Fig. 1. Custom mount for trolling motor for a SUPER SPORT 15
Background Info and Lessons Learned
My goal was to fabricate a bow-mounted electric trolling motor mount for my latest Whaler, a 1988 Super Sport 15, which could be easily be installed and removed from the boat in seconds without the need for tools. I also did not not want to make any holes within the hull to secure the mount. This would ensure an unmodified hull appearance whenever the mount was removed to utilize the boat for activities other than fishing. As such, the mount was designed not to utilize fasteners to secure it to the hull. Instead, the mount utilizes the lip of the bow, the bow norman pin, and a sliding key to secure the mount to the hull. This is the third such mount which I have produced since the early 1990’s, the first being for a 1970 Sport that I owned at that time. The details of the second mount (for an '87 Super Sport 13), including tracings, was documented within the thread found here: https://continuouswave.com/forum/viewtopic.php?f=6&t=5156&#p34588.
The mount for the Super Sport 15 was produced from 3/4-inch KING StarBoard rather than marine plywood and was assembled with stainless steel machine screws. The mount installs over the lip of the bow, over the bow light, and the rotates downward over the bow norman pin. The mount is designed with internal runners which permit a KING StarBoard key to slide into the mount beneath the bow norman pin. The key is locked into place with a pair of stainless steel turn-buttons. As part of a modular design approach, a Minn Kota Quick Release Trolling Motor Mount was installed atop my fabricated mount. As the electric trolling motor is fairly heavy, this modular approach permits the electric trolling motor to be mounted after my fabricated mount has been mounted onto the boat.
Mount Construction, General Hints
- Consider using KING Starboard or marine-grade 3/4-inch plywood rather than standard grade plywood. Use of KING StarBoard eliminates maintenance and may minimize the possibility of abrasion of the hull surfaces in contact with the mount. While more expensive than standard grade plywood, marine grade plywood has the advantage of durability, additional layers, no voids, uniform strength, and quality finishing.
- KING StarBoard may be easily cut with a table saw, band saw, router, hand saw, and a file. Reciprocating saws may cause the material to heat up and bind the saw. If using a handheld electric jigsaw, the latter may be reduced by frequently quenching the blade in a cup of water. I recommend performing as many cuts as possible with a table saw.
- Consider creating a mockup with scrap or lower cost material before committing to final materials.
- Consider creating a template for the sides from a piece of material which may be easily filed or sanded (ex. Masonite, etc.). Using the template which I have provided as a starting point and then make the necessary modifications to fit your boat.
- Dry fit mount before committing to drilling for final fastening of cleats and runners. To facilitate this end, I used a brad nailer and stainless steel brads to temporarily fasten the cleats and runners to the plywood. Should they later need to be removed, then they may simply be pried from the mater or clipped off and hammered flush. When final positioning of these items has been determined, then holes and countersinks may be drilled to permit fasteners to be installed.
- For fastening, I recommend use of wood glue (for mounts constructed of wood) followed by stainless steel machine screws, washers, and nylox nuts. Stainless steel fasteners may be economically purchased in bulk from online sources such as the Bolt Depot.
- Repeated assembly and disassembly of the stainless fasteners may cause galling of the fasteners, requiring that they be cut off to be removed. To prevent galling of the stainless steel fasteners, consider using mild steel fasteners until final assembly. Never use power tools in conjunction with the stainless steel fasteners.
- For mounts constructed from wood, protect the mount with quality sealer / finish. I used several coats of Petit 1015 Captains Varnish.
