Source of Waypoints

[Warren Milberg]

In helping a newish sailor get started with his first boat, we discussed the source of waypoints for his newly acquired GPS. I mentioned my concern about depending on any waypoint that I did not personally enter from, or verify off, a paper or electronic chart. Planning for a circumnavigation of the DelMarVa penninsula, I had used someone else's routing waypoints some time ago and some had been incorrect. Luckily, I noted the errors before they became a major navigational mistake. I have never used anyone else's waypoints since.

What is your source for waypoints for your GPS? If you depend on electronic charts, do you ever verify the waypoints on them?

 

[Dan Johnson]

Warren...

When I bought my chartplotter GPS, I set up routes to the upper and middle bay locations I expected to sail to. Several routes end at points near where a choice of further routes can begin. This was done using the nav chip's chartography. I have since sailed a number of the routes and validated the waypoints placed by sighting out ranges or proximities to channel markers etc. I have yet to make it as far down the Bay as your neck of the woods where I grew up in the summers, but one of these days I'll validate them as well.

I would agree with you that trusting waypoints established by others is a bit risky without perhaps verifying them on paper charts before entering them in the GPS's database.

 

[Stu Jackson]

There are many resources out there

for waypoints, but, like all navigational aids, don't rely on only one, especially if it's not your own.

Most of our waypoints for local sailing were loaded into our old Magellan Blazer years and years ago and documented on a spreadsheet. I've checked them against the Local Light Lists and LNMs.

Once we got our Garmin GPSMap 76Cx I cross checked a few against the handheld and the Map Source software.

Most are close enough that the movement of the buoys with current and the offset of the GPS accuracy itself are just fine for use.

I continue to navigate with simple triangulation to assure that I am where I think I am.

While sailing on Saturday and checking my track against the "chart" on the Garmin charts, it showed me a lot closer to the rocks than I really was! I'd never use one of these things to get me back into my slip on a dark and stormy and foggy night. And I question anyone who would do so, since I've tried it in calm water and clear daylight. They just aren't MADE to be that specific.

 

[Ross]

Re: There are many resources out there

My driveway is one of my waypoints and sitting in my parked car in the driveway the GPS shows me drifting to and fro with 20-30 foot excurrsions. GPS is very good but it ain't perfect. I never enter the exact location of a light or mark usually move my waypoint about 2 seconds towards the safe side.

 

[Warren Milberg]

Ross:
About 10 years ago I was at the helm, but not the owner of a beautiful 42-ft Oyster. We were returning from a an ocean trip and were making our way up the Bay at night. The owner had plotted all his waypoints by using navaids and had ganged the autopilot to the GPS. As we plowed on through the night, I watched the GPS screen as we neared a bouy/waypoint. I looked up just as we were about to hit the bouy -- and quickly took manual control of the helm. We would have hit it had I not done so. Ever since, I have done what you do: select a navaid waypoint and add a few seconds to be safe. Sometimes, the system works too well....

 

[RichH]

Enter them yourself. If your have a chartplotter with graphical input, that job is very easy.

The DelMarVa area uses a mixed bag of chart datums .... some with WGS84 and others still at NAD29.

Mixing waypoints derived from various chart datums can lead to significant navigation errors .... do your own data entry.

 

[Ross]

I have heard of collisions between boats resulting from gps autopilot interfacing and the use of exact navaid positions.

 

[Bill Roosa]

Unless there is fog......

OK GPS is cool but in the Bay there is not much need for it except for in the fog and I'm not sure that I'd be going out in that anyway. Out in the ocean, well there is not much to bump into there anyway that is not lighted so not much to do but waypoint what you want based on where you are going.
Seriously, the bay is chocked-full-of nav markers that are visible day and night what do you need waypoints for?
I use my finger and eyeball the direction to steer toward the next turn point. Most of the turn points I use have a marker near or on the TP. Since I'm only going 7 NM at most till I see something that I can use to get a dead reckoning (DR) fix I usually don't even use GPS.
Somebody said they use GPS to find the outer daymarker (unlit) to their marina channel. Then they use a spot light to find the channel marker inside. I have found that I can find a daymark from 1.7 NM out using a 300,000,000 candle power spot and do the VFR direct or follow the depth contour around to it.
Sailing, for me, is about doing the nav from the helm and confirming with the tools available not using the tools and confirming I'm on course by not running aground.
I'm kinda courous, what are you using GPS for? Controling the AP?

 

[Ross]

Re: Unless there is fog......

Sailed out of Rock Hall on May 15 and sailed south towards Kent Narrows. The fog limited visibility to about a half mile. A check of the charts will show that a course of sw is better because it gets thin a half mile off shore about half way to Kent Narrows. Gps showed me where I was and which way I needed to steer to avoid parking in the mud 'til the next high tide.

 

[Cpt. Jon]

I needed my GPS chartplotter for comfort this weekend in the lower bay. I knew my route, but while sailing around the flats I wanted to ensure that I don't go onto the flats. I was in a well marked channel and would just set one waypoint at a time, at time it was a buoy or marker and other times not, but since we don't have autopilot yet it was no matter and the GPS was just there and tracking waypoints since I had it on for the depths on the charts. Travelling the Bay without a depth sounder on the new boat yet isn't very comfortable.

 

[Paul F]

Always check

We have a pass here called Hurricane Pass because it was made by a hurricane a long time ago. It is tight and the sand moves with the storms. Charted makers have been off for years. Even my own waypoints are off I just corrected two of them the last time through the pass. As far as using NOAA charts and plotting waypoints be careful. My favorite story is was happened to us on the Newport River going south into Beaufort N.C. We were following a Raymarine chart that is like the current NOAA chart 11543 showing an easy branch towards Beaufort. On a run moving at 8.5 kts with the current we hit the hard, hard. The real path is on NOAA chart 11545. Here are the links if you would like to look http://www.charts.noaa.gov/OnLineViewer/11543.shtml
and
http://www.charts.noaa.gov/OnLineViewer/11545.shtml
also added the charts below. The point is only use your own waypoints and then check them when you next pass by them.

 

[rpwillia]

Waypoints are an aid - and just that

I enter my waypoints manually when I am there. But chart details are nice and are good for helping you look for and realize what is out there. When coming up the river (Potomac) at night it is helpful to look at the chart and realize there is an unlit nun or can out there so you can look for it briefly with the spotlight. That is why they call them "Aids to Navigation."

One trip I helped a guy bring a trawler up from Moorhead City, NC to Solomons Island, MD. He had a laptop and GPS that he kept trying to drive the boat with. One time he kept insisting I needed to turn right then, and I pointed out to him the "F@#$*&g buoy was off our starboard bow about 100 yards. Still didn't have a clue. And, did I mention he was a lifelong power boater?