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Bertram 31 radar signature

Posted: Jan 19th, '19, 14:12
by Amberjack
Last summer when transiting Cattle Pass in fog I was surprised by two boats coming through at 15-18 knots. Visibility was varying between 100-150 feet when they passed me in the opposite direction so they were navigating primarily by radar. My old Furuno was OK for big targets, not so good for smaller boats, but my new Garmin seems pretty crisp and detailed. Does anyone know how our B31's show on modern radar?

Re: Bertram 31 radar signature

Posted: Jan 19th, '19, 21:20
by Tony Meola
The low profile of the 31 makes it a difficult target to pick up especially in heavy seas. I have always considered lining the inside of the bridge overhead with copper or somehow install a radar reflector up there.

Re: Bertram 31 radar signature

Posted: Jan 19th, '19, 22:27
by mike ohlstein
A couple of radar reflectors above the headliner, if you have one.

Re: Bertram 31 radar signature

Posted: Jan 20th, '19, 08:23
by moguls2go
mike ohlstein wrote:A couple of radar reflectors above the headliner, if you have one.
Mike, are you talking inside the cabin... above the head liner? Inside the flybridge cavity?

Re: Bertram 31 radar signature

Posted: Jan 20th, '19, 20:52
by Tony Meola
Yes that is what Mike is saying. I was referring to the same thing. We do not make a very good radar target.

Something like this.

https://www.fisheriessupply.com/mobri-m ... flector-m4

Re: Bertram 31 radar signature

Posted: Jan 21st, '19, 13:39
by mike ohlstein
The higher the better, but yes, above the headliner in the cabin is a good start. You can hang one of these from an outrigger, if you like. They weigh nothing.

Image

http://www.apsltd.com/davis-emergency-r ... gL0PvD_BwE

Re: Bertram 31 radar signature

Posted: Jan 21st, '19, 14:49
by moguls2go
I've always considered the superstructure of our hardtop a sufficient radar target; thoughts?

Re: Bertram 31 radar signature

Posted: Jan 21st, '19, 21:21
by Tony Meola
Max

In calm weather the target is good. Get any kind of seas and then it gets tough.

When we used to overnight offshore back in the late 70's and early 80's we used to hang a radar reflector off of the outrigger at night, similar to the one mike posted.. Just to make sure we showed up to any ships while they still had time to avoid us.

If you could figure out a way to hang it up in the overhead that type would work also.

Re: Bertram 31 radar signature

Posted: Jan 22nd, '19, 07:41
by John Nardi
31s have a terribly inconsistent and sometimes non existent signature in 4 foot or better seas...In the 80s when I had my 1st 31 FBC I would do exactly what the other gentlemen have mentioned, especially when spending the night in the canyon...Also, perhaps most importantly, I would rely on in the thick late spring fog when running out shark fishing...You can always ask a friend as you run out how you show up on radar...In my experience, too many people just rely on auto tuning for their radars...When you are either in thick fog, or looking for feeding birds down south, you have to get comfortable which both the gain, clutter and rain clutter adjustments as many times you will need to push the gain on a boat like a 31 to see small targets within say 3-5 miles...John