Baffles and Fresh Water Bow Tank

[Hoodsail]

Project is to rehabilitate my est 80 gal, fiberglass, fresh water bow tank. Two goals, install baffles & apply drinking water-quality epoxy coating on interior. Tank is underneath cushions of my vee-berth, with the bow making up the port and starboard walls of the tank. My short videos giving an inside look of the tank that is approximately 42" long, 21" deep (at deepest point) will not load so have to use your imagination. Tank has a 4" inspection port a few inches from its stern-most wall (see pic). Plan to cut a 2-2.5 ft x 1.5 ft section of the top off to gain access to the entire tank. Prep the inside and then apply Devoe coating, Bar-Rust 233H (thanks to James at Atomvoyage). Then fiberglass the top back in place when coating finished.

Question: How to baffle the tank? I have begun looking at plastic balls that would fit through the inspection port. Has any used these or another system?
thnks

[Orion Jim]

Since you are cutting a large access panel why not just add a 2’X1’ X1/2” baffle plate (or two) to the underside of the access panel. Maybe G10 with a fillet all around? You’d be able to bring the access panel to a bench to make the modifications so much easier than working inside the tank. Then just prep and secure it in place.
I have a bow tank of 18 gallons with no baffle but I’ve never found it troublesome. At sea I never sleep in the v-berth, and at anchor I rarely hear any swishing sounds.

[Hoodsail]

Jim, good idea and I had considered fiberglassing a baffle to the top and then reseal it. Where I was uncertain was, how many baffles do I need and their design? Is the baffle just a solid piece or do I drill holes (diameter and number?) in it? From what little I have read to date, movement of fluid is most extreme at about 50% capacity. You note in your 18 gal tank you have no baffles, so at 80+ gal do I need baffle(s)? Oh, what is G10? Thnks dave

[Pete7]

My water tank is 130L or 35 US Gal and coffin shaped length ways along the saloon berth. The GRP lid has a single large baffle going across the tank suspended completely from the lid. There is a gap varying between 1/2 - 1" around the baffle so it doesn't touch the bottom or top.

I haven't drilled into it so it could just be several layers of GRP off cuts bonded together and then glassed to the underside of the tank lid with a layer of flow coat as a top surface.

I have never heard water sloshing back and forth or side to side, so does work.

Do fit hatches so you can clean both sides of the baffle afterwards. I have the clear version of these installed for perhaps 6 years and are still air tight. They hiss if you open them whilst filling the tank. That'll do for me

Pete

[Orion Jim]

Originally Posted by Hoodsail

Jim, good idea and I had considered fiberglassing a baffle to the top and then reseal it. Where I was uncertain was, how many baffles do I need and their design? Is the baffle just a solid piece or do I drill holes (diameter and number?) in it? From what little I have read to date, movement of fluid is most extreme at about 50% capacity. You note in your 18 gal tank you have no baffles, so at 80+ gal do I need baffle(s)? Oh, what is G10? Thnks dave

Structural fiberglass board. https://www.defender.com/search.html...+board&x=0&y=0

[Hoodsail]

So Pete, your one baffle is solid, no holes, and it is glassed only onto the lid. Is your lid removable then? I have one 4 inch inspection port and thinking of increasing it to 6 or 8 inches or possibly adding a second 4 inch port to aid cleaning. I saw the ports you attached on line which look perfect.
Jim, thanks for the link, I frequent Defender regularly. Will pick up some G10 , thinking 1/4 inch, there and place one solid baffle across the width of my tank glassed onto the top. Will decide how high off the bottom the baffle will end when I get into it. Will follow up with pictures as I progress. Thnks to you both.

[Scrimshaw4]

I just checked the specs for the Devoe Bar Rust 233H that you referred to. Devoe only has a Bar Rust 235 and it's specs specifically state that it's NOT for potable water. I have a fiberglass tank that need to be partially recoated after repairing a crack and have not been able to find a Food Safe / Potable water constant contact approved epoxy coating. If anyone is aware of one in the US I'd appreciate hearing about it.

