Surfboard holder for car top

[pkerrigan21]

Hey everyone,

 

I am new to the forum so I wanted to introduce myself and say Hi. My name is Pete and I live in sunny Florida. I have had some problems with various surfboard holders for cars and would like to make my own that I know will work.

 

My idea is to take a magnet, most like a Neodymium manget since they are strong. I want to use that as a base that I can stick to the roof of my car (using a protector for the paint). This piece would basically hold my board using a system of bars that are connected to the magnet and will hold the board in place on top of the car.

 

I need to determine what size magnet I will need, since different magnets have different pull forces. I want to make sure the board doesn't pull so hard by the wind that it rips the magnet off the top of the car.

 

How can I determine what pull force the wind will have on my board once it is attached to the top of the car?

 

Thanks again!

 

I also wanted to add I am trying to determine what pull force the wind would have when the car is moving at 100mphs on a board that 6 feet 4 inches long, 24 inches wide, and is about 1.5 inches thick.

 

I found all kinds of magnets rated from 5lbs of pull force to 200+.

 

Sorry, I am just not very good with the physics stuff, so thanks in advance for the help

[Phi for All]

Any magnet is only going to have about 20% of its pull strength available against the shearing forces you'll have from the wind against a surfboard on your car roof. You need to have the magnets coated so they don't scratch when forced sideways instead of pulled upwards.

 

How much weight is involved in the board and the system of bars? How fast do you want to be able to drive? Are you removing this whole apparatus every time you arrive at the beach?

[pkerrigan21]

Any magnet is only going to have about 20% of its pull strength available against the shearing forces you'll have from the wind against a surfboard on your car roof. You need to have the magnets coated so they don't scratch when forced sideways instead of pulled upwards.

 

How much weight is involved in the board and the system of bars? How fast do you want to be able to drive? Are you removing this whole apparatus every time you arrive at the beach?

 

I saw the stuff about coating it and I have that covered, thanks for the heads up on that though

 

The system is dependent on the wait of the actual magnet(s) that is going to be used. The board ways under 10 pounds, the actual part of the system that holds the board weighs about 10 pounds. My original thought was to have it all come together on one center piece shaped like a cylinder which would be the magnet. This board holder could be stuck on and removed whenever you don't need it on there.

 

I basically was trying to think of something that would be easy to put a board on with, wouldn't require you to use straps that go through your car window, and would support the board. I liked magnets because they can stick right to your car - just like the pizza delivery signs. The main thing would be to determine how much pull force I will need in a magnet. If that force is too great meaning I need a much bigger magnet, it might just not work out.

 

Thanks for the help