Furuno GP-33 GPS review by Jedi :)

[s/v Jedi]

I have been enjoying the reliability and stability of the Furuno GP-32 GPS for years after having countless problems with the Raytheon units. That unit is for sale now that I switched to the GP-33 because I need a N2K interface now.

The very nice thing is that the GP-33 comes with the exact same antenna as the GP-32, meaning I could just unscrew it from the old unit and put it into the new unit, without pulling cables, modifying antenna mount etc. The GP-32 now sells with a brand new antenna because I didn't even have to take it out of the plastic wrap. This alone was reason enough for me to select this unit.

The rest of the installation was very easy for me too. I mounted the included bracket under a shelf at the navstation, connected a standard N2K cable and the existing antenna cable and popped it into the bracket. The old power/data cable could be removed completely.

I am comparing the features and performance of this unit with a Maretron GP-200 sensor (no screen) as that is what I have. In general, the Furuno reports somewhat lower signal levels even though it has the best antenna position.

Compare to the Maretron sensor:

(the Maretron is a sensor without display... it's status is shown on a Maretron DSM-250 display here)

Also visible is that the Furuno is using 9 satellites while the Maretron is using 11 satellites and thus getting a higher precision, estimated at 3.1 meters vs 15.6 meters for the Furuno. Both units have been active for more than 24 hours when I took these shots within a minute of each other (sats in same positions show that). Both units have a lock on a WAAS satellite but these do not transmit correction data for my position, so they can be ignored.

Okay, on to the available screens. Let me start with a couple that are totally useless imo:


These are speed and course over ground graphical presentations that I will never want to see. I'll try to get rid of them. On to the better screens:

This is the plotter display. I like it but it is just a fancy version of otherwise the same as the GP-32 had. I would want to see lay lines here for example... which the "remote data" RD-33 display can do by the way!

Here we have the highway display. It's perfect in my book. This exact same display is available on the RD-33 remote display and will be used in our cockpit to guide the helmsman when close to reefs, jetties, sand bars etc.

This looks to be a good default display while underway. It shows everything except position itself. Note the red triangle on the compass heading graphic, showing where the waypoint is. These triangles and/or dots are very popular with all the display designers at the moment and they are indeed very handy when you know what they mean.

Every GPS has this display of course but I include it anyway

N2K When I compare the output from the Furuno with the Maretron, I find that HDOP and accuracy are missing from the Furuno, but I am not even sure if these are in standard PGNs or in vendor proprietary PGNs. I can not display this information on a Furuno RD-33 display so I used the Maretron DSM-250 instead.

Verdict from the Jedi council: A very nice GPS + screen unit which will continue the reputation of the old GP-32, sold for around $470.- . Furuno also sells a sensor, named the GP330b, which is an Airmar unit and it would be nice to compare this with but I unfortunately do not have that unit. The GP-33 does not come close to the performance of my Maretron GP-200 sensor, which is still the sensor to beat IMO. This Furuno is my backup GPS.
If money is no issue, I would opt for a Maretron or Furuno N2K GPS sensor and use the Furuno RD-33 display. This results in better performance, more options such as lay lines (when wind data is also on N2K network), but at much higher cost of course.

ciao!
Nick.

[s/v Jedi]

Also visible is that the Furuno is using 9 satellites while the Maretron is using 11 satellites and thus getting a higher precision, estimated at 3.1 meters vs 15.6 meters for the Furuno.

After more studying of the manual I found that the 15.6m number on the Furuno is actually the height above sea level according to WGS-84, and not the accuracy Furuno might want to make this clear on the display

With some math using the dilution of precision info, I put the accuracy of the Furuno at 4.96m compared to the 3.1m of the Maretron (DoP 1.6:1)

I did find the 15.6m a bit much although I never expect better than 15 meter outside WAAS coverage.

cheers,
Nick.