Looking for help on a telescoping trailer

[DanBerger]

I'm rebuilding my trailer for my 20 and I thought I would make it a telescoping trailer while I was at it. I'm thinking that I need to make a big frame with cradles on one side to hold the boat. I get the idea of using wires and a winch to winch the frame in and out, so I'm good there.

What I need is advice on how to mount the moving frame to the trailer frame so that it slides out. What has anyone else used? some kind of industrial ball bearing drawer slide? How about those rubber boat rollers? I was also thinking about a strip of plastic between the sliding frame and the trailer frame. Even lubed up, that might be too much friction.

How do you get the sliding frame to lock in the compressed position? Just a pin through the sliding frame and the trailer frame?

Do you need to put legs on the end of the sliding frame under the hull so that it is supported when extended? I'm thinking the trailer would fall over.

[gahamby]

I'm thinking rubber rollers mounted over and under on some Uni Strut. Two sets forward, two sets aft. One set on center line, one set outboard. Box tube trapped in between with hull cradles on the outboard end. A trailer tongue jack on the outboard end of each box tube. This would all be readily available trailer hardware, except the Uni Strut. That can be had at the electrical supply or Loews. Not a lot of searching or custom fabricating.

[havliii]

Telescoping trailers very rarely work well, just too many moving parts to get wracked up, jammed up, twisted, out of alignment. You can tilt the 12 foot boat and fit it into a legal box for the highway or better still narrow the boat to 11 feet and then tilt trailer it. You'll never miss the 1 foot of 'lost' beam, you'll be way happier never again having the assembly nightmare and you'll save hundreds of dollars on aspirin, without the headaches!

my 2 cents.

[J Drew]

Dan,
Maybe I can help?

I'm not the best photographer but there's a wheel on each piece of square tubing that telescopes with about 1/8" +/- clearance. There's 4 independent slides, because it telescopes from both sides of the trlr. The tube attached to the trlr has a wheel on the bottom, just at the end of the tube. It is mounted below the tube so that it is just above flush with the bottom of the tube, the movable tube rolls on it. The tube that mounts the cradle has a wheel on the top of the tube, just at the end. The wheel on the cradle tube runs inside, it is basically flush with the top of the tube it's mounted to.
It does have spring loaded pins that secure it all the way in and all the way out.
All the way out is stable enough for boat assembly without any support

When I first got my boat, it had telescoping beams. I found that if the boat isn't correctly squared on the trlr, it likes to blind and if the round plastic curved pieces that shim the two round tubes of the beams are worn, it likes to blind. The wheels must roll freely and any debris can be very frustrating.

With fixed beams, I build it every time, which is extra work but when I roll the hulls out independently, it is much easier.

[J Drew]

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Like I said, I'm not a photographer.
Be glad to "try" to get better pics if needed

[Bill Roberts]

Here we go again. `1978 factor telescoping trailer. Cost then was $2500, cost today $5000. Telescoping in or out was controlled by a continuous cable thru both beams. Movement out and in was always in concert, never jammed. Set up time was 15 minutes from 8 ft wide to 12 ft wide with tight tramp. Could b moved by hand crank wench or push button electric wench. Push button always drew a crowd.

[Bill Roberts]

Drew,
These pictures are of someones home spun idea of how to build a telescoping trailer. This is all junk. The rollers have to be steel or aluminum.
The inner, moving beam, must be moving on rollers at all times. At the outlet of the fixed half of the telescoping system there must be a roller above and below the telescoping part of the beam. The lower roller carries the vertical load of half the boat. The upper identical roller has a center groove in it for the telescoping out cable to bend around this roller 180 degrees and head toward the center of the trailer and around a block and headed toward the wench. Both beams are rigged like this and the wires connected as they came forward and headed to the wench as one wire.
TRAILEX TRAILER COMPANY tried making an aluminum telescoping trailer using their stock extrusions and it was very bendy, sloppy, floppy and did not work well.

[J Drew]

It may not be shiny and new, and it's not aluminum, but it works just fine.
When it telescopes, it rolls out adequately and the rollers work like they need to.
Let someone else spend the money on a fancy trlr, I'll keep my "junk" !

[Jonathan Levine]

These pictures are of someones home spun idea of how to build a telescoping trailer. This is all junk. The rollers have to be steel or aluminum.
The inner, moving beam, must be moving on rollers at all times. At the outlet of the fixed half of the telescoping system there must be a roller above and below the telescoping part of the beam. The lower roller carries the vertical load of half the boat. The upper identical roller has a center groove in it for the telescoping out cable to bend around this roller 180 degrees and head toward the center of the trailer and around a block and headed toward the wench. Both beams are rigged like this and the wires connected as they came forward and headed to the wench as one wire.

Yes, I realize that I'm responding to this thread about a decade after the fact, but perhaps future generations...

