Following my meeting with Andy Mitchell, being kind enough to show mw around his JR Kingfisher.

  I was wondering is it possible to use a 5" od 1/4" walled tube to house the bottom of my 4" od hybrid mast??

I am planning to use a deck shelf system using hardwood ply and make a deck collar at the hatch level.  Would it be possible to bond a 5"x 1/4" ali tube from the hull through the deck shelf & through the hatch?  I had planned to pack a couple of discs of 3/4 hardwood ply into the base and then heavily bond it to the hull with grp.  I would need a drain hole to let any moisture out.  By using this tube it would be easier to get the whole thing plumb and I could reinforce it to the deck/hatch in various locations to give added strength. 

A bolt going through both tubes at the foot should secure it and wedges at deck level. 

One issue I have considered is getting the electrics from inside the mast through the tube an into the cabin?

Your thoughts on this would be appreciated!

Thanks Mark