Blogcation

I'm going to take a break from blogging for a week.

See you again in August!

bob

Closer to scrunchies

Please welcome new contributors Christy and Jason from s/v Hello World!  Christy has here a sewing project that we could all probably use at one place or another aboard...

We had some unused bulkhead space just next to the companionway. And we were always losing our sunglasses. So I sewed together a bulkhead pocket using Don Casey's instructions in Canvaswork & Sail Repair. It turns out to be a GREAT place to put all of these little things that we use all the time and want easy access to either from down below or in the cockpit: sunglasses, camera, deck key, swiss army knife, etc. And it fits really nicely behind our chartplotter which swings on an arm and caused this bulkhead to appear as wasted space - alas it is not!

I'm a fairly novice sewer (read: I used to make hair scrunchies when I was 8) and I found this to be reasonable to do. My husband makes it a habit to leave the boat when I break the sewing machine out - there tends to be a bit of swearing in any of my sewing projects. This was definitely not as hard as replacing the dodger glass, and not quite as easy as scrunchies, but closer to scrunchies than dodgers :)

It was definitely helpful to think about what we'd put in this thing before I put it together. This way, we ended up with a few custom pockets for our parallel ruler and watermaker ppm tester. With a little forethought, we were able to make it a great custom fit for the space too.

Christy & Jason
s/v Hello World
Seattle, WA

Parasitic losses

If you have an SSB, you are probably like most boats - you have an insulated backstay for an antenna.  And because that insulated backstay is not a quarter wavelength at the frequency you are transmitting (I am assuming here...), you need some kind of antenna matching network between the transmitter, which has an output impedance of 50 ohms, and the antenna, which is probably considerably less.

The impedance transformer allows the transmitter to push power into a 50 ohm load, so all is good on that side, but what is happening on the output side of the antenna matcher?  Do you have coax running from the matcher to the antenna (you do if the antenna matcher is inside the transceiver).  Well, unless the insulated backstay is fortuitously that magical quarter wavelength, that coax is *not* the isolated feedline you might expect.  Both the shield and the center conductor are active parts of the antenna system.  It is as if you replaced the coax with twinlead.  Consequently, you cannot presume that the outside of the coax is inert as far as RF signal is concerned.  That is, you cannot use the normal rules for running the coax past metallic objects.

If the coax were being fed at its natural impedance, running it alongside of a metal object (say, a rain gutter, or more particularly, a backstay) would have little effect on things.  But when the coax is fed at the wrong impedance, the shield is active.  If you run it near metallic objects, they too will become part of the antenna system.  And if they are grounded, there is a good chance that their effect will be negative - that is, they will decrease the effective radiated power.

So let's go back to that coax feeding the insulated backstay.  Do you have it tightly fastened to the lower, uninsulated portion of the backstay like our PO did?  Not good.  Tho it will be following along the path of that portion of the stay, it should be held away from it in order to minimize coupling of the signal to ground.  On Eolian, it is.  Now. 

Using a trick I learned from Tom on s/v Warm Rain, I made standoffs to hold the coax away from the grounded portion of the backstay.  These standoffs are simply 2" pieces of 1/2" CPVC water pipe that I got at the hardware store.  I drilled the pipe with a 3/8" drill on 2" centers, and then cut the pieces apart thru the holes.

The standoffs are installed using snap-ties (use black ones - they will last a lot longer in the UV from the sun) going around both the coax and the stay, and passing thru the inside of the standoffs.  This is one of those cases where a picture is worth 1000 words.

73, Bob
WA9BVE/mm2

SOG: Save Our GPS

This is a public service announcement, copied from s/v Sea Trek's blog:

There has been a lot of discussion recently on how the U.S. government could possibly allow LightSquared, an independent 4G LTE provider,  to put up 4,600 transcievers sending broadband data services in the L band with such power that could significantly interfere with nearby GPS frequencies. Possibly causing complete failure for a high quality civilian GPS like your automobile GPS, even under an open sky, and for critical units such as those used in aviation. The GPS units on our boats that we have become so dependent on can also be affected according to major GPS manufacturers that have been doing extensive testing. There has been quite a discussion over at the Panbo Website for a few months now and there is a lot of details on the current status. This morning I received an email from the Coalition To Save Our GPS with an urgent Call To Action. I think everyone might want to read this and consider responding.

