Monday, June 22, 2020

Do You Have a Buffing Wheel?

Do you have brass items on your boat?

If you do, then you will be familiar with the slow, inevitable change that comes over brass when it i exposed to moisture and sea air... it turns dark and dingy. In fact this is a form of corrosion.  And woe unto you if a drop of salt water should come in contact with the brass - the surface layer will de-zincify, leaving behind just straight copper.

So what is the solution?  Well I don't have a solution that will protect the brass indefinitely - clear spray paint works for a while.  But how do you get it shiny before you apply the clear spray paint?

One method is to use Brasso - it works and does a wonderful job (if you use the old formulation).  But it is a *LOT* of work, making it practical for only a few small items.

The solution for large items, or for a large number of items is a buffing wheel.

So, what is that?  It is a disk made up of multiple layers of cloth sewn together until the disk is 1/2" - 3/4" thick.  You mount it on your grinder (after removing one of the grinding wheels, of course).

When you buy the buffing wheel, also get a stick of Rouge - this is a wax-based polishing compound  that will give you a jewelry finish.  If your corrosion is severe, then get a second disk and a stick of Tripoli (never use a single disk with multiple compounds).  You would use the Tripoli to clean up things and then the rouge for final polish.

Fire up the grinder, touch the Rouge to the edge of the spinning disk briefly, and apply the brass.  You'll be able to tell when more Rouge is needed - polishing will slow down or cease.  This process generates heat and brass is an excellent conductor of heat - gloves are recommended. And while we are talking about safety, dangling clothing, long hair, etc must be kept well away from the spinning wheel. Since the spinning wheel will shed threads during the polishing, safety glasses must be worn.  Finally, be careful - the wheel will try to grab the fitting out of your hands and fling it at the wall with great speed. When polishing near an edge, arrange things so that the surface of the spinning wheel is moving off of the edge instead of onto it.

Light fixtures from Eolian.  The shade in the foreground has not yet been polished.
(The chances are that the brass fixture you are about to polish was originally coated with clear spray paint.  You can polish this off with the buffing wheel, but it is much faster to remove it first with a little paint stripper.)

Before spraying with the clear, wipe off the fittings with paint thinner to remove the residual wax from the polishing compound.

Well, it turns out that I have talked about this before - I am beginning to repeat myself...

Sunday, June 14, 2020

Cabin Warmth

On these early spring days here in the PNW (actual summer, with temperatures in the 70s, doesn’t arrive here until the second week of July) the cabin is mighty cold when I get up.  With outside temperatures in the very low 50s and when there is a wind blowing, the cabin temperature is not much higher than the outside.  We sleep comfortably under our (nearly) year-round comforter, but once out from under it... wow.

So it is my job to rise earlier than Jane and light the Dickinson heater.  This only takes a couple of minutes and pretty soon it is pumping out heat.  The fan installed behind the grill above the heater disperses the heat throughout the saloon and keeps the overhead from over heating. In an hour or so, the cabin is nice and cozy, and just the place for Jane to sit in her seat with a latte and enjoy the view out the windows.

Sunday, May 24, 2020

Preventing Holding Tank Collapse

Some time back I wrote a post about filtering the effluent gases coming out the holding tank vent at the stern.  As anyone knows, when the breeze is over the stern, the odor can be truly revolting, thus the need for the activated carbon filter.

It works beautifully, by the way.  Until, that is, the charcoal becomes saturated.

Then you simply discard the old charcoal and pour in a new batch.

But I digress.

While I was installing the filter, it dawned on me that, although I took many precautions to minimize the pressure drop it imposes on the vent line, those could be inadequate in one special circumstance:  When the tank is being pumped.

Holy cow - if the pressure drop was too great, the holding tank could collapse!  I don't want to contemplate what a mess that would be!  And Drew, from whom I got the idea for the filter, mentioned that he had seen circumstances where the charcoal actually reduced the H2S to elemental sulfur, plugging up the granules... even worse!

