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Old 23-11-2016, 11:33   #1
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Cutter theory

While researching bluewater sailboats I've read time and time again that one of the advantages of a cutter rig is the versatility of the sail plan. Particularly that in heavy winds one can reef the main and use only the staysail, thus keeping the sail area more centered and the boat well balanced.

However most bluewater cutters I've seen have the outer forestay mounted at the end of the bowsprit and the inner stay basically at the tip of the bow, where most sloops have their foresail mounted. So wouldn't it stand to reason that it is no more centered than a sloop? I'm sure the reason is very technical and the position of the mast is different, but I'd love to hear what is the advantage of 2 foresails for far forward.

Thanks,
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Old 23-11-2016, 11:48   #2
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Re: Cutter theory

That is true for a traditional cutter with a sprit or especially a long sprit. I makes one think a sloop with a Solent Stay to fly a heavy weather sail on is about the same.
I love the modern cutter rig though. I found on 44-47 foot mono's that at about 30 knots of wind I would go to the reefed main and only the staysail (no 'sprit on either of these boats), The boat would sail fast and flat with ease. Actually some of my favorite sailing was in 30-35 wind with this rig.
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Old 23-11-2016, 12:11   #3
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Re: Cutter theory

I think that the position of the sails & the mast on cutters are designed around the CLR of whatever hull form the rig is on/in. So that on more traditional boats, usually having good sized sprits, you wind up with the tack placement of the headstays akin to what you're describing. Where one stay is out at the tip of the sprit, & the other at the stem, or just aft of it. Such as is found on a Tayana 37' for example.

Then on a somewhat more modern hull form, things needn't be pushed so far forward in terms of the rig, due to the different hull form & keel, creating a CLR in a different position. As is found for example, on a Valiant 40'. Which still looks somewhat traditional above the WL, but that has a fairly modern keel & rudder profile. And they have no sprit, yet are cutter rigged.

If you go to www.BlueWaterBoats.com & read the writeup on these 2 boats, you'll see that this is more or less the case. So that even with a long sprit, boats like the Tayana are prone to weather helm. Ditto on pilot cutters, & other full keeled, traditional boats. And on the Westsail 32' for example, even with her hugely long sprit in the design's original form, the boat had a lot of weather helm. So that in later editions, the boom was cropped, & the sprit lengthened in order to reduce this.

Some of this information can also be gleaned by reading the notes on the above boats, & ones of their type at www.SailboatData.com And no doubt this is also covered in many texts on boat design, rig design, & sail trim + rig tuning. Since depowering the main, & powering up the jib is a common way of reducing weather helm.

Such texts may cover more of the aero, & hydrodynamic factors which create this. For example that the keels on more traditional boats do a very poor job of generating lift as compared to a fin, or one like is found on the Valiant. So that without such stay placement, the boats are more prone to "spinning out" to weather, AKA weather helm. Thus demanding somewhat different mast, & stay placement.
Then with even more modern/efficient fin keels, & more modern hull forms, the rigs are even further forward, making for smaller foretriangles, & huge mains. So all of these things work together.

Much of this is easier to explain live, as there are a good number of factors affecting each component of the boat, which impact all of these things. But with some study they're easily fathomable.
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Old 23-11-2016, 12:17   #4
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Re: Cutter theory

I think traditionally a true cutter would fly both fore sails for extra power in light winds. A more modern typical cruising setup uses either sail, not both. The clear advantage is that this allows you to have a medium sized genoa on the outter stay, say a 125-140%. The inner stay with a fairly heavy 90-100% staysail. This gives you a clean shaped sail for winds from 8-30kts without furling.
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Old 23-11-2016, 12:17   #5
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Cutter theory

A cutter rig implies more than just an inner fore stay. A cutter also has the mast further aft making the mainsail smaller and the fire triangle bigger. Not all cutters have the head stay on a sprit. Many, like mine, have the head stay at the stem and the staysail stay some percentage of the way back.