Sure, those are all good points, but here are the problems with Bill's trailer. First, it's heavy as hell. Second, it telescopes asymmetrically (4' to port only), putting the whole thing severely off-balance, as well as thoroughly blocking the driver's view if one then has to drive it to and down a ramp. The cables also run through guides (in the form of holes in plates), so if a wire needs to be replaced, it has to be assembled in situ rather than on the bench and then installed on the trailer. Further, the manufacture of the beam/roller system wasn't precise enough: The roller at the starboard end of the inner beam was able to travel just past the end of outer tube when telescoped in, and the result is that the roller's shaft - aluminum tubing - snagged on the outer tube and was mashed when telescoped out, deforming the shaft and freezing the roller, which then proceeded to get dragged back and forth and develop a healthy flat spot. To remove the rollers to have them turned round again on the lathe (leaving barely enough OD for them to function), I had to first press out the mangled shafts, a feat in itself. And the shafts they run on are now SS.

Another consequence of this design is that the centerline of the boat, when expanded, is now 2' to port of the centerline of the trailer (and the mast stand, from which it is believed the mast was supposed to be raised, presumably using a gin pole). Although there appears to be an explanation of how to do this in the manual, I've found it to be incoherent and nobody else I've asked can make sense of it either. Winching to the mast stand would mean raising the mast about 20 degrees off center, and I'm not down with that. It would seem that Bill had a trick that made doing it with this geometry OK, but that secret appears to have died with him. So for the moment I've mounted my winch on an arm outboard of the trailer frame where the boat's centerline is when extended. I'm seriously contemplating doing the necessary cuts+welds to make it telescope symmetrically.

TRAILEX TRAILER COMPANY tried making an aluminum telescoping trailer using their stock extrusions and it was very bendy, sloppy, floppy and did not work well.

I'm in full agreement there. Because of the difficulties with the steel trailer, I started looking for a Trailex - which expands symmetrically, as well as being very light by comparison. There was one listed on beachcats for $2500 USD in VA, but that was too much and too far, though it appears to have been in good shape, judging from the lack of rust on the fasteners. But then I found one in VT for less than half of that - with an SC20 on it - so that's what I just got. Trailex does not build good trailers. As Bill pointed out, they make everything out of stock extrusions and whatever little brackets and plates they need to come up with for a given design, and the result is a trailer that strongly resembles Meccano - with roughly the same strength. On their web site, Trailex likes to brag up their patent(s?) and T-channel bolt assembly system, but as someone who holds a few patents I can tell you that it only means you came up with a new enough idea to satisfy the patent office, not necessarily a good one.

In fact, they way they build their trailers is pure bullshit. All of their aluminum extrusions have T-channels, which they use to mate with the other parts using steel T-channel bolts. The result - over time - is wicked galvanic corrosion that in some cases bursts through the extrusion wall. When I got mine home and looked closely at it this became apparent - as did the fact that every one of the twelve (12) rollers used for the extensions had been attached with a 1/2" steel bolt that had rusted severely enough to completely seize the (plastic) rollers. The rollers may have had steel bushings through them, but there's no way to tell now. In one case the corrosion had reduced to bolt shaft's diameter to 1/8", though in the most beautiful manner (I'll try to add a picture of it here). But in replacing those rollers, you do not want to remove any fastener that you don't have to, because the corrosion may be all that's keeping it in place.

So here's the short version: The extension runs on a pair of rollers that are mounted to brackets attached to the frame above. First, remove those rollers using a cutoff wheel on an angle grinder - it's easy to reach up and cut the bolts from beneath, as there's a pretty big gap between the inside of the mounting brackets and the roller itself. Once you've removed those two rollers, the extension will basically drop away (though you'll have to raise the hull a foot or so to clear the cradle). With the extension removed from the trailer, you can cut the bolt (shaft) holding the inboard roller with a sawzall - you can't reach in there with a cutoff wheel. Assembly is the reverse, replacing the old rollers and bolts with shiny new rollers and SS bolts. And while the extension is off, you'll probably have to straighten out the alignment tangs that are supposed to keep the extensions in line. The good news is that the nuts Trailex used on their T-bolts may be rusty, but don't seize - hit 'em with a little penetrant and they'll turn off. Before reassembling (with new nuts) I chase the T-bolt threads with a die, but doing it where they are. It's pretty simple and quick to replace the lot if you don't take anything apart that you don't have to, otherwise you're sure to disturb something that's going to create more work for you. And don't overtorque the T-bolts or you'll pull the shafts off of the heads.

[Jonathan Levine]

Yeah, it's pretty bad, alright. I've just stretched it out and am adjusting the retraction stops, and when I loosened the nut on the stop and slid it in the T-channel about an inch, I found that there was no metal left behind it - the galvanic corrosion from the bolt head had completely destroyed the aluminum. I wonder what could have been done to mitigate that. Is there a fastener material that would reduce/eliminate this problem? Instead of (presumably) zinc-plated steel, would galvanized or stainless be an improvement?

Notwithstanding that, the Trailex's greatest advantage is that it's Meccano - a fantastic platform for fiddling around and adjusting and prototyping ideas without a lot of otherwise harder cutting and welding. Once I get these retraction stops in place, I'll figure out some expansion stops (there are none now) that ensure it remains centered on the trailer, because as it is you can have the boat expanded but offset to either side. The ultimate goal is to automate the process, probably using a couple of 12V linear screw actuators. It doesn't require all that much force, so if it works I can avoid going to hydraulics, which would be severe overkill. I just have no interest in all that winches+wires nonsense.

I can see that it would be great to have a big shelf full of these extrusions and a few connectors for lashing them together - easy and fun. But in the long run (decades, that is), what crap.