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Note 2017.36 Southern Cross is coming North!!! 36 of 39
BTOVT::HILTON_G "SYS-F-UNIVCRASH% REALITY.SYS Corru" 21 lines 16-APR-1993 20:45
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help!
I need to make / purchase / build / or otherwise find and install
a RADAR mast on the afterdeck of the Southern Cross. I want the mast to
be free standing or mounted against the railing. It needs to be about
10' high and needs to have a single axis gimble to set the RADAR level
to the horizon while the boat is heeled.
I am planning on buying a 10 ' aluminum pole (1/4") about 3" diameter
hollow tube. mounting a base (separate from the pole) on the deck and
getting some brackets for the lifelines. My problem is the TOP of the
mast, I need to build a bracket that is on a port/starboard swivel that
has a pair of lines running down to a couple of cleats on the pole....
ANY IDEAS or CONTACTS about where to purchase / ro get parts
or ideas on building would be GREATLY APPRECIATED!!!
georgia
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Note 2017.39 Southern Cross is coming North!!! 39 of 39
HIBOB::MALOY 20 lines 19-APR-1993 11:16
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> I need to make / purchase / build / or otherwise find and install
> a RADAR mast on the afterdeck of the Southern Cross. I want the mast to
> be free standing or mounted against the railing.
Have you checked the clearance to the end of the mizzen boom? It does extend
aft of the rail a bit. I guess you could mount it on the transom...
On such a clasic boat, I don't think a radar mast would look very good, why not
mount it on the mizzen mast? It's out of the way and doesn't mess up the looks
of the boat as much.
> It needs to be about
> 10' high and needs to have a single axis gimble to set the RADAR level
> to the horizon while the boat is heeled.
There was a gimbal mount for radars advertized in the magazines a while ago,
I'll see if I can find it for you.
Dave. (Who has sailed ~3000nm on the Southern Cross)
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| Edson makes a manually adjusted gimballed mount for mounting a radar on
its own mast. Questus (now apparently part of Hood Yacht Systems) makes
a very nifty hydraulically damped automatically leveling mount. The
price isn't so nifty -- well over $1500 as I recall. Nonetheless, were I to
get a radar, I'd get one.
The loads imposed on the mounting base of a radar mast by a radar
antenna can be very large in high winds and rough seas. For a 10' high
mast you'll need a thick walled pipe for the mast and quite sturdy
bracing at the bottom end. The Edson catalog description of their mast
gives an idea of what is necessary. Simply welding a flat mounting plate
to the end of the mast and then bolting the plate to the deck would be
inviting disaster. I'd suggest that the radar mast should go through the
deck to a base (mast step) strongly attached to the hull. The deck
should be reinforced where the radar mast goes through. This is probably
not a quick and simple project.
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| One of the previous postings had something about a tube over the
backstay, with a bracket welded to it. This would scare me- the load
imposed on a line by a weight placed along it and perpendicular to it
is enormous. Recall the method to tighten a line by snubbing it on a
cleat and pulling perpendicular to the lone. As I recall my
engineering, this amplifies the force by something like the Tan of the
angle- a big number.
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|
Not to be a voice of doom/stick in the mud, but, I wonder if it's
even OK to do your own install? I recall a number of years back, the
FCC required a radio technician licence, at least, to mount a radar.
If the thing fries, or falls on, a crew, the insurance folks may be
a bit slow to pay...
In Georgia's case, the mizzen would be the way to go- get it nice
and high, out of the way. And as far as dropping the sticks, well, all
those big cruisers in Maine seem to have (need!) `em- just have the
crane guy be aware of it-
2 more �
Scott
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| I installed an Edson radar mast through the stern deck of my Morris 36.
There isn't much deck in the stern but enough for the pole to go
through.
I used the fiberglass tube which Edson sells to fit the tube, ran it
through the deck and down onto the hull. I made the deck hole very
snug, chamfered the edge of the dec, and built up a bead of chopped
glass and resin to bond it inplace.
The hull end was cut to fit the curve, and then glassed in. I ran the
glass as high on the pole as possible, working through a locker, and
out onto the hull as wide as possible.
Another addition was to make a stainless plate which conformed to the
outside of the tube above the deck, drill a hole, and then tapped a bolt
into the aluminum pole. This holds it tight and does not allow
movement. This is very important, because there is a lot of force
whipping around when a boat is beating to windward.
I used the standard radar mount, drilled and tapped the tube, bolted on
the mount and mounted the radar antenna.
I installed the radar myself. To install requires drilling a hole for
the wires at the top and bottom. Actually it is easier to feed the
cable if the bottom one is a slot rather than a hole. I left the cable
extra long so I can connect the antenna while sitting in the cockpit.
The extra cable is then pulled back down the tube, into a locker when
the antenna is fastened onto the mount.
I purchased a Raytheon 10x, and the instruction manual seemed to be
written for user installation. It did not seem to be any more difficult
than doing a loran. Just more wires to connect.
Was it worth it you ask? Definitely!!. To use an advertising phrase,
"it takes the worry out of being close". Last year on our way back from
Nova Scotia we spent a day and night in THICK fog. No wind just
motoring. With the auto pilot steering, the person on watch, my wife or
I as we had no crew, stayed under the dodger watching the screen. If a
target was seen, we placed a bearing and range marker on it, and then
watched its relative movement. Anything which came down the bearing line
was a meeting situation and we changed course to avoid, if we were the
burdend vessel. If we got to close and were not burdened we also
changed couse to keep clear.
Having a Radar makes one a real believer in Radar reflectors. Mine is
mounted permanently on the mast.
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