2019 has been a year of HUGE cosmetic projects aboard Party of Five. This is another job that I wanted to complete in Key West 3 years ago, but it slipped off the list due to time. Actually it fell down the list and then the job changed. Instead of replacing the windows, I decided to sand and buff them. I started with 80 grit and moved up through the grits, ending in 1500 before switching to compound. While that didn’t completely remove the crazing, it definitely made a big difference and I called them acceptable until I could actually replace them. I had no idea it would take me 3 years before I got back to that job. That 3 year delay really pushed those windows to the limit as I’m pretty sure they had not been switched since the original owner. That means they were probably 8 1/2 years old. Almost all that time was spent south of Florida.
Not only did this job take me 3 years to get back to, but the damn job spanned over 3 months due to logistics. We actually started this back in Grenada in November and are just completing it here in Martinique (actually today, as I write this. Feb 7). Part of the reason that the job spanned such a long time was that I wanted to use a different sealant than is traditional. Every island we went to we searched for the sealant, but to no avail. In the end I had to order it from the USA and have it sent to St. Lucia, where we completed the woodwork project while we waited for it to arrive.
So what is this magical sealant, that I just had to have?
DOWSIL 795 Silicone Building Sealant!
Yes, I used silicone on my boat contrary to the advice that silicone has no place on a boat. While that advice is true for general bedding applications, its dead wrong for acrylic or glass applications. 795 is a structural silicone that is used to seal windows in office towers among other industrial jobs. Being designed for such a harsh environment gives it the following advantages over the traditional sealants used (namely Sika 295):
- Better adhesion to both fiberglass and acrylic/glass
- Primeless application (just abrasion is required)
- Virtually odorless application (there is just a slight hint of smell if you stick your nose up to it for the first hour)
- MUCH better flexibility. Cured joints can flex over %50 before breaking the bond
- Virtually impervious to UV (eventually it will break down, but will outlast the boat)
- Saltwater compatible/impervious
- Easier cleanup.
- PRICE, it costs $7/cartridge compared to $30 for traditional adhesives (I used 13 tubes)
However with all those advantages, 795 does have one disadvantage. It has a very long cure time. It takes 7-14 days to achieve a “working” cure, but over 20 days to reach full strength. So that means that once the windows are set, the boat is not moving for at least 7 days. A trade off I was willing to make for all the advantages.
(P.S. After working with it, I’m starting to think that 795 might be superior for every job, even bedding. I’m not kidding. The stuff is amazing and I’m willing to bet that if it was used in bedding applications it would not only outperform the incumbents, but outlast them. I am contemplating a test!)
Alright, now on to the main show. Here is how we replaced our windows in 45 pictures (count em). Most of the pics are from the starboard windows as we did it second and it went way smoother. However, I needed to mix some port pictures in as we forgot to take pics of some steps on the starboard side.
1. Alright, there is a step that I didn’t take pictures of. Quincy and I created templates. We took standard brown “shipping” paper and taped it over the existing windows. Then I used a pencil to trace around the edge of the existing windows. After that I cut the patterns out using scissors and rolled them up for future use.
2. Here we have the acrylic laying on some pallets covered with cardboard (the acrylic sheet looks brown as its covered in protective paper). We then unrolled the templates and taped them to the acrylic sheet in various locations (don’t tape continuously or you can’t do the next step)
3. Using a “Sharpie” we traced around the templates ensuring the sharpie touched both the template and the acrylic. This was to leave a nice line once the templates were removed. (Yes, we let Quincy put marks to show which was port and starboard)
4. We removed one template and did some test cutting. We quickly realized that the shoe of the saw was gouging the paper off the plastic. We applied a bunch of tape to protect it from scratching.
5. Full speed ahead with the cutting. We are using a fairly high toothed blade on the jig saw (about 18 teeth/inch). The human powered water spray is crucial to keeping things cool. For fun we tried a couple of feet without the water. The acrylic actually welded itself back together behind the saw blade. Its also important to cut on the inside of the line or your windows will be too big! (Flip-flops and shorts are proper PPE, right? Hey, I at least have eye protection on! No bullshit, wear eye protection. The saw throws tiny shards EVERYWHERE.)
6. One Island Spirit window! A word of warning though. The jigsaw makes tons of tiny sharp shards of plastic. Those shards make kneeling a very unpleasant experience. Actually, I might prefer stepping on legos!
7. All three cut out and ready to take back to the boat. Of course this is the point I realized that the 2 nautical mile dinghy ride is going to be interesting with 4 people and these windows (thanks to Darrin for helping out and taking these photos). At this point I know some of you will comment on some of the cuts looking “less than straight”. Don’t worry, we fixed that with a 40 grit flapper wheel on a grinder. Followed that up with some 80 grit on a random orbital sander.
