It's been a year and my kayak trailer has been through a few configurations. I started with a Harbor Freight 4'x8' trailer w/13" wheels. Originally I used carpeted bunks which came from an old trailer which I didn't like, the kayak slid around when loading/unloading so I changed them to PVC which I learned about on this site.
My next issue was the short trailer was difficult to back up, it changed directions much quicker than my 21' boat trailer, so I wanted to make it longer. Another reason for extending it - I didn't like so much kayak hanging off the rear. Harbor Freight was having a sale so I purchased another trailer kit for parts. Actually added a 4'x4' section to the front of the trailer. That connection between the old and new section proved weak with just the bolts, so I welded the two together and kept the old tow bar on to support the new section. This is what I ended up with as a single kayak trailer.
This shows the added 4'x4' section and the original tow bar with some uni-strut support.
I was happy with that for hauling my own PA-14, but I travel and have other friends with kayaks so I thought about modifications to haul multiple kayaks so we all didn't have to drive separate vehicles. Most of my friends car top and don't have trailers. First thought was to put on a second tier and use J-bars on the sides to haul NON-PA (read normal) kayaks. So I did this:
It worked, everything traveled well the first trip, but is proved a bad idea when it came to unloading the top PA at the ramp. I found I had to stand thigh deep (waist deep at high tide) and lift it head high to load/unload it at the ramp, OR load the lower kayak then pull the trailer forward and carry the second PA up the ramp and lift it up. It was a lot of trouble/effort and needed changed.
The latest configuration will carry two kayaks - I can carry two more on J-bars on the roof of my Durango, if need be so I thing a 2 kayak trailer is the way it will stay.
But I only transport my own kayak most of the time and I didn't want to have the wide 2-kayak a permanent thing, I wanted to make it convertible AND a conversion I could install/remove myself and not take a lot of storage space. The following pictures show the conversion. It takes about 15 minutes (by myself) to install or remove the 2 kayak platform.
The base of the platform uses 3 cross members. I used 2"x6" treated lumber for the middle and rear
as they support the weight of the kayak. The front one is a 2"x4".
The cross members fit into the stake pockets that are included with the trailer. I added a second piece of 2"x4" that sits on the frame, for a little bit more support and stability.
I bolted U-bolts through the cross members to attach the PVC rail sections. These act as studs, I don't have to deal with them each time I do and install/remove, they remain in place so I just have to bolt down the rail sections to the "studs". This is the underside and I used 3 washers so the studs didn't stick up so high and hit the kayak hull.
All 3 cross members in place, rest on the PVC rails of the single configuration for support and you can see the "studs". I doubled up on the rear U-bolts as that is the biggest stress point when loading/unloading the kayaks and I wanted the rails secure.
The pair of PVC rails are connected by sections of uni-strut that maintains the spacing and the "studs" slip through the uni-strut and a washer, lock washer & nut makes the connection.
Loading/unloading the kayaks isn't any more difficult now than with the single configuration. They sit about 6" higher, but still can be backed right to the water and slid on off easily. You may note the different color in the PVC - I hate Home Depot, every time I go to get something they don't have it. I prefer the grey electric conduit as it is UV resistant. That's right HD didn't have it when I went so had to settle for the white PVC plumbing pipe. No biggie it should last many years.
I like the uni-strut, made a bracket to hold my spare tire underneath the trailer.
I painted the trailer with Rustoleum Bed Liner, it's ok but you really should sand and primer before painting - I'didn't, I just washed and roughed up the exisiting paint with a pad and the new paint has chipped off in a few spots. Lesson learned.
With the 5 sections, storage does not take up a lot of room and each is easily handled by myself.