G&M's 'Drop

[swoody126]

getting into the cloth isn't as important if you didn't go thru either direction(you still have a cross grain pattern in full evidence) since this isn't structural

just coat it until the fabric is no longer printing thru your sanded finish prior to priming n top coating

sw

[GarthB]

Spent the past two days widdling away at odds and ends while I brainstormed finishing out the exterior. My main focus has been the wall/roof joint. I know there are a few trains of thought around the forum about this topic and all have had their successes and challenges. Fiberglass tape has been a big consideration and I think that it offers superior strength to the most common alternative - just coating the joint in epoxy and calling it good. The primary challenge with fiberglass tape, however, is fairing it into the rest of the body. On the flip side, just epoxying it isn't sitting super well with me since we live in an area that gets a fair amount of wet weather. I don't want to risk the epoxy cracking at the joint over time and allowing water infiltration.

As a "happy medium" alternative, I am settling on using 1/4" chopped fiberglass strands as an epoxy filler that will be spread over the joint. In my opinion, based on the data I've been able to find, the glass strands should provide more than enough tensile strength along this joint line, especially since the PL premium, screws, and staples are already taking, theoretically, 100% of the load that would be exerted on the joint. With vibrational crack resistance of the waterproofing layer being the only remaining force to worry about, the strands should suffice.

The strands should arrive by the end of the week, so most of the exterior work is on hold until then. For now, I'm working on hiding all of my wiring in the galley and coming up with a "control panel" for the various switches, outlets, and the voltmeter.

[swoody126]

a thin(4oz-6oz) layer of glass cloth/tape is best

over the years i have learned to make my own biaxial glass tape from cloth

i have an old curb find interior door w/ flat surfaces that i set up on saw horses to work on

w/ the cloth spread out smoothly i use a wede metal 4' rule out on a 45º diagonal and use one of those ultra sharp rolling cutters to do the majority of the work and snipping the stray fibers w/ scissors

2"-3" is adequate

when you buy tape from most vendors allz you can get has the fibers registered @ 90º meaning only 1/2 the fibers cross the corner/seam

when the fibers are set @ 45º all of them cross the seam/corner AND the fibers bend over the corner way easier than when trying to go over it @ 90º

i use wood flour to mix a slurry to fill the weave/fair the edge once i have my cloth tacky

the edge of the cloth can be reduced substantially w/ the blade of a SureForm file held in a glove(not in the frame) and simply drug down the edge when the first couple of coats are almost cured(no longer tacky butt not hard)

IMG_4488.jpg (619.81 KiB) Viewed 710 times

sadly forum software wont let me post the proof of concept pics to show you how the fairing works out

sw

[western traveler]

I’m with swoody on bias tape over chopped glass. Though I clearly don’t have swoody’s experience I did a fair amount of glasswork with much heavier cloth than we are using on our builds but we always filled and sanded that work.
When I glassed the underside of my below deck storage on this build, I snipped and folded the corners doubling up the glass on the radius edges just for practice. I was surprised how well it all laid down. I wasn’t looked for perfection though.
Chopped glass is easy to work with. I will be interested in how it goes.

[GarthB]

Swoody and Western Traveler - Thank you both for the input. One of the greatest things about this forum, in my opinion, is that so many people on here set their ego aside and listen to the experience and advice of those who know more than they do. I hope to uphold that standard.

Being a bit of a material science nut, I took some time today to see if I could find any lab testing of epoxy resin with short strand fiberglass as an additive. There wasn't much out there, however I did find two lab reports, which were quite interesting. They're linked below for anyone interested.

https://jmerd.net/Paper/Vol.43,No.2(2020)/247-256.pdf
http://przyrbwn.icm.edu.pl/APP/PDF/132/app132z3-IIp014.pdf

To sum it up, neither of the two reports provided any evidence that short strand fiberglass added to epoxy resin increases the strength properties of the epoxy. In both reports, the epoxy material with the least amount of short strand fiberglass additive was the strongest. Hopefully this helps anyone considering it in the future. Don't solely rely on what the product descriptions tell you.

All of that in mind, I spent the evening cutting some of my 4oz cloth into biaxial strips and will be taping the roof/wall joint. I got the hatch seams glassed tonight:




The tape is an attempt at the "painters tape trick", which I noticed has been mentioned by Steve Frederick on this forum as well as many boat builders on other forums. We'll see how well it worked when I go to peel it up in the morning.

So long as all turns out well with the hatch, I'll do the same with the rest of the cabin tomorrow. I had to fill all of my screw holes tonight before I could move on to the glassing.

[JoeGrz]

Sorry to hear of your epoxy mishap. It looks like you’re back on your way and your build looks great. I would also like to thank you for finding the beefier strut brackets. I received mine and will get them installed this weekend.

