12kW versus 25kW DRSA-X on Smaller Boats

[Quitsa]

A friend who is usually knowledgeable is trying to persuade me to use a 12kW unit on my boat and not the 25kW I was planning to get. His argument is that if the radar is mounted relatively low to the water -- about 9-10 feet in my case, the extra power output of the 25kW causes more spurious returns and actually the 12kW or even 6kW will be a better performer except for extreme ranges and spotting thunderstorms.

Is this a valid point? I will have a six foot array and my main objective is to have the best capability to spot birds at 4-6+ mile range. The conventional wisdom says to get the most power possible to see birds and use the 25kW. I have used 25kW radars many times but always on boats that are bigger than mine where the array was mounted 10 feet or more higher off the water. My old boat had a 6kW 4 foot array mounted about 9 feet off the water and it was quite good at showing birds out to 4 or 5 miles if it wasn't too rough. So of course I assumed more is better and was going to a 25kW until my friend gave me some doubts.

 

[Johnny Electron]

Smaller boats tend to have less space for mounting antennas and items. I see no negatives to having the 25kw as long as you don't have too many items blocking the radar and reflecting power back at it. Smaller boats with long antenna arrays might look more like a helicopter than a boat, depending on the size of the boat and selected antenna. Honestly, you can do what you want with a 12kw easy, especially with the "X" series that uses a longer transmission pulse putting 50% more power on target than previous DRS units. No company comes close to the Furuno radars and that is a fact. I have a photo of a 12kw lighting up over three states of coastline on the East Coast. I agree that a 25kw is a bit overkill for small boat especially if have items mounted around it, your reflections are just going to be that much stronger. It all depends on the install but if it is a smaller boat under 30ft, I personally would see no need to go 25kw unless you are going with another brand that needs it to keep up with our 6kw.

 

[Quitsa]

Thank you. I should have explained that the boat is not so small (38 feet) and there is already a 6 foot array with a "brand x (or maybe "g")" radar. Let's be polite and say that I really, really miss the Furuno radar I had on my old boat. It looks big but not ridiculous.

There is nothing forward or next to the radar to interfere with the transmissions. Aft there is a some pipework from a marlin tower and upper helm.

My friend's argument was reflections off the surrounding water being more of an issue with the 25kW. If there is no downside to the 25kW, my inclination is to go that way because I assume that it will give somewhat better bird returns at the outer limit of 5-6 miles. Is that a correct conclusion?

 

[Johnny Electron]

I agree with you. Worst case you might need to turn on a small sector blanking aft to prevent reflections off those items but if you do, it would likely to need to be set with a 12kw also. 38ft is a great size for a 25kw. With the bird mode on the x series, you will have one killer system.

 

[Quitsa]

25kW/6 foot array it will be. Thanks.