Tag Archives: Comms

Pacing the Snail

Since we returned from Texas via Annapolis, the weather hasn’t been conducive to crossing to the Abacos. This season has been plumb remarkable in that regard. So we decided to do some (more) mods.

Helix

GlobalStar external antenna awaiting wires.

We have added equipment to boost our satphone performance four-fold, and have ordered Satellite TV. Both installations require snaking cable through the seat locker, and I only want to unload that area once, so we are stuck waiting for the TV antenna, receiver and associated stuff. This is our second approach to satellite TV afloat because we decided we did want to be able to receive while underway offshore.

ProtoBase

Prototyping TV antenna base using dowel and corrugated board rather than the measure thrice and cut once stainless tube and aluminum plate. Don’t you just love cable ties?

Seems American Express has a policy we didn’t know about. If you want to ship “big ticket” (they don’t have a set $$$ for this) items somewhere other than your billing address, that shipping address has to be on file with Amex. Finding this out after we placed the order cost us a shipping day, and that cost us a weekend of waiting (although severe weather truncated Saturday work hours).

Ready for aluminum plate and antenna.

Ready for aluminum plate and antenna.

In the mean time, we have done all we can to make it just a “tighten some bolts and snake some cables” task. Marine Connection Liquidators in Fort Pierce, BosunSupplies in Arnold, Maryland, and OnlineMetals have made it possible.

The weather report still makes crossing an iffy prospect over the next seven days, and the diver doesn’t come to scrub the hull and lube the prop until Wednesday. After that, Fort Pierce and Lake Worth currents are favorable 7, 8 & 9 April so we have our fingers crossed for good wind and no more government SNAFUs.

A TRICK. If you want a 1″ stainless tube a bit longer than cut and don’t want it depending entirely on the set screw, put 1/4″ x 1″ washers in the bottom of the end fitting before inserting the tube and tightening the set screw. The same can be done with the appropriate washers for 7/8″ tube and 1-1/4″ tube.

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.

Noises Off

AISOFF2For those of you following us via Automated Identification System (AIS) sites on the web, we have shut the transmitter down for the first time since 1 October 2012. We will transmit again whenever we move the boat (especially in this busy harbor).

Likewise the SPOT Tracker is off (and has been for a while). There is a good chance we will be replacing it with more capable technology.

Cap Goes for A Swim

27 April 2013, Powell Cay

Janet suggested we sail back to Green Turtle Cay to take advantage of the WiFi there and then sail up to Powell Cay while we had a few days of good winds for anchoring there. And so we did. We reached to GTC with staysail and main. From there to back NW to Powell we used the genoa only and kept a steady 7 knots on the meter. The weather was absolutely gorgeous; nearly clear sky, turquoise everywhere and 17 to 22 knots of wind. I know that seems a bit much, but after decades of Chesapeake light summer airs, it is nice to be sailing where, even when the wind is near 30kts, the configuration of these islands and cays can make for some great sailing. The breezier it gets, though, the fewer boats we see.

At our furl the sails point, my ball cap blew overboard on a gust. We hit the Man (cap) Over Board button on the chartplotter and fell off the wind to furl the genoa. That done, rather than follow the chartplotter course back to the cap’s assumed position, we motored slowly along the track we’d made. Two minutes later and 50 feet from the MOB waypoint, Janet hollered, “Slow Down,” and she scooped the hat from the water with a boat hook. The cap was bouncing along the hull.

Why didn’t we follow the chart plotter’s suggested course? It would have brought us back to the cap with the waves right on our bow — cap on crest, see it, cap in trough, miss it. By backtracking, we had the waves abeam and could look along the tops and troughs, increasing our chances of seeing the cap. Still, eagle eye (literally) Janet only saw the khaki at our bow! Usually I wear bright yellow caps — the better for waving at folks. But my favorite isn’t so bright any more, and I got it in Alaska. Time for a new one. Chicken with stuffing and green beans for dinner.

Unexpected Progress and “Why Fie!”

Leaving the Abacos and Hope Town is not easy. The place has a magnetic attraction for us. Much of that is built upon what these places don’t have*. But we had it all laid out – go to Marsh Harbour on Wednesday for a Thursday hair stylist appointment, hull scrub, and incidental provisioning and then start slowly making our way west as the winds and seas allowed.

First, Wednesday, Janet says, “I’m going to call the stylist and cancel, this can wait till the States.” OK. Two hours before high tide at 1200, we pulled away from the Hope Town Marina dock having said goodbye to all our new friends on the staff. Seriously, friends.

Fourday001We zigged and zagged our way out of the narrow harbour channel and shallow approach and set course for Point Set. There was more wind than we expected, but the water was about as rough as shag carpet – transparent turquoise carpet.

As we rounded Point Set, Janet said, “If it’s this benign in here, it can’t be too bad at the Whale.” I radioed an open query for information on the Whale, and a charter fishing captain came back with, “2-3 and nice.”

