I recently pulled my great uncle’s MRC Explorer out of the woods. It’s a long story, but this canoe sat in the woods for some 15 years. All the wood has rotted off, but the hull has held its shape, so I figured I’d try to get it back into the water. I’ve filled in any gashes or scrapes that had gotten down to the ABS layer using PC-11 epoxy. I’m repairing cold cracks with G Flex. A mill shop in town is making new ash gunwales for me, and I’ve got seats and a yoke coming to me in the mail. What I need now is measurements. The original wood rotted off years ago, so I don’t have any good reference for hardware placement. I need to know how long to cut the yoke and seats. MRC has a general Explorer schematic, but it doesn’t seem to specify how wide the yoke or seats should be cut. I’ve got a handwritten serial number on the hull: MADA6783M79H. Is there someone on the boards here who knows this model, and who can help me nail this project?
When you get that info, just remember that the seats do virtually nothing to control the distance between the gunwales, since any lateral force applied at the right-angle connection between the seat frame and the hanger will simply cause that joint to flex (that will simultaneously be true for the connection between the hanger and the gunwale). Find out how long the thwarts should be, and exactly where they should go, and then once they are installed, cut your seats to fit the space that is available at the locations where you want the seats to go. Also consider that sometimes the contour of the sides of the hull will necessitate making the seat width a bit less than the distance between the gunwales would suggest, so that the 90-degree joint of the seat frame to the hanger is actually “more open” than 90 degrees.
Is it a 16" Royalex Explorer or a 17’ 2" Explorer? The 16’ boat was much more common and MRC outfitted it with a single center thwart/yoke. The longer Explorer had a second thwart between center and the stern paddling station.
The hulls are symmetrical so there should be no confusion regarding where to position the center yoke. Put it at the longitudinal center of the canoe. MRC specified a gunwale width of 35" for the 16’ Explorer (37" for the 17’ Explorer) and they usually measured that at the outside edge of the molded hull, which did not include the width of the outwales. Many or most Royalex hulls will tend to collapse inward somewhat without gunwales and thwarts.
Simply mark the center of your hull on both sides. It is best to do this by attaching a string at the stem on one end and swinging the string in an arc to both sides of the hull. Then attach the same string to the opposite stem to confirm that your marks on the hull are equidistant from both ends. Get a stick about a yard long and cut it to an appropriate length so that you can use it to “jack out” the hull so that the width at center at the outside edge of the molded hull is 35". Now measure from the inside of the hull center at one side to the other. You will cut your center thwart so that it is slightly shorter than this length so it is not pressing against the sides of the hull when installed. Pay attention to the contour of the inside of the hull when you take this measurement. If the hull is flaring out or inward to any extent, you might want to cut the ends of your thwart/yoke at some angle other than plumb.
When you install your gunwales, have the hull jacked out to width. Otherwise the wood and the hull will be stressed against the wood screws after you install the yoke.
In addition to a center yoke, MRC used short carry handles near each deck plate. The exact placement of these is not critical. Just position them symmetrically at each end, far enough from the deck plates that you can comfortably get your hand between the plate and the carry handle.
Positioning the seats allows you some latitude and you do not need to put them in the exact position that MRC did. I would first determine where you want to place the bow seat. This will usually be determined by how much leg room the bow paddler will require. The seat must be placed far enough aft to that the bow paddler legs are not uncomfortably jammed up against the front of the hull are jammed to close together in the narrow of the stem.
Once you have the position of the bow seat determined, you can position the stern seat. I usually figure that the center of gravity for a seated paddler is going to be about 1 1/2" forward of the front edge of the front of the seat frame. If you want the canoe neutrally trimmed for paddlers of about the same weight, mark that position (1 1/2" forward of the seat frame) and measure how far it is from the center of your center yoke. Now measure the same distance in back of the center of your center thwart. Mark that position and mount your rear seat so that the front of the seat frame is an inch and a half rearward.
Many folks like to trim their canoes slightly bow light and I have found that many stock canoes are outfitted in that way so you can adjust this to suit your preferences.