OK, something needed to be done.

I settled on a lightly spring loaded check valve installed in parallel with the filter.  Installed so that its flow direction was inbound, to allow incoming air to bypass the filter.  Here's what it looks like:

Filter with bypass check valve

I had some difficulty in locating a suitable check valve.  One without some kind of spring to hold it shut would leak holding tank off gases out the stern, rendering the filter essentially ineffective.  But if the spring were too strong, the holding tank would collapse before the valve opened.  I finally hit upon the perfect solution - a check valve designed to be installed in the "bubbler" lines in a hot tub - it opens at 1/4 psi - perfect!

Problem solved.


Friday, May 22, 2020

Starting The Season Right

Although we use Eolian year round, overnighting at the dock at least once a week, there is that special night - the one that marks the beginning of the boating season.  For us, that was last night.  We are fully provisioned and will leave the dock for 10-14 days tomorrow morning.

And every year, for the first night of the season, it is a tradition aboard Eolian that we watch one of the best sailing movies ever made: Captain Ron.

Tradition satisfied, 2020.

And following on, the next movies will be episodes of Death In Paradise.


Friday, April 24, 2020

Third And Final Hatch Cover

The first two hatch covers that I built were nearly identical, even sharing two of the three critical dimensions. The final cover, the one that covers our butterfly hatch (called that because when the flaps are open it looks like a perched butterfly, I suppose) is completely different.

This cover has two ends which are vaguely "house" shaped and one long piece that drapes from one side, over the top, and down the other side.  The old cover was in really sad shape - that long piece had shrunk up width-wise from 22" (the width of the hatch) to less than 20", pulling the two end pieces way up.  But I determined that the two end pieces were roughly the correct size and shape, so I disassembled (really easy - the thread was completely rotten) the cover and made a pattern (using Sailrite Duraskrim) from an old end piece.

An end piece pattern is made!
Then, to get the real length of the long center piece (not trusting the shrunken old piece), I simply measured the circumference of the relevant edges of the pattern, allowing an additional 2" for a hem at the bottom of each end.  Then I stitched the whole thing up using my trusty LSZ-1.

Trial fitting
The trial fitting proved satisfactory, so I proceeded with the windows, again using Strataglass.  First it was necessary to layout the location and size of the desired openings, and then add a line 1" away on the outside all the way around to make a "fold-to" mark;  to make a finished edge where the fabric meets the vinyl, I wanted to fold the edge under 1/2" for a hem.

Layout for the windows
After using a hot knife to make the cutouts and the corner notches (to allow the folding under of the hems), the cover lost a lot of its structural integrity - it became very floppy!  I had anticipated this, and so before I made those cutouts, I measured the diagonals from the opening corner marks for future reference.

To make the hems, I pre-creased the edges to the lines and then applied Sailrite's Seamstick basting tape inside the creases to hold the folds in place.  I then made another application of Seamstick to the hems, but left the release paper in place.  I laid the Strataglass over the openings, arranging the canvas so that the Strataglass and canvas were shaped properly...  using those diagonal measurements I took before I made the cutouts.  Then I carefully pulled the release tape out from under the Seamstick, fixing the Strataglass to the cloth and stabilizing the shape (the Seamstick not only serves to hold things in place for stitching, but it also serves as a water seal in the hem).  Then a double round of stitching to make it all permanent.  Lather, rinse, repeat for the other window.

Finally, installation of snaps to match the studs on the hatch completed the project.



Thursday, March 26, 2020

Solar, And Temperature

These cool, partly cloudy spring days provided me an opportunity to see the temperature dependence of solar panel energy generation right up close and personally.

In one particular instance, it had been cloudy for at least an hour.  There was a gentle breeze blowing and the temperature was in the high 40s.  Because of the breeze and the shade, my solar panels were cool.

Then the clouds parted and the sun came out, pretty much all at once.

