Jan 302013
 

Week 1: Module1: 1/30/13

Yesterday we heard from the crew about some big swells so what happens if the JRH flips over, or capsizes as it is referred to in the nautical world?

Does it look like this?

tintin-movie

Thanks to some really cool innovations it does not! In fact the JRH is self-righting! Self-righting what does that mean?

To better understand this let’s explore what happens to a sealed plastic bottle in the ocean. This plastic bottle can survive huge storms, be spun around end over end, and continue to float. Now, if you glue a pebble to the inside of it the bottle will always “right” itself with the pebble returning to the lowest point. What do you think would happen if you glued a pingpong ball in there? What about both?

Check out this video of a self-righting rowboat. (a different model than the JRH)

Why did that boat flip back over?

If we examine the bottle a bit more we see that it is an air tight container with weight, or ballast, on one side. Ballast can be any heavy thing that is fixed at the bottom of the boat to give it a low center of gravity. On the JRH, the ballast takes the form of the food, equipment and emergency stores of water. What do you think would happen if the ballast was on the deck of the boat?

There are three factors that affect the self-righting capabilities of a boat; buoyancy, center of gravity, and the shape. We addressed center of gravity with ballast and since the JRH floats we have addressed buoyancy. The shape of a self-righting boat only needs to be such that it is unstable when capsized so that it “wants” to flip back over.

Let’s explore the self-righting in the JRH. The design of the JRH includes a cabin that can be sealed to prevent any ingress of water.  Imagine the plastic bottle with both the pebble (ballast) and the pingpong ball (air tight cabin) inside. We now have a self-righting rowboat, which comes in really handy in the middle of the ocean!!!

For more in-depth info about self-righting rowboats check out this site http://angusadventures.com/oceanrowing/seaworthiness.html where much of this info came from.

 

Stay tuned for more info about the JRH on a live chat sometime next week with Greg Spooner, rower from the historic 2006 row and mission control for this expedition. Start thinking of questions!

 

Education Team

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