Trailers: Enclosed or Open - Make verses Buy?

[Raymond]

Its likely many racers have asked themselves these very questions; we did. There is no right answer because the answer to one might drive the other and besides, everybody has different needs, wants and tastes.

A few years ago when we started our transition from ASH to CSH we were having these debates at least twice per race weekend; once on the drive to and once on the drive home. While we could get a C boat on the top bunk, our old trailer was obviously too small for C boats. This debate was full of wants and needs. Every pro and con was listed and thoroughly discussed. We looked at our racing program budget and surveyed the market then looked at the budget again. This post is the story that followed that decision.

We decided that we were going to pursue an open style trailer. After some searching we found one for sale across Lake Michigan from a guy named Joe Z (I can’t pronounce his name let alone spell it). We made arrangement to meet somewhere between Chicago and Milwaukee and the deal was made. The trailer came with a few unexpected extras like boat carts and some old setup tools: thanks Joe.

We also knew that we could not leave well enough alone (we never can) and immediately (during the drive home) started planning the direction this next project would take.

Follow along as we chronicle this project.

[Raymond]

Once home, we dutifully skipped dinner and immediate went into inspection and brainstorm mode to figure out what the steps in this process would be.

On our next free weekend we jumped in feet first. We started by probing at the box structure and before you know it we were past the point of no return wound up stripping the trailer down to its skeleton.

After putting some boats on it a few weeks later to see how we liked the configuration, we decided that we needed more room between boats so we got out the cutting and welding tools and started reconfiguring the bunk layout.

You can't see it in these pics but even the fenders came off. Oh yea, we were in deep at this point. Notice the leaves on the ground? Date stamp this as the fall of 2011.

[Raymond]

With winter bearing down on us we got the frame mods done, got it all cleaned up and painted and put her away for the winter.

Over the course of the winter we drew up some renditions of what the trailer could look like (inside and out). For the inside we decided we were going to make the portside a work bench and tool box area and the starboard side would hold the motors. For the outside we decided we were going to follow advice from a friend and build the box using MDO (Medium Density Overlay). It’s an exterior grade sheet good with an impregnated barrier coat on both large surfaces that is extremely clean and flat.

When the spring of 2012 arrived we commenced with making and fitting the motor board. That is about as far as we got for a while until mid summer when we finally bought our first load of supplies; the MDO.

[Raymond]

Here is a pic of a science project we have going to see how well the MDO will hold up. We glued two pieces of MDO to a piece of standard 3/8” plywood and set it out in the back yard where it gets plenty of sunlight, sprinkler water (and dog water)) These pieces have been out there for two years now. The one on the left is untreated. The second from the left is epoxied and the one on the right is a piece of scarp from the bin in the garage.

[Raymond]

With the supplies at home and good weather overhead, we started making saw dust.

We used the frame itself as a template to layout the cut lines and mocked up as we went. Once one panel was cut to size, we tacked it in place with a few fasteners so we would have a good reference for the next panel. With countersunk pilot holes drilled into the panels, we used a self- tapping flathead counter sink screws. These screws worked real good cutting into the steel frame. I was dreading this part but was pleasantly surprised how well the fasteners cutting feature worked.

At this point our paces seemed to be speeding up.

[Raymond]

We endeavored to keep the inside gaps as tight as we could and cut the outside overlaps about 1/16” long. It was our intent to give us something to cut back to, rather than something to have to fill later. Yes we were doing our best to follow the best practice principle of measure twice - cut one.

You will notice that the 4x8 panels are smaller than any side of the trailer is wide or tall and that we were destined to have some seam lines. To help align the panel split line and provide strength to the split line area, we made doublers on the inside to span beyond the edge of both panels in the split line area. These doublers served a second purpose which was to also hide the external lighting wire harness. We don’t have any detailed mock up pics of the inside at this stage but we will call out the doublers in later pics when we present them.

