Outdoor build of GA Kodiak, Orange, CA

[Brian.Dixon]

Wow ... the paint/primer looks pretty hefty stout!   We had shaker cans of zinc chromate primer in the USAF and never once stopped to consider if it's poison or not ... I'm 60 and still alive

bd

[json]

Ya, that’s a good point. Idk. It’s all risk. when you were spraying it in the Air Force brian how diligent were you about surface prep? Any feedback about how that affects how your results were? The results I saw from painting that square foot make me think that surface prep isn’t as big of a deal as I am making it. My thinking is get it wiped down with acetone well and then just go for it. Maybe you have some feedback in that area? As for application it doesn’t seem like it takes much. Just a light spray and ready to roll. Let me know if this is inline with your experience.

[Rbob]

Json,


Just my 2c.

I have painted a few aluminum things (very few)  but I can attest to using the aluma-prep and alodine conversion coating to being the best.  I painted an aluminum drift boat for a customer over 30 years ago and it still looks new, of course it is stored inside but I used the acid cleaner and alodine conversion coat before applying epoxy primer and single stage enamel paint.

I coated my aluminum fuel tank with raptor after cleaning it with a scotchbrite and some cleaner (cant remember!) and thought it would be bullet proof, after pulling up the floor a couple years later most of it had flaked off...  It may have been the raptor liner not being able to expand/contract with the aluminum but it was a failure.  We did some repair work on my aluminum boat, sandblasted where it was pitted and my son blew it off and applied "allmetal" filler and sanded it smooth, I knew it needed to be cleaned with the aluma-prep first so I checked the adhesion with a putty knife and every patch easily came off so we re-blaste the spots and cleaned with aluma-prep before applying the filler.  You must clean the aluminum of the oxidation which is mostly invisible, rinse with water, blow it dry and immediately apply whatever product you are using without hesitation... 

If you try cleaning the backside of your test piece with aluma-prep, rinse and dry you will find the aluminum feels sticky which is clean clean clean, and paint will stick to it.


I am a fan of epoxy primer, not so much of a fan for etching primer.  For etching primer to be effective it has to be sprayed on wet or it wont etch and it runs easily, spraying it on dry does nothing for "etching".  2-part epoxy is king in my opion.  I will post a link for the aluminum cleaner, open up the technical process document below it and it will have the info you need.   The other link for the epoxy primer you will find very useful, they also have epoxy primer high build that is underwater rated polyamide cured epoxy.

https://www.aircraftspruce.com/catalog/cspages/alumiprep.php

https://tamcopaint.com/collections/primers/products/dta-epoxy

[json]

Rbob - thanks a bunch for your details on your experiences. I considered the alodine and alumiprep, I think I will get some and try it on my test piece like you say.

[Rbob]

Json,

Just to make your head spin, most aluminum tanks are not treated or have any special coating and they seem to have a good reputation for longevity.  (someone may correct me)  I like the way Dan Boccia installed his aluminum tank, although I am not sure what prep he did, but applying uhmw runners so no crevice corrosion can occur and allowing water / air to flow under the tank is a first class install.  Crevice corrosion is failure waiting to happen.

There are others that have installed aluminum tanks so maybe someone will chime in and offer advice.

[json]

Ya, my head has been spinning for weeks about all of this haha. I love how Dan installed his tanks, and would like to do the same with mine, but the fabs wouldn't sign off engineering wise about hanging them. They also had to go and drop it in there that 5200 doesn't stick well to aluminum either, so wherever you bed in 5200 you are creating a crevice corrosion opportunity (like seating supports across the bottom). But then I wrestle with painting because unless I do it perfectly I am basically creating a giant opportunity for crevice corrosion to happen in and of itself if paint flakes or separates and moisture finds it's way in.

I made a coffin for the tank that I don't expect water to get into. I put a drain plug in the aft end that I intend to open each time I put the boat in storage or get ready to take out to check for moisture ingress and/or fuel leaks. If I do the full cover 5200 seating for bottom supports that others have mentioned (djeffrey and Dan, among others) then I think I probably won't have a problem for a long time, but who knows. I guess maybe ability to determine failure early is more insurance maybe than doing things exactly right. I just struggle with 150+ gallons of fuel on the loose potentially.

And at the end of the day, like a lot of other things on this project, I am likely just overthinking it and could really get 80% of the results in 20% of the time if I just realized it and moved forward. A boat that was 80% of perfect would be pretty good I think...

[Rbob]

Just found a great article on bonding to aluminum:



https://www.permabond.com/materials_bonded/how-to-bond-aluminum/

[kennneee]

Json- I built a tank coffin on my boat a well. Instead of a drain plug I installed a hose fitting. Attached to it is a clear piece of hose that has the other end fastened to the top of the coffin bulkhead. It acts as a sight glass so that I can see if there is any liquid in the coffin. If I want to drain it I take the top of the hose and point it down to the bilge area. That was part of my “over thinking”. Seems like a good idea.

[json]

Json- I built a tank coffin on my boat a well. Instead of a drain plug I installed a hose fitting. Attached to it is a clear piece of hose that has the other end fastened to the top of the coffin bulkhead. It acts as a sight glass so that I can see if there is any liquid in the coffin. If I want to drain it I take the top of the hose and point it down to the bilge area. That was part of my “over thinking”. Seems like a good idea.

