So I was talking on the beach the other day re speed sailors who use lead and we discussed how the added mass reduces the sails pull over the sailor and how this extra mass makes the mast lay off more in the gusts so I am wondering if this is the case should lighter weight sailors be using sail designed around flex top masts ?
I have used RDM in some sails and noticed how much softer they feel in comparison to SDM at the expense of some bottom end pull so if we used a flex top mast would we retain the bottom end and still get the softer feel in the gusts ?
An interesting topic for sure.
IMHO, the flex top sails probably handle very similar in regards to your question as those designed for those masts. They take a different approach to producing pretty much the same feel in that regard. Putting a more flex top mast in a CC designed sail never worked for me. It looked fuller and more twisted but was always slower. I tried it with both SDM and RDM's. In the end we got far better results from changes in the actual sail shape.
On the other hand, I agree with you completely re the RDM feelings and that is why - as a lighter guy- I use them in most of my slalom and speed sails.
I dont find any penalty to 'bottom end' pull on RDM's but that may just be particular to my sails -designed specifically for RDM - and the conditions I sail in.
Adding weight in my case seems to add some nice stability to me in 'on edge' conditions, and does allow the sail to 'breathe' a bit better. It is of course, only really an advantage in fully powered conditions on a speed course and I very rarely use more than about 5-6Kg (went to 8+ at Luderitz, and most of the top heavy guys were wearing 10, or more!
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Select to expand quotesailquik said..
An interesting topic for sure.
IMHO, the flex top sails probably handle very similar in regards to your question as those designed for those masts. They take a different approach to producing pretty much the same feel in that regard. Putting a more flex top mast in a CC designed sail never worked for me. It looked fuller and more twisted but was always slower. I tried it with both SDM and RDM's. In the end we got far better results from changes in the actual sail shape.
I'd agree, though I noticed when I've used my NP mast in a Severne looked wrong, the tip had dramatic twist for the first 2 - 3 battens then if I tried to get more twist the sail just flattened out. This is on my 9.5m raceboard sail.
I've noticed that my 7.2m RSS sail which is a 2008/9 model or there about looks not so nice never feels quite right on the new FX100 mast. After my X9 broke I got the FX mast but it looks to me when I downhaul, no matter how much it twists but then stiffens up the batten above the boom. So it has this floppy tip and then firms up rather than a nice even twist down to the boom. I'd love to figure out if batten tension or something could minimize this some as I swear I can feel the effect. Or more so I was feeling the effect and when I'd look at the sail notice the odd profile.
Thanks for the replies.
My thinking was more towards using sails that are specifically designed around flex top masts not using flex tops in cc sails. Sorry for confusion.
Thanks for the clarification Col. 
My experience has been that just using a slightly overall softer mast seems to do what you were speculating about.
The interesting thing for me is that RDM masts that test on the MCS scale exactly the same as SDM masts, actually feel 'softer' to sail.
It is sometimes a bit hard to find slightly softer masts, but I have oticed that some mast manufacturers, especially in their RDM lines, offer softer than 'industry standard' IMCS in some lines and sizes of masts. Hot Sails Maui comes to mind as one whose smaller RDM's are a couple of points softer than most other brands..
Select to expand quotesailquik said..
The interesting thing for me is that RDM masts that test on the MCS scale exactly the same as SDM masts, actually feel 'softer' to sail.
No one has looked at the damping provided by the friction between mast and luff sleeve on sail "feel". If it is significant it could explain the differences between RDM and SDM as well as the difference in feel between smooth finish high end and rough finish low end masts. Maybe? Maybe not? Just a thought.
No one has looked at the damping provided by the friction between mast and luff sleeve on sail "feel".
Probably because there would be no way to measure it if it did in fact exist or if it had any effect if it did.
Select to expand quoteyoyo said..
No one has looked at the damping provided by the friction between mast and luff sleeve on sail "feel".
Probably because there would be no way to measure it if it did in fact exist or if it had any effect if it did.
You could rig two identical sails but spray one of the masts with a silicon lubricant, the other with surfboard wax. Send expert sailors to blind test them and see if they can pick one from the other?.
Select to expand quoteIan K said..yoyo said..
No one has looked at the damping provided by the friction between mast and luff sleeve on sail "feel".
Probably because there would be no way to measure it if it did in fact exist or if it had any effect if it did.
You could rig two identical sails but spray one of the masts with a silicon lubricant, the other with surfboard wax. Send expert sailors to blind test them and see if they can pick one from the other?.
....why would you! 
Select to expand quotepeterowensbabs said..
....why would you!
Some people just have to know stuff.
