Spars, Mast Hinge, Part 7: Gluing G-10 Step to Original Step

The new, G-10 mast step, glued, sanded, and painted
Having drilled all the necessary holes in the G-10 mast step and the mast hinge hardware for Oystercatcher, my Ericson 25, it was now time for me to glue the G-10 step to the original mast base/step.
I would use three, 1/4 inch wood screws in the original wood screw holes, and I would use one, 1/4 hex head bolt in the original 1/4 inch hole (although I would not use this bolt during this glue-up to hold the G-10 step in place).
On the boat, I tested the G-10 step for fit. All the holes lined up well with the original holes, and the centerline of the G-10 step lined up correctly with the centerline reference I had earlier marked on the deck.
I still needed to countersink the three holes for the 1/4 inch flat head wood screws.
This would allow me to set the heads of the screws slightly beneath the surface of the G-10.
Now I could do a full dry-fit of the hardware. I didn't want to find out at the last minute that the screws could not be fully seated into their positions.
This full dry fit was useful, for it did reveal that the 1/4 inch bolt could not be seated fully while the three wood screws were seated fully. Even though I would not use the bolt to secure the G-10 during the glue-up, I went ahead and cleaned up the hole at this time.
I hit the hole with my 1/4 inch bit. This did the trick.
Then it was time to make sure that the 1/2 inch hole for the centerboard line was as smooth as possible.
There could not be the slightest obstruction in this hole. Otherwise, the centerboard line would be impeded.
Before proceeding to the gluing of the G-10 step to the old mast base/step I took the time to make a shim for the old aluminum mast step. I had begun to wonder about the corrosion that would take place through longtime contact between the stainless steel hinge and the aluminum step.
This fiberglass was from the same piece that I had earlier used to create the shim for the anti-compression block.
The xylene removed the wax still present on the fiberglass from the boat mold during the time of manufacture in 1975.
I sanded it smooth so that it would be perfectly flat beneath the mast.
I then drilled the appropriate holes.
Finally, I sanded the edges so the piece would correspond exactly to the shape of the step.
Now I began to focus again on the old mast base/step. With that same quarter sheet sander loaded with 40 grit paper I had sanded away all of the gel coat from the top of the old base/step.
I had also taped the work area with Gorilla brand white duct tape.This would prevent the epoxy from running out of the work area, and it would make it easy for me to get nice, clean lines from the fillet of epoxy that I planned to lay down along the edge of the G-10 step.
After cleaning everything well with epoxy, I did one more dry fit - this time to make sure that my tape lines were as accurate as possible.
Then I mixed up the epoxy and wet out the work area and the bottom side of the G-10 mast step with neat, i.e., unthickened, epoxy.
Then I thickened the epoxy to a peanut butter like consistency with colloidal silica. I built up as much epoxy as possible around the edges of the old mast base/step where there was the potential for gaps between the deck and the new G-10 step.
After I had screwed the three, 1/4 inch wood screws fully into place, I used the plastic stir stick to create a fillet all the way around the base of the G-10 step.
By this point in the refitting of Oystercatcher I had created many fillets. Otherwise, I don't believe that I would have created as nice a fillet as this one. They do take some practice.
A couple of evenings later, after the epoxy had cured, I returned to the boat to do some clean-up work on this job.
I began with a 50 grit sanding drum on the Dremel. This helped me bring greater uniformity to the curvature of the fillet all the way around the G-10 mast step.
I then installed a smaller version of the 50 grit sanding drum to work on the stubborn areas around the corners. In my experience, corners always present some problems when making a fillet.
Having completed the sanding, I now removed the tape. The lines were neat, but predictably there were some tiny ledges here and there that had been created due to the thick edge of the duct tape itself.
These ledges I removed with chisels.
I ended up having to create a special notch in the fillet in the vicinity of the through-hull for the mast wires and VHF coaxial cable. Notice that I had previously dug out the plywood core around the perimeter of the hole and filled the void with thickened epoxy. I learned of this approach to routing the wires and coaxial cable from Tim Lackey, a link to whose website concerning his refitting of Glissando is on the homepage of this blog.

Persistence with the chisel eventually led to clean lines that led directly (or almost directly) to the deck without any ledges.

While I was at it, I removed the excess cured epoxy from my earlier filling of the holes for the cable clam for the mast grounding cable. The plywood around these holes I had also dug out and filled with thickened epoxy.

In preparation for the painting of the G-10 mast step, I re-taped the perimeter with Gorilla brand white duct tape. Around the white duct tape I laid down blue paint masking tape as an added precaution.
I also plugged the 5/16 inch holes with wads of blue masking tape. I wouldn't allow any paint to get down there and foul the threads. These were the holes, of course, where I would soon mount the halyard organizer plate, the bottom plate of the mast hinge, and the anti-compression block.
Prior to mixing up the paint, I wiped down all surfaces with the appropriate thinner for this paint.
I likewise wiped down the anti-compression block, since it too would be receiving paint.
I've written many times about Pitthane two-part polyurethane paint by Pittsburgh Paints, so I will not belabor the point here. If you're interested in reading more about this paint, then refer to the Labels section on the homepage of this blog. That will take you to other articles I've written on the subject.

The first coat went on well.

A day or two later I came back and roughed up all the surfaces with 150 grit paper. This would help the second coat to adhere by providing it with some "tooth," as it is called.
Time for the second coat.

A day or two later I came back and removed all of the tape. Not bad, but it could look better. That's what I thought.
I didn't like it that there were still tiny ledges here and there around the joint between the fillet and the deck.
Therefore, I bought a tube of NP1 Sonolastic polyurethane caulk from the local hardware store. This is the good stuff, and it's less than half the price of "marine" polyurethanes such as 3M 5200 and Sikaflex. I had some other joints to fill on the interior of the boat at this time, so this tube did not go to waste. I've said many times that in this lengthy refitting I never worked on just one project at a time. There were always multiple projects, often overlapping or interrelated.
A bead of NP1 gave this job a nice, professional, finished look.
This ends this posting on how I glued the new G-10 mast step to the original mast base/step on Oystercatcher, my Ericson 25.

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