Tag Archives: Techniques

The 80% Solution

80pcbagI learned long, long ago there are tools that should never be beyond reach, tools that are reached for most of the time and tools that one hardly ever touches, and storing them in the same place doubles the length of most jobs.

So we have the 80% Bag. It’s a repurposed shaving kit purchased for too much money at a Colorado Resort. It holds the 20% of our tools associated with 80% of the things that need doing aboard (Boat Tailoring/Electronics excepted). The side pocket has 5×8 index cards and a pen for remembering measurements. It weighs in at around 4 pounds and is kept in the foot-well of the nav station where we can find it by feel in a black out.

The other 160 lbs of tools used in the few remaining tasks are stored amidships halfway between bow and stern. We have used every single tool aboard at some point in 39 years of cruising. However, it is possible some have not been used in 38 years!

The 80% bag seldom has to be zipped all the way open as the most frequently contentsused tools in it tend to lay in the top. The fab five of tool-dom being: a reversible palm drive screwdriver with reversible phillips/slot apex, a small crescent wrench. small needle nosed vise grips, diagonal cutters, and a bicyclist’s socket tool.

I have my Leatherman and SOG multitools but tend to reach for them only for a few weeks after watching a MacGyver re-run.

WiFi Antennas and Tidal Fluctiation

AntennaPatternsMost WiFi installations are designed for short distances and fixed and stable environments. Most cruisers are interested in longer ranges and operate from moving (even if anchored, moored, or slipped) and unstable platforms (pitch and roll). When setting up a WiFi antenna/booster for this reality, it is useful to know when it comes to antenna gain,  more can result in nothing.

RangeAntennas are rated by decibels (dBi) — power gain — usually referenced to an omnidirectional* antenna. When increasing antenna dBi from “2” at constant transmit power, this loosely translates to range improvements shown. This range comes at the expense of reducing the vertical width of the central beam of energy coming from the antenna. See top graphic.

Where tides are concerned, let’s assume the shore-side provider wanted things to stay dry, and the antenna to “see” as far as possible. In our case, at high tide, the shore WiFi antennas (yellow dot below) for our dock will be about ten feet higher than our boat antenna. Given the picture above, the half angles of 12.5°, 15°, and 20° are worth considering, if one’s boat is close to the shore antenna, it is possible to be below these angles as the tide drops. In our hurricane hole marina, the angles and antenna geometry create the picture below:

Good

High Tide Antenna Beams (Red arrow is tide range.)

Low Tide Beams

Low Tide Beams

Three things then happen.

  1. Connection via the main beam weakens due to edge attenuation (For us, when this happens, we get an 83% signal strength reduction that lasts about three hours).
  2. Reflections off masts, and rigging and hulls more effectively compete with the main signal for the connection,
  3. Connections through side-lobes† do the same thing — In sum, WiFi services slows, fades in and out, and some folks start firing up their 3&4G hotspots to stay online.

If the marina is using a higher gain antenna than 5 dBi:

  1. Avoid slips too close to the shore antenna — 120 feet out and beyond should work, however being farther out means more mast and rigging interference.
  2. Connect to a dock antenna farther away (on a different dock) for the same reason. Also possibly better from a mast and rigging standpoint.
  3. Keep a low gain antenna (2-3 db) on hand for situations where a close in slip is unavoidable or another shore antenna is unavailable.
  4. Hoist an antenna in the rigging to approximate the height of the shore antenna

* WiFi antennae can be referenced to dipoles, but those are rare in this application.

Well made 8db WiFi antenna pattern (vertical plane)

Well made 8db WiFi antenna pattern (vertical plane)

†Side lobes (teal color) are small beams of energy caused by the interaction of wave patterns coming from the antenna. More sophisticated antennas (e.g., radar) have very complex designs and management algorithms to eliminate these and their effects.

Posted via my Android Phone because lighting fried one of the marina’s routers and the overload on the survivor coupled with low tide made it the only working connection.

New Crew Member

IMG_0027Cooking aboard takes a surprising amount of time even with a microwave, pressure cooker, gimbaled oven and a few more pre-prepared items than we used ashore. And of course there is dishwashing !&*^#^%#^. We now have a new crew member to help with the cooking.

Last month we were at the Navy submarine base south of here to buy some tour tickets, and we stopped at the Exchange to see what was what. Lo and behold, a four-quart Crockpot® on sale for $14.99 whispered, “I wanna go cruising,” as we walked past it.  (The checker actually asked if we wanted to buy an extended warranty! His trainer was standing there.)

We used our large (and automatic) Crockpot a lot living ashore because we like stews and soups and sauces and gravies and moles that take a while to develop their flavors.  This one will be used to make end of day meals less of a chore. It draws little enough running it while underway via the inverter with the engine running works fine. At 14 inches ear-to-ear, it can sit diagonally in the sink.

Last night’s Chicken Catchitorre with farfalle was proof we had reliable new galley crew.

And to make life even easier, we now have a commercial kitchen floor pad to make the Crockpot reduced standing in the galley less taxing.IMG_0033

A Conducive Day

Finally a day with conditions conducive to creativity.

