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The Timetable.

By Dermot Tynan, over 9 years ago.

The official start to hurricane season is June 1st, this year. The traditional end to the season is the end of November, but the hurricanes seem to wane out by early to mid-November. A back-of-the-envelope calculation says that it'll take up to sixty days to get from Start to Finish. That's a worst-case estimation, but useful nonetheless. If we are to launch before the start of the season, we'd need Beoga Beag sailing to the start line by April 1st at the latest. Let's face it, that's not going to happen. We don't have the pilot boat designed yet, we have extensive testing to do on the pilot boat, we need to then build the main boat, and start to fit her out. No way are we going to make that date.

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Why Antigua...?

By Dermot Tynan, over 9 years ago.

A first pass over the route and the finish line suggests Antigua could be a good destination. We last visited in 2009 and this is as good an excuse as any, to go back.

The finish line is from latitude 10 degrees to latitude 25 degrees North, which is all of 900nm long. However, according to the rules, we must declare a 50km (27nm) segment of that finish line. Although the finish line is pointing True North, when you consider the race is from Northern Europe, that means that the line is heavily biased towards the starboard end. The Northern tip, in other words. Finishing on this end of the line shortens the final leg.

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Mother

By Dermot Tynan, over 9 years ago.

The main computer on board Nostromo in the film Alien was called Mother. It seems only right that we should call our main processor by the same name.

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BB Phone Home.

By Dermot Tynan, over 9 years ago.

There is a race requirement which states that "Any boat which fails to transmit for more than 10 consecutive days will be disqualified."

While there are a number of ways of reporting position data back to Mission Control, from elaborate HF transmitters through to simple satellite position locators, we'll be using a Rock Block satellite modem. These devices can send byte sequences back to dry land via the Iridium satellite network. We will be sending four updates a day, of exactly 250 bytes each. Each message will include two or more payloads.

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The Main Systems Design

By Dermot Tynan, over 9 years ago.

In terms of the system architecture, we're planning on using two separate computer control planes to manage and steer the boat from start to finish.

At the lowest level, a custom Atmel (ATmega8) board will act as a basic "autohelm", driving the boat to a specific True Wind Angle or TWA. As the breeze shifts, so too will the boat, to maintain that TWA. This is a basic PID algorithm for controlling the rudder and mainsail in relation to the specified TWA and is very similar in design and implementation to your average sailboat autohelm.