Stupid question: are the larger radomes better than the smaller ones, and if so, why?

F

Foulweather Jack

Member
On another thread, I've corresponded with the very helpful administrator of this forum about the possibility of upgrading my old, 2007 era Furuno system with an older analog radome. I've been told that if I go with the newer MFD, I would need a new radome.

Can anyone explain the difference between the 19 and 24" models?

About me and my boat: I have a 2007 Boston Whaler Conquest 235 that I use for inshore and nearshore trips, mainly taking family to the barrier islands on the coast of Georgia. I'm not a hardcore fisherman or cruiser, but would like to have better radar for those rare times during a storm or when I get caught out at night.
 
If you look at the specifications for the solid state 19” and 24” dome radars, you will see that the only difference between them is that the beam width of the 24” is 3.9 degrees while the 19” has a beam width of 5.2 degrees. This is a function of the antenna width. It means that if two targets are close together, the 24” will show them as two distinct targets under circumstances in which the 19” will show only one. It also means that the 24” might show smaller targets that do not appear with the 19”.

It isn’t quite so simple because both sizes have advanced signal processing that is supposed to allow them to have better resolution than the antenna size would provide and their “enhanced” resolution is supposed to be similar.

As with many things in life, with radar bigger is always better, however. If all you need is to see other boats, land, and aids to navigation, either one should do fine.
 
Domes use less power as their shielded array doesn't have to fight the winds. As Quitsa says, the larger the array, the better the eyesight. Via post processing some of the models offer Rezboost that can help the target separation making it like a small open array. While Rezboost is useful on domes, it is almost unnoticeable when using that feature on open arrays. The 19" with Rezboost will serve well particularly for those who lack the space for the larger 24".
 
Big open arrays have more detail from the smaller beam width. Coastline detail, boats versus nav aids, etc.. More gain from the bigger antenna array = smaller beamwidth, more range.
Dome radars are better protected; all moving parts are safe and dry inside the dome. Dome will be less sensitive to boat motion as well due to the less fussy beam shape.

Newer NXT (solid state) radars do a nicer job at having the picture look good at all ranges/distances. Traditional magnetron (including analog) radar often need some adjustment to look good at various distance ranges.
 
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