Rebuilds Repairs Scupper Drains

Repairing Westsail 32 Scupper Drains

I will start with a disclaimer. I live aboard Satori so when it comes to boat projects, I am able to peck away at a project for as long as I need. The scupper drains will take a long time, so you will either need long days, or to be close enough to the boat to spend short periods of time over the course of a single day during daylight hours. The cost for such a repair is only what you need in materials, but you may also need to purchase one or more power tools. You will need a marine supply store that can do a better job stocking fiberglass repair products than West Marine. You may want to consider purchasing some of these products online to save money. I suggest that you preorder what you need before starting in on the project. You will also need to source a 12″ x 2″ OD fiberglass tube to replace whatever was used on the initial install.  I just ordered mine from Bud Taplin of Some installations were originally bronze pipes, others were stainless pipe, and mine were PVC pipe that were mostly sealed to the hull. The entire project may take a month, depending on how often you’re able to tackle the work and the amount of daylight at the time. I took a few weeks on the first side, going slow to get it figured out without too many mistakes. It was my first time working with polyester laminate, and more extensive epoxy work than I had ever done. I also wanted to complete the project with a professional finish. Instead of finishing with gelcoat, I could have simply painted over any fiberglass or epoxy. I could have also plugged the holes with epoxy and called it good. I figured I would not only complete my first fiberglass project, but also figure out how to do a semi-professional job. I dug in and figured it out, and now it’s another skill I carry with me that I don’t have to pay someone to do. It only costs time and materials.


A primer on sanding

The first topic I want to cover is sanding, because it is where you’ll spend money on new toys unless you own these already. To get the detail needed with controlling your fiberglass surface, you will start with a variable speed orbital sander. It will fairly easily remove gelcoat, smooth a surface to prepare for final coat, and buff the gelcoat surface to a shine. It’s a very versatile tool, and something you absolutely need when working with bare fiberglass and gelcoat surfaces. The next level in detail can be achieved with a multi-tool. It has three pointed tips which will allow you to get into small spaces. You can control the speed just like the orbital sander, and even buy a cordless version to make it easier to use. Finally I suggest having a Dremel with the little drum sanding attachment. For very small detail and working an edge, this little guy cannot be beat. I also went with a cordless version, but unfortunately the battery life is pretty short. In hindsight I would have bought a corded version, but I’ve managed to make the cordless work on a number of big projects. For sandpaper you will need from 60 grit all the way to 1000 grit. You can make a few big leaps to limit the different grits you carry. I have 60, 100, 240, 400, 600, and 1000 for both the orbital sander, and the multi-tool. I would also suggest getting both a 3″ and 5″ hook and loop pad for the orbital sander so you have a versatile range of surfaces you can work with. For removing gelcoat you will use 60 grit most often. For preparing the surface for another layer or finishing, you will want to smooth to about 200 grit. For smoothing gelcoat for polishing, you will start with 200 grit to even the surface after painting, and work your way to polishing compound and a foam buffer. These tools are going to speed up your work considerably, and the different grit sanding pads are going to allow for a decent finish.


