Bleach and Aluminum Corrosion

Rev. 10-14-2014

I've got a series of 4 articles on water treatment coming out in the next few months, describing a simple approach, soup to nuts. One of the more interesting things to come of it is a treatment that seems safer for aluminum tanks. Both of these images show the worst pit after 14 days, at about 200 magnifications.

Puriclean Aqua Mega Tabs, 1 ppm free chlorine. Later I determined that I could lower the dose 4x below this and still maintain the same free chlorine due to the cyanurate buffering. Overall, the surface has been smoothed rather than pitted, with ~ 50% reduction in weight loss.

Both photos are same magnification; the bleach roughened the surface more.

So expect 10-20x less than this.

Bleach 1ppm, free chlorine.

Safer for aluminum tanks? That is my impression, particularly if the dose is lowered below manufacture recommendations to the lowest effective dose, but more confirmation work is needed.

What about hydrogen peroxide? During the writing of my water treatment articles, numerous sailors asked me to consider H2O2 as an alternative to bleach for aluminum tanks. One problem, of course, the lack of established standards for sanitizing with hydrogen peroxide. The Water Quality Association (certifying organization, similar to NSF) recommends 30,000 ppm hydrogen peroxide (3%), which is full-strength drug store peroxide, and 3 hours contact is required. Compare this to 30 ppm for bleach with a required contact time of 1 minute. There is no recommendation for routine use, but health approvals place and absolute limit of 1000 ppm peroxide, which is most likely below the effective dose. Not at all practical, and any stories of effectiveness at lower levels from cruisers are anecdotal and probably not based upon any science.

But just for laughs I did some corrosion test, using 3000 ppm peroxide for 4 days (ASTM D1384 test coupons at 65F).

No pitting... but remember this would have taken 40 pint bottles to sanitize a 25 gallon tank, even then using only 10% of the WCA recommended dose. Not practical.

• Aluminum. Minor discoloration, no pitting.
• Brass. Minor discoloration
• Copper. Minor discoloration
• Solder. significant corrosion, about like bleach on aluminum. Expect premature failure.

Compared to other products? The top image, without blemish, is Aqua Mega

 

Fresh Water Flush--a Miniature Water Closet?

Seawater contains bacteria and sulfate. Flush with seawater, deprive the bacteria of oxygen for long, and facilitative (those that can go aerobic or anaerobic) start using sulfate (SO4-) as an electron source. The result is H2S (rotten eggs) and the head stinks. The cure? Either use the head every 8 hours (thus, smell is not a problem when living aboard or actively cruising) or flush with fresh water.

But you can just plug the freshwater pipe into a manual head; water will blow through, flooding the compartment, and bugs can swim up-stream. The water closet, introduced a century ago, prevents both by employing a float valve and creating an air gap (bacteria can't fly, as a rule).

What about a miniature water closet? $38 from McMaster Carr

Made for commercial ice machines, this unit holds enough to flush 3' of 1.5 inch line--not enough for most manual heads--and refills at 0.33 gpm, or about 1:20 seconds per full flush (12 strokes or so). Clearly, a larger size, holding about 60 cubic inches, is what is needed. It could also be expanded by mounting a 1-3' length of 3" pipe under it to serve as a reservoir (4' of hose can be flushed for every 1' of 3" pipe). Mount it to a bulkhead somewhere handy and you should be good to go. A pair of valves would allow switching from seawater and isolation.

But I haven't tried it. I'm happy enough with sea flush and a rinse with potable using the shower head before going home.

Knees, Close-up and Dirty

 The protruding wire does make for some odd bumps and can be sore against pants, and kneeling on the cap is out of the question.

 
31 years ago during an informal club bicycle race I dodged a pedestrian, got into the gravel, and shattered my right knee cap into 16 pieces. It healed up well, all things considered, though it is lumpy and 20% larger than its mate. I still have some wire, the back side was rough enough that sustained cycling was out for almost 25 years, and I had some permanent weakness in my right quad; I tended to favor it.

A little rough on the backside, but the Doc says it will go the distance. Not bad for that long after that much repair.