[Smitty]

Well, for some reason I can't click on your photos and make them larger. Anyway, I take it the MDO is some kind of treated chipboard or flakeboard? And that you are gluing it to plywood for strength (the plywood) and weather resistance (the MDO); have I got that right? Are you using that combination for the "deck" that's affixed to the trailer frame, which is likely to have guys standing on it occasionally? I have an old 3-boat trailer to rebuild, and am interested in your project (just wish I could blow up the pix!!). I'm not too happy with the original "eyeball-engineering" design of the frame on mine, but can add some doublers and gussets and it shouldn't flex too badly. All the amateur-built trailers (and I guess most of the commercial ones) that I've seen have beam axles, sometimes have some sort of cheap shocks and sometimes don't, and never have swaybars. Seems like if you want the smoothest ride for your trailer over lumpy roads, and a controlled amount of sideways body roll going around turns, you'd want independent suspension like any modern car or pickup truck, gas-shocks, and a swaybar. For guys who can weld, any of this is easy enough to do. What do you think about this?

[Raymond]

Smitty,

I don't know much about why you can't click on any of the pics to make them larger but in an attempt to figure out why, I think I learned somthing about allowable files sizes. I kept getting errors when uploading my pics so I made them smaller; I think I made them to small. I am going to attempt to load a larger file detail pic of the MDO for you to see. If you want to see any of these pics in greater detail feel free to send me your address and I will send them to you. I will also load them via the attachment button V the picture icon button.

No, MDO is not a chipboard or flakeboard; it is a fully ply sheet good with a resin impregnated top and bottom layer.

Yes, it is 3/4" all the way around to include the deck.

This trailer a straight axle leaf sprung unit that we did not do any suspension upgrades to. To be honest it really never occurred to us. In retrospect this trailer pulls good so I don't think this kind of mod would interest us. Don't get me wrong, its interesting but time and budget constraints prohibit.

Please let me know how this new pic behaves.

[Raymond]

Once we had all the panels cut and tacked into place we blew it all back apart and cut some strategically placed relief passages for the lighting harness to route through. We then painted the inside of each panel: We were striving for a clean look and did not want to see paint bridging the frame and panels which was likely if we waited to paint after assembly.

[Raymond]

With the panels all cut and painted we were ready for final assembly. The first order of business was to make the lighting harness that will supply the marker lights. Once we had the harness tied loosely in place we commenced with assembling the panels up. We drilled and counter sunk pilot holes as we went. We waited until this point to drill the rest of the holes to ensure perfect alignment with the steel framing. You will notice the double row of screws along the panel split lines. We routed the harness to the front left hand inside of the box with the intent to run it straight down and out the bottom to the rest of the main trailer lighting harness. This exposed section you see will eventually be hidden by a cabinet that is planned for that corner.

We gave the hidden harness design much thought and made adjustments as deemed necessary. We made the exit holes oversized to help us feed the excess wire back in after making the lighting connections. We struggled with keeping the wire in the channel during assembly so we taped it down into the channel; this proved to be a bad choice but we did not recognize it until the box was fully assembled. The tape somewhat restricted the free movement of the harness (in and out of the exit holes) which was going to prove challenging once final lighting assembly came around. At this point we started second guessing ourselves but quickly came up with a number of solutions that would prevent us from opening it back up and redoing it.

By the end of that day we had the box assembled and the deck laid. Things seem to be moving along at a good pace but…that is not the case; we are a long way from being done at this point and the hard work had yet to be done.

[Smitty]

Now I can see better; you do nice work. Thanks for straightening me out on the MDO.

Anybody working on trailer frames ought to see the project-of-the-weekend I have. Yesterday morning some landscapers I do work for rolled in with a three-axle tilt-bed equipment trailer (medium duty, carries one or two smallish excavators). They chain up two excavators to it, pull it up on its side, then lay it down upside down (suitably blocked-up), six tires sticking up in the air, then say, "Hey Smitty, ya gotta fix this." BOTH frame rails, of 6" channel, were broken through the 2" lower flange, all the way up the 6" web, and were ready to break the upper 2" flange!!! They had barely avoided some real driving excitement.

The lesson here for trailer modifiers is HOW the frame broke. Some fool (and I think it was at the factory) had used a cutting torch to blow a big hole in the lower 2" flange of the channel so he could pass a pair of little 18ga electrical wires to the trailer brakes, instead of passing the wires AROUND the frame rail and zip-tying them as appropriate. I'm talking about rough-cut, sharp-edged 1 3/8" diameter holes made in the lower 2" flange of the channel, in six places, one hole per brake unit. So, between one edge of the hole and the outer edge of the flange there was about 1/4" of metal, under load, and that's where the break started. Both sides of the trailer.

