ACC Forestay Location

[SuperPiper]

I viewed some photos from the America's Cup gallery. It seems that the fleet has either extended the bow of most boats or has moved the forestay aft.

Do you figure that this modification is due to rule changes or due to different sailing conditions in the Mediterranean? Are we all about to shorten the foot of our jibs in response to some newly discovered aero-dynamic efficiencies?

However, it was the America's Cup and not necessarily the REAL WORLD.

Originally Posted by SuperPiper

I viewed some photos from the America's Cup gallery. It seems that the fleet has either extended the bow of most boats or has moved the forestay aft.

Do you figure that this modification is due to rule changes or due to different sailing conditions in the Mediterranean? Are we all about to shorten the foot of our jibs in response to some newly discovered aero-dynamic efficiencies?

However, it was the America's Cup and not necessarily the REAL WORLD.

All ACC boats have had the headstay set back from the bow. Most large raceboats under various rules are the same.

This allows for more reserve bouyancy as the bow is driven down by the headsail.

[SuperPiper]

Originally Posted by xyz

All ACC boats have had the headstay set back from the bow. Most large raceboats under various rules are the same.

This allows for more reserve bouyancy as the bow is driven down by the headsail.

In New Zealand the forestays were about 1/2 meter from the bow. In France, they appear to be 1 - 1.5 meter from the bow. I am convinced that there has been a modification.

Don't think it is to do with the aerodynamics but to do with the rule changes. If I remember correctly they have reduced the maximum allowed weight limit to 24t. That has meant that some of th eweight has had to come out of the boats. Hence they are now over the rating limit and have had to reduce sail area. The easiest way to do that is to move the forestay. Could this be a reason for the change?..

[SuperPiper]

That is an explanation that makes some sense.

Do you recall the rationale for reducing the maximum weight?

Not exactly sure why the weight was reduced just that it was. I think it was part of a broader plan to push the boats further appart in the design space. At the moment they are very tightly bunched in a corner of the rule.

To compensate for the reduced weight however the maximum draft was increased so the RM stays about the same.

There was a good article arround somewhere about the changes and what they might mean for the current boats. I can't find it at the moment but if I can I will post a link here. The most noticable changes are the restrictions to essentially ban the HULA, the weight and the draft changes. The full rule is available at http://www.cupineurope.com/LatestNews/Regulation07.htm toward the end of the page for those who are interested.

[Paul B]

Originally Posted by Guest

Not exactly sure why the weight was reduced just that it was. I think it was part of a broader plan to push the boats further appart in the design space. At the moment they are very tightly bunched in a corner of the rule.

Actually, the change to the displacement limit in the rule is sqeezing the fleet into an even tighter corner. There will be even less differences in this new generation. Seahorse Magazine has done a nice article about this development.

I don't see the headstays locations changing that much. All the boats had somewhat different locations in the past, but I don't think I've ever seen any at a half meter.

Here is a pic of Prada and AmOne in 1999. Pretty far back on these.

[Paul B]

Team NZ were much more than a half meter as well.

[Paul B]

Alinghi in this configuration is quite far forward. Using the crewman for scale it appears to be more than a meter.

[SuperPiper]

But, somehow this is what I remember from the cup in 2003:

[Paul B]

Originally Posted by SuperPiper

But, somehow this is what I remember from the cup in 2003:

That is one of the TNZ boats pictured in my post above. The angle in your photo may be deceiving somewhat. Even so, it still appears to be more than a meter in your photo.

Look at Seahorse Magazine Issues 274 to 278. There are a lot of good photos of many of the boats from the 2003 LVC and AC. In particular in 278 there is a comparison of sailplans for Alinghi and TNZ. In their sailplan drawing both boats have a headstay offset by about 2 meters from the bow.

Some of the other boats look to have even more in some modes.

If you go back to the 1992/1995 boats with destroyer bows you'll find less setback, but those boats were not very fast and that area of the rule was abandoned.