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

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

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

wrote:

snip
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.

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.

So, all your people who remember your physics...

I never had any of that. :-) Good luck!


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

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

-- Geoff

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

-- Geoff

Sounds like a few stainless steel washers between the mount tray and the
radome housing on the low side would fix the problem then.

Up here in Maine we would use a piece of Cedar shingle. ;-)

Jack

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

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!