Understanding Radar

[weephee]

I recently purchased a 38' sailboat that used to have radar but its gone. I need to purchase another one but I can't afford a new so looking for used. The boat came with a Garmin 742xs so it needs to be compatible with that. Would a garmin GMR18HD work. I think the 18 is the diameter of the unit. Is 18 a good thing vs. 24 Could someone explain the 4 KW rating to me. Thanks

[tkeithlu]

I can't speak to the switch.

An 18" dome gives less detail - a bigger smear - than a 24. The wider the antenna, the smaller the angle of the beam, ergo, more detail.

KW give you range. 2.5 is minimum, 4 is better, basically seeing something big at long range. 2.5 will run out at about 16 miles and 4 at about 24.

If you are replacing the whole thing, consider the Furuno or Garmin wireless domes. I combined a Fununo with a refurbished iPad as a receiver for under $1,000, and like it. It's easy to install, because all you need up the mast is a honkin' big 12v DC pair.

Congrats on the new boat and good luck with the project.

All of this is bottom end radar. On your boat it's fine. You're not going to hit it any time soon, so you'll probably use the longer ranges only to keep an eye on the shoreline.

Learn to use it by running it in full sunlight, comparing what you see in the radar with what you see with your Mk I eyeball.

[contrail]

Garmin tech support can and will give you a factual reply.

[weephee]

Thanks for the replies. Great information