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Wednesday, March 3, 2010

Bubble Sorting Boat Modifications

Once we acquired Ariel, our list of all the things we wanted to do to her to make her ready for sailing around the world began to grow. It grew and grew and grew and grew. Over the past few months, we began to question all the items on the list. How many were "must haves" ? How many were "should haves"? and how many were just "desires"?

Our list contained 80+ boat modifications. But how many were absolute needs? To identify this we did what is called a "Bubble Sort" (wow, a computer algorithm I learned in college is paying dividends!).

To do the Bubble Sort, we listed our 80+ items one by one straight down a page. Then, starting at the top, we asked our self "Is item 1 more important than item 2?" If yes, then no change. If no, then item 2 goes above item 1 on the list. We then ask the question, "Is item 2 more important than item 3?" If yes, then no change. If no, then item 3 goes above item 2. We then ask the first question again (since there is now a new item 2). This is best expressed by example.

Let's use this simple 4 item task list:
  1. Replace main sail
  2. Replace rusted bolts holding engine to boat
  3. Fix navigation lights
  4. Replace batteries
We start with, "Is replacing the main sail more important than replacing rusted bolts?"
Our answer, "Well, the main sail works fine. It has one small tear that Val can fix ... but the rusted bolts can break and the motor would fall into the ocean. So, number 2 is more important than number 1"

The example list now stands as:
  1. Replace rusted bolts holding engine to boat
  2. Replace main sail
  3. Fix navigation lights
  4. Replace batteries
Is fixing the navigation lights more important than fixing the main sail? In our case yes, our navigation lights are turned 90 degrees plus the steaming light is out.

The example list now stands as:
  1. Replace rusted bolts holding engine to boat
  2. Fix navigation lights
  3. Replace main sail
  4. Replace batteries
Is fixing the navigation lights more important than fixing the rusted bolts? We answered yes, so that moves the navigation lights up the list.

The example list now stands as:
  1. Fix navigation lights
  2. Replace rusted bolts holding engine to boat
  3. Replace main sail
  4. Replace batteries
Then we ask if replacing the batteries is more important than fixing the main sail. The answer is yes.

The example list now stands as:
  1. Fix navigation lights
  2. Replace rusted bolts holding engine to boat
  3. Replace batteries
  4. Replace main sail
Is replacing the batteries more important than fixing the rusted bolts? We answered no, so we can now stop.

When we applied the bubble sort to our list of 80+, we ended up with a priority order of everything we wanted to do. Then we walked up the list, from the bottom, asking ourselves if something was required to be done for us to start our voyage. Once we hit the first item of something we believed was critical for starting the voyage, we noted that from this point up the list as "must do to sail." We resolved that there are 12 such items.

Here is our current list of must do items, in priority order:
  1. Replace mast navigation lights with LED ones (steaming light is out)
  2. Bottom Paint (currently covered for lake life, not ocean life)
  3. Fix fiberglass fractures above waterline
  4. Replace splashwell steering plate with a fiberglass one (one is rusted)
  5. Replace all rusted bolts (one is on the motor mount)
  6. Replace batteries (ours are 5 years old and swollen)
  7. Install Radar system (already bought, just needs to be installed)
  8. Troubleshoot and fix windvane
  9. Inspect standing rigging and replace as needed
  10. Install fuse between 30amp shore power receptacle and circuit breakers
  11. Replace engine fuel line (it is a bit weathered, it will soon start to show signs of cracks)
  12. Add manual windlass
We've agreed that we should still have the funds to complete all 80+ items, we just won't spend the funds until something goes from a "should have" to a "must have."

The Bubble Sort technique is fantastic since it allows you to apply whatever rules you want in determining priority. If you change how you pick priorities, you simply run through the list again. You could do the sorting based on costs, you could do sorting based on safety, you could do sorting based on your skills for doing your own repairs, and more. You can even run the bubble sort in each different priority picking mode, then compare lists, and then identify which items always appear near the top and simply work on them.

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