Update.
The Hobie cradles mounted to the C-Tug cart were a failure. The C-Tug's high centre of gravity resulted in the cart tipping forward no matter how tight the strap was.
I wanted a more portable dolly cart that was able to be fitted into the hatch and realised I didn't need the C-Tug. I could use the same Rhino bar cart as in the start of this post and make a shorter cart out of it. Here are the details:
Begin by cutting the ama supports off the Hobie trailer cradles
Cut the length of bar slightly wider than the cradles. The same fittings can be used. You can also use Uni-strut and channel nuts. I have ordered stainless steel channel nuts now I know this works
Cutting a slot in an eyebolt allows a boat hook to twist and lock in place for the handle
Of course the problem with a narrower dolly cart is that the wheels will contact the ama. If you wheel your boat with ama extended it won't be a problem. I have some narrow launch spots and the boathook helps to keep the folded ama off the wheels
The smaller dollycart now fits easily into the hatch
The HD foam wheels also fit.
This narrower dollycart make retrieving the TI a much simpler operation.
I still prefer the scupper cart for launching though as the keeper pin is much simpler to use than strapping a cart on when the TI is on my trailer. I decided to modify the cradles so they fit my favourite all purpose cart.
Using a hole saw I drilled holes for the cart posts.
The cradles can now be used on a scupper cart to provide better hull support.
PS
The carts got a thorough test this last week and I'm happy with the results. One problem that needs improving is that the handle tends to undo the eyebolt when positioning the cart under the hull so I need to work on that.
I am also working on a cart that has a dual role of scupper/dolly cart. Here is a sneak peek:
By tilting the scupper cart forward and repositioning the cradle you have a dollycart.
It's only at the prototype stage. More details later.