Building a hardtop - fairing (part 3)

Once all the fibreglassing for both pieces was completed it was time to start working on preparing for fairing and primer painting.

The goal was to try taking advantage of not having joined the two pieces just yet to advance the first and second round of fairing because it would be easier to work with just half the area instead of the full piece.

The first step on this task was to apply a primer on both topsides, then the fairing compound to the low lying areas followed by sanding to level and then move on to the painting preparation tasks.

As part of the fairing process, we decided to apply an epoxy sealer to further protect the structure from any eventual water damage, a bit of overkill.

We were familiar with the International products and were comfortable using the Interprotect Primer it is quick-drying and leaves a satin finish that should be easy to sand before the next coats of fairing and paint.

We used a short nap mow hair roller for application, but to tell the truth, we had problems with this product. Maybe because the paint we were supplied with was old and coupled with changing weather that brought us lower temperatures the dry time took a lot longer than we had anticipated before we could sand, we found the paint was sticking to the sandpaper and binding it up making the process very long.

To avoid further delays we had to juggle working on both pieces at the same time, something that proved slightly challenging given we were working on our foredeck while at anchor!

After having such a good experience with the Moravia Epoxy (a Lloyds approved product) on the previous stage of construction we decided to use one of their fairing compound products called Mastofill.

We found Moravia’s Epoxy Filler Mastofill to be a very good product, but again due to the falling temperatures brought by the changing season the dry times were much longer than expected, in fact double.

The technique of applying the Mastofill was to use a long wide metal trowel and lay it flat level to the work and at a 20-degree angle and pull the product in a levelling motion. We followed the application by sanding to level as needed with longboards and an orbital sander. Followed up by filling any obvious low spots with more of the same product and repeating the process until we were happy by eye. We could have added a further process by dusting a dark colour then longboard sanding to find further lows but this overall process was very tedious and time-consuming so we skipped that step, we don’t believe this was a detriment to the finish.

Overall, this part of the project progressed a lot slower than we had anticipated.

The curing times for each product turned out not to be clear on the specs, resulting in quite a few days of idle. Given that we were working on the foredeck with the two pieces simultaneously we were limited on the tricks we could pull to change work from one piece to the other or from one side to the other.

It took us two rounds of the fairing and sanding on the two pieces topsides to achieve a level we were happy with and whilst in part small areas of the primer were sanded off in this stage of the fairing process we still expect a good level of protection.

After joining the two pieces we would need to repeat this entire process so we didn’t worry too much at this point.

On the undersides, we chose to only do the epoxy primer and fairing at the lip edge area, since these will be the only areas that might be exposed to the elements similar to the topsides. The reason for this decision will be obvious at a later stage.

We were now ready to proceed with the slightly overwhelming process of joining the two pieces into one.

Stage 3 - Fairing period daily work summary/description:

Day 21 (2021-11-04)

Removed the peel ply from the port side piece except for the edge that will be the centre of the Bimini once the two pieces are joined and the big window area. Identified the areas that needed to be repaired/treated such as low spots and a few areas that the peel ply didn’t adhere fully so required some sanding and epoxy filling of those low spots. Prepare for epoxy primer.

Day 22 (2021-11-05)

Applied the epoxy primer from International paints and waited and waited...

Day 23 (2021-11-06)

After waiting nearly 24h the epoxy primer still wasn’t fully dried so decided to waste no more time waiting and to move the portside piece to the front of the mast again to work on the starboard piece.

Removed peel ply from the starboard piece except for the edge that will be the centre of the Bimini once the two pieces are joined and the big window area. Identified the areas that needed to be repaired/treated such as low spots and a few areas that the peel ply didn’t adhere fully so required some sanding and epoxy filling of those low spots.

At the end of the day returned the port side piece on top of the starboard one in advance to the works the following day.

Day 24 (2021-11-07)

Slightly sanded the epoxy primer, washed off the debris and applied the Mastofill throughout the topside of the port side piece including the side edge.

Day 25 (2021-11-08)

Spent the entire day sanding the Mastofill (fairing compound), using the normal orbital sander and the air compressor orbital sander both with 80 Grit sandpaper, followed by hand sanding with 100 and 120 Grit, while vacuum cleaning at the same time. Making sure the dust and particles were not picked up by any breeze and ended up in the water.

Day 26 (2021-11-09)

Applied more fairing compound on areas that needed to be readdressed after the previous day sanding efforts. Allowed it to touch dry before moving the piece forward of the mast where it stayed drying until the following day.

This allowed us to keep working on the starboard piece. Applied a layer of epoxy primer and let it dry overnight.

Day 27 (2021-11-10)

Returned the port side piece on top of the starboard piece.

Sanded the second round of fairing on the topside of the port side piece, marked a few more small spots that will need a third round. Flipped the piece, removed the peel ply from the underside and started tackling the areas that needed to be sanded to remove excess epoxy or because they had issues that needed to be sorted.

Decided that only the edge would be filled with the fairing compound and up to where would the false ceiling come to.

Day 28 (2021-11-11)

Sanded the edge a bit more, masked with tape the areas to be worked on and applied the fairing compound to the whole edge and sides.

Day 29 (2021-11-12)

Sanded the entire edge and identified the areas that needed more work to be done. Applied some thickened epoxy in some areas that needed further reinforcement. Moved the port side piece forward of the mast again to allow us to work on the starboard piece.

Day 30 (2021-11-14)

Slightly sanded the epoxy primer, washed off the debris and applied the Mastofill throughout the topside of the starboard side piece including the side edge.

Day 31 (2021-11-15)

Spent the entire day sanding the Mastofill (fairing compound), using the normal orbital sander and the air compressor orbital sander both with 80 Grit sandpaper, followed by hand sanding with 100 and 120 grit, while vacuum cleaning at the same time. Making sure the dust and particles were not picked up by any breeze and ended up in the water.

Applied more fairing compound on areas that needed to be readdressed after the sanding efforts.

Day 32 (2021-11-16)

Flipped the piece, removed the peel ply from the underside and started tackling the areas that needed to be sanded to remove excess epoxy or because they had issues that needed to be sorted.

Applied fairing compound on the edge area up to where would the false ceiling come to. Also applied epoxy in a few areas that required filling.

Day 33 (2021-11-17)

Sanded the second round of fairing on the topside of the starboard piece, marked a few more small spots that will need a third round.

Reaching this milestone meant that it was now time to finally join the two pieces!

***You can find other posts of this series at Building a hardtop - the idea, concept and material choices (part 1) , Building a hardtop - the construction (part 2), Building a hardtop - joining the pieces and painting (part 4) , Building a hardtop - stainless steel works and installation of equipment (part 5) or Building a hardtop - costs, other numbers and conclusions (part 6)

***In the spirit of sharing our dreams and experiences we have shared this blog post in the NOFOREIGNLAND.COM website sailors community.