With all of the twists and turns presented by Lightsquared, it may be time for all of us as boaters to voice our concern and let our Representatives in Congress know we are less than pleased with the possibilities. Here is Mary Hanley's email.......

We hope will take a moment to file your comments with the FCC about the LIghtSquared proposal. Please also feel free to share the information below with your employees, members, colleagues and other concerned GPS users. The link provided will take them to an easy-to-use express filing form. If you want to file more extensive comments at this link you can do so at this link: http://www.fcc.gov/ecfs-expert. Be certain to personalize your comments. The FCC may discount mass and duplicate submissions. The Coalition to Save Our GPS will also be filing comments. The “reply to comments” period is August 1-15.

HELP SAVE OUR GPS!

Please Submit your Comments to the FCC by July 30

Background

In January, the Federal Communications Commission (FCC) conditionally allowed a company called LightSquared to offer wireless broadband services in radio frequency bands adjacent to those used by GPS receivers.  Based on feedback from public and private sector GPS users, the FCC told LightSquared that it could not launch service until testing could be completed to determine the extent of the problems that LightSquared would cause.  The report of that testing was submitted to the FCC on June 30^th and it showed that there would be massive interference to GPS from LightSquared’s proposed operations.  The FCC has asked for feedback from the public on the report. Comments will be taken until Saturday, July 30.

What can I do?

Everyone who cares about GPS should let the FCC know about the threat that LightSquared poses.  In writing to the FCC, we encourage you to cover the following points in your own words:

·         How you use GPS technology in your business and/or personal life

·         What would happen to your business/personal life if GPS became unavailable or unreliable

·         While more capacity for wireless broadband services is important, it should not come at the expense of GPS, which is critical to our country’s economy

·         The results of the testing that were performed at the FCC’s request are conclusive – they show that GPS reception would be wiped out by LightSquared’s proposed service.

·         Now that the test results have shown interference to GPS, the FCC shouldn’t allow LightSquared to keep trying out modified versions of its plan to use the spectrum near the GPS band.  LightSquared’s operations and GPS are fundamentally incompatible and the FCC should order LightSquared out of that band.

How do I tell the FCC to save GPS?

The FCC has an easy-to-use portal on its website to submit feedback on the testing results:

(1)  Click on this link for the FCC’s Electronic Comments Filing System (ECFS):  http://fjallfoss.fcc.gov/ecfs/upload/begin?procName=&filedFrom=X  

(2)  In the box which says “Proceeding Number,” type:  11-109. It is important to include this docket number with your comments.

(3)  In the designated boxes, enter (a) your name or your company’s name, and (b) your mailing address/city/state/zip.

(4)  In the box which says “Type in or paste your brief comments,” do so.  Click “Continue”.

(5)  A review page will load listing all of the information entered.  If correct, click “Confirm.” (6)  If you have trouble, contact the FCC ECFS Helpdesk at 202-418-0193 or e-mail at ecfshelp@fcc.gov.

Mary F. Hanley

Prism Public Affairs

1825 Eye Street. NW – Suite 600

Washington, DC 20006

O: 202-207-3664

C: 202-258-9048

mhanley@prismpublicaffairs.com

www.prismpublicaffairs.com

Night site

Mike and Rebecca on s/v Zero to Cruising have found a neat little LED nav light for your dinghy. Using this, or something like it, is a good thing to do, whether required, encouraged or ignored by the local gendarmerie...

South of the litigious United States, navigation lights on dinghies become much less common. Although areas with established cruising communities may suggest that they are used, it is still unlikely that one will be pulled over by an officious Coast Guard officer for failing to do so. With that said, there are very good reasons for using lights while running in the dinghy at night. Many of the locals zip around in their boats at high speed and at night, they do so without a single light on board. A high speed collision with a boat like this, or even between two inflatable dinghies, would really put a damper on an evening. And believe it or not, we have heard that each season at least one person around here gets seriously injured in an accident just such as this. For this reason, we knew that we needed a good light.