Seafoam King Starboard Plastic Sheets:
- 2 pc. 20 1/8" x 8 1/4" x ¾” – Raw Cut, No Radius (One piece used for top; one piece ripped to produce 2 pc. ¾” x 1 ½” strips top side wall cleats; remainder of material ripped into ¾” x ¾” strips for cleats, and key runners)
- 1 pc. 8 1/4" x 7" x ¾” – Raw Cut, No Radius (Bow Face)
- 1 pc. 8 3/4" x 8 1/4" x ¾” – Raw Cut, No Radius (Locking Key)
- 2 pc. 18 5/8" x 10 5/16" x ¾” – Raw Cut, No Radius (Sides)
- 1 pc. 10 3/8" x 8 1/4" x ¾” – Raw Cut, No Radius (Upper and lower aft face pieces)
- 45 pc. 1/4"-20 x 2" Stainless Steel Phillips Flat Head Machine Screws
- 8 pc. 1/4"-20 x 3" Stainless Steel Phillips Flat Head Machine Screws
- 53 pc. 1/4"-20 Stainless Steel Nylox Nuts
- 53 pc. 1/4" Stainless Steel Washers
- 2 pc. Stainless Steel Single Wing Turnbuttons
Electric trolling motors are expensive. To protect against accidental loss, you may want to consider utilizing a tether. When the trolling motor is installed on the boat, one end of the tether may be connected to the Minn Kota quick release mount and the other end of the tether may be secured to the bow eye nut (located inside the hull, aft of the norman pin).
Should anyone be interested in fabricating a copy of this mount, then please note that I will adding PDF files of measured tracings of this mount to a later post within this thread.
Fig. 2. The first step of the fabrication process is to produce a poster board template of the hull's profile which the mount will come into contact with.
Fig. 3. A mockup of the mount is then produced from masonite and 3/4-inch plywood scrap. The sides (two pieces of masonite which had been tacked together) are tested for fit. The height of the mount is based on providing clearance for the combined sidelights navigation lamp. The inside width of the mount is determined by the wider of the combined sidelights lamp and the length of the bow norman pin. The upper surface of the mount should be leveled fore-and-aft to match the benches.
Fig. 4. The mockup with the aft side open. The upper runners and the key are visible. Note how the key slides beneath the bow norman pin to hold the mount in place. Note the slots within the runners to permit the norman pin to pass through.
Installation of the locking key runners
- 1. From 3/4 x 3/4-inch material create four locking key runners whose lengths will determined by the distance from the rear of the mount to the angle.
2. With the aft faces of the mount not yet attached, position the mount in place over the bow norman pin.
3. Insert a loosened combination square beneath the norman pin on and against the rear edge of one of the mount’s sides.
4. Draw out the square’s ruler until it just clears the norman pin and note this measurement (Note the application of light colored masking tape the inside of the mount to improve visibility of pencil marks). This measurement will mark the rearmost edge of material which must be removed from that side’s runners to permit the mount to pass over the norman pin.
5. Repeat steps 3-4 for the opposite side.
6. Insert a combination square beneath the norman pin on and against the rear edge of one of the mount’s sides.
7. Raise the adjustable square until it makes contact with the norman pin.
8. Mark the inside of the mount’s side to denote where the lower edge of that side’s upper runner will be installed.
9. Repeat steps 6-8 for the mount’s opposite side.
10. Remove the mount from the boat.
11. Reposition the square at one of the marks made and extend the line fully forward.
12. Repeat step 11 for the opposite side.
13. Unbolt the sides from the mount.
14. Position the bottom edge of a upper runner on one of the lines.
15. Use a brad nailer to tack the upper runner onto the mount’s side (this will be a temporary fasten).
16. Repeat steps 14-15 for the opposite side.
17. Place the locking key against the bottom edge of the upper runner on one of the mount’s sides.
18. While holding the locking key in place, position a lower runner onto the mount’s side and pressed against the locking key (remember that the key must be able to slide, recommend using a piece of thin cardboard (ex. Posterboard, notepad backer, thin washers, etc.) between the key and the lower runner to create consistent clearance).