Start on the inside

You can begin by removing the original spun bronze pieces and bolts. Mine were just simple plates that were bedded with 4200. The bolts are what eventually caused the leaks. Over time the standing water corroded the bronze bolts, so I removed the bolts and plates, and was left with holes on both sides. After they were removed, I drilled out the holes to expose raw fiberglass, and then countersunk the hole a bit to allow the epoxy to have something to grip. This took about an hour max for each side. The next few hours was removing the adhesive sealant on the inside, which is only accessible through a locker. There is limited visibility on what you’re working on so you need to be creative and work patiently to get all of the sealant removed to expose the inside surface for new fiberglass. I did not remove the PVC since it was bedded pretty well already, so I added the fiberglass tube to the inside, and then built up the surface on the inside with epoxy and chopped strand mat (CSM). Epoxy has a much better adhesive quality than polyester resin, so it’s the preferred material for building a semi-structural layer against PVC. PVC does not bond very well to any adhesive, but if you give it a rough oxidized surface then epoxy has a much better chance of bonding. Spend hours chipping away at the adhesive in the locker. Take lots of breaks, use your smartphone to take photos of hard to reach places to see your progress. Remove anything that will impede in getting the job done quicker. Use whatever tool you can to assist in preparing the interior surfaces for epoxy. Once you have the surfaces prepped, start by filling the holes with epoxy. Put masking tape on the inside of the hull and use an epoxy thickener to keep the epoxy from running out of the hole. I am a fan of West System 105, 205, and 404 for epoxy work. I use a one time use syringe for filling the holes, because you can squeeze small amounts into the hole to make sure there are no air gaps. Once the holes are filled, use masking tape to cover the holes for curing. This will hold the thickened epoxy in place while it cures. Once you have the holes filled, you can start layering up the inside of the tube. If you had to remove the old tubes then here is where you would use a small amount of epoxy to set the tubes in place. I would still start with the inside and build up the corners with a combination of CSM and epoxy. It doesn’t take much. A quarter of an inch should be okay for the corners. The hull will flex, and you will want this part of the hull to flex as well. If done correctly, the fiberglass should be able to flex enough without cracking or breaking. Perhaps not. Time will tell. Once you are finished building the inside of the hull, you can work on the exterior.

Filling the drain pans

Westsail thought it would be an advantage to have a gap between the scupper drains and the drain pan. In case something small was washed or rolled into the pan you could still recover it. Seems like a good idea, right? Sure, if that area happened to be made water tight. Unfortunately it was not in their design, so ended up being a common leak point. I decided that a better feature would be to try to prevent any standing water at all, but still allow for adequate draining when a wave happens to come over the rail. Unfortunately the way Satori sits in the water, her bulwark gutters hold some water when she’s not sailing, and there is nothing I can do to prevent this without compromising the balance of the boat. Having so much standing water is not good for any boat. So in my case I decided to try to prevent as much as possible. To get both sides to drain evenly could be problematic, and probably not worth the effort. As long as water can quickly drain out of one pipe then you will have solved the problem. I cannot fix the bulwark gutters without having another major fiberglass project, but I can fix the drain pans so they have almost no standing water at all. The first thing to do is remove any gelcoat from the pan and an inch or more away from where you’ll be layering fiberglass with CSM. Once you have sanded away the gelcoat and primer you should be able to decide where the ring of water sits and begin layering up to the height of the ring. You can take several days, but the entire project should only take about four or five layers before you are finished. I say layers because polyester resin and CSM can only handle about 1/4″ before it becomes difficult to keep an even surface. I did the layers in daily increments so I could do a pour test to see how the pan was draining after every layer. To ensure proper curing, I would paint a thin layer of mold release agent after an hour of curing so I could get a proper hardness for sanding. I would sand in between layers, and then build up the next layer. Eventually I ended up with a mostly even surface, and was ready to sand for fairing compound.

Prepare for gelcoat

Once the final layer was finished curing, I used fairing compound to fill in any holes, or low spots. At first I tried to use a putty knife, but that proved to be a pain in the butt. I eventually just used my finger to smear fairing compound in places that I wanted to fill. For small low spots I did use the putty knife to flatten it for sanding. It only takes about thirty minutes to fully cure, so once it was dried I was able to take 200 grit paper and hand sand the rounded corners, and use the orbital in the flat areas. It took a couple of passes to get all of the crevasses filled and smoothed. Once I was happy with how it looked, I cleaned up and prepared for gelcoat. I’ve never worked with gelcoat before, but I figured being liberal is better than going too thin. I did a first pass using a throw away paint brush, allowed it to cure for about thirty minutes, then did another pass to fill in any areas where I could see underneath the gelcoat. Getting inside of the tubes was a bit tricky. Gelcoat is kind of runny, and difficult to work with. It wants to smooth out, and once it begins to cure, seems to want you to leave it alone. I went liberal enough to where I could go back and sand the uneven surfaces flat. I wanted to smooth the edges and blend the new gelcoat with the old. I did not want to end up with a layer that was so thin that I would end up sanding through and having to reapply. Once it was cured for about an hour, I used a foam brush to apply mould release wax over the top so it will cure hard enough that I can sand to even and blend before polishing.

