Fiberglass Tank Details

Fiberglass and polyethylene tanks are the best for marine use in my opinion.  Both materials are impervious to corrosion and they will last as long as the boat.  Already they are a clear winner as no other tank material will last as long as the boat.  This fact alone creates a serious issue.  What happens, say, 39 years into the boats life when the metal tanks start leaking?  Well as we know its a major pain to remove them and it is impossible to replace them.  They have to be cut up just to get them out and that, of course, means that a new tank will not fit inside the boat to replace them!  But what do the builders care?  Most of them aren’t in business for 40 years anyhow unfortunately.

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In all honesty, it’s a miracle that our tanks lasted 39 years.  The Underwriters Laboratory (UL) did a study on aluminum tanks on boats in 1994 that determined that a “0.090-inch (2.3mm) plate (the minimum thickness permitted by the ABYC for aluminum fuel tank construction) has a service life of 6.5 years in the marine environment; 0.125-inch (3.2mm) plate (commonly used for more heavily built tanks has a service life of 17.4 years.” – Boatowners Mechanical and Electrical Manual, Nigel Calder.  Ours have lasted at least twice that long so I’d say that’s a pretty good run.  However, imagine this:  the builder decided to build an integral fiberglass tank into the hull as part of the build out.  That tank would still be 100% perfect today and would never have to be replaced.  So why don’t they do this?  Apparently it is more expensive.  I don’t know enough about the costs of having custom aluminum tanks made up to compare the expenses but I would just have to imagine that it might be worth it to market the boat with higher storage capacity.  You can almost double tank sizes by removing all the wasted space caused by “drop in” tanks.  Even the polyethylene tanks are huge space wasters, though I do give them credit for wasting less space than metal tanks since they can be molded to pretty much any shape one would want.   Check out all this wasted space around our water tank in the forepeak:

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Quoting Nigel Calder again in his book “Boatowners Mechanical and Electrical Manual,” he says that integral fiberglass tanks are an ideal option and he lists the following positive attributes:

“They exploit every possible cubic inch of available space,”

“They eliminate the small air spaces between tanks and the hull in which debris and objects can get lodged,”

“If built into the bottom of the boat, they effectively form a double bottom so that if the hull gets breached in the area of the tank, the boat will still not take on water,”

“The ability to fully utilize all the available volume in the bilges often removes the necessity to place additional tanks under settee berths and sleeping berths.  This lowers the center of gravity on the boat and frees up prime storage space.”

I 100% agree with Mr. Calder and I am so happy that we finally decided to tackle this project.   The only major concern I had was the resin used to lay up the fiberglass leeching into the water.  Some people in the past have said that this can impart a bad taste to the water, others like Calder, have said that they never noticed the taste.  Taste or not, I worry about whatever chemicals might be soaking into our water supply.  Recently this is of primary concern because of our two little stowaways – as a responsible father I need to ensure that my kids are drinking 100% pure, non-carcenoyinic, H20.

With that in mind, let’s take a look at what epoxy is made up of… Most epoxies are made from bisphenol A and epichlorohydrin.  Epichlorohydrin is a known carcinogen and bisphenol A you may have heard called “BPA.”  Studies of BPA have shown that it binds to estrogen receptors and can mimic the action of estrogen.  The FDA has banned the use of BPA in baby bottles amid concerns that it can negatively affect development.  It should be noted that we are most likely talking about trace amounts and it seems that the studies are somewhat contested.  I am not sure anyone really knows the negative effects and honestly, I don’t think I would care too much if it was just me drinking the water.  However, since we do have two developing twin stowaways I want to be extra cautious.

