One of the biggest things is are you going to use it in direct sunlight? if so the Navman 5500/5600 is best the lowrance not bad, the rest not really good enough. PBO did a really good test on all of these small plotters in 2004. see if you can get a copy
Shop around on the internet for prices... You can get up to 50% off the list price.
If you get lured by the significantly lower prices in the US, take care to specify the right (12v?) voltage of the boat.
From the 6-7in models I saw, I noted the following:
- Nobody beats Raymarine for screen quality (superior resolution and brightness). Unfortunately, their overall size is larger than others for the same screen size.
- The new Furuno GP7000 is good - fast and clear with reasonable overall size - but too deep for convenient flush-mounting. The (older) GP1850 has crappy screen with poor resolution and clarity
- The Simrad CP/CX 30 series has good contrast screens but very slow processors...
- The Standard Horizon CP175 is a good value for money. It has a fast processor and a reasonably bright screen. The resolution is average, however; you give up something when paying half price...
- The SEIWA Barracuda (or Interphase i169cs, same thing) are impressive... Very fast processor, good brightness, good resolution, and smart software. Moreover, it has the smallest overall dimensions for a 7in plotter.
Finally, check out the clearance promotions offered by Raymarine on its older systems (RL70 & 80) as they are being phased out of production (less than half price). The prices are quite attractive for what used to be premium machines; just remember to compare them to today's offerings.
I had to forget Garmin (for now). They use their own charts, and I've already paid through the nose for my Cmap and Navionics charts - I don't need a third format.
Cmap v Navionics:
I've had both C-Map & Navionics -compatible plotters. Navionics maps are better looking because the coastline is rastered with a lesser degree of detail, resulting in a smoother image. This is poor practice, in my opinion, and could even be dangerous at night.
Moreover, Cmap updates its maps more often, and I have found them to be more accurate - and have a local office with production capabilities everywhere.
All of the above plotters I described use Cmap, apart form the C and E series of Raymarine, that use navionics.
Navionics has far lower "system requirements" from a plotter, and this allow makers to save money on the chipset.
Raymarine (that sells its plotters at about the same price as everyone else) is using these savings to offer you far more expensive displays.
Geonav (a navionics company) doesnt.
For these reasons, my favourite plotters are Raymarine's C series and SEIWA's Barracuda. I decided to go with Raymarine, as I don't mind the lower detail of Navionics and I was impressed by the screen quality.
A final point:
Do consider a handheld plotter; Geonav 4c or Ray 400 (it's the same machine). There is a number of reasons:
- You can take it with you at the cafe (or home) and study your next course
- It's 3.5in screen held 10cm from your eyes in a bouncing boat is a lot more useful than a 10in screen a meter away
- You don't have to spending time bent over a fixed plotter trying to plot your course
P.S. Garmin has come our with a revolutionary bit of kit, the 3010 and 3006 that link to a series of satellites to display useful weather data on the plotted map screen. Visit their site; I love the idea.
Unfortunately, the weather data coverage is for USA only; maybe one day it will expand to Europe.
You may want to consider this possibility...