View Full Version : Mast Tuning
11th June 2007, 04:20 PM
I'm trying to understand better why/when and how you tune your sails using different mast types vs mast lengths. I've read some of your earlier posts describing this but I still don't quite get it.
For example, lets take a Hucker 6.6 as an example. Assuming you are going to rig on a 460, given a choice, how do you decide when to rig it on a Joystick vs a Speedstick vs a Lightstick vs a Backbone and what benefits vs drawbacks do you get from your various options?
When/why do you decide to go to a longer (or shorter?) mast than recommended as optimum? It's unclear to me how you go about combining the decision of choosing a mast type (ie, Backbone vs Lightstick) with the decision on mast length (ie, optimum length for a given sail vs next size up).
How does wind strength & sail size factor in (ie, you're rigging a larger sail on a light day vs a smaller sail on a heavy day)?
I'd also like to understand how the decision making process changes for different sail types - ie, if instead of rigging a Hucker you were rigging a Retro, NX, or a Glide would you make the same decision?
On a related note, someone recently told me that even though you could rig a Backbone 460 on a Hucker 6.6 or even up to a Retro 7.5 you probably wouldn't want to do this since the Backbone 460 isn't as stiff as the non-RDM 460 masts and so what you end up with is too soft and doesn't have a very stable CE. Would you agree or disagree based on your experience (ie, when would you rig, say a Hucker 6.6 or Retro 7.5 on a Backbone 460 instead of a Joystick 460 or Lightstick 460)?
By the way, Roger, did you ever get a chance to compare the Redline 460 to the Lightstick 460 so see if they are about the same?
Thanks for helping me understand these complex issues...
13th June 2007, 12:37 PM
No, I was pretty busy teaching this last weekend, so I have not been able to weigh rigs and test different masts. I hope to do that in about a week as I'm on a mission to fix a ship at the moment.
As far as using different masts to get different shaping in your sails, I think you need to decide what you want the sail to do (that it isn't doing on the recommended "best" mast) before you start using other masts or mixing and matching tops and bottoms.
Let's talk about the 5.6 Hucker here as I have the most experience with using different masts in that sail.
The sail was designed on a 430 Joystick or Speedstick (bends are pretty similar between the 75% Joystick and 100% Speedstick) so if you want all the power and "loft" that the sail was originally designed for, use these masts.
If you want more low end power, and a little less loft (more twist in the top of the sail) try the 5.6 Hucker on a 430 cm Backbone.
The Backbone doesn't fill the luff sleeve as fully as the Joystick/Speedstick, so you get a little more draft in the front of the sail when it's loaded up, and the tip section of the Backbone is significantly stiffer than other RDM's but not quite as stiff as the Speedstick/Joystick.
If you want to use the 5.6 Hucker as a slalom racing sail, then the trick is to rig it on a 460 Backbone mast and downhaul the stuffing out of it.
The 460 Backbone is IMCS 24-26 (vs 21-23 for the 430 Backbone) and the additional stiffness will pull the extra material in the luff sleeve out and give the sail a very fine and smooth leading edge.
The 460 Backbone is also a bit stiffer in the top than the Joystick/Speedstick/Backbone 430's so you get very limited twist in the top, but with the massive amount of dowhaul, you get twist, but it does not extend into the upper panels beyond the ends of then anit-flutter (mini) battens.
The reason it's not so good to rig the 6.6 Hucker and the Retro 6.5/7.5 on a 460 Backbone is that the bend characteristics are a little different and the diameter is so much smaller. You get more draft in the front, but unless you really downhaul a lot, the luff sleeve doesn't pull back until the mast fills the the front of the sleeve, so you get some looseness on the leading edge.
You can of course keep downhauling the Retro or 6.6 Hucker until you get the luff sleeve to fill out an tension the panels, but by then you would have pulled alot of the power out of both the top and the bottom panels of the sail.
So, the decision on what mast to use is all about what you want the sail to do.
More low end but less stable on the top end, use acompetitive brand RDM.
A bit more low end with a slight bit more twist at the top, use a Backbone in the appropriate size.
Full on bump and jump sailing.... use a Joystick/Speedstick in the recommended size.
