Any marine plywood will work ( 1/4" for the hull and 1/2" for the bottom) but Meranti or Hydrotek is the most cost effective. Oakume works well and Sapele makes a beautiful boat but is expensive and a bit heavier. Scarfing the plywood will be needed. Links and info for scarfing the plywood are included, it is not as difficult as it sounds. There are many ways to create the bevel on the ends of the plywood but the simple way is to use a belt sander. The bevel doesn’t have to be perfect, it only needs to feather out. You can use your garage floor or driveway to join the plywood. Snap a line or use a straight edge to keep the plywood straight. Use plastic sheet to keep epoxy off the surface, lay the plywood down, put epoxy on the bevel surfaces and lay together keeping a slight space in between them and keeping them straight. Another piece of plastic on the top and a 2 x 4 across the seem with a few bricks or weights to hold the plywood together. You don’t want to clamp the wood as that would squeeze out all of the epoxy, a small space is needed for the epoxy to be strong. When the scarfs are done, continue coating the plywood with epoxy to coat the whole sheet, both sides - 1 coat. Then sand lit all down and you are ready to makes the cuts for the hull. Coating the plywood seals and adds strength to it. If you want to stain your hull, do so with water based stain after making the bevels and before scarfing.
Find marine plywood by searching on net for "marine plywood (your state)".

Hull lengths needed
(sizes indicate 1 finished piece, both hull pieces are cut from 1 sheet):

18 Foot Fly Fisherman -

• Hull - 4' x 18' (3 - 4' x 8' sheets for hull & 1 sheet for rub strips etc.) 4 total
• Bottom - 5' x 15' (2 - 4' x 8' sheets for bottom & 2 sheet for floor boards etc.) 4 total

17 Foot Fly Fisherman -

• Hull - 4' x 17' (3 - 4' x 8' sheets for hull & 1 sheet for rub strips etc.) 4 total
• Bottom - 5' x 15' (2 - 4' x 8' sheets for bottom & 2 sheet for floor boards etc.) 4 total

16 Foot Standard -

• Hull - 4' x 16' (3 - 4' x 8' sheets for hull & 1 sheet for rub strips, can be built to with 2 sheets) 4 total
• Bottom - 4' x 14' (2 sheets for bottom & 1 sheet for floor boards) 3 total

14 Foot Standard -

• Hull - 4' x 14' (2 - 4' x 8' sheets for hull & 1 sheet for rub strips etc.) 3 total
• Bottom - 4' x 12' (2- 4' x 8' sheets for bottom & 1 sheet for floor boards etc.) 3 total

10 Foot Mini Drifter -

• Hull - 4' x 10' (2- 4' x 8' sheets for hull & 1 sheet for rub strips etc.) 3 total
• Bottom - 4' x 8" x 3/8" (1 sheet for bottom & 1 sheet for floor boards etc.) 2 total

Ribs, Seats, Chines, Handrails Etc.

Any hardwood will do for the handrails and ribs etc, Oak is fine but I recommend White Ash.

Marine epoxy - Don recommends coating the hull and bottom pieces both sides with marine epoxy after they are cut. It seals real good and adds strength to the plywood. If you plan to stain the hull, you will want to do that first before scarfing the plywood. West System is the best and they have great info on applying it, but there are others like Totalboat.com. A gallon or so will do for a 16' standard.

Finishes - Use good marine urethane varish or marine paint with good UV holdout, you will be sorry if you use cheap stuff. Look at bottom of page.

UHMW plastic is sometimes used on the bottom of boats but putting it on is a tough job and if not done correctly will destroy the bottom of the boat. I recommend Coat-It, it is remarkable stuff. Look at bottom of page.

Stainless steel screws and bolts, square drive screws are best.

3M 5200 caulking (2 tubes) for the bottom chine battens. Amazing stuff, will not degrade, statys a bit flexible and does not dry out.

Tools needed would be a table saw, variable speed reversable drill, belt sander, hand saw, 5 6" Clamps, skill saw, adjustable #8 counter synk and screw driver bits for drill. A chop saw is handy. Other useful tools that can be rented for the short time you use them are an electric planer, router and saber saw.

Cost - I have heard of boats being built for $250 out of construction grade materials, but I think you would want something better looking and of better quality after putting in the work to build a boat which will take about 150 hours give or take. $900 to $1200 should build a fine boat.