chartplotters

[iandodsworth]

I am about to purchase a chart plotter which I intend to install on the coach roof next to the companion way. lf I go for an integrated aerial will the metalwork of the spray hood or the boom interfere with the signal? Is an external aerial always the best choice?

 

[pvb]

Should be OK...

In most circumstances, an integral antenna will work fine. Some people even mount integral antenna GPS units at the chart table and report satisfactory results!

 

[nigelhudson]

We've just installed a chartplotter in the instrument housing above the companionway. It has an external receiver but we didn't relish the idea of threading the antenna lead through the boat to the pushpit which is the traditional location. So we installed the receiver on the top of the housing. The result is a very strong signal - we generally get WAAS quality. It would have been easier to have used a plotter with an internal receiver but the external gives us more options for the NMEA signal.

 

[Richard10002]

I have a Lowrance with internal aerial. It doesnt work much down below but, if I sit it at the top of the companionway steps, which is under the sprayhood, it works fine.

 

[gjgm]

Re: Should be OK...

bit surprised.. Im'm sure the antenna need line if sight ?

 

[Anonymous]

My Navman 5500i works fine most of the time in the saloon of my Nauticat which has a fairly thick roof. In rain and thick cloud it fails then I go over to the Raymarine external GPS that I can pick up on the NMEA bus. Aloft, I have a fairly substantial canvas and stainless canopy, with large solar panels directly overhead and it works there in all weathers.

I will be very surprised if you have a problem.

 

[Channel Ribs]

The antenna on most models will work fine with the boom and sprayhood in the way.

Which on are you considering?

 

[ditchcrawler]

I have a handheld Raymarine RC400 which works down below OK.I have bought a bigger plotter(7inch Eagle) & I have the aerial mounted on some velcro above the hatchway under canopy & it works fine.The plotter is mounted on a Ram bracket to one side of the hatchway.The Ram stuff is great & I can move the position of the bracket on the ball to suit my position at the helm as I steer with a tiller.The whole lot is removeable.

 

[macd]

Re: Should be OK...

GPS uses UHF frequencies, which are 'line of sight'. But that's not to say it has the same properties as your eyes. Some things, it can 'see' through -- as, you'll be well aware, can mobile phones, which also use UHF.

 

[Robin]

We use a Navman 5500i on the coachroof exactly as you suggest and it has always worked fine. We have a Navman 5600 at the chart table and fixed it's 'external' aerial also down below after trying it out over a number of weeks and it too works fine, in both cases the signal strengths number of satellites used are as good as or better than from another Raymarine GPS aerial mounted in the clear on our stern gantry.

 

[Dave99]

Standard Horizon CP175 is a fantastic set. If you are looking for something a bit bigger then they now have a widescreen version.

 

[Guest]

[ QUOTE ]
I am about to purchase a chart plotter which I intend to install on the coach roof next to the companion way. lf I go for an integrated aerial will the metalwork of the spray hood or the boom interfere with the signal? Is an external aerial always the best choice?

[/ QUOTE ]

For where you plan to fit the plotter - internal antena is best and will work fine ... why best ? No cables to worry about except power.
With most plotters even with internal antena / GPS engine - should it fail - it can have GPS signal / data fed from another GPS machine such as cheapo hand-held ... (I have eTrex as my back-up and have sorted connection to my Lowrance if required.)

For my Lowrance 3500C .. it is external antena and I just lodge it in window held by curtain inside cabin ... works fine.

 

[Oldhand]

Re: Should be OK...

I think the signal strength for mobile 'pones is some orders greater than for GPS so not a good comparison...

 

[macd]

Re: Should be OK...

With respect, that's neither here nor there. My point simply was that 'line of sight' is not necessarily the same thing as line of human vision/line of visible spectrum. GPS receivers patently 'see' through mediums that our eyes cannot.

 

[gjgm]

Re: Should be OK...

well, I ve learned something!

 

[Dave99]

I am sorry I have got to say this although everyone else is thinking it. VHF is "Line of Sight" due to the curvature of the earth and the fact that the waves only come out of the antenna in a vertical orientation )hence the reason the wavelength is roughly the same length as the antenna.

GPS is transmitted by Satellites! Thats why its called the Global Positioning System!!!

These days modern sets have good receivers. A fixed antenna GPS will usually receive "down-below" as the signal passes through the deck. This depends from boat to boat depending on thickness.

You will have no problem with a cockpit mount on a yacht or console mount on a RIB.

If you prefer not to have the cables etc. then buy a integral antenna version

 

[Guest]

[ QUOTE ]
I am sorry I have got to say this although everyone else is thinking it. VHF is "Line of Sight" due to the curvature of the earth and the fact that the waves only come out of the antenna in a vertical orientation )hence the reason the wavelength is roughly the same length as the antenna.

GPS is transmitted by Satellites! Thats why its called the Global Positioning System!!!

These days modern sets have good receivers. A fixed antenna GPS will usually receive "down-below" as the signal passes through the deck. This depends from boat to boat depending on thickness.

You will have no problem with a cockpit mount on a yacht or console mount on a RIB.

If you prefer not to have the cables etc. then buy a integral antenna version

[/ QUOTE ]

There's another vote for no problem !!

As to others and the VHF / Mobile phone stuff ..... you get used to it after a while ... /forums/images/graemlins/laugh.gif