For slalom racing (for the 5.6 Hucker for sure) use the next size larger Backbone mast.
For Retro's (for sure the 7.5) you can get more shape in the top of the sail with a 490 IMCS 28-30 than you can with a 460 cm IMCS 24-26.
Big guys like a bit more shape up at the top of the sail, so the 490 Joystick/Speedstick is the reommended alternate mast.
I'm working on trying a 490 Lightstick bottom with a 550 Lightstick top section in the '07 9.5 Retro to see if I can't get a bit more shape up top to get even more incredible low wind "grunt" than the Retro already has on a 490.
I will be testing this in Hatteras in the coming weeks.
The basis for using the different masts is that they all have somewhat different overall bend characteristics. This can be used to add or take away "tension" in the various panels. A stiffer mast gives more panel tension, and a softer mast removes some panel tension.
Hope this helps,
13th June 2007, 04:12 PM
I really do appreciate your taking the time to help me understand mast tuning. Thanks to your ability to explain these complex issues, the light is slowly coming on and the parts are beginning to drop into place.
Overall, it sounds like you're saying that the biggest differences are between RDM's (ie, Backbone) and SDM's and not as much between the different SDM's (ie, Joystick vs Speedstick vs Lightstick) since the latter have IMCS's that are very comparable.
As far as what I am trying to acheive, it is mostly how to use mast selection to augment my current use of DH in tuning the rig to best handle either gusty conditions or, if steady, underpowered or overpowered conditions.
So, for gusty conditions, am I better off just adding more DH to the optimum mast OR going to a slightly softer mast such as a Backbone (so the rig twists off more in the gusts) OR going to a slightly stiffer mast to maximize rig stability?
For light steady conditions (for a sail that's a bit small for the conditions), am I better off with less DH on the optimum mast OR a stiffer mast to minimize twist OR a softer mast (such as a Backbone) to provide better pumping?
For heavy steady conditions (for a sail that's a bit big for the conditions), am I better off with more DH on the optimum mast OR a softer mast with more DH (for more twist)?
Thanks for your help :)
13th June 2007, 08:19 PM
Jay, I think you got the jist of what Roger is saying. Don't forget that Huckers are designed to be bump & jump sails. Roger brought up that a 5.6 Hucker with a 460 Backbone makes for a great slalom sail. I can attest to this. I can tell the difference between how the 5.6 feels with a 430 zFree and 460 Backbone. Big difference. For kicks, I rigged my 6.6 Hucker on my 460 Backbone. I could tell it wasn't going to be an optimum setup (just look at the luff as Roger described).
My point is you have your summary correct except you are forgetting to factor in how you plan on using the sail. This goes beyond just the conditions.
I go with a smaller Hucker and rig it with a little downhaul (for power) if I expect the wind to pick up. Then, I only have to downhaul more. If I expect the wind to die down, I rig a larger Hucker (or Retro) and downhaul the snot out of it. Then, I only have to let out the downhaul if the wind dies. The decision on what sail to use also depends on the board I'm sailing. If I am on my iSonic 105, I typically want the larger sail to help me get through any lulls.
A complex issue... a very complex issue indeed. :-)
14th June 2007, 02:52 AM
o2bnme, thanks for your input.
Maybe I'm not sure what you mean by "how you intend to use the sail". I'm still on the learning curve since I've only been sailing a couple of years (I'm probably a bad intermediate; I waterstart and am in the harness and straps but need to work on my stance and jibe etc). So at this point I mostly go out on sails from 5.0 up to 10.0 and go BAF. I think of B&J mostly as sinkers used in swell conditions and I don't sail anything below about a 120 L board at this point. I find myself in swells in 25 mph winds but I don't jump. I think of slolam as going for max speed on flatter water but I'm not really into that yet since I'm still working on improving my fundamental skills. So given that's where I'm at (a learning B&Fer, does that change how I should be looking at mast tuning? As I said, I'm interested in making it easy to deal with both gusty and changing (ramping or tapering) conditions. Your comments on how you deal with the latter was very helpful. Given the addtional info I provided on how I currently sail, are there any other things I should think about? Thanks!
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