While back in Florida we jury rigged a light for next to no money, doing our best to keep the Coast Guard at bay. The idea was OK and it was even featured on the Small Boat Projects website as a way of avoiding the “marine tax.” Sadly, it ultimately broke and we stopped using it, running instead with just a hand-held flashlight. I’m a little bit embarrassed to say that we finally broke down and forked over some real cash for an actual marine light. This one is so cool though, it’s hard not to be impressed. Red, green and white LEDs shine very brightly from the unit which runs on 3 AAA batteries. The cool feature is that the light attaches to the engine by four very strong magnets (you first bolt the base onto the engine cowling by drilling a small hole in it). We have a little lanyard attached to the light just in case the magnets fail but they are so strong, I can’t see it happening. Why this is a good feature is that the light can be removed and thrown in your pocket when leaving the boat at the dinghy dock, thwarting any would-be “tiefs.”

I should point out though that even with our super-duper light illuminating our dinghy, we almost had a head on collision the other evening with a fast-moving, non-lit dink. I don’t know what that guy was thinking! It was only my fast reactions that kept us from plowing straight into the other boat. So, even if you are are well lit, keep a good watch while out on the water. In the dark things can come on you very quickly.

Here's a link to a vendor selling these lights: Budget Marine that Mike provided.  Can you find them cheaper in your locale?

Clever Cover Up

Mike on s/v Chalice shows his carpentry and design skills again, with this cleverly designed cover:

The Cabo Rico has a lot of these oblong holes in it. Most are trimed in teak rings, and I have had to make some new ones to replace the old ones. Well there was one over the nav station, which I thought was strange. It gave access to some wires and that was all. I didn't like the look of an open hole over my head, so some creative hatch making was called for.

Oval holes.

From Update_10_30_07

I did see an idea for a way to build a hatch that would work. It was plastic and only round. So I needed to build an oval one. Here is what I did.

I removed the trim ring. I cheated a little and used the trim ring to get the inside measurements, then I glued up two boards, drilled a hole for the 1\4 inch bolt, used a forstner bit to recess the knob I was going to make. I then used a hole saw to cut the knob, sanded on a belt sander the finger grips. On the inside I made a cross piece that will press down on the hole edge. Then added two pegs to the back to prevent the cross member from spinning. I had to rough up the threads on the bolt a little to make it turn the cross member. If I didn't, then when I opened the hatch, the cross member would not rotate out of the way. The bolt was epoxied into the knob. When closing it, the cross member will hit the pegs and not spin, instead it will tighten down. One could make this fairly water proof with an o-ring for the knob and some silicon in a bead to seal the rim.

The parts.

From Update-8-17-2010

The Backside.

From Update-8-17-2010

Assembled.

From Update-8-17-2010

From Update-8-17-2010

In Use.

From Update-8-17-2010

How many holes?

Bob over on Boat Bits has posted a sobering rant that every boat owner should read.  Here is a tease - a short test from the end of the post:

So here is a quick and handy test to see if you have a too complicated (spelled unsafe) boat...

1. How many seacocks and thruhulls do you have?
2. Do you know where they all are and how to get to them in a hurry?

If the answers to #1 and #2 require ponderation of any sort exceeding ten seconds you have too many holes in your boat.

But I'd like to amplify that a little.

It isn't just that you have to know where all the seacocks are and be able to reach them..  You must be able to reach and operate them when the boat is sinking:

• It is pitch black inside the cabin because the batteries are shorted out.
• You are at sea, in a storm (of course...); the boat is rolling.
• The floorboards are floating.  This means that the bilge is under water - water that is now probably mixed with battery acid, diesel, and oil.

And under these conditions, you must be able to hold your breath, squeeze your eyes shut and submerge yourself into the water.  You must know where the valves are... by feel, and be able to operate them holding your breath, submerged in foul water.

Think you can?

Bug Screen for Companion Way Hatch

It seems that this is the time of year when folks are thinking about straining the bugs from the air they direct below for ventilation. Here's a solution that Paul on s/v Solace came up with:

In addition to our new bug screens placed on the hatches inside the boat, we came up with an idea for the companionway hatch that is easy, cheap and functionally easy to apply and use.

My wife sourced curtain mesh from a haberdashery (that is a curtain/fabric store) along with weighted line used to weight the bottom of curtains. She sewed a bungy into the mesh which sits along the top of the companionway slide and we had convenient power out sockets on which to locate the bungy hooks.

From the bungy, all around the edge, was sewn the weighted line/rope that we also bought; to give the mesh the ability to form to the companion way entrance.

Egress is now easy to just brush aside the mesh and then throw the weighted edge back over the companion way once you have made your way through.

From inside