Aft or Fwd leaning radar mount

[Bateau Ivre]

I am going to install a Raymarine RD-218 radar radome on my 2005 340DA next week. Trying to make a decision as to whether I should mount the radome with an aft or forward leaning radar mount. I have look at several pictures and found both mounts installed. I can't decide which has the better appearance and I don't see any operational differences as long as I keep the bottom of the radome above other objects mounted on the radar arch due to interference. Any opinions?

 

[Creekwood]

The mount should be forward leaning at rest so that when you are running at speed with a bow angle up about 5 to 7 degrees, the radome will be level or as level as possible so you have good range. Read the installation manual for the RD 218 (on-line at Raymarine if you don't have the paper version). It explains it quite well.

 

[Bateau Ivre]

Understand the bow rise elevation principles at cruise or at rest position as this could be adjusted with shims or wedges to ensure that the plane of the radar is level with the horizon or water surface at cruise speed or slightly below. I am referring to the actual radar mount (physical device) from an asthetic perspective whether it's appearance looks better at rest/moored forward or aft leaning. In review of several 340s for sale I have seen both mounting scenarios.

 

[Gofirstclass]

Personally I like to see a forward leaning mount on express cruisers and vertical or aft leaning mounts on flybridge boats. Don't ask me why 'cause I really don't know, it's just a personal preference.

FYI, you may find that you can adjust for the bow rise angle in the setups of the radar without having to use wedges. Check the manual for that adjustment.

 

[tdschafer]

My old mount was a stainless Seaview aft leaning and looked good to me. I replaced it with a dual mount when I added the satellite dome. It's funny because it leans back for the TV sat but the radome is forward. I also used a 4 degree wedge under the radome to compensate for the angle at cruise.

 

[psubill78]

I am going to install a Raymarine RD-218 radar radome on my 2005 340DA next week. Trying to make a decision as to whether I should mount the radome with an aft or forward leaning radar mount. I have look at several pictures and found both mounts installed. I can't decide which has the better appearance and I don't see any operational differences as long as I keep the bottom of the radome above other objects mounted on the radar arch due to interference. Any opinions?

Operationally, no difference. You can offset any angles on plane regardless or which way it is leaning.

After looking at tins of pictures, my gut always feels that matching the radar arch lean looks best. So on your '05, your arch leans forward, so should your mount...

 

[melida]

Personally I like to see a forward leaning mount on express cruisers and vertical or aft leaning mounts on flybridge boats. Don't ask me why 'cause I really don't know, it's just a personal preference.

FYI, you may find that you can adjust for the bow rise angle in the setups of the radar without having to use wedges. Check the manual for that adjustment.

GFC, thanks for that tip.

I have Raymarine 2kw radome mounted on my arch without any angle and thinking to play with shims of it to lean it forward as I leaned the vhf antenna forward and it's perpendicular to the sea surface while on plane.

I looked again to the installation guide and users guide and saw that the radar alignment chapter. There is "Bearing alignment" which tells about to seeing targets on plane like at moored.

Am I missunderstood this or it's what you mentioned about the bow angle setting without playing with the shims or any welding job.

TIA.

 

[Bateau Ivre]

I appreciate the posts/comments and after several hours of sale site reviews and trips to various marinas I decided on a forward leaning mount. I would have to agree with GFC, and so did the mount manufacturer, that the line of mount should be consistent with the angle of the radar arch from an asthetics perspective. I did some weight and moment calculations based on the angles of the forward vs. aft mounting scenarios and the forward mounting scenario provided the best results. It included less sheer and stress results on the fasteners and radar arch base mount. So to note, either means of mounting works and there are no risks of material fatalities with either mounting scenario. I placed the order with Specialty Marine Products today and should have the item in had after the holiday. I decided to go with a 2 degree angled mount. After sea trials I will adjust if necessary with shims. My decision was based on how I would be operating the boat if the radar was a necessity and not normal cruising speeds (i.e fog or night cruising). I will have photos available if anyone interested after I complete the installation.

 

[Gofirstclass]

Melida, the bearing adjustments are used to align the "radar picture" with what's ahead of the boat. When I installed my Simrad radar the "picture" I was seeing was off by about 15 degrees from what was actually ahead of me. I anchored the boat in an area where I could look a mile or so upstream to a bouy on the radar screen and the bouy was directly ahead of the centerline of the boat, then using the bearing adjustments I aligned the picture so it showed the bouy directly ahead of the boat.

The angle I was referring to above allows you to electronically "tip" the antenna scan downward to approximately match the bow rise angle when you're on plane. Without doing that adjustment (or using a wedge) the radar signal is basically shooting off into the sky. You will get some radar returns to the antenna but the returned signal won't be as strong as it should be. By doing the angle adjustment to angle the beam downward, it compensates (electronically) for the bow rise and gives you a stronger signal.

To picture that, think of using a flashlight with a narrow beam and wanting to shine it on something, but instead of shining it directly at the object you shine it a few degrees above the object. You will still likely see the object, but not as brightly as if you aimed the flashlight beam down a bit to where the main part of the light beam was hitting the object. Same thing with radar. Once you aim the main part of the radar signal downward a few degrees you will get a stronger return signal. Look through your manual to see if there are adjustments for changing the beam angle up or down. Some radars have it but some may not.

I hope this helps.

 

[melida]

Melida, the bearing adjustments are used to align the "radar picture" with what's ahead of the boat. When I installed my Simrad radar the "picture" I was seeing was off by about 15 degrees from what was actually ahead of me. I anchored the boat in an area where I could look a mile or so upstream to a bouy on the radar screen and the bouy was directly ahead of the centerline of the boat, then using the bearing adjustments I aligned the picture so it showed the bouy directly ahead of the boat.

The angle I was referring to above allows you to electronically "tip" the antenna scan downward to approximately match the bow rise angle when you're on plane. Without doing that adjustment (or using a wedge) the radar signal is basically shooting off into the sky. You will get some radar returns to the antenna but the returned signal won't be as strong as it should be. By doing the angle adjustment to angle the beam downward, it compensates (electronically) for the bow rise and gives you a stronger signal.

To picture that, think of using a flashlight with a narrow beam and wanting to shine it on something, but instead of shining it directly at the object you shine it a few degrees above the object. You will still likely see the object, but not as brightly as if you aimed the flashlight beam down a bit to where the main part of the light beam was hitting the object. Same thing with radar. Once you aim the main part of the radar signal downward a few degrees you will get a stronger return signal. Look through your manual to see if there are adjustments for changing the beam angle up or down. Some radars have it but some may not.

I hope this helps.

GFC, thanks for the detailed reply.
I want to do the red paragraph you wrote.
But couldn't find info about that at first look to my manuals.
Gonna check it again.
I don't want to make a welding or playing with the shims both for not spending unnecessary money and keeping the radar dome at current level position while needed at slow speed or fishing.