Her bilge keels were too wide apart for the wooden sleepers on the trailer, and the length from front sleeper to rear one was only just right for the boat. This meant lots of juggling to get her placed exactly in the right place on the trailer. But having got that far we found the tractor couldn't pull her out, rear wheels slipping, front wheels in the air. It wasn't heavy enough, not enough ballast in the wheels and on the front of the tractor. This is a problem for all boats, not just the test one, though it was one of the biggest and heaviest, which is why it was used for the test, of course.
The digger, with new starter motor fitted, had to be hitched to the front of the tractor to help pull her up the slip. All went well, both pulling hard, the trailer's front wheels got beyond the top of the slip, and it kept coming up till the rear wheels came up to the top of the new concrete of the slip and onto the short section of hard packed earth, when they sank into it, to almost half the wheels' depth. We were now stuck, the trailer couldn't move forward or back, till the rear wheels could be lifted out of the earth.
This took several hours of manual prising up of the rear wheels using long steel girders over wood block fulcrums, with steel packing pieces added progressively to lift the wheels out. Steel plates were then placed under the wheels and the tractor and digger hitched up again and out she came, at last.