Vibration mounts for 48" radar array

[crck0848]

I'm looking for a way to quiet the sound from my DRS25ANXT radar. It's mounted on the hardtop above the helm, and it makes a noticeable sound when running. I think it could be solved by adding vibration isolation mounts between the radar and hardtop. Has anybody done this?

I'm pretty sure the noise is just normal gear noise. It is not new; it has been the same since I installed the radar last year. The only reason it's a problem is that the bridge is so quiet (60-65 dB at 8 knots). When the radar is running at the low rotation speed, I don't hear it. At the high rotation speed, [EDIT] I hear it enough that it's mildly annoying.

You might be able to hear the sound in this video clip.

 

[FishTech]

You are correct, that is the normal tone for our radars. Using a sheet of neoprene or cork between the radar and mounting surface will do wonders to dampen the sound when it reverberates in/on tops like yours.

 

[crck0848]

Thank you @FishTech -- that makes total sense. Neoprene will add a little bit of compliance plus some damping, but the unit will still be firm and stable in rough weather. Excellent solution.

 

[crck0848]

Well, I've done what I could and didn't have much success.

This was my quick-and-easy first attempt: On the inside of the hardtop underneath where the radar is mounted, I applied 8 square feet of Boom Mat. It's a self-adhesive damping pad covered by a shear layer of metal foil. It helped a little at higher frequencies, but not nearly enough.

So then I added a layer of 1/4" neoprene between the scanner and the hardtop. I enlarged the four holes to make sure the studs would not touch the fiberglass. I also cut neoprene washers and put them on the underside between the fiberglass and the nuts, so the scanner is totally isolated from the fiberglass. The result: high-speed mode is quieter ... but still so loud that I probably won't use it.

[EDIT: I had over-tightened the nuts. After backing them off to be only finger-tight, it sounds much better.]

Of course, the underlying issue is bolting the scanner directly to the thin fiberglass hardtop of a super-quiet enclosed flybridge. I should probably consider other mounting arrangements such as a ScanStrut mount, although I hate adding more height to the boat.

In the meantime, I can always disable high-speed mode so the radar always runs at 24 RPM.

 

[gtstang462002]

I just turn my stereo up, lol. I have a new boat that I am fixing to a mount a DRS25A-NXT radar on top of a scan strutt only because I have one to mount it to. I will let you know if this helps with this boat. On a side note, the old raymarine that I took off that boat was noisy as all get out when I put it on a boat that I am getting ready to sell and I didn't hear it all on the ocean that I took it off of.

 

[gtstang462002]

Finally got the radar up on the scanstrut. It is a little quieter than my other boat that is mounted directly to the hard top, but only marginally. I would say the juice isn't worth the squeeze just to try and make it a little bit quieter. My goal was really just to get the radar up as high as possible here for finding birds and I already had the strut that the previous owner had mounted a Tracvision to and planted it directly in front of the radar that was bolted to the hardtop.

 

[crck0848]

Thanks @gtstang462002 -- good to know.

With my neoprene mounting, I had initially overtightened the mounting nuts. I backed them off to finger-tight (locked in place by a second nut) and it helped. I still notice the sound at high speed, but it's much better than before.

Also, I now run the radar only in low-speed mode unless I'm in a situation that really needs high-speed (such as a narrow channel or tight marina). At low speed, the sound is totally hidden by engine noise.

 

[Quitsa]

Thanks @gtstang462002 -- good to know.

With my neoprene mounting, I had initially overtightened the mounting nuts. I backed them off to finger-tight (locked in place by a second nut) and it helped. I still notice the sound at high speed, but it's much better than before.

Also, I now run the radar only in low-speed mode unless I'm in a situation that really needs high-speed (such as a narrow channel or tight marina). At low speed, the sound is totally hidden by engine noise.

I appreciated your recording. Every so often I think there is something wrong with the motor or gears on my DRS25A-NXT. I have had it for three years and of course after a while, it is hard to remember whether it made the same noise when first installed. Yours sounds exactly the same as mine so I guess they are all that way. I have a similar situation with the radar mounted on a hard top directly above the helm. I might try putting neoprene under the pedestal like your did. It should be pretty easy.

I am thinking of using thick neoprene washers instead of sheet.

 

[crck0848]

@Quitsa - yes, you could use neoprene washers instead of a sheet. Use them above and below the fiberglass, and enlarge the holes so the studs can't touch the fiberglass at all.

 

[gtstang462002]

It is definitely the harmonics of those large radars. I have 2 of them and they both sound the same. One is swinging a 4ft stick and the other a 6.

 

[Quitsa]

Now it's been maybe 7 years but I would swear that the DRS12A magnetron I had on my old boat was quieter and made a more uniform sound. It was also mounted on the hardtop above the helm.