: I'm still collecting information before I attempt to build a kayak and have
: many questions. I have been reading the pro's and cons of s glass , carbon
: , kevlar and a mix of all and i'm trying to work out what would be best
: where. So far I thinking the best for strength to weight would be S glass
: on the outside with a carbon kevlar inside?? I know S is not as clear but
: stronger for the same weight. So a few questions for a strip baidarka that
: will see open ocean with surf landings

If you are acquainted with Doug Adams book (and radio show, and movie) The Hitchhikers guide to the Universe" you'll recognize that the ultimate answer is 42. You may also realize that once you have the answer, you still have questions about how to apply your information.

Same goes with kayak building.

My suggestion is that you limit the scope of your research. Don't waste time looking fo rthe ultimate anything--just deal with the data that you need to get out ONE boat which will suit your needs. Even then you may be overwhelmed.

For instance. let us assume that S-glass is indeed somewhat stronger than E-glass of the same weight. What do you want to do with that info? Do you want to use a thinner and lighter S-glass to replace the specified E-glass, and save weight, or do you want to replace your E-glass with the wame weight S-glass to get more strength? At this point you would probably start looking at cost of materials and their availability, and find that it would take 45 days to get the material you need shipped to you, at an exhorbitant price. So now you find that you can indeed solve your questions, but then can't actually get the materials to build the boat--and you are back with new plans, and no work done on the boat.

Let's break that line of reasoning. Start at the beginning. You want to build a baidarka from wood strips. What design have you selected? What materials does the designer think the boat should be built from? If the designer has specified 4-ounce E-glass then it might be OK to use 4 ounce S-glass, but ask the designer if 3-ounce or 2 ounce s-glass would work instead. The designer would be the most logical place to start asking specific questions about their design. Odds are good that they are alive, have an e-mail address, and would be happy to correspond with someone who is paying good money to buy a set of their plans.

: 1. What would be the ultimate layup for strength to weight?

You can search the archives of this board for months and get lots of opinions. on this. You can delve through Sam McFadden's research and statistics (also found in the archives) and get more info. None of it will actually help you until you know the answer to one teensy additional question, namely: "How much strength do you need?"

For most small boats you could get all the strength you need with 1/8th inch thick (3mm) cedar covered with 2 layers of 2-ounce glass on both sides. that might be great for a 15 foot kayak for smooth water and a 100 pound paddler, but obviously you aren;t going to build an aircraft carrier from the same sized materials. Bigger boats are made from bigger parts. So again, we get back to the question of: "What plans you are using?" Then we add to that the questions of "How big are you?", and "What is the displacement, length, beam etc. of the design you are building?" Once we have that info we can start to look at the large number of options, and narrow those down to something you can work with. Anything beyond that is simply distracting.

: 2.Vacuum bagging inside and out will save how much weight?

A few pounds. The big savings is in sanding time. If yo do the vacuum bagging right you'll have smoother surfaces when you pull off the bag. The downside is that you'll spend nearly as much money on peel-ply and breather fabrics as you do on your fiberglass. Add in the ocst of a bag 22 feet long and your just about triple your 'glassing costs. All that ot save a quart of resin? Not really worth it to most people.

: 3.slanting the bulkheads to allow for some flex??( I was thinking to line the
: whole inside in 1 piece first ,then use carbon kevlar tape for the inside
: seams and fitting of the bulkheads.

This seems to be two parts: bulkheads and seam tapes. The question is confuseing so an answer might be meaningless. Please clarify this basic issue for me: Do you want the boat to flex or to be stiff? Carbon is great for stiffness, but it tends to also be prone to crack rather than flex. Kevlar is not used for stiffness. It is good for impact resistance, but (weight for weight and size for size) it is not as strong for binding seams as glass. The seams are not straight, flat areas, but made up of compound curves. Bias-cut glass fabric works nicely for these areas and is to be preferred over woven glass tapes. If you use glass for other areas of your boat you can frequently cut the strips from the excess fabric.

The greatest amount of flex is allowed when your bulkheads are perpendicular to the centerline of the boat. If the bulkheads are slanted -- which might be a nice comfort feature if you plan to use them as foot rests--then you increase the area of the hull which is kept rigid by the bracing of the bulkhead.

If you mount the bulkheads tightly to the hull: There are some people who believe this creates areas where stresses can develop. If you mount the bulkheads slightly away from the hull, using a wide tape of glass fabric, you have some ability for the hull to move. If it moves too much, you'll crack the resin-soaked tape.

So, does the design even call for bulkheads? Are you sure you want to put your bulkheads close enough to use as footrests, or would you rather have a slightly larger cockpit area, and use adjustable footrests so you can change your sitting position, or adjsut the seat, to help balance the boat, or compensate for wind or loading? Can you use bulkheads made from closed-cell foam? Would you be interested in using float bags instead of bulkheads? You have a few choices here.

: 4. Will cutting wood out of the bulkhead just leaving an "X" of
: wood in the middle and laying 1 layer of kevlar over the whole thing make
: it lighter than wood alone? Yes it will , sorry just answered my own
: question. Has any one done this ?

If you cut away wood from your bulkhead it will be lighter than if it is a solid piece. If you then add any resin or glass or kevlar to it then it will get heavier than plain wood--not lighter. Your lightest option would be to remove the bulkhead completely and replace it with hollowed-out hardwood dowels wrapped in a layer of s-glass and polyester resin. Or, use a bulkhead frame, which is your bulkhead with the center cut out of it. No "X" at all.

: 5.Zurcon??? A very well respected kayak maker here in Australia is offering
: this as a strip (I assume a rubbing strip) Has any one heard of this? I
: was thinking of just using Leading edge tape as I have in the past as a
: rubbly strip and still will use it around tow cleats and where the paddle
: hit the deck near my feet etc.

Sorry, never heard of the stuff. If you can point to a site where this is offered I'd be interested in reading up on it.

: 6. best coaming style for USE not just looks. I love the idea of a full
: recessed coaming like in the discussion a little further down but I think
: it would be too slow to use when your launching through surf. What the
: general thought on that?

How would a lower coaming be slower to use? It is easier to trip over higher ones. Recessed ones, when built properly, so that the water drains away from them, should have enough room around them to fasten your sprayskirt just as easily as any other coaming. If you plan to roll this baidarka, then the lower the back of the coaming the easier it is on your poor back. If you are dealing with lots of waves breaking over the front deck you may wish a higher peak to the deck and coaming simply to deflect more water away from you.

Remember that YOU are the one building this boat, and you have the option of doing it both ways! Start with building the boat. when you get to the deck, leave an opening about 4 to 5 feet long over the cockpit. Glue a deck beam under the ends of the strips, and leave a lip, or edge, exposed on those deckbeams. Now, build a coaming over the center seciton of the deck, stripping from the fore deckbeam to the aft one. When you are done you can simply lift up the center of the deck. Make one center with a recessed coaming, another with a raised one. You can make a third with a mount for oars and a rowing seat, if you wish. Some type of bronze or stainless steel bolts can secure your coaming of choice to the deckbeams. Unbolt it and change the coaming to suit your fancy. If you want, you can leave the wide-open cockpit with no coaming, build up the floor a little, and ride in the boat in a manner similar to a sit-on-top kayak.

7. I think this is from the double question you posed earlier.

I hope some of this makes sense to you, and that you will get back to us with some more information on your project. The more specific the information you have, the better we can focus our opinions and answers. 'Cause you don't want universal answers--you want very specific information. And we will try to help you there.

PGJ