: I completed a Shearwater 16 coming in at 40 lbs . This is still
: heavy for my daughter 5:3 , 100 lbs to lift on to a car.

: Looking on the internet I came across Betsie Bay Kayaks where there
: is a 16 ft kayak at 28 lbs . Expensive .
: I was thinking of building her a Shearwater 14 and aiming for below
: 30 lbs.

: To achieve this weight I was thinking of the following:
: Using 3mm Okume rather than 4 mm
: Sheathing the boat in Carbon twill 4.7 oz. Actually I like the look
: of Carbon and the weave is very attractive and I plan varnishing
: the carbon. Will this save weight .? cost is not a factor here ,
: just weight saving
: Alternatively using 4oz S Glass satin cloth on the outside , this
: would be painted with linear polyurethane.
: Eliminating glassing the interior , only using glass at the seams .
: Making the cockpit coaming of carbon
: Eliminating endpours
: Judicious and carful use of resin.
: I understand that S glass is 25% stronger than E glass, and that
: Carbon is 100%stronger than E glass but consumes more resin(
: weight)
: Could a 30 lb weight be achieved ?
: Opinions of contributors would be greatly appreciated.

Certainly a lighter boat is possible. The strength and stiffness of a plywood boat is focused on the fillets joining the panels. Make those strong and you could cover the boat with cloth as light as silk-- so the thickness of the plywood is practically irrelevant. Just look at the plans or form of any skin-on frame kayak to see what I mean. The fillets are basically fiberglass stringers which are cast in place where the plywood panels intersect. Go as thin as you wish on plywood, or make up your own panels from 1/16th inch cedar and cut those to shape. Or, start from scratch with a plan for a skin on frame boat. Since she is 100 pounds and you are considering a shorter boat, why not also consider one which is an inch or two narrower? That may lead you on a search for plans, or you may decide to get a kayak design program (there is at least one really good free one around) and design your own. Take a look at Tom Yost's site, yostwerks.com, to see what he has. If you build a foldable boat like Tom shows, the weight will not be a factor. The boat comes apart for transport and storage. She could load two packages, each one the weight of two gallons of milk, into the trunk of the car instead of lifting it to the roof.

With marine plywood construction, why bother with glass at all? Marine paint or varnish will last for a few years, and then you put on another coat.

If you feel you need it for strength or stiffness, 3 oz s glass on the INSIDE will give better strength than having it on the outside. To increase stiffness you could use "D" shaped channels of carbon fiber strips running lengthwise. Why cover the whole insides with it?

You could use a 1/2 ounce or 1 ounce glass on the outside just to give a little scratch resistance. The thinner the outside glass the less resin you'll use to kill the weave.

Add some aluminum powder or graphite powder to the resin to increase the scratch resistance. Graphite powder might give you the 'look' of carbon fiber, and would increase the slipperiness of the hull slightly.

Take a look at GAboats.com to see some very light canoes. Add a fabric deck and it becomes a kayak.