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Old 08-05-2018, 09:19 AM   #1
bethfit
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Transporting Canoe Car Top....

Hi All,

Just wanted to pick some like minded brains......

For many years we car topped our Bell Morningstar on various Nissan X-terras. It worked out fantastic. The factory rack was perfect. We always used straps as well as bow and stern lines and never had any issues. It was like it was part of the vehicle regardless of speed and best of all it was super quiet!

We recently made a switch and bought a 2018 Nissan Frontier with very similar factory rack to the X-terras. We also put a cap on the back with the Yakima rack. Seems like a perfect system once again. Very secure. However, we are getting a VERY loud growl and vibration that was very unexpected(only when canoe is on top). We have tried obvious adjustments with very minimal improvements. Just wondering if anyone else has encountered such issues and if there is some obvious simple fix that we might be missing. Open to all suggestions....thanks so much!!
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Old 08-05-2018, 09:41 AM   #2
Jack
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I have carried my canoe on top of my pickup trucks for a lot of years, with and without a cap. I have experienced that vibration only when using strapping to secure the canoe. When I used quality ropes I did not. In my experience I have found that when putting a twist in the strapping the annoying vibration would stop. I believe the wind flowing across the strap caused the vibration. This method works for me, and I believe that truckers also do this.
Hope this helps.....
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Old 08-05-2018, 11:43 AM   #3
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I can pretty much guarantee if I forget to put a half turn twist in my NRS straps then I will get an awful resonating vibration from them at highway speed.

I have also seen some canoe and vehicle configurations that will howl just from the wind flowing inside, like blowing on a soda straw. Stuffing something like a dry bag under the canoe to break up the airflow may stop that.
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Old 08-05-2018, 01:01 PM   #4
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Aerodynamics are a funny thing...really hard to predict those compressible fluids without some serious computing power and many years of experience!

If it's not the straps, try flipping your boat end for end. It seems like you have some funky flows between the cap and one of the seats. If you can identify the culprit, you may be able to alter the offending flow paths with a buckled in PFD or some foam blocking...Then again, it could be the cap that's resonating. If that's the case, adding some constrained layer damping to the inside of the cap might help.

When we put MDB's Swift on my Element, it will howl like crazy if it is stern forward. Air gets scooped under the seat support and creates a resonance in that support. If the boat is bow forward, it's much quieter.
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Old 08-05-2018, 01:27 PM   #5
bethfit
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Thanks guys for the ideas. We have heard that about the straps, but we never twisted the straps before when we carried it for years on the X-terra. That's an easy fix(if that's the problem) and will absolutely try that next time out.

flipping it end for end is an interesting idea and will try that as well. My thinking is probably more along the lines of what stripperguy & wilderness mentioned about disrupting the airflow. The dry sack type thing might be an option.....will look into it.

Thanks so much for the input when/if we figure it out we'll let you know how it worked out. Next trip is in several weeks!
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Old 08-05-2018, 07:09 PM   #6
Gatorman
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I had a similar issue that was solved by installing a Yakima WindJammer airfoil on the front crossbar. It was an inexpensive (~$15) solution. Unfortunately I don't think Yakima makes this anymore. You may need to look on eBay for a used one.
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Last edited by Gatorman; 08-06-2018 at 11:42 PM..
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Old 08-07-2018, 08:34 PM   #7
bethfit
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Quote:
Originally Posted by Gatorman View Post
I had a similar issue that was solved by installing a Yakima WindJammer airfoil on the front crossbar. It was an inexpensive (~$15) solution. Unfortunately I don't think Yakima makes this anymore. You may need to look on eBay for a used one.
Thanks Gatorman....

The foremost crossbar in our situation belongs to the factory rack on the Frontier. I see they do make some wind fairings that are more"universal fit" that may be able to be adapted to our situation. Might give that a shot as well...hell, after the last 6 hours of deafening howl we'll do anything!!!
Wouldn't imagine it would help if it wasn't mounted on the most forward crossbar??
Thanks again for the suggestion....
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Old 09-04-2018, 03:55 PM   #8
datdweeb
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I had the same issue with ratchet straps - sounded like a loud angry beehive on top of my car. Another easy solution instead of twisting the straps is to stretch a bungee cord between the straps on each side of the vehicle (the bungee cord will fold the strap over slightly, preventing the flat wind resonance).
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Old 09-04-2018, 04:53 PM   #9
bethfit
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Thanks datdweeb...We'll give it a try. We were able to find a "Rhino Rack" air foil that
fits & clamps on to the the forward most cross bar on the factory rack on the Frontier. That and the idea with the straps and I hope we have it solved. Just got the air foil mounted over the weekend and are scheduled to have the canoe on top(on & off) for better than 2 weeks in the very near future. It will be nice to be able to hear ourselves think going down the highway...
Many Thanks again everyone for the input & insights.....we'll let you know. If you see a Bell Morningstar on the side of the Northway it will mean it didn't work and we couldn't stand it anymore ...lol
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Old 09-05-2018, 09:20 AM   #10
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Late to this party but another vote for putting a few twists in the straps. Worked for us.
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