There's been lots of discussion on prior threads of the virtues of a soft rig vs a stiff rig (ie, see recent thread: "Lighter = Less Forgiving?"). One of the reasons discussed is the benefit of automatic gust response reducing the amount of work needed to control the boat and keep it powered up in windy/gusty conditions. I'm a believer in this benefit, having seen flexible masts work their magic on monohull dinghies and having experienced the challenges of a stiff mast on my own dinghy. I was thinking that if this is the case, why is it that so few cats (and no US made cats to my knowledge) use them?

I suspect it's considerably harder to design a properly functioning soft rig than a stiff rig since you need to take into account the "stiffness distribution" along the full length of the spar and match it with the sail cut to be sure the overall combination strikes a balance between being able to develop sufficient power, keep an appropriate sail shape in different degrees of mast bend from downhaul etc, and properly auto depower at the top. The windsurfer masts/sails are fairly eveloved in this regard.

Either most cat manufaccturers don't want to go to the trouble or maybe they feel that any comprimise in stiffness will be too much of a comprimise in power. This raises an interesting issue which I'd like to bring up for discussion: Maybe heavy cat manufacturers CAN'T use softer rigs for this reason. My instinct is that a self depowering rig might only work well on a lighter boat. I suspect that what lets a softer rig work properly with a lighter boat is that the lower mass allows it to accelerate and this in turn allows the rig to power up again sooner, offseting the effects of depowering in the first place. Specifically, as the lighter boat accelerates, I would think the resulting change in apparent wind would allow its mast to staighten sooner and therefor power up the rig more quickly than it could have otherwise (ie, even before the gust has fully passed). On a heavier boat, the softer mast might spill air in a gust, but due to the boat's inertia, the rig won't be able to powerup again until fully after the gust has passed, effectively reducing overall power during this period compared with the ligher boat scenario.

Another area that might be interesting to discuss in this regard: tapered masts vs less stiff non-tapered masts impact on bend geometry and automatic gust response vs rig power. I would think this is a complex issue because bend geometry and dynamics must be related to material stiffness, thickness, and cross sectional profile including tapering if any. My assumption is that with a uniform wall thickness, simply tapering the mast allows it to become more flexible so just varying the rate of taper would allow one to program the bend geometry. Windsurfers use tapered masts as part of tuning the mast stiffness profile and I know some larger high tech sailboats do as well. The Stealth has one. The Taipan uses a straight mast but it's rig is reproted to be quite refined and responsive none the less. I would think that a straight mast would bend mostly near its center, whereas with a tapered mast one should be able to program the position and degree of bend. Maybe more central bend on a straight mast can be compensated for by the right sail cut but I would think that the best automatic gust response would be achieved with a softer mast higher up than lower down. This would let you keep the lower sail powered up all the time maintaining maximum drive in the rig while reducing heeling moment from higher up.

So, in addition to the above issues, I'm curious if sailors, designers, and sailmakers have input on:

1) whether there are real advantages to tuning the bend geometry and dynamics using a tapered mast (I suspect there is)
2) if this does in fact offer even better sailing characteristics such as gust response than a flexible straight mast (I suspect it should)
3) if it might even allow sailmakers more flexibility to cut the sail in a way that offers additional benefits over what can be done for sail shapes on flexible non-tapered masts (such as allowing an even more powerful sail due to larger draft and better control of the sail draft as the mast bends due to downhaul adjustment).

If there are benefits to the above, I assume the reason they're not done currently is due to cost of R&D as well as manufacturing costs. However, it might be in part lack of demand from the buying public due to lack of education on what they should look for in a better boat. Sometimes a specific technology is more expensive only becuase it's done in lower volume; if enough buyers insist on it, prices come down automatically as market pressure forces it's adoption by manufacturers. So I propose by discussing these issues, even if they a slightly esoteric to some, that ultimately we could all benefit.

Lots to discuss!

Jerry