The ubiquitous Streaker..

Originally posted by Medway Maniac Originally posted by iGRF It would be better if it were a carbon 'I' beam, but they haven't spotted it yet. And why, pray, do you believe that an I-beam would be better than a closed tube?

I just love re-educating you river folk..

So now let me start with the obvious question, why was it deemed better to have square sectioned alloy rather than closed alloy tubes?

Shall I wait for you to answer or shall I go straight in with the blinking obvious..

No, I think I'll wait come on then 'brain of the medway,' you tell me..

Well all that may or may not be, but the logic I was applying was the simple fact that they seem to have to use excessively large tubes for the boom to overcome the side flex and a smaller section I beam could be used to do the same thing, be a tad lighter but more important have the kind of surfaces that better loan themselves to having things fixed to them, then again a squared tube could to the same, I just happen to have a thing about I beams and I beam battens that also work quite well.

So an I beam boom in carbon should also work, but Rupert is correct I think I'd sooner head butt a tube or rectangular tube than an I-beam, but then booms really don't need to be as long as they are if the sail were looked at and encompassed a foot batten with clew overhang.

I've seen yachts sailing around with I beam booms big enough to walk on, so it isn't as though the idea isn't out there (and from decades ago), so I suspect it has been rejected rather than not thought of.

Way before carbon, I think. Could be wrong, though - not kept up to date with yotty stuff.

'I' beams are crap in torsion, and your boom actually has to deal with a fair amount of the stuff.
The yacht booms you have seen people walking on are often a carbon torque tube with a U shaped outer skin. The flanges at the top of the 'U' are what the crew walk on and the gap between the opening on the 'U' and the torque tube is where the mainsail is flaked into.

At the end of the day the actual size is fairly insignificant, and often having a larger diameter allows you to thin down the section. There is as ever a trade to be done here.