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Old Radar, Pathfinder Plus, SL72  

 

Josh Ormsby
(@c1josh)
Active Member
Joined: 2 months ago
Posts: 3
June 21, 2020 12:23 pm  

Hello,

Been a longtime lurker, I really appreciate the site.  Now I have a real project ahead of me and I have a bunch of questions. I recently purchased a 1988 O'Day 35 with a boatload of old stuff onboard. The first and most obvious is the old radar that basically blocks the view from the helm. It's a Raymarine Pathfinder + SL72 with a backstay mounted support structure that pivots as the boat tilts. Maybe it's an old Scanstrut unit, I don't know.

I have removed the display and will be mounting an Axiom 7 MFD in it's place so that we can retire the handheld GPS to backup duty. I know I can't integrate the old analog radar into the system, but I may keep it around for those handful of days it might be needed.

My question: is the gimbaled support pole attached to the backstay worth keeping? Does it improve the radar image? Is the image from new digital radars improved with this kind of mounting?  The system seems a little precarious as it lurches back and fourth above the cockpit. I don't want to have it land on my head.

 

Thanks,

c1josh


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Josh Ormsby
(@c1josh)
Active Member
Joined: 2 months ago
Posts: 3
July 7, 2020 9:27 am  

My question: is the gimbaled support pole attached to the backstay worth keeping? Does it improve the radar image? Is the image from new digital radars improved with this kind of mounting? The system seems a little precarious as it lurches back and fourth above the cockpit. I don't want to have it land on my head.


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Ben Ellison
(@ben-ellison)
Member Admin
Joined: 2 years ago
Posts: 122
July 10, 2020 8:54 am  

Hi Josh. The performance of any marine radar is better if the antenna is level with the horizon both because the transmissions are focused horizontally and the antenna will better receive the returns you want if it's horizontal. You'll see that the vertical beamwidth of radars is typically 25 degrees, but that's graded on a curve with max power at 0 degrees tapering off 12.5 degrees up and down (and there's also some tx/rx above and below the 25 degrees). In short, if your boat is heeled 15 degrees to port, your radar is mainly aimed into the water at left and sky to the right. And the same applies to magnetron and solid-state radar.

All that said, there's always been debate about the value of radar gimbals versus the hassle, and I don't see them used very frequently on newer boats. On the other hand, if you do have ScanStrut they are well made and should include a dampening mechanism that may need adjustment. Finally, my Duffy 37 came with a Pathfinder SL72 and though long gone, it worked pretty well.


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