That's a cool idea, I use sight glasses like that when I brew beer, that would be handy if it was highly visible for sure.

[json]

I have the cuddy largely wrapped up at this point, there are some polish things to do but I will get to them a little here and a little there. I am getting ready to install the tank, and have been trying to get over to home depot to get 5200 and some other odds and ends for that. I got more ply today and cut out the decking for the pilothouse section, which fits pretty well. I am thinking instead of nailers I am probably just going to try the cured bead of epoxy that was mentioned somewhere in these forums. The Gougeon brothers method for setting bolts worked awesome, I put some fibers in it for extra assurance, but I doubt that they will ever be necessary. They seem rock solid. A couple kicked off and bubbled all over the place so I had to dig out the bubbles and re-pour, which is a good brush up about using regular hardener in hot temps, that stuff kicks quick when it starts semi-hot. Good not to have a giant cup of it.

[json]

I have been wrapping up a lot of odds and ends, and things are starting to feel like they are moving again a bit. The under deck stuff seems like it takes forever and a day, but I feel fairly good about what came together.

I hemmed and hawed about installing my tank for a long bit, it's gigantic and I just kept envisioning 180 gallons of fuel on the loose.  In the end I went with the zinc chromate and primer, which seems to be pretty solid, as I have moved the tank around on things quite a bit after it was primed and none of the primer chipped off on contact points, just some minor scuffs. I put both some longitudinal supports under the bends on the bottom of the tank as well as 5 vertical supports on each side (including the end blocks) so hopefully that's sufficient to keep stress from breaking the tank from repeated flexing and warping. I ended up using 4200 to install it because I had the angle welded in to keep the tank from moving fore and aft, so the adhesive was largely a formality aside from providing a solid platform for the tank to rest on. If I ever have to replace this tank I am hoping that I am thankful for that decision.

I went the pool noodle route as well, it cost me about $130 for all the noodles to fill under the ph deck between the dollar store ones and target. Target's noodles were a better deal at $2 from the dimensions they gave online but when I showed up to buy them the $2 ones were 2 different sizes, so who knows and whatever. I think for the under cockpit part of my boat I am going to shoot for more watertight accessible storage with drain plugs, as it's more utility and probably more buoyant than pool noodles, just takes more planning and more work.

Got the pilothouse decking installed, the windshield cut and fit. I am probably going to try to fab and install the pilothouse aft bulkhead with the windshield and roof supports all at the same time so I can try to minimize heat warping.

I also got a killer super quiet pneumatic sander (aircat 6700) and a 50' hose for my shop vac so I can put the noisy part of my sander in my garage and not annoy the neighbors. I might need a bigger compressor going forward but this sander is night and day better about how low profile and light it is compared to my motorized one, which is bulky and can't fit really anywhere but is pretty good for flat or open spaces.

[Brian.Dixon]

Looks like you're making GREAT progress!    Did you really mean 180 gallons ... or is it 108?  Where does the f'w'd end of the tank start and where's the aft end end?  It's best to keep the fuel CG near the aft pilothouse bulkhead if you can.  If you've got it forward of that, it may be a good idea to offset it by locating batteries at the transom and/or moving the CG of the outboard further back with a jack plate or motor bracket.  I can do the math if I know the size of your tank for sure, boat length (28 ft), and a measurement of where the f'w'd and aft ends of your tank is ... measured from either bow or stern as long as I know which.

[json]

Thanks Brian, it's 185 gallons, 10' long, centered 12' 3" forward of the center of the motor mount on the transom (so fore end is 17' 3" and aft end 7' 3"). My hull is actually about 29' long, I am not sure exactly anymore since I put the pulpit on, but if memory serves I was just over or right on 29', as I was able to stretch my bottom assembly and stringers for the extra foot or so when I was installing those. I did install the tank slightly forward of where I was going to install it originally because I am going to be sticking a pretty large bait tank somewhere in the cockpit (maybe over the aft end of the fuel tank or 9' or so fore of the top of the transom), so that is another 6-900 lbs that I was trying to balance into the equation.

[Djeffrey]

Really coming together. Nice work

[json]

I got my house walls in place but not finished, and tried to keep the window layout to the Prince Rupert, which other than the sloped forward windshield and the full length splash rails I am going to try to follow fairly closely. I found a company that's just up the road here that does windows (Mark Plastics), and got a quote for those which was more expensive than I had thought (probably reasonable for 14 windows) but I have seen a lot of people who swear by his product in contrast to DSG and Motion, so I might get another quote from Wynne too but will probably go with Mark. I can physically go down there and have a look and talk to him too which is nice.

I have the roof laminated up and glassed, trying to find time and help to hoist it on top of the boat to mark out the ph outline. I ended up laminating 6mm and 4mm okoume, eventually I want to put an aluminum tube helm up top so I figured I should enforce it a bit. I also wrapped some glass around a corny keg and made a cylinder for the curb visor I am going to make, that was simple enough and seems solid. I might back it with some biax, I think I have some laying around.