Originally Posted by Smiths_Cat
Hi Rolf,

a moving rigg isn't bad. Actually it has improved aerodynamics. In many dinghi classes "pumping" (e.g. periodical change of the sail inflow conditions or sail angle) if limited or forbidden, because people feel that their seems to be an advantage by doing so.
Hovever if the motion causes excessive hull drag due to splash or nose diving, it can't be good. There are many possibilities to do cure the problem: Hull shape, T-foil rudders and reducing inertia.
Reducing inertia is always good, but unfortunately the standing rigging is only small part of the mast-sail system and this is only a part of the whole boat inertia. Hence the gain by playing with lighter standing rigging is small.
Hull shape has significantly improved in the last years. For example my Javelin sails far smoother in waves than the 4 ft longer Tornado. I would expect similar or even better wave-going behaviour for the F16, becase of the lower mast and lower inertia.
The most efficient way would be a T-foil(ed) rudder. It will not only damp the pitching motion, but transfering the energy from pitching in thrust (negative drag). However in calm water you would have drag penalty.

The advantage of essier rigging is on F16 size boat fairly low. I didn't feel any difference.

The jib makes a difference: From your comment I see that we agree that a sagging jib is not good (especially upwind). If you don't have a too flexible mast the main sheet will keep the forestay tight. But when you react to a puff by opening the main your jib would start to sagg in exactly that situation where you want a flat jib.

Every rope from organic (e.g. plastic, anorganic = metal) suffers from UV and water. The question is how fast.
BTW I know of carbon fiber only used with resin, hence a rod and not a rope. So the UV and water resistance of the resin would be important. It should have some addtitional protection (e.g. PU or wax).

I guess some googleing would reveal you, that
Dyneema is good againbst UV and water (I replace the unbraided dyneema ropes on my boat only once a year), Vectran is used for tugging dipping sonars and on space-exploring vehicles, hence I would think of good resistance as well. Aramid and PBO are on the low end of the table.
I can tell you that Aramid (Kevlar) has so poor water resitance that we don't use it in our business (even not with epoxy resin and PU coating), but an aircraft has a different utilisation of course.

Regarding the drag increase due to diameter, I think I made some calculations already on this forum.
Btw is 5mm a bit much for a single hander?

Cheers,

Klaus


Moving rig due to elasticity in the stays is for sure slow. No other way to look at it, just plain slow.

The best way to reduce pitching from weight aloft is to reduce the weight smile The hard part is to achieve that without the drawbacks of some of the cheaper solutions.

On the topic of Vectran and UV..... its a shocker! its been a while since i used the stuff but I recall it was suffering 50% los in strength within weeks of being exposed. Its up there with PBO in that regard.

The thing to remember is that there are some really nice solutions to these problems, like easy rigging who have a nice way to seal the fibres in a watertight and UV proof cover, so the PBO from them lasts a very long time (we use X40 stays like this for more than 5 years)


Also the Maffiloi ultrawire is a good mid range solution too.



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