  • Cooler, Check!
  • Breezier, Check!
  • Cloudier (UV issue), Check!
  • Colorful characters about, Check!
  • Low tide, so running back and forth to boat is exercise, Check! (making a virtue of bad timing)
  • Place to sit and stitch (enclosure changes, odds & ends, etc), Check!
  • Lightning, Thunder and Rain before 1400 — who let the dogs out?

“Grade D” precedes a F(ail)

I’ve been SCUBA diving since I was 13. (Somewhere there is a picture of me in a double hose rig with an old 38 cu. ft. tank.) I have enjoyed it all but a very few times. But working around a boat hull with a tank and buoyancy compensator isn’t much fun — don’t bang the hull, don’t snag the BC, don’t get bottom paint on the gear.

not the way to do it

One Breath at a Time, Not the Way to Do It!

So a few years ago, I bought what could be called hookah gear. Basically, it was a hose that allowed me to leave my tank on the boat or in the dinghy while I swam unencumbered as deeply as 60 feet (not that deep was the objective). The limitation was tank capacity. Cleaning a boat bottom can really burn through the air supply,* and I really don’t want to be hauling two 80 cuft tanks around just to make sure one is full.

So, I decided to add an air compressor to the boat. I have friends who use them, and just about every commercial boat diver I have encountered uses them. With our solar panels, running one off the inverter is no problem (neither is running the genset later to make up a deficit on a cloudy day). Pressure output and reserve tank capacity are issues, but the smallest of the “pancake” compressors out there is adequate for diving to the depth of the keel — really all I want. Diving deeper on an anchor would be nice, but now we are talking higher pressure and larger reserve, and space is at a premium. I looked at commercial hookah systems and the prices are outrageous for something I might use twice a year.  Actually at ~$1000 – $5000. they are just outrageous, period…

PancakeSo, for ~$40, I bought an oilless compressor (a widely used one for boat maintenance hookah) planning to add a NIOSH Grade-D (see below) breathing air filter to the output side using inline couplings.

Oops.

Such filtration for a single line 24 CFM system was available for ~$75 just a few years ago. That number is now between $400-800. Why? A principal material used in these filters was declared carcinogenic. It isn’t, if it’s is properly processed and packaged, but the government… The higher price tag is because Grade-D air must now be delivered via a much more complex (and very retro) filtration system — just the replacement cartridges cost as much as the entire filters used to. It doesn’t help that most of these filters support multiple lines and have bells and whistles that aren’t necessary in a fresh air supplied hookah system using electric power. So now I know why so many of the commercial units have no downstream filtration at all or claim Grade-D performance using components that can’t meet that standard.

Why does it matter? Lungs are hard to replace and once degraded they stay that way.  I was part of Texas A&M’s Hyperbaric Physiology program as a student and a lab rat (in the parlance of the time a lab rat was an experimental subject or a student who worked in a lab — I qualified on both counts). Dr. Bill Fife led the program, and I learned pretty much all there was to know in those days. It was a world of lots of experimental and anecdotal data and not a lot of underlying science yet. But many of the old surface-supplied divers of the world suffered through their post diving years with either the effects of overstaying their underwater welcome (decompression sickness) or breathing bad air. After a few autopsy photos of such diver’s lungs, I developed a real fondness for clean air. NIOSH Grade-D is a high standard. C and above are medical grade and higher. The standard is described in ANSI/Compressed Gas Association Commodity Specification for Air, G-7.1-1989.

So setting up the hookah I wanted became a case of go big (bucks, weight, volume) or go home — to properly filtered, tank supplied air.

I’m looking at where to put the tank.

*Resting respiration at the surface is 5-8 liters per minute. This can burn through a tank in about four hours at the surface. When work is being performed at the surface (scrubbing and position maintenance) this can drop to 80 minutes. When depth is considered (5.5 foot draft) a tank will be good for about 70 minutes. If one is in good condition this can be quite a bit longer ~120 minutes. In any case one bottom cleaning is going to require a tank fill

Lingering

30 April 2013, Crab Cay

We got our first rain in quite a while. It was a blow-out squall from a distant downpour. The wind might have gotten to 20 kts for a few minutes, but it really was short-lived. All but sprinkles missed us. Some hot stuff fired up over Florida, but it lost energy well before reaching this part of the Bahamas. The winds at 15-18000 feet are pretty much from the due west, so each day the trof to the north of us is in place, we expect to see this kind of thing. During a sunny spell, I took some time to add chafing gear to the lifeline turnbuckles where the genoa sheets have a tendency to rub.

By sunset the sky looked a bit shredded but stormless. The air went light and warm for a bit, then the cooling trade winds returned. Lying there watching the stars out the open hatch, we heard the first few drops of rain like someone dropping M&Ms on the canvas hatch cover. We got the hatches battened. It rained hard enough and long enough to clean off most the salt and to send us off to sleep.

Lentil soup and fresh baked cornbread for dinner.