Can port length be too short?

[Vinny415]

So I’m trying to come up with a dual 12 ported box tuned to around 35 Hz. 

 

I have max dimensions of 33” in width and 13” in height. I found a program online that shows my port length needs to be 5.8” long. This seems too short for what I’m trying to achieve. Can anyone help? 
 

Here’s a pic of the design from the website

[fishchris1]

Of course it can, but luckily for me, she said I was okay 😀

[Dafaseles]

3 hours ago, fishchris1 said:

Of course it can, but luckily for me, she said I was okay <img src=">

I see what you did there!