Unlevel Self-Leveling Radar Mount
 

I'm down in Guatamala installing a Questus hydraulically damped
self-leveling radar mount for a new RayMarine radar. Not that it
matters, but this was a back-stay mount version for which I made an
adapter to mount it on a radar mast. That part works fine. For an
idea as to how the radar is mounted, see:
http://www.questusmarine.com/2kwradars18diameter10.html

When I mounted the 2 KW radome, I found that it was tilted about 5
degrees. When I placed a 2 lb dive weight on the outer edge of the
higher side, it leveled out. It appears that the weight of the radome
isn't equally distributed.

I really don't want to place anymore weight on the mount, so I was
thinking about bolting the radar platform so that it was level. The
arm will be at a 5 degree angle, but I'm not worried about aesthetics.
However, I am wondering if the dome will remain level at all degrees of
heel. My physics are pretty rusty.

So, all your people who remember your physics, how about engaging that
portion of your brain for me!

Thanks in advance, Geoff

Geoff:

I would be really surprised if an offset center of gravity on the Raymarine
scanner was your problem. It looks pretty symetrical inside to me. Two lbs
to level it out- no way!!!

But what can affect how the radar scanner lays at rest is if the mount is
not square and inline to the centerline of the boat. If it is off then the
Questus will tilt a bit to balance out.

David

Did you try it with radar rotating?

Paul
www.jcruiser.org
wrote in message
ups.com...
I'm down in Guatamala installing a Questus hydraulically damped
self-leveling radar mount for a new RayMarine radar. Not that it
matters, but this was a back-stay mount version for which I made an
adapter to mount it on a radar mast. That part works fine. For an
idea as to how the radar is mounted, see:
http://www.questusmarine.com/2kwradars18diameter10.html

When I mounted the 2 KW radome, I found that it was tilted about 5
degrees. When I placed a 2 lb dive weight on the outer edge of the
higher side, it leveled out. It appears that the weight of the radome
isn't equally distributed.

I really don't want to place anymore weight on the mount, so I was
thinking about bolting the radar platform so that it was level. The
arm will be at a 5 degree angle, but I'm not worried about aesthetics.
However, I am wondering if the dome will remain level at all degrees of
heel. My physics are pretty rusty.

So, all your people who remember your physics, how about engaging that
portion of your brain for me!

Thanks in advance, Geoff

The Radome weighs 14 lbs. To guess that it's off by 2 pounds isn't
unreasonable. Let's not discuss the fact that it's not balanced. It
isn't. The plate that the radome sits on is semitrical. The
centerline to boat is not an issue. The Questus mount should be level
irrespective of position of the radar mast with the centerline of the
boat. If the boat is heeled at 20 degrees, the entire boat is at 20
degrees.

-- Geoff

On 17 Jan 2005 18:23:06 -0800, wrote:

The Questus mount should be level
irrespective of position of the radar mast with the centerline of the
boat.

======================

I read his reply a little differently, thought he was raising the
issue that the rotating scanner inside the dome might affect the
balance depending on how it stopped. As someone else asked, have you
tried it with the scanner rotating?

I feel like this topic has degenerated into a discussion of whether or
not RayMarine has produced a radome which is balanced along an x/y
axis. Let's just assume that it isn't based upon my imperical
evidence. The dome weighs 14 Lbs and that's approximately distributed
as 8 lb on the starboard side and 6 lb on the port side. This is not
an exact measurement nor is my estimate of a 5 degree tilt to one side.
It's a guess, but it's real.

Regardless of the actual weight or angle, the real question is whether
or not the pendular offset will remain constant at all angles of heel.
If you look at the photo which I referenced before (
http://www.questusmarine.com/2kwradars18diameter10.html ), you'll see
that the center of effort (perhaps the wrong term) is 1" to 2" below
the center of rotation of the gimballed mount. From that attachment
point, the arm holding the radar platform extends about 11" and is
offset about 5 degrees from perpendicular to the horizon. If I attach
the the radar platform such that is parallel to the horizon when the
boat is not heeled, will it remain so when the boat is heeled to either
side? I think so, but was just checking my logic.

Please note that I'm in Guatemala and Internet access is iffy. Please
just try to work with me and answer this based upon the data provided.
-- Geoff

The tilt is side to side, not front to aft.

-- Geoff

Something is seriously wrong with the installation to require that much
weight to balance a gimballed system. The manufacturer should be consulted
before any modifications are made to compensate for so great an error. In
order to use the same language when discussing the problem, you might
consider the following genrally accepted descriptions.

Univ Marine Slang (bad)
-- ---- ------ -----

X ROLL HEEL Lean

Y PITCH RISE Tilt

Z YAW HEADING Point

\ |
\ |
\|
X -------------
|\
| \
| \
| \Z
Y

Best regards,

Jack Painter
Virginia Beach, Virginia


wrote

I'm down in Guatamala installing a Questus hydraulically damped
self-leveling radar mount for a new RayMarine radar. Not that it
matters, but this was a back-stay mount version for which I made an
adapter to mount it on a radar mast. That part works fine. For an
idea as to how the radar is mounted, see:
http://www.questusmarine.com/2kwradars18diameter10.html

When I mounted the 2 KW radome, I found that it was tilted about 5
degrees. When I placed a 2 lb dive weight on the outer edge of the
higher side, it leveled out. It appears that the weight of the radome
isn't equally distributed.

