stringer at chine???

HAHAHA ))
I am just trying to find the easiest and the cheapest way. I am not insisting that my ideas are right but if we reduce the duration of every operation, finally we get huge time not to be wasted. I just give a simple example please read this: http://en.wikipedia.org/wiki/Single-Minute_Exchange_of_Die
http://en.wikipedia.org/wiki/Lean_manufacturing

 

http://en.wikipedia.org/wiki/File:StitchAndGlue.svg

Dcockey in almost every book, they say use double layers on each side of fillet. Then you can compare two case again. Please add two coat at oustside both case-1 and case-2.
I think you hate new ideas ) Do not forget you must use stringers... You can check Capehenry21. The designer used different method at chines.

 

So why did you draw only one layer of tape without thickened epoxy filling the gap between the edges of the plywood, as shown in the wikipedia article you referenced.

I like new ideas, but don't think all new ideas are better than all not quite so new ideas.

 

You might want to consider the amount of time that will be involved with filling the gaps on either side of your rounded chine and ensuring adhesion to the wood.

Beveling the chine is a quick operation with some practice, particularly when epoxy is used for the adhesive which can tolerate relatively large gaps and therefore decreases the required accuracy.

 

The rounded chine log as drawn by Metin_mehel will have a huge stress riser and this should be evident to any reasonable engineer.

As DCockey suggests, there are general rules of thumb with fillets and taping schedules, which also don't appear to be applied in the drawing above.

The Wikipedia image of a taped seam is precisely why this information service should be taken with a grain of salt (the whole salt shaker at times) as it's about the worst presentation of a "taped seam" and the drawing is incomplete.

Again, I'll reiterate the need for research. Try Harold Payson's book as a start.

 

Ok, please draw it for me. We compare two cases. I did not draw the details. It does not mean my idea is wrong. It just shows that you are trying to refuse. So I said add two fiberglass layers on outside. What changed? We compare two cases. So case-1 is stronger because of second area moment of inertia. You can not change this! Even par! You said reasonable eng. knows case-1 has stress risers. How do you know? Which engineering fact supporting your idea? This kind of people newer find inventions! No mathematical support, just someone's experiences. Ok if someone did it, then par accepted.

 

A major defect in all batten seam, chine log type construction is that the battens collect water , junk and form a great environment for deterioration to form. Your rounded chine log would collect great quantities of bilge junk.

Elegant batten seam construction has a bevel on the top face of the batten to allow water and bilge junk to escape .

The lack of chine logs in a taped seam construction eliminates this. You should investigate taped seam construction.

Also when working with plywood its best to encapsulate both the interior and exterior surfaces with a thick layer of epoxy to waterproof the structure. Very challenging to apply this film on the inside of a hull with so many battens.

 

Consider the stiffness of the assembly as a whole, not just the chine, batten or tape. The moment of inertia of those elements is not the correct metric for evaluating the stiffness of the system. The plywood provides most of the stiffness when he panels are not co-planar. In that case for the assembly to bend at least one of the panels has to deform in-plane, and plywood is much stiffer for in-plane deformations than for out-of-plane bending.

 

Michael could you please explain more?
Meanwhile of course all wooden parts must be encapsulated by epoxy.

 

Dcokey, why do we use stringers?

 

Well......poor a cup of water down the inside of a hull on a chine log seam or batten seam hull and the water may never reach the bottom of the boat...it will get collected on the tops of every batten.... standing water and bilge junk is Not good. In a ideal world the inside of a hull would be perfectly smooth like the inside of a coke can.

Also consider the engineer properties of ply wood ,the timber chine log and glue. When you form a good glue bond between the chine log and the plywood plank this bond will be as strong as the wood fibers under the glue. With a 25 mm chine log this means 12.5 mm surface contact on each side. Or 12mm of strength in the joint before failure. If you eliminated the chine log and used 100 mm biax tape your glue line..bonding surface.. would be 50mm on each plank and as a result much stronger and much more reliable..

Also With a timber chine log its grain orientation is important or the chine log may split...pull apart with the grain.

Im no fan of epoxy tape construction...messy...but from an engineering poit of vew it is supperior.

Also consider that with chine log there will also be mechanical fastening. Perhaps you pull them all out after the glue joint has cured..perhaps some break, perhaps some of the holes are not filled properly. encapulated plywood and timber is not happy with holes and fasteners that may alow moisture penatration..

 

Michael,
Do you know Capehenry21 boat? Can you give me examples about the big boats (7-12m) which are using taped seam connections?

 

Personally I have no experience with large taped seam plywood boats...Ive only ever built small skiffs.


Plenty of large, heavy duty, robust, taped seam construction boats around. Try google....Sam Devlin.... http://www.devlinboat.com/

Many homebuilders are building them and they record their build progress and techniques with Blogs.

 

All of you are ahead of me in areas of engineering, but 2 cents worth;

Metin, I'm betting you're a young engineer wanting to blase your own trail here away from acceptable practices. As an engineer, if I were to commision a build from you to build in the method you purpose, would you put your seal to it? Would you bet your license, my life and perhaps the lives of others?

Build it your way and build samples using traditional methods, then test all three in a controlled manner and see how your ideas fair.

I'm not taking sides here, but PAR and others have good advice, I'd rather have a boat built with proven methods than expiremental methods. You can certainly build a stick built structure on top of a concrete block wall, that is still conventional practice, but mixing the two along any wall presents problems that are more time consuming than just sticking to the conventional method, as such have evolved from experience.

 

http://www.dixdesign.com/ch21.htm