Window sizes/placement for DS sails

Moderator: GreenLake

Window sizes/placement for DS sails

Postby Bob Damon » Tue Oct 15, 2013 9:09 pm

Hi folks, in the Summer 2013 Quarterly I wrote an article inquiring if the Class needs to control the size and location of vision windows. The attached picture will explain more than words, but currently we do not control the size or location of windows. Nor do we control the material used for the window, so potentially laminated type windows could be used. I am interested in feedback if the Class should consider controlling size, location, and material for windows. Thanks! Bob Damon, Class Measurer
Attachments
DS NAC 2013 24.jpg
Note window size differences
DS NAC 2013 24.jpg (55 KiB) Viewed 5316 times
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Re: Window sizes/placement for DS sails

Postby GreenLake » Tue Oct 15, 2013 10:13 pm

Bob, I don't race under class rules, but where I do sail in races we have rather extreme traffic, and collision windows can be a valuable safety feature that I would not want to see restricted. I also don't think that they should be mandated. I assume your question is based on the concern that someone could try to turn the whole sail into a "window" and essentially going to laminated sails by a back door.

I further assume that small windows for 'telltales" are not a problem since the way they affect performance would be primarily by letting you observe the telltales not because of their aerodynamics.
However, looking at the larger windows your photo, I would say that any large windows that are placed higher, or extend higher than the ones shown on the windward boat would no longer qualify as "collision" windows, since they would only be useful for that purpose at ridiculous angles of heel.

I can't speak to the rationale that caused DS 13164 to sport such a large window in their jib, but if I had one, I would get used to it quickly and loath to give it up.

I would be interested to find out whether DS 13156 and DS 13164 are shown during trials to determine whether the larger windows give a performance edge. If they did, and I was racing against DS 13164, then I would probably not mind upgrading my sails, because I would justify the added expense with the increased safety, and benefit from that on crowed waters even when I'm not racing.

But, because I never see another DS to race against here, my views are just my very personal take.
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Re: Window sizes/placement for DS sails

Postby Mike Gillum » Wed Oct 16, 2013 12:02 am

Bob,
The story I've been told the reason for the large windows in the SLO Sail jibs of the Morro Bay DS Fleet was that they were spending more time repairing their boats following collisions because they either didn't see each other or the moored boat anchored in front of them!
Having raced against most of the Morro Bay Fleet over the past several years I haven't seen indurability issues given the dissimilar materials (mylar/dacron) that see a lot of wear and tear while tacking to clear the moored boats or sitting at the MBYC dock luffing between races.
Nor do I see any performance advantage gained over the conventional jibs made by the other sail makers active in the DS Class.
Perhaps to avoid any chance of an arms race set a limit based off of the SLO Sail jib that governs area, height from the foot and non-reinforced Mylar?
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Re: Window sizes/placement for DS sails

Postby Bob Damon » Wed Oct 16, 2013 7:10 pm

The additional question remains is where does the requirement that the sail be made of a "woven cloth" end and a window of mylar/vinyl begin? The Thistle class has a similar requirement of woven cloth for the sails and specifies the size and location of the windows. The Flying Scot class has no rule about windows but they are present on their sails. To date, I do not know of any competitive advantage to the SLO sails with the larger windows, but as a "One Design" how do we want to deal with the issue. Many years ago, Doyle Sails created a main with a full-battened top batten that was technically legal, but seemed to be faster in light to medium wind and the class changed the specifications. Again, great discussion for the class to look at this. Thanks, Bob
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Re: Window sizes/placement for DS sails

Postby K.C. Walker » Wed Oct 16, 2013 9:36 pm

Bob,

It would seem to me that what Mike has to say on the SLO sail showing no apparent advantage and that it is most likely the largest sail window currently used in regattas, use it as the prototype for a rules change. If the California guys that race against the Morro Bay fleet agree, it seems that presenting a rule change for clarity as a "one design" maximum measurement is an excellent idea.

With the clarity on the rule, I could see a lot of people adopting a larger window. It would not be an expensive change but it sure would add to safety. From what Mike says, it seems like you could easily get an endorsement from the Morro Bay fleet as to the advantage, safety wise, to present in support of a rules change.
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Re: Window sizes/placement for DS sails

Postby GreenLake » Thu Oct 17, 2013 2:20 am

I totally get the safety advantage of these large windows. Our lake can get crowded with over a hundred boats from 9' to 70'. I did have a collision that I might have avoided had I had a full-sized window, because it evolved so fast that there wasn't time for my crew to alert me. Luckily it was only the 9' boat...

When there appears such an obvious (to a jury anyway) safety advantage, I would think twice about putting DSA in a situation where it would appear to legislate against "safety equipment" for no compelling reason (that is absent competitive advantage that would destroy the class).

Anything much larger in terms of windows would probably not add a safety advantage, and if fact, totally transparent sails would become a liability (reducing the visibility of the boat - there was a tragic accident with a windsurfer a few miles from where I spent my vacation this year and lack of visibility was one factor). Therefore, K.C.s suggestion of using the SLO sails to define an upper limit makes a lot of sense to me.
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