8. Now I had to figure out what to do with the completed windows while I looked for the “schmoo”. Yup, they lived in this spot for 3 months.
9. TIME TRAVEL.. Its now 3 months in the future and I have enough components where I’m confident enough to make GIANT holes in the side of my boat. This is the part of the job I was most worried about. I had removed automotive glass in the past and knew how hard it was to actually cut that sealant (they have special tools). I thought long and hard and this was my best solution. I found this nice flat wood saw at a shop and figured it would work well. So I used a long screw driver to pry and then cut the sealant in front.
10. The goal is to pry just enough to spread the crack open, but not break the acrylic. What these pictures don’t show is the actual force required on the saw to cut that sealant. I was super sore the next day. Not just sore, but I actually cracked a tooth because I was clenching my teeth so hard during the tough points.
11. SONOFABITCH, I pried too hard and it broke. However, that is probably a good indication that these windows needed changing. There is no way you could snap new acrylic that easy. This is the hardest part of removing these windows. The center pillar had glue applied to the entire thing (like 4 inches of glue). However in my case that glue had not completely cured in the entire life of the windows (ya 8 1/2 years and still not cured). So I was able to pry the window away and stick the saw all the way through cutting the sealant (sounds easy as I type it, but I used a huge amount of force to do this).
12. Ok the windows is fully removed and I’m using a utility knife (actually, its a lock blade Buck knife) to clean all the old sealant off the flange. The vacuum is key, otherwise old sealant goes everywhere and leaves black stains. You can actually see the gooey sealant on the center pillar. (Yes, I should have put on sunscreen at this point)
13. Almost done. This step actually took longer than removing the entire window. If you are thinking of hiring this job out, you can save %75 of the labor by simply removing the old windows and prepping the flanges.
14. A crucial step in any job. You must bleed on it for good luck.
15. After the “mechanical” removal of the sealant, then I cleaned everything with Acetone.. MULTIPLE TIMES. This was followed by a good hand sanding with 80 grit paper.. Finally MORE ACETONE CLEANING.
16. We found some cracks in the actual window frame on our starboard side. It appears that there was a manufacturing defect and someone just filled it with gelcoat (no it was not thickened filler, it was gelcoat). We ground out the bad spots in preparation for new glasswork.
17. The Dowsil 795 requires a 1/4” thickness to cure properly. We used some plastic spacers glued to the boat with cyanoacrylate (Super Glue). The only plastic we could find onboard was red, so we painted it black with Kyrlon! (you can also see the new fiberglass work here, 3 layers laid at different angles)
18. I now had a giant hole in the side of my boat. Its damned prudent to have a tarp ready to be deployed immediately. Its no fun to watch liters of water pouring in from a squall as you run around trying to find all the shit. Ask me how I know!
19. Ok the clouds have cleared and its time for a dry fit. At this point we cut little spacers to keep the window at the right height to the keep the gap correct. Many of you might be asking “How will that work, do the spacers remain?”. No, for this first step we will only be applying sealant between the window and boat, this channel will remain mostly free of sealant in this step (except oozing).
20. At this point we also dry tested the holding devices (we called them squeezers). On this window we used longer screws and washers. This allowed us to adjust how tight they were without screwing the fastener deeper and risking going through. You may also notice we put marks on the tape where the holes are. This helps once the “schmoo” is applied and the holes disappear. The final thing we did is number them so we knew exactly where they went after the dry fit was over.
21. Back on the inside we used a “Sharpie” to mark the inside of the flange. This is hard to explain, but you don’t want to mark around the window you can see. You want to make the lower ledge that is usually covered by foam. Stick the Sharpie in and mark the deeper ledge.
22. The Sharpie marks give a guide of where to sand the window. You want to make sure you are sanding below anything visible. We used 80 grit on an orbital sander. After we cleaned it up with just water on a rag and followed by a dry paper towel. This abrasion is key to a good bond as it provides a “tooth”. Don’t sand divots into the acrylic, but you want nice deep random scratches.
24. Alright the messy part is about to start. I made sure to have enough sealant cartridges on hand (it takes about 3 1/2 for this part). If you think Sika 291/295 or Dow 4200/5200 are messy, this is a new level. I’m pretty sure my kids got some on them sitting 3 feet away from the worksite. You DO NOT want to go back into the boat once the Schmooing starts. Just so your wife can say “You were warned! I told you so.”, you will ruin any clothes you are wearing.
25. Be generous, it will make the job easier. However its a balance, way too much will have to screaming “ITS EVERYWHERE” later on!
