Friday, September 2, 2016

Walling By Number

Moving a stone building (or in this case a stone boat) stone by stone, is not something to be taken on lightly. The chances of having all the stones fit back together properly are slim. Once a couple stones get put in the wrong place, or worse, go missing, the whole integrity of the original structure is compromised. 

Below is the procedure we will be using to best tackle the moving of the Farley Mowat Boat Roofed House the week of our Canadian Thanksgiving here in Port Hope Ontario. 

I suspect accurately reproducing this dry stone structure at its new site near the Ganaraska River will be more difficult than building it the first time. Built ten years ago, both as as a tribute to our good friend the Canadian author Farley Mowat, and as a replication of an example of first millennia dry stone walling in Canada, the monument when moved to its new home, will get the recognition and acclaim it deserves. 

The datum line approach will be used for documenting the positions and order of the stones.  It is low tech and reasonably accurate. 

Heritage masonry professor John Scott, who will be working with us on the project, explains how we will go about it

"The boat runs north-south along Catherine Street, so we pick a distance, say ten feet to the east, and create a straight NS line. The line needs to be at the same elevation as the boat grade. This is our datum. We then divide the line into equal parts, say, two feet apart, then measure the distance from the line (at right angles) and record these distances.  At the new location we make a new datum line in the appropriate direction and establish the same distances along the same intervals. This will give the curve of the east side of the boat.  For the west side, from the same datum line we can measure a new twin line on the west side of the boat, say 20 feet from the datum.. this new line will be parallel to the first one. Then we divide this new line into similar equal parts and measure eastward to the boat.. this will give the location of the west curve.

To establish the actual location of each stone, we will use a the method of establishing a right angle from the datum at the bow of the boat, then measuring from this line to the right side of each major stone (because it’s a curve, this will be a sliding measure)… however, if we follow the footprint closely, the stones will tell us where they need to be!

The slope/batter of the ends should be recorded and recreated with a template attached to a long level in plumb position.

When we record each stone, we should take accurate photos that show the stonework clearly.  I like to make a drawing of the stone, however there is a neat software that makes this much easier.. designed by Bobby Watt’s excellent crew!  

Anyway, the drawing should show each stone.. because it is roughly coursed, I would start at the right side of the photo and number each with a code that makes sense, such as E-1-3 (for east wall, first course, third stone from the right).  For more random areas, use something like, E-1-3a, b, and c (to show that there are three rogue random stones in that area of the course, and you would refer to the drawing to sort out where they belong).  

Before we remove each stone, use an appropriate marker or paint to label each stone.. label the top of the stone such that you can read it if standing in front of it.. this way you can tell which way is up and left-right when it goes back together.  I like to take an extra step an mark the face of each stone with chalk before the dismantling begins.. just in case the stone collapses during the upper dismantling.. for example, when the boat is raised.  The chalk code also gives a confident certainty when labelling the tops during dismantle.  

Then the stones should be grouped together, for example, each course should be grouped in one skid or group of skids so they can easily be located during the rebuild. We would normally keep track of the elevation heights however as there is no mortar I suspect this will be less of an issue."