Before you can answer that question, you need to accuratly define your objectives.  At some point weight and durability become trade offs.  Colin Chattman of Lotus fame once described the perfect race car as one that crossed the finish line first, as the engine blew up and the wheels fell off.  Can you forgo graceful overload characteristics for lighter weight?  In the life of a recreational vessal there are going to be "Oopses", and the lighter you make the structure the less well it will handle them

Personally if weight were that important to me, then wood would not be the way to go.  Tensile on e glass is about 22.5k psi, spruce maybe 450 psi, okoume not even close. 

As a kayak builder and auto mechanic I must state that Lotuses (Loti?) while pretty were mostly unreliable junk. Wooden kayaks,on the other hand, if built with to the proper specs can be fun, long lasting and strong. And also pretty. Don't skimp to save a few ounces, it ain't worth it.

My opinion, of course, your mileage may vary

Dan

Woodworm,

The glass on the Shearwater hybrid decks is there to seal and consolidate the individual strips. It provides additional tensile strength and abrasion resistance. It was specified by the boat's designer from Day One. It's part of the prototype, not an added marketing gimmick. Ignore the troll. He's so wrong, let me explain. (What movie is that line from, anyone?)

First, comparing the mechanical characteristics of a Chessie cambered plywood deck to those of a Shearwater hybrid deck is a meaningless apples-to-oranges comparison. They're different sizes, shapes and made of different woods assembled in a different process.

Next, the guy who drew the original Chessie (Chris Kulczycki) based it on his personal experiences and a tiny production run. The deck fiberglass was added after thousands of builders built and used thousands of boats. Some reported cracking, leaking, wood discoloration and other problems. It's normal to see differences between the class leader and subsequent fleet boats in any branch of boat/shipbuilding. Or anything for that matter - cars, planes, computers, etc. The later production models always differ from the prototype based on experience with an extended pool of users over an extended time.

The other thing to keep in mind is that Chris is a craftsman, an experienced boatbuilder and an experienced paddler. Many of CLC's customers are newbies building their first boats. Many are also newbie paddlers. So the boat design had to be adapted to increase the chances of successful building and paddling by all skill levels. The design has to work for newbies but perform well enough to make the experienced folks happy, too. That's why the current plans specify things that are not in Chris' book.

The skin on frame boats are another meaningless comparison. Nylon and vinyl are flexible polymers with completely different characteristics than glass and wood. The polymer skins do not carry primary structural loads the way that the plywood skins on the Chessies do (that's why they have to have frames).

If you're still worried by the troll, go to Eric Schade's website. He designed the boat and sells the plans. He doesn't sell fiberglass or epoxy and he will give you the designer's point of view about the glass.

Be safe crossing bridges in Norway,

Laszlo

I finished my 2nd build, a Shearwater Hybrid, this spring.  I'd say that 'glassing the deck is very important & necessary.

Some things I did to save weight:

Instead of using 9oz. fiberglass tape to reinforce the seams, I cut up strips of 4 oz. cloth. This uses less epoxy to fill.

I kept the reniforcing fillets on the slim side.

Instead of doing the type of "end pour" that the instructions call for, I used Nick Schade's technique with dams, filling the epoxy with microbaloons to a paste consistency. Keep 'em small.

Eliminated the reinforcing tape on the bottom panel puzzle joints. I figured that this joint will have a layer of fiberglass on each side anyway. The tape creates quite a bump inside the cockpit , and it takes a lot of epoxy to level it out. Nor do you have to completely fill the weave of the fiberglass in the cockpit.

Eliminated the "football" shaped piece of fiberglass on the bottom. I simply covered the entire bottom with one piece, and made 4" reinforcing strips at the bow & stern.

My Hybrid weighs in at 41 lbs. I think that unless you plan on using the boat hard, there is just a tiny bit of "overkill" in the instructions.

Nick,

First off, I don't work for CLC, I never have worked for CLC. I'm one of their customers and what I wrote is my own personal observation & opinion. It has nothing to do with CLC management or employees so any feelings of resentment should not be directed towards them.

Second, if you do not like being called a troll, then simply do not use trollish login names and trollish vocabulary while delivering a trollish message and then no one will call you a troll.

Finally, if you look at the CLC homepage, you'll see their free shipping offer.

Enjoy Scandanavia.

Laszlo

Wow, been about three years since I had to delete an entry on this Forum.  But I got about thirty complaints-to-the-moderator this afternoon about that one!  Posting with an obscenity as a username will do it.  Plenty of room on the Internet for shouting, but folks are nice in these here parts so keep it clean.  

thank you for your thoughts, 

if it was only a question of weight, I have access to approx 40 lbs overweight. As an engineer I now we tend to stay on the save side... so I thought I ask

Im not sure which way I will choose, because I plan for heavy usage I will do some extra glass on some parts as N.Schade desrcibes in his book. The question raised because a company here were I live states that glass all over the hull is an overkill and that easily could be reduced without loosing durability. There was a big discussion on that point, and Ithougt of asking here were a lot of builders of clc boats are around.

 I was just interested so no need to fight.

a lighter boat is nice when putting onto the car or when need to carry  it around