26. Another amazing benefit of using 795 is the working time. It has a “skin” time of about 15 minutes so you don’t need to panic. Lay it on nice and thick.
27. We “trowled” the sealant flat for a better result once the window is actually set. Our trowel was just a tongue depressor. (In case you are wondering why there are “jerry cans” in some of the pictures, they were used as weights for the tarp. After the one “incident” we keep things close at hand for quick tarp installation).
28. Next the window was set. We used just a few “squeezers” and the bottom spacers I showed earlier. Then came the important part. We took the protective cover off so that we could see where the sealant may be short. Some people might think this is crazy as we then had to re-tape in later steps, but I think that trade off is worth it. Having a consistent solid bed of sealant under the whole window sill is key to ensuring no leaks for years.
29. Yup, this front part didn’t have quite enough sealant, so I’m removing that “squeezer”. This way I can pry the window back and squirt more sealant into that spot.
30. Alright, the window is set and all the supports/squeezers are in place. I head back inside and clean the excess sealant using a popsicle stick (or tongue depressor) cut to the right size. In our case we didn’t need to be super anal about this step as it would be fixed later. We just made sure the sealant in the visible parts of the window was cleaned up!
31. Ensure you have TONS of paper towels on hand. We like to recycle and found the beer tray made for a good garbage catch. Remember that even looking at these dirty paper towels will spread that “schmoo” in spots you can’t even imagine.
32. PAUSE…. VERY IMPORTANT.. WE DID NOTHING FOR AT LEAST 3 DAYS (36 hours). Dowsil 795 is an “atmospheric moisture” cured product. That means it needs moisture from the air to start curing. So we left everything to allow the air to get to that 1/4 inch thick layer and start the curing process. We felt that backfilling anywhere immediately would hinder that process. Not to mention that removing the “squeezers” would probably lead to the window flexing outward and having a strange final resting position.
33. Missing pictures.. Dammit we were busy! Anyway, 3 days have passed and I have now removed the “squeezers”. We then re-taped both the boat and window as its time to backfill the channel. I operated the gun while Rhonda smoothed everything out with a tongue depressor (if you don’t have these on your boat, GET THEM). This step took way less “schmoo” that I thought. It takes about 1 1/2 cartridges for this step.
34. A closer look at the smoothing process. Its messy!
35. Oh damn. One of the hardest steps in the whole process. You must wait at least 7 hours before peeling the tape (better overnight). Its just so hard to wait that time as this will be the first time you see what the finished product looks like. Mmmm oh so good!
(P.S. There is an entire subreddit dedicated to stuff like this. However there is also an entire subreddit dedicated to zit popping. So what the hell do those people know!)
37. Ha.. You thought I was going to show you what it looked like completely peeled. Well patience my friends, you will have to wait for the end.
Here we moved on to the next step and it may be a little controversial. You see this part was actually filled with a foam tape from the factory. However we decided that wasn’t’ the best solution and instead just backfilled that channel with more 795. I can’t claim this was my idea as the previous person that replaced the windows in our boat did the same thing. Personally I think this is a better idea as the foam was prone to breaking down and becoming ugly. I think the factory used foam as it saved expensive sealant and was easier to do.
38. Just squirt it in there. Now I know what you are thinking, “Dude there is no tape on the window, only the boat. That is going to be a nightmare to smooth”. If this was Sika 295, then I would agree, but with 795 its not a problem.
39. Ok, here is the smoothing process. We used a pair of scissors to cut a nice square end on a tongue depressor. Then using a “multipass” technique I squeeged it off the window and pressed it into the channel.
(I know a few of you just said Leelou Dallas Mooolteeepass in your head).
40. You do not need to be perfect here. That little bit of 795 left is easily cleaned up after it sets up a bit. That is the advantage of the long cure time with this product. Even after 24 hours of curing it has not developed a super tenacious bond with the acrylic yet.
41. Even though I knew I could come back and clean things up the next day, I’m a little bit obsessive and this is where I stopped while the 795 was still wet.
42. The next day I came back with a sharpened popsicle stick and removed those lines of 795 left by the tongue depressor squeegee. (After cutting it with scissors, I rubbed the now flat end on sand paper until it had a knife edge)
43. Here is a picture of the tools to give you a better idea in case my description was too poor!
44. After all the edges were cleaned up, then I first cleaned the window with dry paper towel (yes dry). The dry towel will remove the silicone “haze” that may be left from all the processes. After that, I used a small amount of dish detergent and paper towels to do a final cleaning.
46. Wow that one is even nicer!
47. Yup, its time for a couple of money shots.
48. Oh hell, if that ain’t sex on a stick, I don’t know what is!