How did you come up with this idea?
The inspiration for this project is the Microtransat Challenge (http://www.microtransat.org). Like many others, we wanted to be the first to send a robotic sailboat across an ocean. Then, shortly after we started working on that, we saw that not many people were trying to do it with solar power, so we switched from sail power to solar power.
What are you trying to prove by making this journey?
Nothing. Just having fun and learning stuff.
Is there anything novel about SeaCharger?
We’ll let you be the judge of that, but for the most part we’ve tried to avoid novel in favor of simple and proven.
How fast does it go?
About 1.3 m/s (2.5 knots) in calm water, and a bit slower in rougher conditions.
Where do you sit?
You don't. It's unmanned.
Does it have any sensors on it?
Not other than the sensors it needs for its own navigation (like a magnetic compass). Trying to keep it simple.
Can you communicate with it?
Yes, it has a two-way satellite modem. Typically every two hours (the interval can be changed), it sends a message containing its position, battery voltage and current, heading, pitch and roll angles, rudder angle, etc. It costs about $0.30 every time it sends a message. We can also send it commands to follow a different course, restart the thruster, or do one of many other functions.
Does it keep going at night?
Yes, it has a battery that gets charged during the day and keeps it going at night.
How does the boat know where to go? And once you launch it, can you control where it's going?
The boat has two different navigational modes, and these can be changed via satellite at any time. The first navigational mode is where it tracks a set of waypoints. A waypoint is just a specific point on the earth. Prior to launch, the boat was programmed with a set of ten waypoints to follow. Once the boat gets to the first waypoint, it heads towards the second, and so forth. The first three waypoints are off the coast of California and the last seven are off the coast of Hawaii, although the location of the waypoints can be changed at any time. There are no waypoints out in the middle of the ocean, so the vast majority of the time the boat will be going from waypoint 3 (near California) to waypoint 4 (near Hawaii). In between waypoints, the boat essentially draws an imaginary line (actually not a straight line, but a "great circle" line, which is the shortest path between two points on a sphere) connecting the waypoints and attempts to stay on that line. Wind and currents will tend to push the boat off that line, but it'll try to steer back to that line. The other navigational mode is where the boat is commanded to track a certain heading, which means it will point its nose in a certain direction. But that doesn't necessarily mean it will travel in that exact direction, as wind and currents will change its course. If you look at the tracking page and the boat is sort of all over the place, it's probably in heading mode. If it's following a nice, very slightly curved line, it's probably in waypoint-tracking mode.
How do you prevent it getting hit by ships while at sea?
For the most part, we just rely on the fact that the ocean is a very large place. However, we also monitor the location of vessels (there are various websites that allow you to do this) and will alter SeaCharger’s course to avoid them.
How do you prevent seaweed or other debris from getting wrapped around the propeller/rudder/etc.?
This is certainly a possibility. Most debris is found close to shore, so if the boat can get out a few miles, it has a good chance of avoiding it. If SeaCharger starts slowing down noticeably shortly after being launched, we’ll turn it around and fix the problem. If it starts slowing down well into its journey, then we’ll just have to hope for the best.
What about the Pacific Garbage Patch?
Ever seen the first Star Wars movie where they're stuck in the trash compactor? Well, this is NOT what the middle of the Pacific Ocean looks like (not yet at least). From our understanding, it's mostly tiny particles of plastic suspended in the water. Nevertheless, we expect SeaCharger to stay well south of it.
How long will it take to go to Hawaii?
Probably about 50 days if everything goes well. UPDATE: it took 41 days.
How come your website is so amateur and you take so long to answer emails?
Actually, nobody has ever asked this, but we can imagine you might be thinking it. Every part of this project is done in our very limited spare time, so while we do the best we can, there isn’t time for everything.
What are you going to do if the boat makes it to Hawaii?
We definitely want to meet it there as it comes to shore. After that, we’ll probably just clean it off, put it back in the ocean, and see if it can make it back. UPDATE: it did make it to Hawaii, and after a few days of rest, it was re-launched on a journey to New Zealand.
Is it really sturdy enough to survive in the open sea?
We’ll find out. UPDATE: yes.
How about a really bad storm?
Probably not.
What are you going to do with the SeaCharger project once this Hawaii attempt is over?
We’ll be glad that it’s over… whether successful or not. There are no plans for doing anything else with it. UPDATE: After it made it to Hawaii, we decided to put it back in the water and head to New Zealand. If it makes it to New Zealand, we're going to stop while we're ahead. Really. FURTHER UPDATE: It didn't quite make it, but got very close. See the tracking page for details. Right now SeaCharger is spending six months in the NZ Maritime Museum. After that, we might ship it back to the USA and do a post-mortem.
Why is the boat's course so erratic sometimes?
Well, first of all, it's not because currents or winds are blowing it off course. So far, the boat has never encountered a current or wind that is enough to blow it off course, as long as the propeller is still spinning. But if it's in cloudy weather, then it might run out of power, especially just before dawn. Then the motor will shut off and it'll start drifting. If I know this is going to happen, sometimes I put it in "heading mode" where it just tries to keep the nose pointed in a certain direction instead of trying to travel in a straight line (meaning that any current perpendicular to the heading will push the boat around to the left or right). The advantage of this is that the boat doesn't waste time trying to get back on its previous straight-line course once the sun comes up and the propeller starts spinning again. Also, sometimes the course is erratic because I'm trying to find a spot with a more favorable current. But that almost never works!