551.6 watts

I know it's a little hard to read, but the blue system monitor at the lower right is showing 551.6 watts.

A few minutes later, the solar panels were still in full sun - that is, no change in energy falling on the panels.  Yet, here is the output:

Later, 532.4 watts

Yup, output has dropped to 532.4 watts as the panels heated up...  that's a drop of 3%.  That is a pretty significant drop.  You folks in the tropics should be able to get a pretty substantial increase in solar output if you can figure out some way too cool your panels...

(FWIW, the biggest reading I saw came later in the day when the sun was higher, and again just after a cloud has passed:  571 watts.  I love seeing that current meter needle buried!)


Friday, March 20, 2020

New Hatch Covers, Again

When we assumed responsibility for Eolian way back in 1997, she had covers for the hatches, but they were solid canvas, making it very dark down below - not an ideal situation for a liveaboard.  So we put some clear vinyl into the covers, first stitching it around the perimeter, and then cutting away the canvas that covered the vinyl.  In this way, the shape of the original cover was preserved.  When cutting away the opening, we left a 1/2" allowance which we folded under and stitched down with a second row of stitches.

But the best vinyl we had available to us in Seattle was not the good stuff, and it clouded over in 7 or 8 years, necessitating a replacement.  Which we did.  Again.  With the same crummy vinyl.

Now here we are again.  But this time the problem is bigger.  In addition to the failed vinyl, now the stitching is rotten and the Sunbrella has shrunken up.  But, in the intervening years, I have learned a few things.

Always 100% cloudy down below

Stitching is rotten too...
So now it is time for a full fresh start.  And this time, I am using Strataglass, the top of the line vinyl ($216 for a 54"x110" sheet, and worth every single penny of that.).  It is a three-part lamination, with fluoropolymer outer layers that prevent migration and loss of the plasticizers which make vinyl pliable (without the plasticizers, vinyl is hard...  records are made from unplasticized vinyl).  The fluoropolymer layers also greatly reduce UV degradation.

Some design work was needed...
  • What is the size of the hatch?
  • How big should the vinyl cutout be?
  • How long should the skirt be?
  • How big should the bottom hem be (it should be wide enough so the snaps pass thru at least a double layer of fabric)?
  • How big should the fold back hem at the vinyl be?
  • And finally, where should the seams be located?  This is important to limit the fabric thicknesses to be sewn thru.
I didn't want to make the cover from a big piece of fabric and then cut out the center (following the process that got us here via the original covers), because that would be a huge waste of Sunbrella.  So I cut 4 strips of fabric that satisfied the design criteria above, hemmed them, and stitched them together, making an open square.  (Note that I am using Tenara teflon thread - no polyester thread is suitable for outdoor service.  Polyester thread will last about 5 years outside in the sun; Tenara has a lifetime guarantee.)

It was a little tricky attaching the floppy open square to the vinyl - judicious use of basting tape saved the day.  As a secondary benefit, the basting tape sealed the vinyl to the fabric, making a water-resistant (waterproof?) joint between vinyl and fabric.

Now we need corners
Now to make the corners...  I used the procedure outlined in Jim Grant's book below.  Wrong side up, you place the square over the hatch and crease the corners.  Mark the end points of the creases, which should be the actual outside corners of the hatch, plus a little wiggle room.  Stitch up the corners at a 45° angle from the crease.  In the illustration below, Jim suggested cutting off the triangles; I just stitched them to the sides.

At this point I should make yet another recommendation for Sailrite.  All my canvas work supplies come from them (including my sewing machine!), and they are constantly giving back to the community with hundreds of how-to videos and tutorials.  In fact, this book was written by Jim Grant, who I assume to be part of the Sailrite operation which was created by the Grant family way back in 1969.

Ta Da!
Now to get the full advantage of the new, clear vinyl, I have to clean the plexiglass on the hatch itself - it is dirty and water stained from the rain, etc. that the failed cover let in.