The wire broke during the healing process, but its purpose was served. No need to remove it. Notice the spacing is less on the right side, though I may not have been standing straight.

And as a result of favoring it, I tend to come down more straight-legged on occasion, which ironically, is the opposite of a favor. Additionally, having very flat feet (feet pronate inwards), a disproportionate amount of weight is carried on the medial side, in spite of wearing orthodics for the past 30 years. A year ago I felt and heard a pop in my knee when stepping high on a boulder, heel to butt with all of my weight on that leg; I started a tear. It bothered me some, never felt right, but never caught. Then a few weeks ago, while helping my daughter move back into college, the tear spread. I felt like I was taking light loads, not moving too fast, and I never felt anything... until it tightened up an hour later. ~ 8 trips up 6 flights was too much.

A nice little tear. Though it would bear weight, bending the knee more that 10 degrees cause locking and lots of pain.

 Cleaning Up...

And a few signs of wear, but not too bad for an old guy. Should go the distance, with some increasing pain.

While it is too soon to say much, just one day after surgery it hurts less than it did. They say I can go back to skiing and all that, but I think I'm done with that; I know I can't back down from the double blacks, so I'm better off going sailing and wearing a brace, just to be sure.

But for the next few weeks... time to write, I guess.

Update, 9-13-2014. As surgery meds wore off, the pain showed up. I strong recommend getting a Breg Polar Care 500 ($168), whether insurance will cover it or not. My wife had one left over from knee replacement surgery, and this is the only way to keep ice on the knee at night. This really helps with both swelling and pain. The temperature is adjustable, but if you wear an Ace bandage on the knee, the amount of insulation is perfect for comfort. Lasts about 10-12 hours on a fill of ice. The knee version (not pictured but very similar) comes with Velcro.

During the day, packs of frozen veggies (one over, one under) are best, conforming nicely. We get ones we don't like (lima beans) so that we don't accidentally try to eat something that has been refrozen 20 times.

Update, 9-18-2014. I'm mostly off the cane, but I walk slowly and stairs are still far out of the question.Still icing (Breg) at night.

Update, 10-5-2014.  Started on exercise bike. Mowed part of the grass yesterday, but did no try to finish. A little muscle soreness today, but the joint seems fine.

Re-hooking

After about 5 years of faithful service, my collection of saltwater plugs was looking sad. One fish lost to a hook that snapped off, a little too much metal gone. Time for new teeth.

Is it worth the trouble for a few lures? These are good sized lures, $10-$15 each for 8 of them, so yeah, time well spent. About $2 for the hooks and 15 minutes work, they should serve another 5 years. It's also good to inspect the rig, trim the end off, and tie new knots.

Other lures are generally just replaced. Jigs are cast in one piece, and generally the skirt goes first. Blue fish hose eels are generally too chewed up to worry over, and the stainless hooks last forever.

Boot Drier

A few days ago I was following a thread on a sailing forum regarding how to best dry a pair of high-dollar leather and Goretex seaboots. Suggestions from experts ranged all over, but missed that most obvious answer; a boot drier. Perhaps this won't resonate with warm climate folk, but it should; I've seen enough mold and mildew in Florida to make it the state plant... if it were a plant.

I built this one15 years ago in an evening, for the specific purpose of drying wet snow gear, but it has certainly been used far more for rain soaked gear.

Even the most sodden boots, shoes, or gloves are dry, warm, and fresh in a few hours. Odor is eliminated, as there is no chance for anything to grow. Wet gear has a proper place, and space is conserved since less gear is needed. The materials came entirely from the might-need bin, but I suppose it could be built for $30 if everything were purchased. It could be made longer, for a larger family, with very little change in cost.

The fan provides just enough flow. A bit of flashing creates an internal baffle, directing all of the air flow over the bulb before it goes to the pipe outlets. A 60W bulb seems to provide just enough warmth, but a larger bulb or lamp-base heater could adapt the design to larger sizes. Hardware cloth keeps small fingers and trash out. Pipes could be made longer for sea boots. The unused pipes are plugged by dropping a large bolt in the hole, focusing the heat on a reduced number of holes. The weight is sufficient to keep it from tipping over.

