Reworking the Cockpit

After taking a week off recovering from the Sound Rowers La Conner race, which I participated in my Escapade pedal boat (see http://soundrowers.org) and took photos of the event for the club, it was time to return to work.

The next stage in the building process is to put together the cockpit.

To do this, the following steps need to be taken:
1. Design the mount for the gearbox.
2. Modify the torque box to accommodate the gearbox and mount.
3. Clean up the edges of the torque box panels and underseat panels so they mate properly.
4. Add stringers to the rear hull to spread the sides to fit the rear deck.

Step 1: Design the mount for the gearbox
I had a number of grandiose ideas for how to mount the gearbox and make it adjustable. Some of these designs would require TIG welding, which is fine with me as I happen to do that as a hobby. On the other hand, if I could do this using off the shelf bits and pieces, then so much the better for anyone else who wants to do this on their own.

The design I ended up with is to use to simply use two flat panels of 1/8 inch thick aluminum that are bolted to either side of the torque box, with a series of 1/4" holes along the top edges in each panel. The gearbox is then bolted to a pair of right angle aluminum stock that extends an inch beyond the front and rear ends of the gearbox. Holes drilled in the extended section are aligned with the series of holes in the plates previously mentioned, and bolts are passed through securing the front and rear of the gearbox. Wing nuts or nylok nuts are used to hold the bolts in place.

Optionally, four very short bolts could be used if the two long bolts prove to be too loose in practice.

The weight of the gearbox is resting on the angle aluminum stock against the top of the torque box.

I'll take photos of this set up after I fabricate it.

Step 2: Modify the torque box to accommodate the gearbox and mount




Ok, now that the gearbox mount is designed, what modifications are needed to the cockpit to get it to align with the stuffing box?

As it turns out, the Involute gearbox is a pretty big beast. Measuring from where the seat back would be (2.85 meters, or 9 feet 4.20 inches from the stern) to where the center of the crank spindle is located (approximately 37 inches for my legs), the rear edge of the gearbox would be nearly an inch below the top of the torque box. Also, the stuffing box is too short for the top panel of the torque box.

The solution I chose was to trim about an inch from the torque box side panels starting just in front of the seat bottom, continue forward for about a foot, and then taper back to the original top edge at an angle parallel to the stuffing box. This would provide for a length of several inches longer than the Involute gearbox and allow it to be adjusted for shorter and longer legs.

I would have preferred to have left the gearbox up higher as this would have allowed for more heel clearance and possibly the use of standard length crank arms. Unfortunately, however, this would have caused the stuffing box to have emerged from the seat bottom rather than just below the seat bottom. The angle of the propeller shaft would have increased a bit, too, causing a bit more stress on the shaft.

After taking numerous measurements while seated in my Escapade, I decided that using shorter crank arms as on the Cadence would give me just enough clearance under normal circumstances. The stuffing box will stay at the original design angle.


By making the transitions gentle enough it was possible to bend a single piece of wood to comprise the top panel, simplifying construction and making for a nicer appearance.

The original top panel, though long enough to reach from the front bulkhead to the stuffing box panel, could not be used as it had a long oval hole cut in it for the stuffing box to emerge. So, using some of the scrap wood that was delivered along with the original panels, and the original top panel as a template, I cut a new torque box top panel.




While doing measurements and trial fits I noticed that the torque box side panels had a tendency to not want to stand perpendicular to the deck. This would only get worse when it was time to glue them, so I cut some foam bulkheads for under the seat and under the gearbox area. An additional piece of foam was positioned just under the top panel so the bolts securing the aluminum side panels for the gearbox mount would pass through it. This would help to keep the torque box from deforming under the pressure of the bolts and to help keep water out of the torque box.

Step 3. Clean up the edges of the torque box panels and underseat panels so they mate properly.

A small rectangular piece of wood was cut and drilled for the stuffing box panel mount. The sides were beveled to mate with the beveled edges of the torque box at the front of the seat bottom.

The rear end of the top panel of the torque box was notched at the corners so that it extended under the stuffing box panel mount by about 1/4 inch. I used a band saw to cut the notches and a flat file to adjust them to fit.

The two small, roughly diamond shaped panels were also beveled with a sanding block to fit on either side of the seat bottom.

The sides of the hull needed some filing in the area where the fillet material was present, and beveling with a sanding block to make a nice fit.

The front edges of the sides of the torque box also needed some touch up with the block sanded to get them to fit snugly against the front cockpit panel.

Step 4. Add stringers to the rear hull to spread the sides to fit the rear deck.

Since I plan to put the rear deck in place right after the cockpit is completed I double checked the fit of the sides of the hull with the deck. Near the stern I found that the hull was not spread apart enough at the deck, so I added a couple of small pieces of foam to spread the sides. This was also necessary near the seat back, as the sides had a tendency to push inwards.

I think that when the rear deck is glued in place I will use half a dozen or so clamps across the top. This is needed to make sure that the hull stays straight relative to the deck. However, in order to make sure the clamps don't inadvertently squeeze sides rather than align the deck with the sides, I'll use more right angle aluminum pieces inside the clamps. The pieces will be covered with shrink wrap plastic so they don't become a permanent part of the boat.