Electrical, Grounding Bar, Copper, Part 3: Installation

The copper grounding bar, installed
Having constructed and dry-fit the grounding bar for Oystercatcher, my Ericson 25, it was now time for me to permanently install it to the hull. Of all the tasks involved in this project, this one was the easiest to complete. It did, however, require a second set of hands, so I delayed this part of the project (and several unrelated projects) until a good buddy from out of town was around for a visit.

We began by countersinking all of the holes. We did this so that the adhesive/sealant would form a gasket of sorts between the copper bar and the hull.
Here's how the aft-most holes looked before we countersunk them.
Here they are afterwards. Big difference, right? The outlier hole is where the original bronze grounding bolt was located. I would later grind out this hole and fill it with epoxy and cloth.
After countersinking all of the holes, we lined up all the new bronze bolts, fore to aft, so that we could easily access them when the time came to install them. Pay no attention to the outlier. That's the original 1/2 bronze grounding bolt. I just put it in this picture for the sake of comparison. All the other bolts are 3/8 inch silicon bronze from Top Notch Fasteners in Minnesota. Notice that the bolt on the far right (which is the aft-most bolt), has extra hardware on it. You'll recall that this bolt, which is longer than all the others, would serve as the new central grounding point. All the lugs from the grounding cables would be secured to this bolt. Notice also that the next bolt is shorter than all the others. I had earlier cut this bolt with a hacksaw to make it fit within a shallow area in the bilge.
You'll remember from the previous posting that I had determined that the copper bar, at five feet in length, was too long for this boat. Four feet, as I had earlier determined, was the more appropriate length. Now it was time to remove that excess one foot of copper. I began by scoring the bar with a chisel.
I then used a hacksaw to make the cut.
Part of the way through the cut, I switched to my other hacksaw. The new blade made a big difference and made quick work of this little job.
A file helped to take down the rough edges.
A Dremel, with a 50 grit sanding drum attached, was also helpful, especially for removing the burrs around the holes that I had earlier drilled in the copper. As you see in the picture below, I also made use of a bronze brush.
Prior to the installation of the bar, I made sure to clean it thoroughly with acetone, so as to remove any contaminants on the surface that might hinder the sealant/adhesive.
My buddy and I also performed another dry-fit. I was somewhat concerned about the length of the bolts, and I wanted to make sure that they would not interfere with the storage shelf that I planned to install on top of the cleats which you see pictured to the right.
In this dry-fit, we also wanted to see what gaps might exist between the copper bar and the hull. This would determine the amount of adhesive/sealant we used. Despite the curvature of the hull, it was not difficult to make the copper bar conform to the shape. Nevertheless, narrow gaps, perhaps 1/32 to 1/16 of an inch, existed here and there.
In addition to cleaning the copper bar with acetone, we cleaned all of the bronze hardware.
We also decided that it would be a good idea to shorten the screws that would protrude into the aft locker of the V-berth. We had determined that they would not interfere with the storage shelf. Nevertheless, we didn't want an extra inch worth of bronze sticking up from the hull. The closer to the hull the better. That way, there would be less leverage on this bolt, if anyone or anything should ever accidentally hit it.
The bolts cleaned up well and presented no problems in terms of threading the nuts.
When everything was lined up, cleaned up, and ready to go, we broke out the Sikaflex-291 LOT adhesive/sealant. This is the same polyurethane adhesive/sealant that I had used for the installation of the new through-hulls and flanges. I avoided more tenacious polyurethanes such as 3M 5200 and 4200, because I wanted to be able to remove this copper bar, if necessary. I should note that the letters LOT in the product designation stand for Long Open Time. Having this long open time was helpful, since this installation was more time consuming than one would assume it to be.
In retrospect, we could have gotten away with using a good bit less Sikaflex. Given, however, that there were known gaps here and there, we over-applied this product, simply because it would be very difficult to fill any of these gaps after we had already begun to bolt the bar to the hull. We needed to have that adhesive/sealant in place from the very start.
We also coated each of the bolts with Sikaflex in advance. This is the same thing we had done when we installed the bronze bolts for the through-hulls. Hats off to Maine Sail for this advice. See the Compass Marine link on the homepage of this Ericson 25 website for more details.
When we first got the bar loosely bolted into place, there was some concern that we had not applied enough Sikaflex in advance, as there were numerous gaps here and there in the bead that was being pushed forth between the bar and the hull.
When, however, we tightened the nuts, a nice, full bead began to be extruded.
Eventually, there was so much Sikaflex along the edges of the bar that I found it necessary to remove much of the excess.
Using the plastic stir-stick, that I normally used for epoxy, I created a fillet, not unlike the fillet I had created for other projects with epoxy.
This filleting process created something of a mess.
Paint thinner, i.e., mineral spirits, is the recommended solvent for the clean-up of Sikaflex.
The key to success when using this solvent with Sikaflex is speed. Despite the fact that this was the LOT version of Sikaflex, it nevertheless began to skin-over quite quickly. This was my experience with Sikaflex 291-LOT on the through-hull project, and it was my experience with it on subsequent projects. Once it begins to skin-over and thus begins to cure, it is not easy to remove, even with vigorous wiping.
Fortunately, I worked quickly enough to remove everything that I wanted to remove. Some might wonder why I did not remove more of the Sikaflex. In other words, some might wonder why I created the fillet in the first place. My thinking was this - I wanted to minimize the chances that water might find its way between the copper and the hull. I was not worried about water entering the bolt holes. I was, though, concerned that if water were allowed to reside in any small gaps between the bar and the hull, then blistering might eventually occur, or at a minimum, the growth of marine organisms might take place (once the ablative bottom paint had become ineffective). Yes, lightning is said to dissipate most readily along the edges of a bar. I did, however, leave the edges of the bar exposed. I doubt that those parts of the sides of the bar that are covered by the fillet of Sikaflex would prevent any hindrance to the lighting seeking ground.
Back inside the boat, I used the minerals spirits to clean up the excess Sikaflex from the bronze bolts.
It was nice to see, at last, these bolts permanently mounted in place. Note how close to the hull these bronze bolts are, now that I had cut them down to their smaller size.
The completed installation.
When all was said and done, we didn't neglect to throw a few burgers on the grill and pop a few cold ones. Not a bad way to end this part of the project.
This completes this posting on how I installed the copper grounding bar in Oystercatcher, my Ericson 25. In the last posting of this four-part article, I describe the steps I took to fill the hole for the old bronze grounding bolt with epoxy and cloth.

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