Why fractional rigs?

Mast head versus fractional rigs

What is plainly obvious is that those with mast head rigs defend them as being better while those with fractional rigs reckon they are better.
Certainly where I sail (race) it involves a lot of tacking and the inner forestay certainly gets in the way along with the generally larger jib makes the mast head rig slower to tack.
I love my fractional rig even though I lost a mast through failure of swept back spreader to remain swept back. The tacking of the jib is certainly easier.
The swept back spreaders do cause sail chafe but if you accept that then running down wind is no problem.
I note however that the Clipper race boats a newish design are masthead rigs in fact cutter rigged. But thne they go for robust rig and long ocean legs.
Yes almost all other new designs are fractional. olewill
 
In North America before IOR we had the CCA rule (Cruising Club of America) and the norm was a masthead rig with a large main and small foretriangle. Below is a good example, the S&S designed Finisterre, winner of 3 Bermuda Races among many others. The CCA rule did not count mizzens so there were many yawls.

Also below is the Albatross 50' design by Groupe Finot to show the other extreme. It is a cruiser by the way, not a racer. Read more about it here: http://www.finot.com/bateaux/projtprepa/croiseur50/croiseur50_pres.htm

A fractional rig requires less changing of jibs than masthead rig. Tacking is easier, sheeting loads less as well. Mains are easier to handle than jibs being on 2 booms. Modern slab reefing and full battens make reefing easier than the once common roller reefing mains. A boat like the Albatross shown only needs one jib, main, and asymetrical instead of the multiple foresails a masthead rig requires.

Stu - a triatic is the stay between the main and mizzen mastheads on a ketch.
 
Be silly not to utilise the sail trim advantages of an adjustable ( fractional) rig but, cruising offshore before the days of digital access to assistance, possibly the masthead multi-stayed rig was favoured by cautious cruisers as there is less cyclic flexing of the alloy mast which is also under compression at the same time.....and offers some built in redundancy if one shroud fails- not that uncommon amongst people I actually know who sail a lot of miles.

I am sure the equivalent fractional rig with big swept back spreaders and single point attachment to the deck offers weight, component and build-time advantages to the designer and manufacturer.

If you read comparative reviews of say the sporty Sigma38 which was designed with FR and offered MH too , the former is possibly even better at cruising!

Nostro, I had a wee unstayed junk rig which was worry free and bloody amazing with the sheets cracked but required ingenuity to drive to windward!
 
I think people are confusing fractional /masthead rigs with inline / swept spreaders.

Not all fractional rigs have swept spreaders, as Lakey pointed out. Edit - although fractional rigs typically have swept spreaders to eliminate or reduce the need for running backstays to tension the forestay, many fractionally rigged racing boats have in line spreaders but the stick will fall down if a runner isn't on.

I think the advantage of fractional rigs might have something to do with the aeordynamics of the sail. I believe it is important, for the efficiency of the foils, for the top of the main to see "clean" air. Putting the jib all the way to the top of the mast disturbs the air flow over the top of the main, reducing its efficiency.

NB - this what I have picked up over the years in dock chatter and read in magazines. It might be total *******s.
 
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I don't think a fractional rig, properly done, would be much less expensive than a masthead rig. The tapered mast of a fractional will cost more than the straight extrusion of a masthead rig.
 
mitiempo said:
I don't think a fractional rig, properly done, would be much less expensive than a masthead rig. The tapered mast of a fractional will cost more than the straight extrusion of a masthead rig.
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No indeed, it is more expensive. That's why cruiser options are often masthead. For one thing, a fractional rig is almost always taller for the same sail area. Many yachts now are some sort of compromise, more like 9/10 than 3/4, so there is a bit of mastbend not much and runners are not much needed.
 
lw395 said:
No indeed, it is more expensive. That's why cruiser options are often masthead. For one thing, a fractional rig is almost always taller for the same sail area. Many yachts now are some sort of compromise, more like 9/10 than 3/4, so there is a bit of mastbend not much and runners are not much needed.
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True. like any rig there are both conservative and more extreme versions.
 
Dead downwind is slow anyway so not as much of a disadvantage for fractional swept back rigs as is commonly argued. I go reach and reach and always think ahead to avoid a dead run at all costs, it's dangerous too.
 
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dt4134 said:
I'd say it was the other way around. IOR encouraged racers with masthead rigs with large overlapping genoas and that spread to the cruisers of the time.

Look at something older like a Folkboat with its fractional rig as a comparison.

I have to admit I far prefer fractional rigs. I find masthead rigs frustrating at times because there is so little you can do to adjust the sailshape.
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Now IMS and IRC are perhaps biased toward fractional, but certainly punish the extreme genoas of old.

For cruising, perhaps a cutter rig is what we want?
 
lw395 said:
For cruising, perhaps a cutter rig is what we want?
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Depends what type of cruising. Cutter for offshore distance cruising is ideal a la Vancouver.

