Mast head or Fractional rig

No one has asked the obvious questions...
1) What type of sailing activity do you propose to enjoy...
2) Where do you propose to do most of your sailing... (In a local bay around the buoys on weekend 'races' or other trips of shorter of longer duration/distance...)
3) How many crew?
4) How much money do you have to spend?
5) Will it live onshore when not being sailed?
6) Do you desire to 'live aboard'?
and think (write down) at least another 20 questions to be satisfied in your boating activity... then delete the LIKES and keep only the MUST HAVE... BOATS are a compromise... some compromises exclude some activities/functionality...

 

I always thought this was a pretty silly argument.

Each type of rig has advantages, and of course disadvantages. Making a blanket statement about which is 'faster' is pretty meaningless without further defining the conditions you are trying to design for.

FR's for instance tend to have smaller tacking angles (sail closer to the wind). However when they come equipped with 155% genoas that diminishes pretty quickly.

MH rigs tend to be faster in light air, and on jib reaches. But again that can go the other way too.



For me the rig is only a small part of the equation, with the specific conditions of the day playing a much larger part than rid design. For instance in extremely light air my Olson 30 can sail circles upwind around a J-27. But add 10kn to the conditions and we watch them walk away from us.

 

A J27 walking away from an Olson 30? I'd say someone isn't sailing the O30 very well.

 

Wow. Obviously someone hasn't been paying attention to rig design for the past 15 or 20 years.

Saying there is no difference using AR as a factor shows you either don't understand how sailplans are designed or you are throwing in a strawman to try to CYA on your silly argument.

Headsail size for a fractional rig is smaller, based on rig design. How you can't understand this is beyond imagination.

No one would design a sailplan like that. Either you have no idea about designing sailplans or you are putting up another silly strwman to try to prove a silly argument.

Once again you don't seem to grasp that things have changed since the mid 1980s. Modern fractional rigs have no more "strings to pull" than a modern masthead rig.

 

When designing your rig.....

.As you can see, the masthead rig's " Masthead" is very cramped for space. Notice how close the Spi halyard crane and block is to the roller furling headstay. Jibing a socked asymmetric spi can be a challenge on a cluttered masthead rig. . Also remember a Masthead rigs" Masthead " is expensive to build and heavy when compared to a 15\16th fractional.
Also notice that on modern roller furl masts the genoa halyard exit sheave is placed much lower that the headstay in order to develop the correct leed angle to the genoa furler swivel. Many people forget this when designing a mast.

Also consider "two to one " halyard for main and virtually any other halyard. They really save weight and remove compression load from your rig. All of you gear at deck level can be one spec down with 2 to ones. Many times on smaller boats, hoists with a two to one can be accomplished with manpower alone.

 

Great discussions.

I don't really have an opinion. I'm just confused. We like to post colourful flow diagrams that show the interaction of the mainsail with the jib. You know the ones. They show the mainsail in the upwash from the jib. They prompt us to discuss the improved efficiency that the jib affords the main. They prompt us to debate the controversial slot effect and the abstract circulation theory and the advantage of the multi-element air foil.

But then, all that just falls apart at the hounds and above on a fractional rig. Good aerodynamics below the hounds? Garbage above?

Maybe the fractional rig is all about mast control. So as materials develop and the technology improves, will we see the masthead rig reinvented?

 

Airflow could be one consideration. Many other practical considerations for the masthead, fractional debate. Weight aloft, mast bend main sail shape control. Even interior layout . The fractional rig mast will be farther forward on its step possibly freeing up valuable interior space or deck space. or...big Genoas and foresails are hard to handle, big main easy. Or shifting gears...faster to throw a reef in a big main than to change a headsail. Or easier to sail a fractional rig..."mainsail only " than a masthead. The long boom and mast forward on a fractional causes the boom end to drag in the backs of waves offwind...many details. It sorta depends on what type of boat and for what purpose the boat will be used for. Each system has its benfits and drawbacks.

 

On the same boat, fractional, as compared to masthead rig will most always have:

1) lighter section of mast => less weight aloft
2) smalller area headsails => smaller sheet loads => smaller winches => ....
3) incredibly adjustable main sail => smaller number of headsails => less work to change them => less space and weight to store them... (eg. just 3 headsails (storm, working and big or genoa) instead of ~8 on masthead boat (storm,heavy weather, working, genoa 1, 2, 3, reacher) for similar adjust-ability to wind conditions ).

and
4) for so long, as spinnaker size is not strictly determined by fore triangle dimensions, as it was in IOR Rule, possibility to carry BIGGER spinnaker, hoisted on the higher mast; same is true for light weather ghoster, if someone is inclined to have and use it.

 

Overall efficiency is the highest ratio of lift to drag. High lift per area foils like a jib and main do not have high L/D ratios. But how the areas are split has an effect on the L/D curve.

Multi element foils are not an advantage unless something prevents a single foil from being used.

For some sailing vessels it is tipping over. Most boats cannot sail with a rig tall enough to use a single foil. Multiple foils are used to keep the Centre of Effort low. This low centre of effort forces the area to be more for and aft. Schooners are not great upwind, multiple foils cannot sail at the low apparent wind angle a single foil can. Off the wind large area with low CE make schooners very fast.

For some sailing vessels it is an area limit. C-Class Cats go as high as possible and remain stable but the area limit means they need higher lift per area than a single foil can provide. Multiple element foils are used because area cannot be increased. Large camber is needed because the rules do not allow flying sails and increased area off the wind.

If there are no constraints, you would see sailing rigs that look like glider wings, not like biplanes. When Boeing wants to increase efficiency, they build longer wings, they don't add a second wing.

R

 

Actually it is more expensive for the sparbuilders to build a fractional rig than a masthead rig.

 

Oh the humanity! Are you saying that masthead rigs on cruising boats are the cheapest rigs they can put on the boat? Imagine that ...

 

All development class I know of that measure actual sail area, have a large main and a little or no jib. That means that with limited sail area, that is the most efficient. Overlapping sails are mainly to take advantage of non-measured sail area. From the areodynamic point of view, they are not too good.

 

Fraction rig more expensive ? You would have to justify that. A good masthead rig is also a tapered section. Spreader roots, rigging attachments are similar.
The masthead pictured has very much engineeing and fabrication time compared to a fractional.

Perhaps you are correct...I have not lost a rig in many years so I have not purchased new one. But when I look at the long line of bareboat charter boats in the port with fractional rigging, I wonder.

Regardless of cost...masthead vs fractional is almost always decided by the task at hand. I personally prefer the 15\16 style and would only ever consider it.

 

Fractional rigs, with complicated rigging are in vogue. People like fashionable boats, which usually follow racing designs. It has nothing to do with efficiency, cost or speed.

 

Please tell us about the "complicated rigging" present in modern fractional rigs?

Forestay, backstay, upper shrouds, lower shrouds, intermediate shrouds (on multi-spreader rigs). Sounds just like the rigging you find on a masthead rig.