• 110v computer fan
• ceramic socket with 60W bulb 
• box and switch
• a salvaged cord
• 3/4" lumber and some screws
• 3/4" PVC pipe stubs
• a bit of flashing and some hardware cloth
• paint

What would I change? I should have built it for 8 pipes (4 boots + 4 gloves) to better serve 2 people. I should have made the pipes just a little longer (no so much that it could tip over) and drilled a cross-wise hole near the end (so that they cannot be blocked if the boot is sitting on the end). But Jessica is off to college, so it's really just me playing outside, and it works quite well as it is.

I've been tempted to build something similar into the boat--it's really sweet to have warm, dry shoes in the winter--and perhaps I will if I start cruising more in the off season, now that school schedules don't matter.  Perhaps something that diverts warm, dry air from the mini-dehumidifier.

Idea Drive

I get hooked on testing boating related stuff, On one hand, the projects sometimes become rather time consuming, but on the other hand, when I run out of projects I get bored, and my wife tells me that is bad.

A few of the things I have written about for Practical Sailor, not including follow-ups:

• Gasoline additives--phase separation (none work)
• Gasoline additives--corrosion (yup, some really work)
• Gasoline vent filters--best adsorbants (silica gel lasts for years)
• Gasoline vent filters--effect on corrosion (yup, helps, may be main factor)
• Diesel vent filters--effect on corrosion (yup, helps)
• Diesel additives--biocides
• Diesel additives--corrosion
• Wire Corrosion--1-year saltwater environment chamber test of spray and grease inhibitors
• Sanitation hoses
• Holding tank chemicals
• Holding tank vent filters
• Dehumidifiers and desiccants
• Joker valves and chemicals (PG antifreeze lost)
• Joker valves--field trials (Raritan won)
• Glycols--winterizing, burst point, and corrosion
• Glycols--biological fouling resistance
• Glycols--engine coolants
• Whipping twine
• Sewn splices--strength testing
• Abrasion resistant line coatings and chafe guards
• Mildew preventatives, both coatings and vapor-type.
• Water repellant treatments for canvas. Long-term.
• Flexible window materials (Strata Glas etc.) and waxes. Long term.
• Water filtration--filling the tank
• Water treatment in the tank
• Water filtration--final polish at the tap
• Mantus chain hook and bridle
• Anti-mildew chemicals

A few things that are in process:

• Gaffers tape
• Soft shackles
• Battery and coolant top-off water
• One-drop oil tests
• Gasoline additives--anti-oxidation and gum
• Diesel additives--anti-oxidation and gum
• Dyneema lifelines and chafe

What topics are of interest? Test ideas? I do best when there is a chemistry angle, but I'm open to anything; if it doesn't interest me I will pass it along.

Sifting Through Old Pictures

rev. 7-24-2024

Sometimes the basement needs a little cleanup, and since a knee injury has me sidelined from sailing and heavy work, sifting through a box of old pictures was worthwhile enough.


My first boat, a Prindle 16, built about 1984. Photographed with my mother and grandfather. This was the first day sailing with my new asymmetrical chute. Because the they were nearly unheard of on beach cats, kits weren't available, and I had no money, we sewed this one from a pattern of my own design. Very fast. Later I added aluminum hiking racks, a bow sprit, and some additional roach, which really made her into a speedster that tacked downwind.

She taught me how to sail tender boats fast.

Our first week with our Stiletto 27, Cherokee Sun, built in 1981, photo 1992.  Later she got repainted, I added a chute, a bigger motor, and some limited cruising amenities.

The Stiletto taught me to sail tender boats even faster (this one tacked downwind too, with the chute), without capsize, and whetted my taste for cruising. Really, it was having a daughter that got me into cruising. (I went kayaking with my daughter today--she's all grown up and teaching 2nd grade now).

Jessica's First bluefish. Fun stuff. She taught me how to stay a kid.