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Author Topic:   Mounting External GPS Antenna on Small Boat; C-Map Cartography
PeteB88 posted 01-22-2010 11:31 AM ET (US)   Profile for PeteB88   Send Email to PeteB88  
[Give] advice on where to mount [an external] GPS [receiver] antenna [on a small boat like a Boston Whaler 13-footer]. I'm thinking [that a good mounting location for an external GPS receiver antenna would be] on the rail forward of the console. Not sure about where to source rail mount hardware.

I just picked up a brand new [NORTHSTAR] 650 [GPS receiver, chart plotter, and SONAR] and intend to install on my Classic 13. It does not have internal antenna. It seems like a cool unit and uses C-Map cartography. [Give me your] experience with Northstar and C-Map.

Still looking for liquid water to go for a ride. Thanks in advance.

number9 posted 01-22-2010 12:06 PM ET (US)     Profile for number9  Send Email to number9     
Those Northstar units take C-Map Max C-Cards. C-Map site is OK but not great information. If you change region to UK there are some better descriptions of the features.

You won't need a heavy duty mount so something inexpensive like this may work. Mount Link

jimh posted 01-23-2010 08:21 AM ET (US)     Profile for jimh  Send Email to jimh     
A GPS receiver with an external antenna is not the best choice for a small open boat like a Boston Whaler 13. I'd experiment with mounting the antennas for the GPS receiver under the console. It should work alright, even with the wooden top of the console above it.

I have a chart plotter with C-Map cartography. It seems to be decent. As a good example, when we were exploring the remote portions of Iroquois Bay the C-Map had excellent detail. I show some images in my review of another chart plotter which also uses C-Map in

NORTHSTAR has a good reputation; I'd consider it a premium brand.

number9 posted 01-23-2010 08:46 AM ET (US)     Profile for number9  Send Email to number9     
Would like to add I'm very satisfied with my C-Map card and detail on my Northstar and Navman units.
PeteB88 posted 01-23-2010 12:46 PM ET (US)     Profile for PeteB88  Send Email to PeteB88     
I got a deal I could not refuse on this brand new Northstar 650 Explorer. Plan is to install on the 13. We get into some pretty sketchy places with that boat especially on rivers, back channels, chain o' lakes and bayous at night [Humorous narrative of late night boating incident deleted.] We'll see how it goes - wouldn't mind being able to use the Navionics chip as needed for each boat.
dfmcintyre posted 01-25-2010 07:05 AM ET (US)     Profile for dfmcintyre  Send Email to dfmcintyre     
I'll second what Jim said about mounting it somewhere under the fiberglass. Prior to a permanent mounting my antenna, I left it on the floor of the console, found that by wedging it between a drawer liner and the surface mounted compass I got a very acceptable signal. With the antenna even placed sideways. Very little loss versus holding it upright over my head along the console.

Regards - Don

PeteB88 posted 01-25-2010 04:26 PM ET (US)     Profile for PeteB88  Send Email to PeteB88     
I guess I'll put on my down coat and heavy fleece pants and go to my storage shed and see visit my 13 and see where the puck might fit best. I'm still thinking on the starboard rail, just forward of the console.
where2 posted 01-25-2010 10:37 PM ET (US)     Profile for where2  Send Email to where2     
My first Standard Horizon CP150 had an external antenna which was a bit awkward for use on my 15' Sport. The solution my father came up with was to mount the antenna to a stub of rigid threaded PVC sprinkler pipe, which he affixed to the rear of the unit using the surface mounting screw attachment points.

It appears from the PDF manual I have found for your Northstar/Navman unit, that there are brass threaded inserts on the back of the unit which could potentially be used to mount a short PVC threaded stub to the back of the unit so that the antenna essentially becomes part of the unit.

My CP150 turned out looking like this:

Two comments before anyone asks: I turned it around so you could see the back, the antenna is not normally under the rail. We spoke to Standard Horizon and they advised against cutting and shortening the cord on the antenna, thus there is 30' of cord bundled up behind the unit.

westcoastwhaler posted 01-26-2010 06:10 PM ET (US)     Profile for westcoastwhaler  Send Email to westcoastwhaler     
Check out Edson Marine at
David Pendleton posted 01-26-2010 09:16 PM ET (US)     Profile for David Pendleton  Send Email to David Pendleton     
My Raymarine chartplotter uses C-Map cartography.

I use two of their NT+ charts, one covers Lakes Superior, Huron and Georgian Bay, the other covers the entire Mississippi and Illinois Rivers.

The Great Lakes charts are good. The River charts are just okay because they lack the multiple scales available from NOAA charts. Don't expect detailed cartography for inland waterways and backwaters.

If you plan on using C-Map for any length of time you might want to check out Club Jeppesen. I get two updated chips every spring for $89.00 a year.

More info here:

Also, there's a short explanation of electronic chart formats here:

Incidentally, Bluewater is a pretty good place for paper charts. They have almost everything and their prices are good.

weekendwarrior posted 02-05-2010 04:56 PM ET (US)     Profile for weekendwarrior  Send Email to weekendwarrior     
On my 17' I mounted my gps antenna on the inside of the stern, next to the corner where the stern meets the side by the stern rail, on a 12" pole with a swivel base. It is out of the way, shorter than the motor and I swivel it down when I put the boat cover on. It has been there for several years now and that has proven to be a great location as the signal is great and it is out of the way. Hope this helps!
PeteB88 posted 02-05-2010 11:06 PM ET (US)     Profile for PeteB88  Send Email to PeteB88     
Thanks, I appreciate the tips and encourage more ideas. The boat is in my storage shed and I need to take the unit there and check out best location.

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