Saturday, November 12, 2005

Virtual Non-Spectator For Mac

Woke up this morning hyped. The Volvo Ocean race started this morning, checked my e-mail for the update and...what's this? Virtual spectator for the Volvo Ocean race has finally arrived! Details were slim on the website. A desktop application that promises to deliver race results like never before. Putting you right there close to the action. As the site put it:

Observe the racing from the deck Brasil 1, view the rest of the fleet from the top of the mast of The Black Pearl, or follow the movement of the fleet from the outer reaches of earth's atmosphere as the 6-hourly updates give you the latest positions of the race participants.

Move backwards in time and view the historical moves of the competitors. Look ahead to the expected weather systems, and anticipate how each of the boats will react.

Perfect! I can follow the race, analyze the competitors tactics...learn from the pro's. But wait... the last line reads...Please Note: Virtual Spectator is only available for PC

No up virtual PC and run it from that...NOT. Sorry Mac folks, no dice. If you have a PC and check it out let me know what you think. Download it here.

Thursday, November 10, 2005

Ok...Now the Season is Over

Woke up this morning to the site of little white flakes gently falling from the sky. No accumulation but mentally puts an end to the sailing season for me :-(

The light at the end of the tunnel is Jamaica in 7 days :-). Temp is 84 and sunny with consistent. 10-15kt winds over the last 2 weeks. Looking forward to a lot of sailing.

Wednesday, November 09, 2005

The First Leg | Advanced Sail Theory

So this post may appeal to some and not to others. Apologies in advance to the latter. My knowledge hungry tendencies have gotten the best of me yet again and I have managed to dig up some articles on advanced sail theory in the hopes of better understanding the dynamics of the sail and how it applies to trim, speed and pointing. Although one or two of the articles are way to in-depth for me I thought best to present them anyways. Someone out there may benefit!

The first article, albeit a bit hard to read grammatically, gives an overview of the couples and forces on the sail and boat. The article is pointed towards an understanding of the tendencies of the boat to turn into the wind, and focuses on better boat balance through an understanding of the dynamics. The article is a part of written by Pim Geurts, and is the section titled couples and forces.

The next article, Tuning, is another from the same site and covers sail shape and twist. A good read with some good visual explanations.

The next two articles are from Arvel Gentry (Boeing Commercial Airline Company ), although a bit dated at 1981, they have in-depth information on sail theory and lift principles as well as notes on airflow separation and sail interaction. The first is A Review of Modern Sail Theory. This one is pretty packed with technical information and theory.

The second article from Arvel is titled Aerodynamics of Sail Interaction. The abstract for the paper is as follows:
"This paper deals with the basic problem of the interaction between a mainsail and the jib. Since this paper is written for the sailor rather than the aerodynamicist, all aerodynamic terms and concepts are developed and explained as they are needed. The characteristics of the flow about the jib and mainsail airfoils when they are each used alone and when they are used together are discussed and illustrated. Results from these flow field studies give a very complete and accurate description of the jib-mainsail interaction problem.".

A pretty intense read but worth it if this type of information appeals to you.

Think I have beat this topic to a pulp so next post will carry on with the first leg and get into the next phase which will be "the critical first tactical move".

Monday, November 07, 2005

The First Leg | Mainsail Controls

The main sail (in most instances) has the most possibilities of adjustment when it comes to trim. The controls include halyard tension, mainsheet, outhaul, cunnigham, boom vang and backstay tension and traveller. The J is particularly sensitive to minor adjustments to the main. A little traveller, or mainsheet, or a little boom vang makes a noticeable difference.

Positioning and depth the draft of the sail is the key power in the main sail and ultimately speed. The key to speed is lift and creating the surface area to provide lift. The controls are all designed to move and position the draft to ultimately balance between boatspeed and weatherhelm. Too much heel is slow. Generally each boat has an optimum heel angle which should be maintained.

Here are a number of resources for mainsail trim and controls. The first couple are from Sailnet. The first is a good look at the mainsail and explains each control and its general purpose for overall sail shape. It comes in 2 parts. Part 1 of "Mainsail Controls for Performance" can be found here.. It covers halyard, cunningham and outhaul adjustments. The second half of the article covers backstay and boom vang.

The second article from Sailnet, "Basic Mainsail Trim for Racers" Part 1 and Part 2 are more specific to racing and deal more with the angle of attack and twist of the sail, and explores the concept of shape and power more. The article, by Pete Colby, deals with chord length and surface area and other advanced concepts. Very good read.

Performance Racing - Mainsail Trim & Controls by Bill Gladstone deals with some of the same details as the above articles and offers some good visual cues to demonstrate the closed and open leech and twist as well as a good visual that shows how backstay tension affects the main. Also deals with balancing the boat between speed, pointing and weatherhelm.

This article by North Sails is goes over the basic controls as well. If you have read the top few it may not offer much more info

Some J specific links to mainsail trim. First from JWorld Articles, secondly from the J24 class site written by Geoff Moore. If you are a J24 sailor you probably have checked them out already. If not there are a few good tips and vantage points that might help. The Geoff Moore article has some insights into mast pre-bend and the importance of tuning. Will be reading this one again when stepping the mast next season.

Bill Holcomb has written an article (primarily for a Catalina) regarding weatherhelm, indicators and ways to adjust for it. One of the ways is adjusting the main and or controls. Worth a peak, deals with some other factors such as weight distribution etc.

I know this one is a repeat from the a previous post on trim but here it is again. North Sails mainsail trim. Has animated visuals and is broken down into sections for easy reference.

Another article by Geoff Moore written for Shore Sails. Not J24 specific and deals with more general concepts of mast bend. Has some good analogies and ways to look at sail shape. Some interesting insights into reading the mainsail control positions to determine keel and mast position and rake and whether they are in balance with the boat. Will give this one another read before stepping the mast as well.