Category: Education

Pear pram construction

My 3 year old daughter’s current favourite book is Jakob Martin Strid’s Den utrolige historien om den kjempestore pæra. In the story a giant pear is made hollow, and eventually turned into a boat. I decided to try and make a similar upright floating pear-boat out of a normal pear. One that my my daughter could play with once finished. Off I went to buy a pear and tools, the pear I ended up with have these specs:

  • Weighs around 238 g.
  • Displaces approximately 225 ml of water. This means it is slightly more dense then water since the weight of that water would be approximately 225 g.
  • Judging from the pears available in the shop, the one I chose was slightly more symmetric then most pears.

In addition to the pear, the tools I used are shown in the image below:

pear-tools
Pear, knife, melon baller (the MVT in pear pram construction), coins, thread.

The first step in pear pram creation, is to cut the windows using a knife. Once that is done carve out the inside using the melon baller. I recommend making the windows close to the top of the pear. If you make them too low they will result in water intake when launched. It is better to create the windows high initially and expand them downwards once you have a feeling for how the pear floats.

After carving out the core and flesh.
After carving out the core and flesh.

Another great reason for making the windows high up is lowering the center of mass. Pears have not yet been cultivated to float upright, and the center of mass is way too high for that. Having a too high center of mass on a ship is catastrophic. In its unmodified form a hollow pear will most likely perform worse then the Vasa on its maiden voyage.

To lower the center of mass even more, it is important to carve out as much as possible of the “roof”. Since the stalk extends into the pear this is difficult. It is easy to ruin the pear if you use too much force; be careful.

Even with the windows high up and a very light roof, the center of mass is still too high. Initially I added coins on the inside as ballast, this worked if I put the pear very carefully into the water, but it was still prone to capsizing.

Pear in bowl
Coins on a thread prevents capsizing. The pear is finally approved for transport of Lego men

To remedy this I moved the center of mass even lower by adding ballast on a thread below the pear. This was done by creating a knot on the thread and using a needle to get it through the bottom of the pear. Then the coins were added as shown in the picture. To ensure that water would not leak along the thread into the pear, I greased the entry points.

In its finished form the pear is quite stable, it could hold a surprising amount of Lego men without capsizing. I never got around  to test adding a sail, but I think it might be stable enough to support a small sail.

Sadly rot is an inevitability facing all pear prams. If you have a great idea for prolonging pear pram life, please leave a comment.

 

 

Get 1000 the game

My dad is a great teacher, not too long ago he taught me this game he was having his class play. To play you need a dice, pencils, and paper.

Pencil, paper and dice
All the equipment you need.

The game is quite simple, but complicated to master. It works like this:

  • Everyone draws a 3 by 3 table.
  • The dice is rolled and everyone places the rolled value in one of the empty positions in the table. Everyone has to place the value before the next roll.
  • This is repeated until every position in the table is filled.
  • To find your result you add your rows.
A game
A finished game with score 991.
  • The above table would result in the final sum of 123 + 634 + 234 = 991.
  • The winner is the player with the result closest to 1000. This means that 1001 beats 990 and 951 beats 1051 and so on. It is the distance from 1000 that matters.

To play decent in this game, some knowledge of addition is required. To play well you also need to figure out when it is best to play risky, and when to play safe. This is much harder than it may look.

I really hope that after reading this you will try to play this with your friends. If you have no friends willing to play nearby, you can try my asynchronous version. There you can start a game, and then send your friends a link to join that game. Then they can play whenever they want within a week.

Go play Get 1000

If you want to rejoin a game, your 10 last game links will be stored in your local browser storage for a week. These will be listed in your game list. If you saved a join link, you can also use that to join a game.