Sorry I haven't replied to your questions about the centre beam rule earlier but I've been away a couple of weeks.

That proposal you have picked up in the 2007 rules was purely a typo. That heading "Rule6.5" and the three paragraphs that follow simply shouldn't be there. It's a mystery to me how they got there, but I must have done it when I updated the rules so I'm sorry to have caused this confusion.

Mick Floyd has already corrected the online rules on the NMCC website.

The text originated 3-4 years ago when a proposal was made to make the centre beam optional, but the idea received no support at the time and never went any further.

In answer to your questions about rule 6.5:

1) The centre beam is definitely not optional - it's in the Mosquito plans and the BRRs don't say it can be left off.

2) The material is not specified and it could be argued that other materials (like carbon) would be permissible, however the size and wall thickness is very specific and this would limit the kinds of materials that would be possible. It's not much of a loop hole since a carbon beam 50mm x 1.5mm may not actually save much weight - should be stronger though!

3) A beam is a "beam". A piece of string or bungee is not a beam, and neither is a pool noodle.

If you are getting a new tramp and your boat had the aluminium tracks down the sides you can save some weight by replacing the tracks and bolt rope with a piece of spectra between the front and rear beams. You just need an eyelet halfway between the beams to tie the tramp down to the hull.

Matt Kirby has his boat set up like this, and some South African Mozzies too, so they might be able to supply some photos if you're interested.