Hey all,
Just wanted to check my understanding here.I've got a 490 mast, but my (only) sail reads that it suits a 430 or 460 mast.
Am I right in that I would need to extend the turban top out as much as possible to compensate for the fact that this mast is too big for the sail?

Cheers!

Yeah and it's going to be stiff as he1l.
Better trade your mast. That 5.8 will serve you well from 5 to 25 knots....

Could that be why I was finding it easier to sail upwind than downwind?

In light smooth winds you wouldn't notice any difference. As soon as the wind starts to gust and move around, the mast lack of well trimmed flex would render the sail heavy, non responsive or with lots of twitch depending on settings.

A poor match sail/mast will simply reduce the wind range and cause more physical stress on the rider. It may result in pushing you upwind as it'd be difficult to control and sheet out yes.

I've got the 5.5 version of that sail, and it can also be rigged on 460 or 430cm masts. I'm surprised there was enough head-cap adjustment strap length to accommodate the 490 mast!! From experience, I really dislike the sail with the stiffer 460 (ICMS 25) mast, the 430 (ICMS 21) feels much better, more controllable. I weigh in at 75kg; maybe someone heavier than me would prefer the stiffer mast...

You'll be rigging exclusively on the bottom section of the 490, which is close to 40% stiffer than the 430. So, the sail will have a deep, knuckled pocket too far forward, and no twist at all - very taut leech. So, very front-handed will make it hard to load up the fin, and the utter lack of twist will mean that every gust pulls you off balance. Even and inexpensive 30% carbon 430 will offer much better performance, and something like the Ezzy Hookipa or a Nolimitz Skinny will be night and day better.

You can try it but it will be terrible.

I have one of those, an Ezzy Wave 5.8, and I run it on a 400 because I prefer a softer mast than recommended. If you rig that on a 490 and manage to pull it into shape with an outhaul crank (that hasn't been invented yet) it will be rock hard with almost zero twist and the response of a steel beam. Unless you are the size of a silver back gorilla It will pull you up on your toes and you will have to micromanage your sheeting in and out, but then you'll need 50 knots of wind to get going.

The other problem is the 490 is going to put a lot more tension on the sail and it could slowly start to pull the sail panel/batten sleeve horizontal stitching apart, but if you crash and land on the sail that could happen very quickly.