Monday, February 10, 2020

Carbon Foam Batteries 

Recently a friend of mine asked me to opine on carbon foam batteries.  This is what I told him:
First, how a conventional lead acid battery works. There are two chemical reactions going on in the battery as it discharges... at the positive plates, PbO2 > PbSO4, and at the negative plate, Pb > PbSO4. (that's a very simplified version). But here's the rub... PbO2 and PbSO4 are both non-metallic powdery solids. How to keep them in contact with the plates (which, BTW are also made of Pb)? The solution which has evolved over the century or so that lead acid batteries have existed is to form the Pb plate into a kind of grid of fine Pb 'wires' supported by a Pb framework, one which will hopefully provide pockets where the solids can be kept in contact with the plate metal.

The carbon foam battery is a departure from this. In this battery, the 'plate' is actually a sheet of carbon foam. Carbon, because it is a (pretty good) conductor - perhaps even better than the Pb of conventional plates - and because (unlike the Pb plates) it is completely inert in sulphuric acid. But the primary benefit is that each of those millions of little tiny pockets in the foam serves to trap and contain the PbO2 and/or PbSO4 powders, keeping them in intimate contact with the plate.

How is this an advantage?
  • First, imagine a standard car battery - it is subjected to vibration all the time the car is moving. Vibration loosens the powders, allowing them to fall out of the Pb grid, to the bottom of the battery, where they are lost forever from participating in the charge/discharge chemistry, thereby reducing the battery's capacity. In fact, if enough falls to the bottom of the battery, it will create a shorted cell. Consequently, batteries are taller than they strictly need to be in order to give a little room at the bottom for lost reactants. Because the powder reactants in a carbon foam battery are more intimately contained and therefore less likely to be shaken loose, I would think therefore that its plates could be taller while still fitting inside the standard battery form factors, creating a slightly greater amp-hour capacity in the same form factor.
  •  Charge and discharge rates are determined by surface area of the plates. Not the gross size of the plates, but the micro surface area. Carbon foam has orders of magnitude more surface area per unit volume than even the best lead screen design of a conventional plate. Therefore, the discharge rates achievable by carbon foam batteries should be much higher (perhaps only temperature limited? I don't know).
  •  Battery capacity (amp-hours) is determined by the quantity of reactants available. The more reactants, the more capacity. I don't know how the reactant storage capacity of carbon foam compares to the capacity of the lead screen plates.  
  • Never forget that the sulphuric acid is also one of the reactants (not shown above). The acid needs to get to and circulate around the plates for the energy producing reactions to happen.  The carbon foam battery needs to make provision for sulphuric acid circulation in depth in the plates. I don't know how they address this issue. If acid flow channels have to be made in the foam, this will reduce the potential storage capacity of the plate.

So, carbon foam batteries should *potentially* have higher capacity and greater discharge rates, but whether this can be realized in practice will be dependent on the specific mechanical design of the carbon foam plates. This is an interesting technology to watch as it develops...  
Maybe someone out there with knowledge in the industry could comment?


Friday, February 7, 2020

Otter Exclusion Technology, Mk II

Well, so far, so good. I hope I'm not jinxing things by reporting this...

The Mark II version of the otter exclusion technology seems to be working.

First, one or two mothballs tucked under the lines where they are wrapped on a cleat seems to be working to discourage the otters from viewing these as their personal toilets.  This is a HUGE gain!

Our lines - see the moth balls?

The boat we share the finger pier with needs them too
...All the cleats on our finger need to be provided with moth balls if we are to discourage the otters from enjoying this finger pier.

But this seems to be the piece d' resistance... 

The first time we checked after installing these, the two big rat traps had been tripped.  No otters were apparently harmed, since there was no blood.  But those traps make plenty of noise when they go off - perhaps that was enough.

Now, a couple of weeks later, the traps and the boat are unmolested!

As I said...  So far, so good...

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