classic beam construction questions

[matt connolly]

Im soon to embark upon my beam building journey for my tangaroa mk4,I'm wondering if anyone has thought or experience with wharrams 'nails not clamps' technique when gluing the planks together? Also as far as building the beams up in the centre(not sure of the term) for sitting the mast,is it necessary or can the beam be straight across? Any info would be great.

[andy solywoda]

Ahoy Matt,

http://www.sailblogs.com/member/kaimusailing/?show=contents&p=4

[matt connolly]

Sorry for the delay,but thanks for the link Andy.

[Tam Dl]

Not sure what your nails question is, but I have a few thoughts. 

1)  Nails often lead to more efficient construction.  You can simply assemble stuff, there isn't any waiting for sub assemblies to cure, and then cleaning them up and moving on. Think building a house with stick framing, you just start in the morning sawing and nailing and you stop when you run out of energy or light.  There isn't any situation where you stop for 8 hours and wait for something to harden off.

-  So today I am putting shear clamps onto skiff sides.  I could staple them on and hang them in a curve, but to do that I need full length shear lumber, and there will be some scarphs, so that would take a few steps. 

- I can back the two pieces together, and clamp and screw them together as I go making all the scarphs and the assembly in one wet glue.  Which is probably what I will do.  That means one day till I can start skiff assembly

- Or another option is to nail each stick to the ply side, with ring nails, and piece each scarph as I go.  No clamps, or work surface, or sub assemblies.  With bronze nails they can be machined later if required.  That is how they did it in the old days, still works today.  They probably had no trouble getting full skiff length pieces either.

2)  So which is best to have in your boat? 

- I prefer to have all encapsulated parts, bonded, and no fasteners.  With this approach even plastic nails, staples even zip ties have worked their way out.  I haven't seen that myself,  But I have seen rust in disassembled parts.  Reports are from reliable sources though.  So I prefer to take everything out if I am encapsulating, which rules bronze ring nails out (I have left just about everything in, but I generally make an effort to get the stuff out, 12V battery at the ready if you know what I mean...). 

- The other extreme is boats that whether they use epoxy or whatever are actually designed in the nail er up, use waterproof high end materials, sheath at the most below the waterline, and so forth days.  In that case the fasteners may actually be essential to the load path integrity.  I have seen shears that were designed for fasteners but where they were left off and just bonded the whole shear eventually popped.  It is also theoretically possible for fasteners to add stiffness to even a bonded structure, maybe, but since Wharrams aren't engineered, I don't really see that as a likely problem.

- I have converted various structures to WEST that started out nail 'em, as doubtless we all have.  The key is to move in one direction or the other.  To me, the middle ground is a problem.  So bonding/encapsulating is great, nailing is less so but if you bond it and don't properly detail it, it may pop.  You don't want to build it without nails in a situation where the parts were not really  designed for WEST (technique not the glue), and then leave the nails out.

Not sure any of that is what you are asking about, so for what it is worth...