Which materials for my build? Cores, fiberglass, Resins, etc...

My $0.02;
Consider how long much life do you want to give this hull and how soon do you want to be fishing. If you want it to last 5-6 years, the least cost, and on the water soon, go with good exterior plywood and vynilester resin and knock it out.

If you want something your going to pass down (not get your $ back on)
Use Nidacore for your Decks and Floor laminated with Polyester Resin and 1308 Glass. My experience is that 12oz Biaxial is good for decks, some folks say more some less, 1308 Bia worked for me. Nidacore is cheaper than the Diab products and will do the job on horizontal non-structural parts. Use Epoxy to bond them to the boat though, not the polyester resin. Use Divinycell H45 (Diab 45) for Bulkheads and vertical structure, Nidacore doesn't have enough strength on end. If it's an old school solid fiberglass hull that was very thick, it may not need "stringers" that weren't already there. If your replacing existing stringers or just feel they are needed, use at least 8lb two part foam, but 16lb is better. It sets rock hard and very strong. Use 2lb foam for flotation, if you feel the need to not sink in a emergent situation. If your going the "no rot" route you could also do your transom out of poured 16lb foam or some of the higher density Diab product.
Check some online resources for your material too. I'm not saying anything negative about Fiberglass Coating, I've bought from them when I didn't want to wait for something to be shipped, but I've come to the conclusion that I'll waste more on gas and wasted time driving to get my materials then just ordering them and having them delivered to my door. Here are some of the  places I've used;
http://www.carbonfiberglass.com/ (illstreet composites)
http://www.compositesone.com/ (bought my NidaCore from them wholesale, wholesaler not online)
http://www.sollercomposites.com/
http://www.uscomposites.com/ (Foam)
Hope this helps.

 

I use Raka for all my materials.

I used marine grade 3/4" plywood(doubled up) for my transom in my RiverHawk B-60. It will outlast the boat.

I'm about to rebuild the rear deck but haven't settled on what deck material I'll be using. I was somewhat concerned using nidacore (or the like) when fastening seat pedestal deck plates to it. I feel that it would pull out.

Is the 1308 strong enough for that?

Another thing I've read is that when using nidacore more glass and resin are needed which could offset the weight savings of using a lightweight core material.

Just .02 worth...

 

SuperDave..The NidaCore will not hold screws without adding some kind of reinforcement ie; Marine ply, aluminum plate..etc. Also true is that the weight savings is not dramatic. My experience has been that laminated properly with a good resin to glass ratio you might save 15 to 20% on weight. If your lamination is resin rich, you could get really close to the same weight as plywood.

 

10-4.

I was just put pulling some measurements for my rear deck but still can't decide if I should use this 3/4" M grade plywood or go get a sheet of 1/2"

I weighed the left over 3/4" sheet and it came in at 55lbs. Now I wouldn't use all of this of course.

I will say I'm getting pretty pumped about my little build up. It's been a long time since I've gotten back on it.

 

The decks in my boat are all 1/2" meranti as per the design. They will be glassed with biax, however, the plans don't call for them to be glassed. You can buy a 1/4" sheet for $40 and laminate two pieces together or a sheet of 1/2" is $70-90.