I called the marina we were headed for and canceled and asked them to let the fellow who was to have scrubbed our hull know that we had done so. We set course for the Whale. We sailed up to Foote’s Cay and then along Great Guana Cay to the Loggerhead Channel where the report proved correct – 2-3 foot swell with ripples.

We used the engine to come in the north cut off No Name Cay because the wind was on the backstays and had gone light. Once inside we were able to sail again, and we dropped the hook off New Plymouth, Green Turtle Cay around 1800. Through the day our boat speed never seemed to suffer, so the hull scrub may not have been needed in any case.

We didn’t mind missing Treasure Cay; we’d been there for nine days earlier. We didn’t mind missing Guana Cay; we’d been there after our snorkeling on Fowl Cays Reef. Now we have nearly three weeks to explore this side of the Whale, (Foxtown, Allens-Pensacola Cay, Crab Cay) something our late arrivals and contrary winter winds prevented in 2011 and 2012.

The water off New Plymouth was swimming pool calm and clear as the Cay lifted the breeze above us. 300 yards behind us we could see the breeze drop to meet the water. Only later did it get lumpy as the wind went more to the south. After all that sailing Janet still made salmon cakes and sauteed spinach for dinner! YUM!

Thursday dawned behind clouds that sent showers N & S of us but not across. I cooked sourdough blob Belgian waffles again, this time with diced Canadian bacon and sharp cheddar folded in as a short quick swell and lots of boat wakes bumped us around. We were happy to get going at 1400, an hour before high tide, to get into White Sound with its 340° protection. [When the wind swings either side of due south, the approach channel pushes the wind into the anchorage with amplified force, and much tacking at anchor ensues – bad juju for WiFi, see below.]

Friday we watched the world go by, and then part of it stopped by. A young couple headed ashore had an outboard malfunction, as in, no go no more. Neither would it start. They managed to grab our toe rail, and we tied them off so they could assess the situation. Deja rained vu all over us, as they were experiencing what we had last year and early this. We chatted while he pulled, and pulled, and you get the idea. They rowed back and later he got a tow ashore where he could work on a more stable platform (with shallower water to drop parts in). I passed him a can of carburetor cleaner as he went by and a couple of hours later, vavavavoom, he motored back to their Halberg-Rassy 31. He stopped for more chat.

Why, “Why Fie?” As the wind went up into the high 20s, the boat began to tack. It’s what fin keelers do. As the boat began to tack, the mast and rigging moved back and forth across the line of sight between our WiFi antenna and the hotspot about a mile and a half away. Imagine trying to watch a tennis match waving your fingers back and forth in front of your face. The antenna constantly broke lock and lost signal because it couldn’t figure out which reflection from mast or wire was the real signal. For 24 hours we managed about one minute of five connectivity. We didn’t want to go into the marina just for WiFi and wanted both water tanks to be empty before we went in for water, etc. These technologies are great, but they are fragile at the edges. Relying on them is NOT a good idea.

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*Noise, Traffic, Cold, Snow, Ice, Noise, Traffic, Cold, Snow, Ice, Noise, Traffic, Cold, Snow, Ice, Noise, Traffic, Cold, Snow, Ice, Noise, Traffic, Cold, Snow, Ice, Noise, Traffic, Cold, Snow, Ice, Noise, Traffic, Cold, Snow, Ice,………………………………………………

Satphone Realities

GSP1700We bought a Globalstar GSP 1700 Satphone and are glad we did. Several folks have wondered…why? Why not Iridium or IsatPhone? It comes down to money and quality.

Money: Our 1700 cost us $400. Our monthly plan is $30 after all the taxes are added. Our usage limits for voice and data are — NONE. When we want to use it we pick it up and use it. With an exception. The Globalstar satellite constellation has diminishing weaknesses rooted in problems stretching back almost two decades. (These are being systematically eliminated.) There are good times for making calls and bad. The overall availability for the system runs 88-90% and is improving. The graphic below shows the current effects of signal strength “holes” in coverage. The other phones: IsatPhone = $600, Iridium = $1700. For $30 a month we could buy 9 minutes of IsatPhone time or 15 minutes of Iridium.

GlobalstarAvail2

Availability over Three Days. I took out six data points where my spreadsheet was choking on subtraction across midnight, but they don’t affect the picture. There are also a few uptimes less than a minute, I didn’t take them out, but you can see where they are. Availability 88% Worst Downtime ~25 min Best Uptime ~125 min

GlobalstarAvai3

UP/Down Time Distribution over Three Days

Quality: This ties back to another post about quality = fitness for use. The Iridium and IsatPhone costs act as a deterrent to using the phones unless one’s pockets are far deeper than ours or the need is far greater. And I can testify from business usage, the more expensive phones didn’t perform any better than the Globalstar. I just didn’t have to check a schedule provided by the Globalstar Call Times Tool. For us, the Globalstar system offers the best quality at a lower price than some unlocked smartphones.