Items on sports rack interfering with radar

[scross]

For those owning boats with the radar aft of the sports rack: Does attaching kayaks, paddle boards, cargo boxes, etc. interfere with the radar?
On our 2017 C-28 bottom of the radar dome is basically the same height as the top of the sports rack bars. Seems like anything (except a solar panel) mounted to the sorts bar could block the radar beam.
Is this a problem?

 

[bob daily]

All, I've asked the same question about radar placement on other modes ie: the R-29 CB. And have not been satisfied with the answers about if the obstructions cause a blind or shadow sector ,or degenerate false echoes. Would be interested in what others have experienced. Bob

 

[Maggie Anne]

I can't comment about the C28 but I often carry my inflatable dinghy on the top of the cockpit bimini on my R27 OB (which has a forward mounted radar dome) and it definitely affects the radar returns from behind the boat so I assume there would some issues if one had gear on the forward rack of the C28.

 

[CruisingElvinRay]

It will depend on the material and position, but anything in the path of the beam will cause some return.


Sent from my iPhone using Tapatalk

 

[BB marine]

C26 and C28 Cutwaters can have radar performance issues when storing items on the sport racks. Other issues with the radar dome location is the shadowing of the solar panels. ( I personally did not have panels but a fellow Cutwater owner that we cruised with did and he had to change the factory location so he could get close to the panels rated capacity.Issues with the Radar picking up navigation markers and smaller boats when operating at a higher cruise speed 8kts or above . The faster I cruised the higher the bow would go. Even with full larger tabs or drop fins the bow still rode at a high attitude as all Rangers and Cutwaters do. I found the Mast and base that the Radar dome is mounted to was level. Most Radar dome mounts have an angle to pitch the radar dome down. This helps keep the the radar radio signal and returns lower when the boat 's bow attitude is elevated.The radar should be installed so that it’s level while the boat is underway. The bow angle is often ­greater when the boat is running at speed than when it’s at rest. So, if you mount the dome level with the boat at rest, the radar beam will be aimed upward while cruising. This reduces the chance of getting returns of objects that are lower and closer to the boat.

With the combination of the paddle board mounted on the sport rack and the radar dome aiming high when cruising the radar was not performing as I would have liked it to. To make things worse for me I upgraded my Dome when I purchased the boat. The standard dome offered by Cutwater at the time was the 18" dome. I wanted a 24" dome. A longer antenna emits a narrower beam that can discriminate better between objects that are close together than a shorter antenna. There are some narrow inlets on Lake Michigan and fog can come out of nowhere often in the summer.

We purchased a high pressure paddle board that we would carry on the sport rack. It did still interfere with the returns but not has bad as the hard plastic board. If we were planning on doing some distance cruising we would deflate the board and carry it in the cave. This gave the dome a full open area to send signals and and returns in. I also made adjustment screws for mounting the dome. I purchased a metric stainless steel threaded rod and cut the rod into lengths needed. I purchased nuts and locking nuts. I made adjustments to the Radar dome until I was satisfied with the angle. My plan was to make wedges and mount the wedges between the dome and the mast base. After making the adjustments with the "Jack Bolts" (Threaded rods) I found I increased my radar performance. The Radar mast base was not made square and the radar dome leaned starboard to port and looked shotty! I was able to level this too with the "jack bolts" I never did make wedges. The threaded rods didn't look bad and they worked.

Not exactly a sign of quality!
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The jack bolts shown in this photo leveled the dome so it was not leaning . When I launched the boat I was able to adjust the dome so it was level when I was cruising. After a couple of sea trials I had it adjusted and found the radar performance to be better when cruising.
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This photo show a C28 with factory install dome (left) The C26 (my boat right) with the HD24 and the dome angled down.

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[scross]

Thanks Brian! Very helpful information. I see some radar mount modifications in my future!