teardrop trailer underside

[fredo]

I see most builds have some sort of protectant on underside of floor ( epoxy, asphalt, bed liner, filon) but was wondering what is anyone's thoughts on skinning the underside of trailer frame not just the underside of flooring with a sheet of aluminum, like race cars do for less wind drag. my trailer will be 2X2 tubing for the main side rails and then 2" channel for the cross bars - so I was planing on 3/4" ply down on steel, fill the bays with a 2" rigid insul. then covering the bottom with .063 aluminum ( I can get a 5'X10' of that locally.) I have read about condensation inside, so would love to hear other ideas.

thanks

[tony.latham]

I see most builds have some sort of protectant on underside of floor ( epoxy, asphalt, bed liner, filon) but was wondering what is anyone's thoughts on skinning the underside of trailer frame not just the underside of flooring with a sheet of aluminum, like race cars do for less wind drag. my trailer will be 2X2 tubing for the main side rails and then 2" channel for the cross bars - so I was planing on 3/4" ply down on steel, fill the bays with a 2" rigid insul. then covering the bottom with .063 aluminum ( I can get a 5'X10' of that locally.) I have read about condensation inside, so would love to hear other ideas.
thanks

I'd be very concerned about trapping moisture. At 60 MPH or whatever, you'll not detect less drag.

Tony

[Pmullen503]

I got a couple 4'x8' Coroplast sheets (political signs). I thought I'd zip tie one of those to the underside of my trailer to see if it makes a difference.

Probably too small to see an effect on mileage, but they were free.

[gudmund]

speaking from experience - I would not cover it. My first trailer which I had someone build for me = I paid extra to have the floor insulated. He in turn covered it with a aluminum panel which looked good = and looked to be well sealed. In the second/third year I started getting what I thought to be was door/window leaks when driving in rain. Never was able to get the leaks to stop. In the 3rd year the vinyl floor covering bubbled up - I in turn removed it. Than the 4th year, the floor plywood bubbled up which is when I realized where the water could be coming from - ends up the builder had never sealed between the frame/body in front and over time, road debris/water from my PU had been pressuring in past this un-sealed area, thus filling up the insulated cavity created by the aluminum under panel. (the water would just stay inside pressuring up and soaking the floor from under = ending up rooting the whole floor out.) My replacement trailer since is open underneath with a good coating of the black stuff on it - road wash/debris just drops off when traveling and as far as ever needing a insulated floor? - with the 5/6in thick mattress = I don't think so........... after 5 years of this trailer = it is doing just fine!!!! (same brand of doors/windows as before = never have had any problems with leaks like I had 'thought' I had had before) But - hindsight being 20-20 - if I was to cover the underside ever again = I would put "drain" holes in it next time...............
PS = I live in the Pacific NW on the 'WET' (west) side of the Cascades = so yes, I am familiar with rain............as far as 'wind drag' goes, the air spoiler I built off the rear upper edge of my PU canopy has worked out well so far, after almost 20-thousand miles of use these last 3+ years = gaining over 1.4+ mpg overall average increase.......(not much better than 16.0mpg prior and now, minimum of 17.4+mpg consistently on long steady runs...)