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-   -   Masthead versus Fractional (http://www.sailnet.com/forums/racing/67730-masthead-versus-fractional.html)

Cruisingdad 08-26-2010 02:20 PM

Masthead versus Fractional
 
The traditional frame of thought, as I had always been told, was that a fractional rig was always preferred over a masthead. It was interesting, because in teh last race I was in, there seemed to be a real preferenece to move away from fractionals and go to mastheads for the extra sail area. I also found many of teh boats running a asym versus symetrical for ease of use and more versatility. This especailly comes in to play when racing with a short crew.

I have to tell you, after seeing what I saw, it would be hard not to go with a masthead. I wonder if the fractional frame of thought is overblown or out of date (jeff will kill me). I am curious what others think... also what they think about a symetrical versus asym. Now, in medium-heavy airs, I think the argument could be made for a fractional and probably a symetrical. But for lighter airs, I wonder if the mast head and asym will win every time???

Thoughts??

Brian

JomsViking 08-26-2010 02:46 PM

Sure it was a masthead? Many newer fractionals look almost like mastheads (eg 16/20 fraction). But that gives additional sail-area like you say.
We like the Asym for easy handling, and that might mean that we get there faster anyways - even if racing, because we're squirrely DDW so prefer to tack a few times instead. Our boat is a masthead, and we get a LOT of sailarea with the Asym, or even the genoa. But as has been stated also hard work getting it home.

sailingdog 08-26-2010 03:05 PM

CD—

IIRC, a while back, Jeff_H wrote a good post about masthead vs. fractional rigs and how, if given a choice on a boat, getting the fractional rig was a better idea, since it gives you more control over sail shape and such, even if it is a 7/8's fractional rig or so.

JohnRPollard 08-26-2010 03:06 PM

CD,

I think there's a bit more to it than simply masthead vs fractional or asym vs sym. Hull forms, rig geometry, sprits, poles, weight all factor in. It's difficult to be categorical about either one - so much depends on the many variables.

For instance, there was a time when most fractional boats also flew fractional spinnakers (whether asym or sym). Now, it's not uncommon to see a fractional rigged sloop, flying a mast-head spinnaker. Some designs even fly a masthead asym, and a fractional symmetric chute. Lots of variables.

In my experience, asym chutes work best for cruisers that aren't following a windward-leeward course, or for sport boats that can get up on a plane and so take advantage of better downwind vmg (i.e. they sail higher jibe angles, but at faster speeds so the extra distance doesn't hurt them). Asyms can also work well for non-planing race boats, but usually only for long reaching legs (rather than a dead run downwind).

But sometimes, especially in light air, running deep with a symmetric chute works better. That's why from one race to another, certain configurations may seem superior than others.

As Joms said, fractional rigs come in a lot of varieties. Some are SO fractional they need running backstays to support the rig. Others are only moderately fractional, and use more conventional rigs. Some fractional rigs have big overlapping genoas just like masthead rigs. Some masthead rigs are designed to sail well across a wide wind spectrum with a non-overlaping jib.

I think one of the trends in rig design that I like, is the effort to get away from large overlapping genoas. You tend to see this more on moderately fractional rigs, that put proportionally more sail area into the mainsail. Also, with the mast typically stepped a bit farther forward, in addition to easier headsail handling, you also often get the advantage of being able to sail reasonably well, and balanced, under mainsail alone.

There are downsides, of course. One important one is that the fractional rig will likely be significantly taller than a comparable masthead rig - a concern for many with bridge clearance issues.

smackdaddy 08-26-2010 05:05 PM

Good topic CD. I've been wondering the same thing. I'd like to get a kite for the Smacktanic this spring - so this helps understand things a bit better.

Personally, I like the simplicity of the masthead. Like I need anything more complicated like running backstays at this point!

COOL 08-26-2010 05:26 PM

As evident in most modern GP race boats,
the ideal configuration is a Fractional rig with
Masthead Spinnakers, and in some cases
Masthead Genoas.

GeorgeB 08-26-2010 06:17 PM

Cool is right on. Fractional boats allow for jibs to be sheeted closer to the centerline giving the boat more pointing ability. These boats are also often rigged with runners allowing for chicken head tops and roached out leaches. Instead of shifting through the gears by making headsail changes, these boats to a lot of main trimming and reefing. All those extra head sails on a mast head boat become a problem when trying store them on board for longer races/voyages. Mrs B. only allows me to take two when we do our summer cruises.

Symmetric Spinnakers project a greater sail area per a given J than A-kites. To take advantage of an A-kit the boat must be an effective surfer or planer at those hotter wind angles. Our heavier Catalinas and other cruiser boats are better served with symmetrics. Im planning on retiring our A-kite from racing next year as I am frustrated with its relatively poor performance and Im experimenting with doublehanding the symmetric. Im a bit surprised (and a little disapointed) that the new C354 is going A-kite and sprit. They take time off your PHRF number out here for a max girth larger than 180% * J".

tdw 08-26-2010 06:29 PM

One of if not the most difficult aspects of sailing a boat short handed is headsail sheeting. Larger, multi speed self tailing winches have certainly made things somewhat easier but anything that can reduce the size of headsails is OK with me.

I figure that is as good a reason as any to support the fractional rig argument.

COOL 08-26-2010 06:57 PM

Quote:

Originally Posted by JohnRPollard (Post 637070)
CD,

I think there's a bit more to it than simply masthead vs fractional or asym vs sym. Hull forms, rig geometry, sprits, poles, weight all factor in. It's difficult to be categorical about either one - so much depends on the many variables.

This is true, we are making some gross generalizations here,
while in fact there are many variations on the theme.
Some Masthead rigs use runners, or check stays,
some Frac rigs do not have runners, some do not even
have backstays.
Not all Asymetric spinnakers are flown on a centerline sprit,
or tacked to the bow.
For a displacement boat offshore, the fastest set up is an
A kite, on a conventional pole.

Cruisingdad 08-26-2010 07:25 PM

I can talk more about this tomorrow hopefully, but we had a Tiger and a Melges with a Asym that KICKED OUT BUTTS! Very light air, but shifty, which made the Asym awesome. It was a masthead. Manhy of teh racers were saying that fractional was a thing of the past. Me, I just lusted after the Melges...

But good food for thought and makes a good discussion.

B


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