hey everyone, I've been seeing quite a few tornados with a mainsheet system that runs within the boom.

Was wondering if anyone could share a diagram as to how this works? am really curious about this as it seems like quite a clever system.

I'm assuming it is a cascading system?

here you go, this is a basic 8:1 system, you can easily make it 12:1

We didn't use the Ronstan blocks shown at the base as the working load isn't high enough, but the rest works well.

Those secondry blocks need to fit inside the boom. Are they small enough? <img src="http://www.catsailor.com/forums/images/graemlins/blush.gif" alt="" />

Oh wow guys, thanks so much for the diagrams. I would never have thought to run the blocks like that, so it's really interesting. I was thinking of a series of 2:1 but trying to figure out how to stop the blocks from jamming up to each other in the boom.

Another thing i noticed about tornados from pictures (sorry none here in Singapore for me to look at) is that the deck are really clean. i am guessing quite a few lines, like the spinnaker retrieval line is run completely under the trampoline. is that correct? Any other lines that run under the trampoline? mast rotation? downhaul? thanks for the info

oh also another question, what's the benefit of running the mainsheet system within the boom besides less windage?

Marcus,

yes the Ronstan Orbits and the Karver blocks fit in the boom perfectly. I made up some custom cheek plates for the Harken sheaves and also a custom 2 sheave block to attach to the ratchet block.

ckuang.

down haul sucks into the front beam.
Rotation is under tramp.
Tack line runs down stbd hull (for access from trap)
Retrieval line / halyard are on tramp before exiting through tramp to the kite.

For equivalent purchase the internal mainsheet is cheaper, lighter and has less windage.