I am just starting to build one. So i gave been looking on line for various designs. I haven't seen any examples of how people attach them
Aha! Ok. No problem. There are many ways to attach them. The idea is to affix it firmly near the base of the mast toward the bow. I cut a slot in the base of my pole with an abrasive wheel about 2" from the end. I then slid a piece of steel bar through the slot. I have a hole in each end of the bar that allows a u-bolt to fit through it. I slip the u-bolt around the mast, and I thread the u-bolt through the holes in the steel bar. I attach the nuts and tighten, no too tight.
The role of the gin pole is NOT to bear any weight. It simply keeps the forestay above the mast, so it maintains leverage by which to haul the masthead off the stern of the boat.
The length of the gin pole should extend from the base of the mast to the forestay chainplate.
I used 2" aluminum pipe with eye bolts on top and bottom at the end above the forestay chainplate.
The forestay shackle attaches to the top eyebolt.
A 4:1 boom vang rig attaches between the forestay chainplate and the bottom eyebolt. When the mast is horizontal, the gin pole is vertical. As the gin pole is hauled toward the forestay chainplate, the, mast is raised.
Here is a picture:
You will need to construct a crutch or cradle to keep the mast above your sliding hatch, and the higher you get it, the less you have to raise, but there is a tradeoff, as it can get more difficult to use a tall cradle.
All the shrouds aft or in line with the mast are attached prior to raising, and the backstay is attached prior to raising.
The photo shows us raising the mast on my friend's Oday 26.