters. You
īd be surprised how little extra "conventional rigged" sail area youīd need
to drive that nice fine hull along. Good luck and stop pontificating - unless
of course, itīs some marketing ploy

Edited by Slippery Jim
Pass the skiff, man!
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JimC View Drop Down
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Posts: 6662 		Post Options Post Options   Quote JimC Quote  Post ReplyReply Direct Link To This Post Posted: 11 Mar 10 at 7:35pm
Originally posted by Guest#260

... a rotating mast would be a pain especially with a novice crew.

They're not nearly as much trouble as most people think, because as you come in for the tack you grab the handle and heave yourself across the boat with it. However as most people still think that it doesn't make much difference...
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blaze720 View Drop Down
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Posts: 1635 		Post Options Post Options   Quote blaze720 Quote  Post ReplyReply Direct Link To This Post Posted: 11 Mar 10 at 7:23pm
Capsize & Inversion

I have always paid particular attention to this as it is very easy to have to much buoyancy in modern boats - Blaze / Halo are amongst the very best in this regard imho and we intend ICON to be similar relative to others out there.   This will be  partly due to the hull form and partly due to a tall (and 'sealed') mast.  This does not stop inversion but it makes it much less likely or rapid.

Frank B always argued that inversion was a good thing as the boat could not blow away from you.  Well we understand the logic but if it is possible to slow the ingress of water into the mast then again we regard it as a worth pursuing.  We aim not to prevent inversion just to make it much less likely and slower when it does happen.   This gives the crew a much better chance of quick recovery.

Masts - we have a number of very good carbon 'sticks' and they will be tried - but the NS does not hang onto the wing set-up for appearance - remember nothing on the NS is there for 'style' or 'show' - no stylists are/were involved  - all the features are for functional reasons and their worth has been proven.  If you go the 'stick' route you need more area for the same performance in our experience.

Mike L.  
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