Changing out bathtub

[Freddiefreeloader]

In my 1990 229L I have a tub with half of it raised so you can sit down. I plan to put in a full 36 inch tub. I removed the side cover to see under the existing tub and under the seat area is what looks like a vent pipe sticking up almost to the bottom of the seat. Anybody know for sure what this pipe is and what purpose it serves. It comes up off of a T in the tub drain pipe. I will need to remove or really lower this pipe in order to put in a 24 X 36 X 11 1/2 inch tub.
What happens if I remove or alter this pipe and is there another solution for getting rid of this pipe ?

Been working to get this camper like we want it for the past 8 months and hopefully this will be the last project. Just recently came back off a 12 day trip to the Texas coast and really loved the whole experience.

 

[Treeclimber]

Freddie, that IS a vent pipe. There should be a vented cap on the top. Of course the vent allows the water to drain faster and without a vent, the drain will make funny sounds as it drains very slowly.
I have the same vent system for my kitchen sink. Very common in RVs
Tree

 

[ROUGH RIDER 3]

Vent Tube

Instead of a ridged pipe, tee off with a flexible hose that goes up the corner of the tub or up somewhere it will not be seen.