So, what to do?  Well Don Casey, the author of the excellent book “This Old Boat” suggests in a 2011 Sail Magazine “Ask Sail” article that “there are plenty of food-grade epoxy coatings available.”  This may have been true when Mr. Casey wrote the book but I found it much harder to track down these coatings that he made it seem.  I contacted Jamestown Distributors, Defender, West Marine, and Sherwin Williams with absolutely no success.  Defender and Sherwin Williams had the best customer service and they both reached out to their distributors and companies that they thought might be able to help but in the end we all turned up empty handed.  Sherwin Williams does make a product called SherPlate PW Epoxy but unfortunately it does not flex and it will peel off inside the tank – not good.  Interlux used to make a product called Interline Epoxy Tank Coating but it seems like its been discontinued because no one sells it anymore that I could find.  I searched the web and found some industrial tank coating companies and tracked down what they used but these products were rated for massive tank sizes only, leading me to believe that they leeched another not so great chemical into the water that would not dilute enough in a small tank to be safe enough for consumption.  Finally, I came across EcoPoxy AquaPura Potable Water Coating.  Unfortunately EcoPoxy does not sell to the public.  I contacted their customer service and they pointed me to a Lumberyard here in North Carolina.   A lumberyard?  Yes, a lumberyard.  Ok, I’ll give it a shot.  I emailed Carolina Urban Lumber and politely asked if they could help me get the AquaPura.  I received a quick response and they were willing to order it for me!

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I drove down a small industrial side street in Pineville, North Carolina keeping an eye out for some wood and following my GPS.  Pretty soon I came across Carolina Urban Lumber, parked, and walked in.  The door was open but it was not immediately apparent where I was supposed to go so I slowly wandered deeper into the space towards someone that I could see working in the distance.  Before I got too far I was met by two friendly looking dudes whom I told about my special order of Aqua Pura.  “Oh, so you must be Ryan!  We don’t know what it for, but its right over there”  pointing to a shelf with my Aqua Pura 5 gallon bucket and large bottle of catalyst.  I was super excited to finally have this stuff and told them all about what its for and the boat project.  It turns out these were super cool guys and one of them had backpacked around the world and was actually following “La Vagabonde” on YouTube so he knew kind of what we were up to.  We talked for a while and I began asking some questions about wood.  I secretly love wood and would love to be some sort of woodworker one day so it was kind of an irresistible urge to take a look as some of these beautiful slabs they had lying around.



We really need a dining room table in our house so in the back of my head I thought maybe in my dreams I might have some time to make one – “how much does one of these cost” I asked pointing to a medium sized slab.  “Oh, I see, it’s written right here, $675, Ok. Cool.”   “Well, yes, that one is $675 but as a table it will cost $4,000.” he said.  I don’t know if I cursed in surprise at this but either way he could tell I was quite astonished so he offered to bring me back into he shop and show me why.  We walked past massive slabs standing on end into a back room in which a finished table resided.  “WOW – now I see why its 4 grand!”  This table was beautiful.  The guys began telling me about their story and this is where it gets really cool.

Do you know what happens when a developer comes in and clear cuts some woods for a new neighborhood or multifamily complex?

They take all the wood to the local dump and throw it away.

Yes, you read that right… they throw the wood away.  What the hell?? This is crazy.  So these guys work out a deal with the developer.  They still clear cut the plot of land but instead of throwing the wood away Carolina Urban Lumber gets ahold of it and up-cycles it into beautiful, usable wood.  As part of this deal C.U.L. makes tons of beautiful wood serving platters and each new resident gets one when they move in.  The platters are officially stamped and the owner gets a little story about how this wood actually came from the trees that lived on the land in which their house now sits.  They get to tell this story to guests every time someone comes over and they serve up some cheese and crackers and everyone gets to think about their impact on the environment.  How cool is that?  I think its really really really awesome.  The guys told me about how they really care about the stories that their heirloom pieces inspire and that if one day they are on their death bed and they can look back at their life and knew that they dedicated it to work that lives on in this way they will be happy.

Wow.  Talk about cool dudes.  I almost asked for a job right then and there because I wanted to be a part of something so cool.  I love my job too much to do something like that but I have been thinking about a way to partner with them on a project – their whole set up made me want to give them more business.  That’s not and easy thing to do as a business owner and they rocked it.

Please take a minute to check out their website at and make sure to read the “about us” section for another story that you won’t forget.

As we move along in our new video series about the fresh water tank we will do a whole episode on the AquaPura so be sure to stay tuned to check it out 🙂

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