The inspiration for this project is the Microtransat Challenge (http://www.microtransat.org). Like many others, we wanted to be the first to send a robotic sailboat across an ocean. Then, shortly after we started working on that, we saw that not many people were trying to do it with solar power, so we switched from sail power to solar power.
What are you trying to prove by making this journey?
Nothing. Just having fun and learning stuff.
Is there anything novel about SeaCharger?
We’ll let you be the judge of that, but for the most part we’ve tried to avoid novel in favor of simple and proven.
How fast does it go?
About 1.3 m/s (2.5 knots) in calm water, and a bit slower in rougher conditions.
Where do you sit?
You don't. It's unmanned.
Does it have any sensors on it?
Not other than the sensors it needs for its own navigation (like a magnetic compass). Trying to keep it simple.
Can you communicate with it?
Yes, it has a two-way satellite modem. Typically every two hours (the interval can be changed), it sends a message containing its position, battery voltage and current, heading, pitch and roll angles, rudder angle, etc. It costs about $0.30 every time it sends a message. We can also send it commands to follow a different course, restart the thruster, or do one of many other functions.
Does it keep going at night?
Yes, it has a battery that gets charged during the day and keeps it going at night.
How does the boat know where to go? And once you launch it, can you control where it's going?
The boat has two different navigational modes, and these can be changed via satellite at any time. The first navigational mode is where it tracks a set of waypoints. A waypoint is just a specific point on the earth. Prior to launch, the boat was programmed with a set of ten waypoints to follow. Once the boat gets to the first waypoint, it heads towards the second, and so forth. The first three waypoints are off the coast of California and the last seven are off the coast of Hawaii, although the location of the waypoints can be changed at any time. There are no waypoints out in the middle of the ocean, so the vast majority of the time the boat will be going from waypoint 3 (near California) to waypoint 4 (near Hawaii). In between waypoints, the boat essentially draws an imaginary line (actually not a straight line, but a "great circle" line, which is the shortest path between two points on a sphere) connecting the waypoints and attempts to stay on that line. Wind and currents will tend to push the boat off that line, but it'll try to steer back to that line. The other navigational mode is where the boat is commanded to track a certain heading, which means it will point its nose in a certain direction. But that doesn't necessarily mean it will travel in that exact direction, as wind and currents will change its course. If you look at the tracking page and the boat is sort of all over the place, it's probably in heading mode. If it's following a nice, very slightly curved line, it's probably in waypoint-tracking mode.
How do you prevent it getting hit by ships while at sea?
For the most part, we just rely on the fact that the ocean is a very large place. However, we also monitor the location of vessels (there are various websites that allow you to do this) and will alter SeaCharger’s course to avoid them.
How do you prevent seaweed or other debris from getting wrapped around the propeller/rudder/etc.?
This is certainly a possibility. Most debris is found close to shore, so if the boat can get out a few miles, it has a good chance of avoiding it. If SeaCharger starts slowing down noticeably shortly after being launched, we’ll turn it around and fix the problem. If it starts slowing down well into its journey, then we’ll just have to hope for the best.
What about the Pacific Garbage Patch?
Ever seen the first Star Wars movie where they're stuck in the trash compactor? Well, this is NOT what the middle of the Pacific Ocean looks like (not yet at least). From our understanding, it's mostly tiny particles of plastic suspended in the water. Nevertheless, we expect SeaCharger to stay well south of it.
How long will it take to go to Hawaii?
Probably about 50 days if everything goes well. UPDATE: it took 41 days.
How come your website is so amateur and you take so long to answer emails?
Actually, nobody has ever asked this, but we can imagine you might be thinking it. Every part of this project is done in our very limited spare time, so while we do the best we can, there isn’t time for everything.
What are you going to do if the boat makes it to Hawaii?
We definitely want to meet it there as it comes to shore. After that, we’ll probably just clean it off, put it back in the ocean, and see if it can make it back. UPDATE: it did make it to Hawaii, and after a few days of rest, it was re-launched on a journey to New Zealand.
Is it really sturdy enough to survive in the open sea?
We’ll find out. UPDATE: yes.
How about a really bad storm?
Probably not.
What are you going to do with the SeaCharger project once this Hawaii attempt is over?
We’ll be glad that it’s over… whether successful or not. There are no plans for doing anything else with it. UPDATE: After it made it to Hawaii, we decided to put it back in the water and head to New Zealand. If it makes it to New Zealand, we're going to stop while we're ahead. Really. FURTHER UPDATE: It didn't quite make it, but got very close. See the tracking page for details. Right now SeaCharger is spending six months in the NZ Maritime Museum. After that, we might ship it back to the USA and do a post-mortem.
Why is the boat's course so erratic sometimes?
Well, first of all, it's not because currents or winds are blowing it off course. So far, the boat has never encountered a current or wind that is enough to blow it off course, as long as the propeller is still spinning. But if it's in cloudy weather, then it might run out of power, especially just before dawn. Then the motor will shut off and it'll start drifting. If I know this is going to happen, sometimes I put it in "heading mode" where it just tries to keep the nose pointed in a certain direction instead of trying to travel in a straight line (meaning that any current perpendicular to the heading will push the boat around to the left or right). The advantage of this is that the boat doesn't waste time trying to get back on its previous straight-line course once the sun comes up and the propeller starts spinning again. Also, sometimes the course is erratic because I'm trying to find a spot with a more favorable current. But that almost never works!