Rare Mexican Two-Headed Yellow Scooping Crane

I was sitting at my nav station enjoying the piece and quiet when my trance was disturbed by a low growling sound. I recognized it immediately as the ill mannered feeding noises of the rare Mexican two-headed scooping crane. These are bottom feeders dredging up sediment in shallow waters. They have a large yellow articulated arm at each narrow end of their rectangular body with which they do their scooping. They have four column-like feet which they can drive into the soft bottom to hold themselves in place for liesurely feeding. They strain the water out and deposit their food in a large crop in the center of their body. Once this gizzard is filled, the crane will remove itself to deeper water where its waste is eliminated through a trap door.

In this clip we see the crane using its larger arm for feeding.

Sailors count themselves especially blessed to spot these in a marina since we know that the bottom will be kept to a depth equal to the reach of the crane's arms. In mature cranes this can gaurantee a depth of 12 to 15 feet.

The arms are also used for propulsion in a sort of skulling motion. Given this slow locomotion, it is believed that the cranes are non-migratory.

In this clip we see the crane using its smaller arm as a sweep. It is also used to aid the digestive process by moving the stored food to assure full and balanced loading.

With its lunch over, the crane removed to a spot near the shore perhaps to digest its heavy meal. One of its hatchlings may be seen nestling againt the shore. All in all an ungainly bit of wildlife.

Navionics / C-Map Electronic Charts Comparison

This is a brief comparison of the Navionics Caribbean electronics chart chip to the C-Map PC disk charts of the same area. That area is roughly Southern California, Mexico, Central America, the Caribbean, and Southern Florida--everything Virago needs for its trip from La Cruz to the US East Coast. Virago uses a RayMarine chartplotter that in turn uses the Navionics chip for primary navigation. I am installing a back up navigation system using PC-based NavSim Sail Cruiser software and C-Map Max PC charts. I've just installed the C-Map charts, so this is my first look see.

First, I looked at the Navionics chart for Banderas Bay showing the course Virago actually sailed into La Cruz marina last November. I used RayMarine's free planning software RayTech Navigator. You will notice the smaller rectangles around La Cruz, the Three Little Marys, Nuevo Vallarta, Puerto Vallarta, and Yelapa. This is a standard way to inform the user that larger scale (more detailed) information is available for those areas than for the surrounding areas. Behind the scenes, the software is using information from different and more detailed charts and allowing the user to "drill down".

Next, I looked at the same area using the same RayTec software and the C-Map charts. The colors are different, but the water/land boundary is still clear. A nice feature of the software is that you can show an area on the screen using one chart source (ex: Navionics)and then switch to an other source (ex: C-Map) to display the same area. They're synced! My first disappointment came when I noticed that there are no rectangles showing the availability of more detailed information. This turned out to be a limitation of the free RayTech software when viewing C-Maps not a deficiency of the PC charts themselves.

When I viewed the C-Map charts with the NavSim Sail Cruiser software I saw the familiar pattern of small rectangles. I was disappointed that these were present for only two areas: La Cruz and Puerto Vallarta.

I was also disturbed to see that the water/land boundary (aka the shore) was not easily distinguished. If you look closely, you can see that there are bands of blue indicating different water depths. While these do separate deep water shown in white from low land also shown in white, it is not clear at first glance. On virago, where this will be a secondary backup system I can foresee a need to use this under stressful conditions such as after a failure of the primary system. This "feature" is a safety hazard.

In addition, the font for names on land is harder to read than that used by the RayTec planning software. Since both software systems use the identical PC charts, the rendering was a choice made differently by the two software houses. (Please note that there is an internationally recognized standard for display colors and symbols to be used on commercial navigation systems. Neither software adheres to that standard.)

Then I drilled down to look at detailed information on La Cruz. While Navionics does have some large scale (greater detail) information, it is out of date since it doesn't show the two year old La Cruz Marina on my copy purchased only six months ago. This is an ongoing problem so update capabilities are important for all charts.

On the other hand, NavSim Sail Cruiser did let me drill down into the C-Map large scale chart and show me the details of the marina. I expect Navionics will catch up if it hasn't already done so. This is a good reason to cross check the available information on both chart sets.

You will also notice that the area outside the detailed area shows a grid of plus signs. This is a common way to indicate areas that have no large scale (greater detail) information available. The software just shows the same lower detail, but magnified to match the screen resolution of the detailed area.

Another test was to compare the information available for Paradise Village in Nuevo Vallarta. From Navionics we can get the large scale view of the marina with details of the slips.

Looking at the same area on the C-Map charts, we see no details for Nuevo Vallarta at all. Worse still, if we look a the details for Puerto Vallarta, we will see "Paradise Village Marina" in text right where the old Puerto Vallarta Marina is actually located. PVM has been around for over ten years so this error is very annoying!

I won't bore you with all the details, but suffice it to say that I checked out more of Virago's destinations on the trip around to the East Coast. I found that the Navionics charts presented many more large scale charts than did the C-Map charts. I suspect that when most people shop for navigation software they mostly focus on the software's features and then buy the charts the software supports. I recommend that you look just as carefully at the charts available for your cruising area. The software cannot provide what the charts omit.

This is the first line of the comparison.