CBull, I too have had a hard time inserting the cart when I'm still in the water. And because of that, my AI has a few scratches on the bottom from two years of mostly pulling the AI up onto the beach. So I decided this year, to figure out an easier way of inserting my cart in the water. I've placed my cart clamps high up on the poles, so when the poles are inserted they just barely fill the scupper holes.
I find removing the cart is easy. By pulling the AI into knee deep water, I reach under the AI with my foot and place it on the crossbar by the wheels and step down. My cart's wheels are the tough balloon type and they surface immediately. I ease them up to the top by keeping my foot on the cross bar so the cart doesn't come flying out of the water.
Reinserting the wheels have been much more difficult. For a while I had been pulling the AI a bit out of the water, unloading the mast, one ama, the mirage drive and the dagger board. I would fold in one ama and then tip the AI on it's side and insert the cart. Then replace the one ama and fold both of the amas in, load everything back on the AI and pull it up the beach. This was a lot of work and I needed to figure out how to insert them while the boat was still in the water.
Last week I thought I had figured it out. I stood just outside the rear right aka, hanging on to the boat to move it around and keep myself upright. I placed my foot on the crossbar of the cart to lower it into the water and work it so the poles were standing upward. Then moving the AI into position I put my face very close to the rear aka brace and right above the scupper holes. When I could see the top of the cart pole positioned right below the scupper hole I then release my foot. (this is quite tricky) The first time I tried this, it worked perfectly. But the second and third time out, it took me so long to get it right. The water was just a bit too rough and the AI wouldn't sit still. So yesterday after I came in from my sail, I tried to eye ball it again and the cart poles, once again missed the scupper holes and the cart just bobbed up and rested under the AI with the wheels facing the rear. With the cart still on it's side under the boat, I moved the tip of the cart pole near the scupper hole and kept my right hand there to guide it. Then with my left hand I took the wheel which was on my side of the boat, and just rotated it down in the water. The cart pole popped up into the scupper hole!! It worked! It was so easy!
Maybe having the cart clips so close to the top of the cart poles helped? Of course,since I haven't repeated this, I just may have, once again, been lucky. I'll be able to try it again the end of this week.