Bye bye muscle boxes

Alistair Edwards · 18 Nov 2008, 10:45

As part of the gradual upgrade of my Tigress I have removed the 3 muscle boxes and replaced them with string + blocks. In addition to eliminating lots of frustrating friction this has also reduced the weight of the boat by a kilogram.
If anybody wants some muscle boxes you are welcome to have them. They will need some TLC to get them sliding nicely again.

GarryR · 19 Nov 2008, 09:59

I would love to have a muscle box if possible.

You could email me on G.Rucklidge@abdn.ac.uk for details.

Thanks

Dave Croft · 19 Nov 2008, 10:57

Hi Alistair,
Glad to hear you are working on the boat! I agree about the muscle boxes, on the river they will be useless but you need to be sure you can get enough rig tension with whatever you do to replace them.
I would like to get hold of a mast-ram muscle box but I don't think you have used that system. Let me know if you have one though and what you want for it.
Cheers,
Dave

Alistair Edwards · 19 Nov 2008, 05:50

Hi Dave.

I have replaced the muscle boxes on the shrouds with a 16:1 purchase and the one on the jib halyard with 8:1. This is the same purchase that I had with the muscle boxes but with a lot more feel. I can get the boom out much further now and without the need to bash the shrouds to overcome the friction.

Next time you are down with Close to the Edge I would be interested to see how much rig tension you use. I suspect I could be using more, but I am wary about putting too much stress on the hull.

I have routed the new shroud tensioning down to a turning block + anchor point just below where the muscle box used to sit, and then forward/down to an anchor point at the foot of the mast. The load from this section is hopefully quite well braced by the 'rib'(?) that runs forward from the hull to the front of the centreboard case.

The race on Sunday morning is going to be a windy one, so this will put all the knots in my new system to the test!
I have a mast screw rather than a mast ram, but if you can make use of a muscle box you are welcome to one. I don't want any money for them.

Alistair