PBO Sketch­book

Practical Boat Owner - - Contents -

Where best to mount a radar? Dick Everitt’s il­lus­trated guide

A. The radar hori­zon is just over the vis­ual hori­zon, so if we mount the radar scan­ner at about 20ft (6m) we should see a buoy at 6 miles, and an­other ves­sel’s radar re­flec­tor mounted at 20ft (6m) at about 12 miles. Big­ger things like ships and moun­tains, which poke above the hori­zon, will show up at a much greater range.

B. Mount­ing the scan­ner where the low­ers meet the mast is a good sta­ble po­si­tion and looks right. But make sure it doesn’t mask any mast-mounted deck flood­lights.

C. If it’s too high the weight and the windage will cre­ate too much move­ment.

D. I’ve seen a cou­ple of boats with scan­ners that can be hoisted on tracks in fog. But they must be very rigid so as not to spoil the dis­play ac­cu­racy.

E. Some boats mount them at the side to be clear of sweep­ing sails.

F. Mizzen masts are ideal pro­vided the scan­ner is clear of loose top­ping lifts.

G. Radar struts are a prac­ti­cal so­lu­tion, but make sure the scan­ner is not in line with the boom. Oth­er­wise, if you have a tar­get to star­board, the bounced sig­nal could show a phan­tom one to port as well.

H. Strut kits are avail­able with brac­ing bars, ca­ble glands and adapters to fit slop­ing sur­faces.

I. radars don’t work too well if they are point­ing into the sea, so if you in­tend to be on one tack for sev­eral days it might be worth con­sid­er­ing a mount that can be pinned at an an­gle.

J. Oil-damped, self-lev­el­ling brack­ets are also avail­able, to mount a strut on the back­stay.

K. Mo­tor­boats don’t have any run­ning rig­ging to foul the an­tenna, so can have a large, open ar­ray that gives much bet­ter tar­get def­i­ni­tion.

L. Even though the ver­ti­cal beam an­gle is 25˚ some in­stall­ers like to tip the front of the an­tenna down a few de­grees to al­low for the bow ris­ing when she’s on the plane.

M. I’ve also seen these tipped scan­ners in RIBs and on fly­bridges – but I’m not sure I’d want my head that close to the trans­mit­ter for hours on end.

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