19. Use a brad nailer to tack the lower runner onto the mount’s side (this will be a temporary fastening).
20. Remove the locking key.
21. Mark the position of the upper edge of the lower runner onto the mount’s side.
22. Repeat steps 18-21 for the opposite side.
23. Mark the sides of the mount where both upper and lower surfaces of each runner contact the mount’s sides.
24. Mark any excess length for each runner.
25. Mark the upper and lower runners for each side with measurements obtained in steps 3-4.
26. Measure and mark 1-3/4” forward from the marks in step
27. Label the runners so that they may be repositioned exactly in their current positions.
28. Remove the runners from the sides.
29. On a table saw using either a dado blade (alternatively perform multiple passes with a single blade), create a notch which is approximately 0.6” deep between the lines created in steps 26. Note: as the marks created in step 25 represent the aft most face of the norman pin when the mount is fully installed, it will likely be necessary to widen the in the direction toward the rear of the mount to permit the mount to be rotated over the norman pin. In the case of my mount, the lower runner dado cut removed material between 3.9" - 5.66" measured from the runner's aft end. The upper runner dado cut removed material between 4.3" - 5.66" measured from the runner's aft end.
30. Cut off any excess length from the runners using the marks created in step 24.
31. Once again use a brad nailer tack the runners onto the mount’s sides in their original positions.
32. Reassemble the mount’s sides to the mount.
33. Verify that the mount can be installed over the norman pin. If not the dado will need to be either lengthened and/or depth increased based upon where the runners are contacting the norman pin.
34. Verify that the locking key can be inserted between the runners and beneath the norman pin. If not, adjust to accommodate your own hull's specific details.
35. Once tweaks have been made to permit steps 34 and 35 to be achieved, then the exact dimensions of the mount’s two aft piece forming the open for the locking may be determined from the locations of the runners.
36. Disassemble the sides from the mount.
37. Drill through the runners and sides to accommodate machine screws to fasten the runners to the sides.
38. Countersink outer side of plywood to accommodate machine screw heads.
39. Secure runners to mount’s sides with machine screws.
40. Install mount’s two aft pieces of plywood.
41. Once again verify that the mount will install over the boat’s norman pin and that the plywood locking key can be inserted.
42. Disassemble the mount, and perform final reassembly with machine screws.
Fig. 5. The finished mockup for my 1988 Super Sport 15.
Fig. 6. The mockup now partially disassembled to serve as a template for the final mount. I used 3/4-inch KING StarBoard for the this mount as it will result in a maintenance-free mount and will reduce the potential for hull abrasion caused by mount. The KING StarBoard was covered with blue masking tape to protect its surface and to permit layout lines to be clearly visible when cutting and drilling.
Fig. 7. Checking the partially constructed mount for fit.
Fig. 8. Once in place, lines were marked for the location of the upper runners for the key as well as for the slots within the runners to permit the norman pin to pass through them.
Fig. 9.The underside of the mount showing the runners for the key.
Fig. 10. The mount is designed to grab the lip of the bow forward of the navigation light, rotate over the navigation light, and then over the norman pin must pass through the notches within the runner for the key. Note the relatively tight tolerances between the base of the navigation light and the internal sides of the mount. Similarly, the width between the notches is only slightly larger than the width of the norman pin. These tight tolerances are designed to minimize the lash within the mount when fully installed.
Fig. 11. The norman pin must pass through the notches within the runners for the key. As shown within this photo, the mount must rotate a bit further until the lower surfaces of the norman pin are above or at the same plane as the upper key runner's lower surface. The width between the notches is only slightly larger than the width of the norman pin. These tight tolerances are designed to minimize the lash within the mount when fully installed. This photo was taken through the slot for key.
Fig. 12. The norman pin must pass through the notches within the runners for the key. As shown within this photo, the lower surfaces of the norman pin are above or at the same plane as the upper key runner's lower surface, permitting the key to be inserted. The width between the notches is only slightly larger than the width of the norman pin. These tight tolerances are designed to minimize the lash within the mount when fully installed. This photo was taken through the slot for key.
Fig. 13. Completed mount positioned on boat.
Fig. 14. Mount in position and is ready for the key to be fully inserted.
Fig. 15. Key fully inserted and locked into place with stainless steel turn buttons.
Fig. 16. The electric trolling motor locked to the Minn Kota Quick Release Mount.
Fig. 17. The trolling motor deployed.
I'm very satisfied with the way that the mount turned out and I can't wait to fish with the new boat.
Details concerning the rail modifications, pedestal seat, and other modifications to better support fishing may once again be found within the thread at:
I plan to post a thread addressing the restoration and modifications of my 1988 Super Sport 15.