Final sanding, maybe

The orbital sander at level two speed and 240 grit should allow you to level out the surface. Be careful with the edges and corners, and use the multi-tool sander for detail work. Also use level two speed, and try to be careful. Once you’ve leveled out the edges and smoothed the entire surface on both sides, you should be able to hand sand the remaining parts. You can reuse the same paper that was on the orbital and multi sanders. The Dremel will allow you to remove any runs inside of the pipes, but that’s the extent of it’s usefulness with gelcoat. There is a chance that you’ve taken off too much and so you will start to see the fiberglass layer underneath. Unfortunately this is the nature of gelcoat. You either took too much off, or the position of the sander was at an angle. Either way you will want to attempt to do another coat of gelcoat in those areas. Eventually it will blend and you will have no more fiberglass showing. Take this last step slow, and try to remove as little gelcoat as possible while sanding it even. If you need to apply more gelcoat to cover a few exposed areas, then bring it down to a coarse surface using 80 grit and hand sanding. Reapply up to an inch outside of the exposed area, let cure, then hand sand by starting on the edge and working inward. Be careful again about taking too much off. Then once you’ve blended it together, use 600, then 1000 grit to finish. If your hull is polished and shines then you will want to finish with a buffer and compound.

Final words

I warned you about how time consuming this project, didn’t I? Let me remind you that this project is going to take some time to complete. Do it right, and take your time. You will appreciate the result of your patience and effort. It’s going to also school you on fiberglass, gelcoat, and epoxy. Look at the bright side…if you do this correctly you will have minimal sanding to do. If not, then you may have to sand fiberglass and gelcoat for a while to get the best results. It’s difficult to make a mistake that cannot be undone, so keep that in mind as well. Make sure to spend some time doing your homework on polyester resin and fiberglass laminating. Also do your homework on applying gelcoat. You could spend more money on a sprayer, but this can all be accomplished with a disposable paintbrush, some plastic containers, sanding paper and acetone.


Now for the list of materials:

  • Variable speed orbital sander (Porter Cable 7424 or similar)
  • Oscillating tool  (Porter Cable PCC710B)
  • 3″ & 6″ hook & loop disc attachments for the orbital sander
  • Triangular hook and loop attachment for the oscillating tool
  • Sand paper for oscillating tool and orbital sander from 60 grit to 1000 grit
  • A dozen mixing popsicle sticks
  • A couple of dozen pairs of nitrile gloves
  • A dozen eight ounce plastic disposable containers
  • A half dozen disposable plastic trays for fairing compound
  • A half dozen disposable paint brushes 2″ wide (for gelcoat)
  • A dozen acid tinning brushes (for polyester resin)
  • A half dozen 2″ foam brushes (for mould release wax )
  • 1 quart of acetone
  • 1 quart of Interlux 202 fiberglass wash
  • 1 pint of gelcoat with hardener (white or color matched)
  • 1 pint of fairing compound with hardener
  • 1 quart of polyester resin with hardener
  • 1 quart of West System 105 epoxy resin
  • bottle of mould release wax
  • 7 oz container of West System 205 hardener
  • container of West System 404 filler
  • pumps for West System containers
  • chopped strand mat (CSM)
  • cotton shop rags (for cleaning)
  • roll of paper towels
  • 2″ OD fiberglass tube
  • masking tape
  • powerful vacuum with hose attachment and dust filter
  • Dremel coarse grit sanding drums
  • putty knife