This is not your typical micro skiff project, but it may pertain to a smaller audience looking for info. If you find yourself interested and plan on doing something similar reach out to me in a PM and I can walk you through the smaller details that would just take too much typing on here.
Here’s the scoop. I recently acquired an airboat and had been running big Cypress, with the water level low. what was new Fasco steel flex Bottom Paint with gator glide over it became beat up quick.
The rocks quickly chipped through the bottom paint and exposed aluminum.
My intent was to go under the boat and patch these areas, however upon chipping away/scraping and preparing the areas that I was going to touch up, I discovered that the paint underneath the bunks was peeling off by hand (typical boat scenario, start something simple then the scope of work expands) so what was going to be a simple project became more comprehensive.
Fast forward, past removing the engine, cage, rigging and emptying the fuel, and flipping the entire boat over, lets jump to removal of the epoxy bottom.
Don’t do things wrong for the first half like I did, trying to chisel off hard epoxy paint from areas that it was stuck on well . Skip straight to what I found to be the most effective way to remove epoxy Bottom Paint. Use a heat gun or three of them zip tied together, heat an area of the epoxy coating and use a 3 inch stainless steel scraper. It comes right off.
So now that you’ve quickly peeled all the Bottom Paint off your aluminum hull you’re going to prepare for new epoxy.
So far things have been pretty standard, what I’m changing from the standard airboat bottom coating is I wanted to use Basalt cloth in between the epoxy bottom coating to act as a binder so that should I hit rocks. The paint will not chip, flake off, and expose the aluminum but be held together with abrasive resistant fabric. Basically, I was trying to build ripstop pants into the epoxy coating. I’ve never done this before and could not find anything online from anyone else that has tried it so it was an experiment. But it just made better sense to me than simply coating the bottom of your boat in plastic that would chip away when striking objects.
My boat is approximately 12 feet long by 7 1/2 feet wide
I ordered a gallon and a half of Super steel flex from Fasco, 1 gallon of super slick 2000 from Fasco, plus mixing pots, mixing sticks and an aluminum roller and black pigment.
Additional to the epoxy coating. I ordered 12 meters x 1m of basalt cloth 200 GSM (6oz), aluminum etching, which is basically just a mild acid in my case I used on/off and barnacle, buster and a product called Alodine, typically used when painting aluminum airplanes. It is an adhesion promoter, chromate converter. Basically it helps, protect the aluminum and prevents oxidation which does not allow paint/epoxy to stick.
My thought process/intended sequence was as follows
Remove all the Bottom Paint.
Sand/scour the bottom, clean with soap and water, degreaser, and alcohol.
Then follow up with the acid etch
Then Alodine treatment
Dry and hit with a torch.
Began the epoxy with a base layer of super steel flex then follow up with Basalt and more super steel flex then follow up with super slick 2000.
doing all of this before the epoxy fully cured so that I could have a chemical bond between layers.
What actually happened was pretty close to my plan however, I was working in a carport in my front yard exposed to the outdoors and could not control the weather or bugs.
So here is how it kind of went down
After the epoxy was removed, and I arrived at raw aluminum, I prepped that area with sanding as intended, then washed it twice with acid rinsing that off well and followed up with a treatment of Alodine. the Aldine should turn all of the aluminum a nice gold color, but mine came out kind of blotchy, gold and blue. I tried it again and things did not much change. Best I could gather from researching online is when I used the acid etch I should’ve also used a Scotch-Brite pad,(sanding beforehand was not enough) then basically just poured the Alodine and moved it around. Not pour it and smear it with a rag, really the aluminum should be dipped in this stuff, but I could not exactly dip a boat. From what I can tell it worked fine tho, It just wasn’t pretty.
(sidenote Alodine is nasty stuff, cover yourself up well. technically it should all be re-claimed and disposed of properly)
Now I was working quickly dry and start epoxy, but in typical South Florida fashion storm clouds came in and the rain did not let up. If I was not using Alodine, I would have needed apply acid etch again because oxidation forms quickly on aluminum, the Alodine helps convert the surface and extendeds the window of time to coat. So the next morning at 6 AM I started preparing things to lay down epoxy.