However if I sailed close to shore most of the time and enjoy sailing up rivers/estuaries a 7/8's fractional and a self tacking 100% jib would suit me better.
 
Hmm. Cutters. I have a detachable inner forestay/ reefable working jib, sheets and deck blocks set up.. which, without runners, is attached very high to the mast, prob at 7/8 to a fractional comparison.

It really benefits from a barber hauler to the foot of the mast ( as suggested by a more experienced fellow user) to get it dead flat for going hard upwind..
And if I were making or remaking the sail I would 'lose' a couple of metres from the top end as Im not convinced it does very much up there..

Choices, choices eh
 
I have always favoured a fractional rig over a masthead. The main reason being that it is much easier to handle due to the smaller size of the headsails and that the ability to alter the shape of the mainsail with the use of the back stay gives much more control. However I would never have a fractional rig with runners as these are a curse and abomination for the short handed sailor.
My current boat is 3/4 rigged with the provision of a self tacking headsail which makes singlehanded tacking a pleasure. The swept back spreaders do compromise the ability to sail dead down wind; a point of sailing I try to avoid anyway as it is too fraught with the dangers of an accidental gybe for comfortable cruising any way.
 
Swept back spreaders

bbg said:
I think people are confusing fractional /masthead rigs with inline / swept spreaders.

Not all fractional rigs have swept spreaders, as Lakey pointed out. Edit - although fractional rigs typically have swept spreaders to eliminate or reduce the need for running backstays to tension the forestay, many fractionally rigged racing boats have in line spreaders but the stick will fall down if a runner isn't on.
NB - this what I have picked up over the years in dock chatter and read in magazines. It might be total *******s.
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Quite right you have it wrong bbg. The spreaders swept back mean that as the cap shrouds take tension they push the middle of the mast forward so eliminating the need for an intermediate or baby forestay. (really good for tacking the jib) You could have swept back spreaders on a mast head rig so eliminating inner forestay. But it does depend on cap shrouds chain plate being aft of abeam the mast.
Runners (running backstays) are used to put an aft pull on the mast right at the top of the forestay. This because if the main backstay is a long way above the forestay it will bend the mast more than tension the forestay. A stiffer mast or larger fraction (higher forestay attachment) means more forestay tension less mast bend so less need for running backstays. Occasionally you will see a diamond type stay from top of mast down to mid mast with small spreaders facing forward. These stiffen the mast to get forestay tension with less mast bend.
I would disagree when someone said fractional rig has some redundancy. No any failure of a stay in any rig will put excessive bending loads on mast and destroy the mast.
Certainly a mast head rig seems to have more simple support. So some fractioanl rigs will ahve provision for attaching an inner forerstay (or use spin topping lift) to add more pull forward middle of the mast. The swept back spreaders do not seem to provide real robust force forward like an inner forestay.
good luck olewill
 
William_H said:
Quite right you have it wrong bbg.
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I think you'll find that my comments on swept vs inline and masthead vs fractional are correct.

Everything you say about swept spreaders is correct, but not at all inconsistent with what I said. The swept spreaders provide tension for the forestay. They also, as you say, push the lower part of the mast forward. Additional forestay tension can be generated through topmast backstay, either if the top section is stiff enough or if there are diamond stays on the front of the mast. But I assure you I have seen fractionally rigged boats with inline spreaders. Which also didn't have a permanent backstay. If you don't have a runner on, the stick breaks. I have also seen masthead rigs without baby stays.

What I wasn't sure about was the OP's question which was about WHY boats are fractionally rigged. I have heard that it has something do do with keeping clean air flowing across the top of the main, which significantly improves its efficiency. Are you saying this is incorrect?
 
bbg said:
What I wasn't sure about was the OP's question which was about WHY boats are fractionally rigged. I have heard that it has something do do with keeping clean air flowing across the top of the main, which significantly improves its efficiency. Are you saying this is incorrect?
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I was just wondering why you see fractional rigged boats as they seem to have extra mast at the top doing nothing. Why don't they use the whole mast if it is there or just have a smaller mast?
 
Nostrodamus said:
I was just wondering why you see fractional rigged boats as they seem to have extra mast at the top doing nothing. Why don't they use the whole mast if it is there or just have a smaller mast?
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But that extra bit at the top IS doing something. It is holding up the top of the main, and specifically holding it up above the disturbed air coming off the jib.

Or it could just be that it is easier to create the curved shape of the mast (to prevent inversion) and thus do away with a baby stay if the boat is fractionally rigged, but I don't see why this should necessarily be so.
 
Fractional rigs have appreciably lighter masts as below the forestay is very well stayed. Therefore you can often get more canvas for your spar weight than with masthead.

I personally own a masthead boat but prefer fractional for convenience of rig tune and smaller headsails. I don't understand why more boats don't have the folkboat rig for cruising. With 3/4 rig and jumpers stays.
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A sailing acquaintance of mine of old sailed a marieholm folkboat rtw, on the run up thru the south Atlantic he fitted runners.
 
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