I really don't want to place anymore weight on the mount, so I was
thinking about bolting the radar platform so that it was level. The
arm will be at a 5 degree angle, but I'm not worried about aesthetics.
However, I am wondering if the dome will remain level at all degrees of
heel. My physics are pretty rusty.

So, all your people who remember your physics, how about engaging that
portion of your brain for me!

Thanks in advance, Geoff

I just went thru a similiar situation.
I fabricated a stern pole and the platform was angled up.
We solved it by gentlely heating the Questus tubes and removing some of the
bend. Dead level now. Fab'd a antenna array for the top and a engine lift
on the side. Polished it up and you could never tell. Photos avail. if
anyones interested.
Jay

--

Jay A. Howell, CFP
Registered Representative
Financial Network Investment Corporation, Member SIPC
4950 Westgrove Drive, Suite 130
Dallas, TX 75248
(817) 265-3513 personal office
(817) 265-2813 fax
wrote in message
ups.com...
I'm down in Guatamala installing a Questus hydraulically damped
self-leveling radar mount for a new RayMarine radar. Not that it
matters, but this was a back-stay mount version for which I made an
adapter to mount it on a radar mast. That part works fine. For an
idea as to how the radar is mounted, see:
http://www.questusmarine.com/2kwradars18diameter10.html

When I mounted the 2 KW radome, I found that it was tilted about 5
degrees. When I placed a 2 lb dive weight on the outer edge of the
higher side, it leveled out. It appears that the weight of the radome
isn't equally distributed.

I really don't want to place anymore weight on the mount, so I was
thinking about bolting the radar platform so that it was level. The
arm will be at a 5 degree angle, but I'm not worried about aesthetics.
However, I am wondering if the dome will remain level at all degrees of
heel. My physics are pretty rusty.

So, all your people who remember your physics, how about engaging that
portion of your brain for me!

Thanks in advance, Geoff

wrote:
... Not that it
matters, but this was a back-stay mount version for which I made an
adapter to mount it on a radar mast ...

I'm not certain about this. I have a Questus 400 backstay mount that's
always worked well with a small Furuno radome. I think there might be a
problem in modifying the 400, since Questus does provide a similar rig
purpose-designed for pole mounting.

You might contact Questus about this, but frankly, although I really like
the product, I have never had _fully_ satisfactory relations with the
supplier. If you Google a bit you might find a series of posts about my own
installation (and travails) on this subject.

--
Good luck and good sailing.
s/v Kerry Deare of Barnegat
http://kerrydeare.home.comcast.net/

In article ,
wrote:

Turn the radar unit 90 degrees so that it is balanced side to side.

BB

That is a stupid comment and idea. If the guy did that, then his Heading
flash would be 90 degrees off. All the fancy electronic Bearing Lines
would be 90 degrees off as well......... Not a real bright Idea.....



Me

"Me" wrote in message
...
In article ,
wrote:

Turn the radar unit 90 degrees so that it is balanced side to
side.

BB

That is a stupid comment and idea. If the guy did that, then his
Heading
flash would be 90 degrees off. All the fancy electronic Bearing
Lines
would be 90 degrees off as well......... Not a real bright
Idea.....

Consider the source.

Jack Erbes wrote:

Is the tilt front to back (fore and aft) with the front higher? If so
you may have the perfectly designed mount.

A typical mounting wants the radar higher in the front so that lower
edge of the the cone shaped radiation pattern is placed a little more
out in front of the boat. Check the Raymarine manual for more specifics
on this and don't forget, you want to mount a little nose high for the
typical or average underway waterline level, not the level that you get
dead in the water.


I think you have that backwards - if anything you want the radar to tilt
slightly down. By tipping up, most of your forward signal is radiated
upwards where is serves little purpose. Since you already have a fairly
large upward radiation (half of you signal if level), tipping upwards
just reduces your close in signal.

The Raymarine instructions recommend level for sailboats, and tipped
slightly downward for power boats that squat (or raise the bow) at
speed. Since most sailboats also squat at speed, I'd go with the dipped
slightly down for all boats, but increase the downward tilt if you like
to power at high speed in the fog!

Jeff Morris wrote:
snip
I think you have that backwards - if anything...

Thanks Jeff! I recalled having read about the mounting angle in the
manual numerous times, I just relied on memory to recall what it said
and failed.

The recommended installation is for it to rotate parallel to the
waterline at cruising speed.

I hate it when I have a fifty-fifty chance of being right and get it
wrong, you can't hide behind the difficulty or the numbers. :)

Jack

--
Jack Erbes in Ellsworth, Maine, USA - jackerbes at adelphia dot net
(also receiving email at jacker at midmaine.com)

In article ,
wrote:

On Tue, 18 Jan 2005 18:19:44 -0500, "Scott Vernon"
wrote:


"Me" wrote in message
...
In article ,
wrote:

Turn the radar unit 90 degrees so that it is balanced side to
side.

BB

That is a stupid comment and idea. If the guy did that, then his
Heading
flash would be 90 degrees off. All the fancy electronic Bearing
Lines
would be 90 degrees off as well......... Not a real bright
Idea.....


Read the instructions. Most modern RADAR units can be electronically
calibrated
this way.

BB


Really, and would you care to NAME these units that allow the Heading
Flash to be "Calibrated" more than 45 degrees away from Designed Head?


Me who knows better, since I ve been installing them for 20 years