Well, that 1731 is a 4 kw unit, and a nice one at that! The extra power gives more range of course and perhaps more importantly to us small boat guys, better ability to punch through rain. The larger diameter antenna
gives better horizontal resolution as well as increasing the gain (longer range for a given power). All good things...
The power usage difference (about 20 watts greater) can be a detriment, especially on a small boat with limited batteries and generating power. However, one does not typically leave the radar running 24/7 or anywhere near that. In nasty conditions, if you need radar for safety
, you could leave the engine
ticking over to keep up with energy demands.
The weight of the scanner up on a pole may be an issue on a smaller boat, especially if she is tender
by nature. I don't know a thing about your Westerly so can't help there.
Finally, if the radar has a "time in use" feature as many do, you can get some sort of idea about magnetron viability. If it has upward of a thousand transmit hours it could be nearing its use-by date... but that is a lot of hours for a pleasure boat. If it came from a commercial
boat, lots of hours can be accumulated quickly. The rest of the circuitry is like most electronics
-- no way of estimating it's reliability
. A quick look inside to check for signs of corrosion
intrusion might be of use.
Hope that this has helped, mate!