GPS Location advise needed !

[Leolotowycz]

I am a coastal sailor in south west Florida. I am in the process of setting up my boats electronics. I use open cpn on my laptop for navigation below deck and have. A depth instrument in the cockpit. My question is do I need a GPS device in the cockpit or just rely on my laptop below deck? Maybe a hand held in the cockpit also.
Thanks for any advice given.
Leo

[chuckr]

I am not sure what you are talking about. Are you talking about charts or using your laptop with OpenCPN as your chartplotter? We have a Raymarine chartplotter but back it up with 3 different computers that run OpenCPN as backup. One is a tablet. We have had a couple of occasions when the Raymarine failed and we simply brought up our laptop to navigate by.


As for the gps signal - we have a Hamlet Bluetooth antenna that feeds the laptop and OpenCPN

[Alan Mighty]

The general rules for locating a GPS/GNSS antenna are few:

* have a clear view to the horizon in all directions
- meaning that nothing that is opaque to the satellite signal is around

* be oriented parallel to the horizon
- for a monohull sailing boat, that usually means to have the antenna in a low position (as opposed to, say, installing a GPS/GNSS antenna at the masthead, because the masthead (a) may move as the vessel pitches and rolls; and (b) not stay horizontal (i.e. when the mast is not vertical, the surface of the masthead is not horizontal).

I assume that your laptop has a GPS/GNSS antenna, right? Either an internal antenna or something like an antenna that plugs into your laptop PC via a USB port, right?

In that case, you can easily check whether you can use your laptop below decks. All you need is an application that tells you the number of GPS/GNSS satellites that you are receiving and the quality of the signal.

Let's say your laptop PC runs on the Microsoft Windows operating system.

You could search for and download the free app VisualGPS View (VisualGPS, LLC).

You could then check the number of satellites and the signal quality with you laptop above decks.

And then take your laptop below decks to wherever you intend to use it. And do the same check.

If the number of satellites and the quality of the signal is reduced below decks, then you might need to consider mounting a GPS/GNSS antenna above deck.

If you're using a USB device for GPS/GNSS signal reception, that might be as simple as using a USB-USB lead so you have your laptop below deck and the GPS/GNSS device above deck. Or using a Bluetooth GPS/GNSS device.

[fgd3]

Laptops tend to be a little fragile for installation in the cockpit. My approach is to run OpenCPN on a laptop below deck with a cheap USB GPS puck. I keep a hand held GPS in the cockpit. When I am cruising I use OpenCPN to plan my next day's run. Then I connect the hand held GPS to the computer and upload the route(s) for the next day. As long as I can stick to the planned route the hand held GPS in the cockpit is all I need. If I need to change my plan I duck below and check the OpenCPN chart on the computer.


My hand held GPS doesn't have a chart display. Newer models do, so trips below to check the OpenCPN chart can be less frequent.


Fabbian

[svHyLyte]

Originally Posted by Leolotowycz

I am a coastal sailor in south west Florida. I am in the process of setting up my boats electronics. I use open cpn on my laptop for navigation below deck and have. A depth instrument in the cockpit. My question is do I need a GPS device in the cockpit or just rely on my laptop below deck? Maybe a hand held in the cockpit also.
Thanks for any advice given.
Leo

Leo--

FWIW we have two chart plotters aboard as well as a lap-top to run navigation software at the navigation station. Our primary chart plotter is a Garmin 3206 on the bulkhead directly above the nav table. In the cockpit we have a smaller 3205, adjacent to the binnacle, to assist with steering, primarily for my (much) better half when she's "driving" while I am handling something or another as, for example, I can simply ask her to "follow the arrow" rather than saying "steer 305º" or whatever. (I favor steering by a compass heading as that was how I learned to sail but she, having come to the sport/avocation much later, is more reliant and comfortable with the chart plotter and particularly the "arrow pointer" or "street view" modes.) The helm station plotter or Table, mentioned hereafter, also spares one's 'puter the ravages of exposure to weather.

While some may disagree, and several of my friends/contemporaries (i.e. other "old farts"), are adamantly opposed to having a chart plotter at the helm, I have found having both alternatives very useful. Both plotters have cables/plugs allowing them to be connected to our lap-top as well as can a small hand-held "back up" GPS/Plotter we keep at the nav station and take aboard the dinghy when we're "out and about".

If you are only now installing electronics, much of the new gear includes "Blue Tooth" or "Wi-Fi" capability that would enable you to use an Apple or similar Tablet at the helm station obviating the need for multiple chart plotters although there is a certain merit to having "redundancy". As for antennas, the current offerings all seem to work well below decks save perhaps on all metal yachts which saves one a lot of aggravation with the installation of the equipment.

Again, FWIW...

[Checkswrecks]

Originally Posted by Alan Mighty

The general rules for locating a GPS/GNSS antenna are few:

. . .
* be oriented parallel to the horizon
- for a monohull sailing boat, that usually means to have the antenna in a low position (as opposed to, say, installing a GPS/GNSS antenna at the masthead, because the masthead (a) may move as the vessel pitches and rolls; and (b) not stay horizontal (i.e. when the mast is not vertical, the surface of the masthead is not horizontal).
. . .

Two minor points of clarification.

1. If the angle on deck changes, the top of the mast will by the same amount, assuming the mast is not loose. There are at least three actual reasons an antenna is generally not mounted at the top of the mast, although it can be made to function. Installing the cable is troublesome, it's a long run for a GPS cable which can decrease signal and increase potential interference, and some (mostly early) GPS units would pause with sudden fast movements, such as the top of the mast swinging back and forth.

2. The GPS antenna has fastest initial satellite acquisition if mounted level, but once acquisition is made, the antenna does not care about orientation. In aviation, the GPS remains accurate even if an airplane is upside down.

The GPS works by timing signals from more than one satellite. When acquiring the first satellite at start, it "assumes" it is level so it knows where to look for a second and then third satellite. If the antenna is tilted, then it looks in the wrong place. It'll eventualy find other satellites by slowly increasing the search, but this can slow start-up from seconds to many minutes.

Not mentioned and also important is keeping GPS antennae with a clear view of the sky and away from other electronics. Probably the best antenna guidance without getting too technical is below and it has distances for antenna spacing.
https://www.nmea.org/Assets/nmea%20a...ion%202011.pdf