The following are photos of my completed design. It is relatively low-cost to build. It is completely modular and very easy to assemble, and disassemble, in under two to three minutes. It can be used in 3 separate configurations (1) standard "wheels and axle", (2) "wheel and axle with T-handle", and (3) What you might call "solo" mode. In this mode, one person alone can easily assemble Hometrax (without tools) in about 2 to 3 minutes, then load or unload your Catamaran directly to/from your trailer (by yourself) to the Hometrax. You can then move the boat around to where you want to go. Once stopped you can set Hometrax down (with boat loaded) and the boat never touches the ground. Also in this mode, one security line is all that is generally needed to secure the boat.
It looks like I might be building a few more of these, but that is another story - for a different website.
Construction is all aluminum, stainless steel, PVC and nylon. The exceptions are a couple galvanized lock collars and the 5/16 (zinc plated) quick-pins for easy assembly and teardown.
This is a pic of the independantly rotating hull support with heavy duty rubber boot - this whole assembly rotates free from both the wheel and the inner axle.
Worth noting, the outer ring of this assembly has two attachment points for lines (for use mostly in the "wheels and axle only" mode). The attachment ring itself also rotates freely and independant from both the hull support and the inner axle of the Hometrax. This has some big advantages regarding the ease of securing the boat and the repositioning of the Hometrax under the boat.
With the exception of two lock-collars (each with one allen screw), the entire contraption assembles with these 5/16th quick clips.
When disassembled, everything but the wheels easily fits into an already crowded catbox.
Note: the wheels are 12 lbs each and rated for a working load of 600lbs each. The wheels can also be doubled up on each side for a total of 4 wheels - they are actually made to stack/nest with each other perfectly. If necessary, this would provide a huge tread suface of over 18 inches PER SIDE (more than any other portable cat-wheels that I`ve seen by far). It would probably allow someone to pull their boat across almost any surface imaginable. With four wheels I am quite certain the guy/gal pulling the boat would get stuck long before the HomeTrax.
I haven`t tried them on sand yet, but they worked well in some muck.
The wheels are actually "dock wheels" designed to move substantial dock systems across the shoreline and stay submerged for seasons at a time. They are supposed to be effective on all shoreline substrates. But, I`ll have to report back later in the season with my first hand experiences - no sand around my home, and the ice just went out of the lake last week.
Nice looking job. One suggestion I have is that you make the front post attachment a little stronger. As it is, it doesn't have much strength if the boat is on the tracks and it moves forward or backwards when the front post in on the ground. Something will bend and break pretty quickly. Maybe you could replace the straps on each side of the post that attach to the main bar with triangle shaped plates that have two attachment pins into the main bar. Or maybe just add an angle brace? Jack
The vertical post connection is much stronger than you might think by looking at the photo, especially without any scale for visual reference. But I still like the sound of your triangular "2-pin" support suggestion.
The aluminum "straps" are heavy grade and the stock is 1.75 inch square - hefty stuff. The forces on this connection (especially the horizontal forces) are quite small. The attachment really only needs to be strong enough to resist the whole setup from rolling away. Even on a modest incline, such rolling forces are quite small.
The connection itself, while over-designed to support the bows of a boat, is mainly designed to be easily removable during the process of loading/unloading a boat from a trailer.
It is strong enough now so that it is not possible for one man to break/bend that joint by pushing or pulling on the boat - even with the vertical post planted on the ground (I`ve tried that).
The back wheels/axle take at least %90-95 of the overall load. The forward hull support has just enough flex to prevent shock loads to that connection in all planes. The forward support is designed so that when the boat is pushed forward, (while the Hometrax are held stationary) the boat SLIDES over the forward support - with just enough resistance to be comfortable - rather than putting unneccessary forward force on that connection. Keep in mind, when a boat has to be slid forward on the Hometrax, the post is actually planted "on the ground" gaining some extra support and holding power, thereby reducing the stresses on those aluminum straps. This is partly because the whole boat is repositioned very easily by either leaning your backside (straddled) or torso up against the T-handle and pushing or pulling the boat depending on what you`re trying to do.
Also keep in mind, the post is secured with a 5/16th pin and two slabs ("straps") of heavy grade aluminum secured by two 5/16th stainless steel bolts. The breaking/bending forces of that connection range from 2 to 3 thousand pounds vertically (maybe more) and a few hundred pounds (at least) horizontally given the lever length of 18 inches to the bottom of the vertical support.
In the method of a good scientific approach, the main things that I can think of that could over-stress that joint would be;
(1) Someone jumping around on the tramp while the Hometrax is on an incline (2) Gaining speed with the whole contraption (loaded) and dropping it; suddenly forcing the vertical support to act as a brake. (ie. spiking it into the ground at speed) (3) The boat left unattended on the Hometrax to bounce around in a storm without first: sinking the vertical post into the sand (like a spike) far enough so the bows touch ground; OR removing the forward support altogether; Or (most important) securing the entire boat and Hometrax appropriately for the given weather conditions...I have already learned "the hard way" that the H16 likes to fly - trailer, Hometrax, with or without you! I think it is best to secure it all...very well!
Incidently, I will be cutting that post from its existing 18 inches down to about 12 inches. The extra height is not necessary and will make it even easier to store in my 20 inch wide catbox - I prefer to leave the vertical post attached to the horizontal (tubular) hull support during storage.
Dave
P.S. Still, I must admit I do like your idea. But, not so much for strength (although that is an added benefit). With a triangular 2-pin support permanently secured to the vertical post, I could put one pin in place with the support folded under - like a folding table leg. Then by lifting (straightening) the "leg" into place - simply by lifting the T-handle - the hulls would raise and the support would slowly swing down into position by itself. Then I could put the second pin into place. I think this would be better than holding the whole assembly up with one hand and pinning it into place with the other hand...I like it! Thanks.
Once again you have outdone yourself with this impressive design and effort. I am hoping that you could provide more details of the hull support, ie how it attaches to the axle, materials, sources.
VERY interesting... too bad I can't see the pics... any clues as to what features/JavaScript/etc. I have to enable/disable in MicroSquish IE to see the fine pics?
The above (and subsequent) pics show the parts for the hull support and wheel bearing in various states of assembly. Everything fits perfectly and need only be seated with a rubber mallet.