[saywhatthat]

neither of the two reports provided any evidence that short strand fiberglass

most mat has a binder that it reacts to the epoxy. There's some that that's for Infusion that won't have the binder but you have to check or if not you will have trouble. Fiberglass woven give strength Mat gives bulk

[GarthB]

Sorry to hear of your epoxy mishap. It looks like you’re back on your way and your build looks great. I would also like to thank you for finding the beefier strut brackets. I received mine and will get them installed this weekend.

Thanks Joe! Everyone has to have at least one disastrous mishap here and there. It gives the project some character. Hopefully the brackets work well! I've yet to install mine since my hatch has yet to be re-installed.

most mat has a binder that it reacts to the epoxy. There's some that that's for Infusion that won't have the binder but you have to check or if not you will have trouble. Fiberglass woven give strength Mat gives bulk

I appreciate the feedback. It should be noted, however, that I am referring to chopped glass fibers, not chopped strand mat. They most commonly come in 1/4" lengths, such as the ones linked below. Many of the sites that sell this filler material make the claim that it makes joints both stronger and tougher, which, based on the lab testing above, is a false claim.

https://www.fibreglast.com/product/14_Chopped_Glass_Fibers_30

[GarthB]

The painters tape method of getting a clean fiberglass edge worked well and I used it for the rest of the wall/roof joints tonight. Also put it to use for two small patches that can be seen in the photos. The patch on the right was the result of a test to see if I had a healthy base layer of epoxy when the whole resin mix-up occurred.




Once the joints were taped, I applied epoxy with micro added as fairing compound for the hatch. I'll get it sanded down fair tomorrow and do the same with the cabin if all goes well.



Looking forward to getting a sealer coat of epoxy on this thing and moving on to primer and paint.

[GarthB]

Not a lot of ground breaking progress but we got a lot done this weekend. On Friday, we spread micro all along the tape and patch joints on the main body of the camper.



Yesterday, we sanded everything down nice and flat. The micro did a really nice job hiding the tape lines and they couldn't be felt anywhere.



After sanding, we applied a final coat of epoxy over the entire outside of the camper and hatch. We applied it by rolling and then tipping with a foam brush. Aside from a plethora of kamikaze bugs, I couldn't be happier with smooth it cured. We'll get rid of them with a very light sanding prior to applying primer.




Start to finish, the walls received a total of four coats of epoxy and the roof got three, plus all of the fairing compound. Maybe someday we'll flip it upside down and see how well it works as a boat.

The original plan was to apply the first coat of primer today, however, I called Raka to see what the minimum cure time was for the epoxy to be painted and they told me 4-5 days. I'm glad I made the call. We'll prime later in the week and hopefully get the Monstaliner on late next weekend.

Today I got started on the stove and water storage slide out in the galley. I'm not in love with it but it'll work for now with the scrap plywood I've got on hand. Maybe I'll build something a little fancier this winter when I'm looking for something to pass the time and lumber prices have gone down a bit. The water storage container is called an Aqua Brick. I liked that it was slimmer and took up less galley space. Each one holds three gallons and we purchased two. One will ride in the truck and we'll swap it out when the one in the galley is empty.

[OP827]

Could you please share a link to "The painters tape method of getting a clean fiberglass edge"? Thanks

[GarthB]

Could you please share a link to "The painters tape method of getting a clean fiberglass edge"? Thanks

Here ya go: http://www.oneoceankayaks.com/Wshophtm/Shop23a.htm

Instead of doing the final step that was detailed in the instructions above, I took Swoody's advice and ran a Sureform blade along the edge. After that, I applied filler without re-taping so that I could blend the seam in.

[OP827]

That is a great tip that I can use in my future build, thanks a lot!

[GarthB]

So far we've spent the week slathering layer after layer of epoxy on door, hatch, galley wall, and any other potentially exposed edges that were remaining. Once that was done, I got the hatch mounted in place one last time in order to do a final fitment check and to get some screw holes established so that we can keep track of them during the priming and painting process. Thankfully, the new strut mounts seem to be holding up a lot better. They still show minor bending, but they're within my tolerance of being acceptable.

Since the spars are still pretty easy to locate through the fiberglass, I wanted to get all of the "hard to find" attachment points located before they got even harder to find once paint covers everything up.

It sure was satisfying to finally see the completed hatch mounted on the camper. I felt like I was finally getting a good, nearly complete, view of the vision that has been driving this project since the start.





Rolling it into the paint shop for final sanding, primer, and monstaliner:



It'll be a whole different animal when it comes back out.

[Bezoar]

Can't wait to see it! Looking good!