[Hoodsail]

Scrimshaw, good morning: I looked for awhile for water quality coatings for my fibreglass bow tank. A few out there are Ceram-Kote.com, Mas Epoxies, Ecopoxy's Aquapura (being tested for water quality), Brewcoat(sound specialty coatings-Burton, WA), and finally Devoe Bar-Rust 233H. I contacted James at https://atomvoyages.com/, who has used Devoe's 233H on his water tank with good result, noting it applies better than Brewcoat. Altho the specs for the 233H state only steel/masonry, based on James experience I purchased the 233H...would recommend sending him an email for additional info. I have yet to saw the top of my tank off as its been in the 20's here in CT..so more to follow. thnks

[Hoodsail]

Scrim; here is the MSDS for 233 H . it notes suitable for potable water transfer & storage. thnks

[Pete7]

Originally Posted by Hoodsail

So Pete, your one baffle is solid, no holes, and it is glassed only onto the lid. Is your lid removable then? I have one 4 inch inspection port and thinking of increasing it to 6 or 8 inches or possibly adding a second 4 inch port to aid cleaning. I saw the ports you attached on line which look perfect.

Yes, the lid is removable after undoing hundreds of screws and breaking the sealant.

Agreed, 4" isn't a lot I think mine is 7 - 8 inches which makes getting your arm inside easier for cleaning. The alternative is a henderson hatch TCL4 which will work because you have room above the tank.

Pete

[Hoodsail]

Pete, thanks and the Henderson TCL4 access ports look much better than my current access in both size & quality of materials. Will add one of those possibly two. this wkend is forecasted to be 27 F one day and snow the next, so could be a bit before i update. thnks

[Pete7]

The only thing I will say about the Henderson and they are very good, is the large o ring perhaps 1/4" in diameter must be kept squeaky clean, think camera o ring clean.

Since my tank is under the saloon seats I can't use them as they stick up about an inch unfortunately.

Pete

[Scrimshaw4]

I just got off the phone with the Devoe Tech people about Bar Rust 233H. The indicated that the product is not NSF certified for tanks under 260 gallons. I have not been able to find a surface coating for continuous water immersion that meets NSF 61 Standards for Potable Water for small tank sizes (50-150 gal).

[Stu Jackson]

Originally Posted by Scrimshaw4

I just got off the phone with the Devoe Tech people about Bar Rust 233H. The indicated that the product is not NSF certified for tanks under 260 gallons. I have not been able to find a surface coating for continuous water immersion that meets NSF 61 Standards for Potable Water for small tank sizes (50-150 gal).

Interesting project.


Given that ^^^, have you considered getting a separate tank and avoiding all that construction? Ronco makes tanks of all shapes and sizes with holes for fittings where YOU specify.


Of course you'd lose some capacity and would deal with openings to get it in, but I would suggest it would save you tons of work, and not have to worry about safe epoxy.



Either way, all the best of luck to you.

[Hoodsail]

Scrimshaw, thanks for the additional info from DeVoe...did they by chance mention why their 233H product is suitable for larger potable water tanks and not smaller ones? My first thought was, is it an issue of dilution, that being the 233H leaches into the water but at such a level that is below detectable? But with more thought that didnt seem appropriate. thnks Scrim

Stu - i spoke with the Ronco folks and I could definitely use one of their tanks but (despite ad in Defender for 50 gal) the capacity was markedly less, I believe about 30+ gallons for their pie shaped tank. Also their tank must be cushioned or chafe will affect its integrity and given my irregular space it may leak sooner than later. Ronco customer service also noted that their tanks are not baffled, at least in the 30-40 gal range. He did note that I may be able to push their 30+ gal tank thru my 4" access port, but said it would take some doing.. Also I do have a 40 gal flexible Nauta tank secured under my starboard settee, so can use that as backup.

Either way I am committed to cutting a portion of the tank top off (when it warms up a bit here, 19 degrees F today) for access. Since I have a gallon of 233H in the closet I will prep the tank, apply the 233H, and look into a local water testing lab (a bunch of them in new england given all of the pvt wells for homes here) to test for volatile organic compounds once Spring hits. Will fill the tank, let water sit in it for a wk and send for testing. I also have a canister filter in line and need to determine if that will remove any VOCs. I will check back with Atomvoyages too to get more detail from him regarding his experience w/ 233H.
thnks and stay tuned