The guy who made the big holes for the little wires hadn't the slightest concept of loadings and stress-concentrators. With a vertically-oriented frame rail, whether of 6" or whatever size channel, the upper flange is under tension and the lower flange is under compression, or vice versa depending on how the rig is loaded, how it's bouncing and flexing, etc.. Anyway, the neutral axis, the area that is under the least stress, is the middle of the 6" web. If you must make a hole in a trailer frame, THAT's the place to do it (and make the hole small, and smooth, with smoothly chamfered edges). Don't blow big holes in the loaded members!

[Raymond]

Thanks for the Kudos Smitty.

Now that the box was built we moved along to flushing up the edges and seams. For the edges we used a flush trim bit in the router to match the surface height (remember we cut the overlaps proud so we could cut back to level). We then used a round over bit to radius the edges.

White was a good choice for the inside. I forgot to mention that when we installed the split line doublers, we used construction adhesive on the insides of the mating surfaces to help prevent movement that could stress the split line area in service.

With the edges flush we applied a liberal coat of epoxy to the entire external surface using a roller. Once that was cured, we scuffed up the split line and screw hole areas and applied a mixture of homemade fairing compound made from epoxy and West Systems Microlight fairing filler to those same areas. After that fairing compound was cured we blocked those areas flat while also sanding the rest of the box completely.

We now put our final (heavy – multi coat) epoxy barrier coat over the box and bed (top and bottom – notice the bed is not installed – this was to help get 100% barrier coat coverage on both sides and exposed edges) waiting a few hours between coats. We used test panels and once the product passed over the top of the tacky stage, we laid another coat. The thought was to get a thick coat (for flattening work later) without having to sand between coats.

Oh the sanding and blocking to come….there is a reason I am not an autobody man))

[Raymond]

We used epoxy for a barrier coat on this project for three reasons. One - was to ‘seal up’ all the gaps and water proof it, two - to provide a foundation that could be worked without cutting into the resin impregnated surface finish of the MDO and lastly, it was our intention to build it such that it will last for a long time to come.

With all the MDO sealed up we focused our attention back onto the screw hole and split line areas. We filled and blocked and filled and blocked and…as anybody that has done body work like this before knows…we filled and blocked again until we could no longer see any surface flatness deviations in those areas.

[Dave M]

Raymond,

Looks good. Just wanted to give you a heads up (you probably already know this) but Epoxy is not waterproof. It requires a covering such as clear coat or paint to protect it from the UV Rays and water. I am assuming your trailer will be painted once you re finished constructing. Sure is a project from what I can see in the pics. Good job.

[Raymond]

Dave,

Thanks for the complement; How come we did not see you in Constantine on Father’s Day this year?

Help me understand what you mean by not waterproof? Is it because it is not (or better said; not all blends are…) UV resistant. Please see my post over on ‘let’s talk epoxy’ for a better understanding of my confusion.

[Smitty]

I respect anyone who habitually strives for good craftsmanship. Part of this is just being aware of the difference between good and bad work. I recently went to a local car show, and as usual looked at some cars that had multi-thousand-dollar paintjobs applied over bodywork that to my eye was not finished, having curves that were not fair, as anyone should be able to see when they bend over and sight along the length of the body. Even if the owners don't see this, one would think that any professional painter should have seen it right off, and refused to do anything until the bodywork was properly done. Boggles the mind.

Good, Raymond!! Your finished trailer will tell other craftsmen (and try-to-be craftsmen, probably like me) a lot about you.

[Raymond]

Thank you Smitty,

The outside of the trailer is done, just not revealed here in this build timeline yet. The process was tedious to say the least. We strove to get a professional looking result and I think we came very close. Being novice body men / painters, educated at the University of You-Tube, we are pleased with the result. There are a few spots that could use another hour or two of final polishing but that will come when some other projects get done. That is one thing we don’t have a lack of in our garage; projects