I wiped all the aluminum with alcohol and a dried that out.
Began mixing up the super steel flex. I mixed up about 1/3 of the gallon and a half. The mixture is 2:1 . I believe I made a total of 64 ounces. I mixed this in with a little bit of black pigment poured that over the surface and used a roller to spread it around. Purchase rollers made for epoxy. They are a thin nap and don’t fall apart.
I allowed this to cure over the next few hours where it was just barely tacky enough that I could push my finger into it and have a fingerprint, but not stick to my finger.
Now my idea was to start putting down the basalt layers. I was not sure the best way to do this, but a friend of mine came over to help me and the idea was that I would be able to with him drape the cloth over the epoxy. This did not work out. It did not lay flat had ripples and air pockets in it and was very difficult to fix, as the epoxy was very sticky, so should you try and do this, don’t do that. Rather the solution is to wait a little bit longer on the epoxy and roll the basalt cloth and smoot it out as you go.
I could have alternatively put down the basalt cloth directly to the aluminum and poured the epoxy right over that, but I wanted a base layer of epoxy directly to the aluminum first
The basalt cloth is approximately 40 inches wide and three layers of this would cover the bottom of the boat with some overlap, as it turned out, I was sent a little extra basalt cloth so that was used as well.)
the first layer I put on with my friend basically sucked, but the next five layers I put down laid out clean
Sorry, I don’t have any pictures of this. My hands were covered in epoxy and I was working with a short time window. For these layers, I started at the front and rolled to the back, smoothing as I went. I found out I had some extra cloth so I put an extra layer towards the back and one down the middle.
Now that the cloth was laid, I mixed up the remaining super steel flex without any pigment and poured that. I was hoping tha would keep the color of the basalt cloth as it is a nice bronze color but when it wet up, it turned much darker.
I have some fiberglass experience, but not a lot so what I learned when doing this was after wetting up the majority of the basalt cloth rather than continuing with a roller I should have switched over to a squeegee and squeegeed out as much of the epoxy as I could also pushing down the fabric. Most of the time window I had I spent with the ribbed aluminum roller and epoxy cloth roller when I should’ve spent more time with the squeegee. towards the end of my working time, I realize the squeegee was better and that helped out, but similar to me learning how to remove epoxy I found out a little later than ideal.
I was hoping that I would be able to put down my final layer of super slick without pigment to see the weave of the basalt cloth but with it being so dark, I decided to mix pigment into the super slick 2000 I had 1 gallon of super slick with an additional pint or so as back up in separate containers. I mixed up 3/4 of the 1 gallon with pigment and spread that around with a roller.
I allowed that to cure/dry to the point where I could still have chemical adhesion and mixed up the remainder of my super slick with some powdered graphite I had poured and rolled that on top.
I gave all of this three days to cure, then flipped over the boat and put my rigging engine, etc., back on then waited an additional day and took it out into big Cypress to test.
The boat ran well and the Bottom seemed to hold up during testing. I pushed on the boat going 78 miles an hour and no catastrophe.
When retrieving the boat at the ramp the side of the bank/ramp has some rocks on it and thought that would be a good test. so as I pulled the boat up to tie off, hitting some rocks slowly with the front so after I was back at home. I looked at these areas in addition to one other area where I must’ve hit a rock. the product(s) were working as intended. I could see the scratches go through my top layer of super slick, contact the bssalt layer and stop there without any chipping. If I had only used super slick, I think the rocks would have gouged through it enough that I would then end up with exposed aluminum again. I still need to see how this works long-term but as of now I’m satisfied with the experiment.
You can just barely see the cloth if you zoom in, the alternative would’ve been aluminum so I think the cloth is working well as a binder
now with these small areas, should I so choose I can hit them with a little sandpaper and roll/brush a fresh coat of super slick over these areas without risking having exposed, aluminum, and water, pushing between the epoxy and aluminum.