I am in the process of adding a casting deck to my 14' boat (1968 Sea King). I want a deck that is 3" below the top of the boat. I am thinking of using an aluminum angle of some kind every two feet, starting at th transom, and every 2' until i near the bow, have another one. then, i will run a 2x4 accross the width parallel to the transom. A total of 7 beams and 17 angles. The horizontal beams will be supported by vertical 2x4s notched out to the boats ribs. Will the aluminum on the sides of the hull be too thin for the Screws to  support the angles and casting deck? Think of a piece of paper, stabbed by a pencil and ripping the pencil through the paper. That is what i want to avoid. Ripping the  boat hull with rivets and screws because the aluminum is too thin.

Befor you start your construction, I hope you have spoken to others who have made the same conversion on their boats. The center of gravity will be pretty high and I'd think your boat might easily tip over while standing high up on the front deck. It would be a shame to go to all that trouble only to find it isn't safe to stand up on the deck.

1 minute ago, Scott F said:

Befor you start your construction, I hope you have spoken to others who have made the same conversion on their boats. The center of gravity will be pretty high and I'd think your boat might easily tip over while standing high up on the front deck. It would be a shame to go to all that trouble only to find it isn't safe to stand up on the deck.

I agree. The only reason i think this is a good idea is because my friend did something similar to a smaller hull and it handles waves ok, so a bigger boat would do even better. It would be a shame to have that happen though!

 

Pay attention to thickness!

 

All my builds were all aluminum using "T" extrusion instead of "L" angle except for the outer perimeter. To strengthen your "thin" hull add a flat strap on the outside.

 

I did something similar to a 14' Starcraft.  It wasn't the most stable boat after it was done.  I used the existing front bench as a base for the front casting deck.  Same for the rear deck.

 

I think as long as you have other support help underneath, you'll be fine. I used a decent bit of 1/8" aluminum L-angle, both 1.5" and 2" in my boat rebuild. A couple examples below. I fished out of that boat (a lot) for nearly 8 years and never once had to mess with (repair) the L-angle used as bracing. Just use some good heavy stainless hardware along with the thicker aluminum.