Divers measuring a shipwreck. They can even write underwater!
You may be asking, what is an underwater archaeologist? Underwater archaeologists study shipwrecks as a way to learn more about the past. They have many methods for studying shipwrecks, but one of those methods is to create a scale drawing or site plan of the shipwreck. We can learn a lot about a shipwreck and it’s history based upon the artifacts found on board and where they are placed. It takes a long time to take measurements and create a site plan of a shipwreck. Our underwater archaeologist trains volunteers to help. In the activity below, we will show you how to create your own “shipwreck” at home and then how to create a scale drawing of your shipwreck.
This is an example of a scale drawing or site plan of the shipwreck Anthony Wayne. Not all of the shipwreck was visible above the lake bottom, some was buried.
For this activity, you will want to find an empty space in your home or outside to build your shipwreck. We built ours about ten feet long, but you could build bigger or smaller.
This is our shipwreck, showing the different parts of the ship.
Bow – the front end of the ship.
Stern – the back end of the ship.
Port – the left side of the ship if you are facing the bow.
Starboard – the right side of the ship if you are facing the bow.
Baseline – a measuring line that archaeologists place through the center of the shipwreck from bow to stern. It stays in the same location the entire time they are measuring, so they have a stable reference point. The zero end is usually at the bow of the ship.
- 2 Tape Measurers
- We used 1 tape measurer for our baseline and 1 for our measurements, but there are a lot of creative alternatives. For a baseline, you could use a jump rope and tape off every foot. You could use a long piece of yarn with knots at every foot. You could use the same thing for your measurements. If you don’t have any kind of ruler at home, you could use the length of your foot or the width of our hand as a measurement.
- Painters Tape
- We used painters tape for the outline of our shipwreck, but you could used something you find around the house, like a sheet. You could also skip the outline altogether, the outline is not clear on all shipwrecks.
- Be creative you could use anything from your house to create your artifacts. Use a variety of sizes and shapes.
- A Diving Buddy
Carrie and Kate are dive buddies. One diver stays at the baseline and the other diver stays at the artifact.
- When measuring a shipwreck, divers always work in pairs. You can do this activity alone, since you won’t be diving, but it’s more fun with a buddy. Divers use hand signals to communicate because they are wearing SCUBA masks. See how much of the measuring you and your buddy can do without talking.
There are two methods for measuring your shipwreck, offset measuring and triangulation. Both methods begin at the baseline, but offset measuring uses one measurement from the baseline and triangulation uses two measurements, creating a triangle. You can print the handout to record your measurements or use a blank sheet of paper.
Underwater Archaeologists often divide a shipwreck into quadrants to make it easier to know where they are measuring. They have to be careful that they’re in the right place. For our measuring examples, we will be measuring the location of a point on the outline of the ship and then we will be measuring the location of an anchor. Both of these examples are from the starboard bow quadrant of the shipwreck.
Before you begin taking measurements, draw a rough sketch of the shipwreck and label the points you are measuring (for example, A, B, C, etc.) Underwater Archaeologists will do this before a dive so that the diving buddies both know what they’re looking for.
Offset Measuring uses two measurements and a right angle to find the location of an object. For our example, we will measure from the baseline to a point on the outside edge of the ship. Underwater Archaeologists take many measurements of the outside edges of a shipwreck, so that they know how large it was and if artifacts are inside or outside of the shipwreck.
For offset measuring you are recording two measurements for each point. A point could be an artifact or a point on the exterior of the vessel. Some artifacts might be big enough that you want to measure more than one points.
You will record the measurement from zero along the baseline and you will record the distance of the artifact from the baseline. The measuring tape should be at a perfect right (or 90 degree) angle from the baseline or your measurement won’t be accurate.
The second method for measuring a shipwreck is more common and more accurate. For this method you are taking two sets of measurements from the baseline to create a triangle. The baseline is one side of your triangle and when you measure the other two sides, you can recreate the triangle and they will always meet in the same place.
Step 1: For the first step, you will choose a point on the baseline that, when connected to the artifact, would make one side of a triangle. You will record the measurement from zero along the baseline and then record the measurement from the baseline to the artifact. Because the anchor is large, we picked a point in the middle. Be sure the measure to the same point both times.
Step 2: For the second set of measurements, pick a new point on the baseline, that when connected to the artifact would create the other side of the triangle. You will record the measurement from zero along the baseline and then record the measurement from the baseline to the artifact. Make sure to measure back to the same point you used for the first set of measurements.
You can continue to take measurements for all of your artifacts if you would like. Divers usually only take a few measurements during a single dive, because they have to be careful about not diving for too long. Measuring a whole shipwreck takes a lot of dives!
A site plan is a scale drawing of a shipwreck. A scale drawing uses the original measurements and converts them into smaller measurements, so an accurate drawing can be made, just in a smaller size. The site plan of the Anthony Wayne, shown above had a scale key, so that anyone reading it could figure out the original sizes.
For the examples, we used a scale of 1/2 inch = 1 foot. That means, if an original measurement was 5 feet, we would draw it at 2 1/2 inches. If the original was 10 feet, we would draw 5 inches. There is a drawing page included in the handout available above, but you can also use blank paper.
Supplies for Drawing
- A pencil
- You will be erasing some of your marks on the final drawing.
- A pen
- For the marks you aren’t erasing, it is nice to use a pen or marker, because you can erase the pencil and these marks will stay.
- A ruler
- You can use a tape measurer, but a ruler is easier. If you don’t have any measuring tools, you could measure using the width of your index finer or thumb (use the same finger each time).
- A compass
- A compass is really helpful for drawing your triangulation measurements. If you don’t have one, you can tie two pencils together using a piece of string. Make sure you have a longer piece of string, so that you can re-tie the pencils for each measurement.
Now we are going to draw the measurements from our earlier examples in a smaller scale. In the example here, we measured 2.25 inches from zero on the baseline and then, holding the ruler at a right angle from the baseline, measured 2 inches up to find Point B. If we measure multiple points along the outside edge of the shipwreck, we can then draw a line through those points to show the outline of the shipwreck.
Triangulation sketching is a little more complicated. For this method, you use the compass. We already drew the outlines of the shipwreck and now we want to draw in the location of the anchor.
Step 1: For the first set of measurements, we measured along the baseline from zero 2.5 inches. We then set the compass points 2.75 inches apart. The point of the compass should be on the baseline and then use the pencil to make a circle around the baseline point.
Step 2: For the second set of measurements, we measured 5 inches from zero along the baseline. We then set the compass points 3 inches apart. We placed the point of the compass on the baseline and drew a circle around that point.
The place where our two circles intersected is where the anchor was. We marked the point with an X in pen and then erased our pencil circles. We can sketch the anchor around that point. To be more precise we could measure multiple points on the anchor.
For your shipwreck, you can use these methods to create a site plan for your whole shipwreck! Have Fun!
When Underwater Archaeologists are finished measuring their shipwrecks, they leave everything where they found it. You should probably clean yours up.