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This does indeed make for an easily handled rig, well balanced when shortened. It has some disadvantages too. It is often rigged with a yankee rather than a bigger overlapping headsail which is easier to tack, easier to see under and less likely to scoop up large amounts of seawater when beating, but it may not be as fast to weather as a sloop.

I'm very happy with my cutter with the staysail on a self tacking boom. A great thing about the trade offs of sailboat design is that there is something for everyone.
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Old 23-11-2016, 12:55   #6
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Re: Cutter theory

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Originally Posted by Tayana42 View Post
A cutter rig implies more than just an inner fore stay ...
HAH! This is one of few things that I'm irrationally annoyed by in a serious way. Many people don't know better than to believe that an inner forestay is somehow a "cutter stay," even though there exists no such thing. Even on a true cutter, it's a staysail stay. Often when someone says their boat is a cutter, or cutter-rigged, it's actually a staysail sloop. The phrase "cutter-rigged ketch" is as ridiculous as the phrase "schooner-rigged sloop," yet I see the former on a regular basis.

Makes me crazy. I have to remind myself that the world outside will be exactly the same whether or not I correct somebody on this. So I just drink my beer and silently think unkind thoughts about their intellect...

Yes, it's irrational of me. I can't help it...
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Old 23-11-2016, 15:52   #7
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Re: Cutter theory

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Originally Posted by Laskadog View Post
While researching bluewater sailboats I've read time and time again that one of the advantages of a cutter rig is the versatility of the sail plan. Particularly that in heavy winds one can reef the main and use only the staysail, thus keeping the sail area more centered and the boat well balanced.

However most bluewater cutters I've seen have the outer forestay mounted at the end of the bowsprit and the inner stay basically at the tip of the bow, where most sloops have their foresail mounted. So wouldn't it stand to reason that it is no more centered than a sloop? I'm sure the reason is very technical and the position of the mast is different, but I'd love to hear what is the advantage of 2 foresails for far forward.

Thanks,
The flexibility of a true cutter is really nice. One can maintain speed over a much larger range of wind conditions without excessive heel. Thus cutters are preferred by some spouses as long as the sails are utilized correctly. On a broad reach one can carry all three sails in lighter conditions and still maintain speed compared to a sloop.

The thing that defines a cutter is the position of the mast and thus keel. A lot of sloop designs try to become "cutters" by adding a bowsprit and an inner forestay. But the defining characteristic is the placement of the mast relative to the stem and stern. The mast of a cutter is more than 40% aft of the stem (after station 4 in NA lingo). Just adding a sprit to a sloop doesn't change the keel and usually won't get the mast aft of station 4. Thus these are sloops with two head sails rather than cutters. A "true cutter' with a fin keel will have a different location of the mast further aft and keel to compensate for the extra sail by keeping the right amount of weather helm.

A cutter is the most flexible/desirable sail plan of any single masted mono IMO. But it is also more expensive to buy and maintain due to the extra sail. They are truly a joy to sail on long passages.
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Old 23-11-2016, 16:46   #8
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Re: Cutter theory

My boat is a true cutter rig, with the mast so close to the middle of the boat that it looks a bit odd at first glance. The boat definitely goes to weather better when flying the staysail but it requires some careful trimming to get the slots working well.

In my experience the people who usually call a solent rig a cutter rig are people who don't know what a solent rig is.
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Old 23-11-2016, 17:31   #9
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Re: Cutter theory

Quote:
Originally Posted by Laskadog View Post
While researching bluewater sailboats I've read time and time again that one of the advantages of a cutter rig is the versatility of the sail plan. Particularly that in heavy winds one can reef the main and use only the staysail, thus keeping the sail area more centered and the boat well balanced.

However most bluewater cutters I've seen have the outer forestay mounted at the end of the bowsprit and the inner stay basically at the tip of the bow, where most sloops have their foresail mounted. So wouldn't it stand to reason that it is no more centered than a sloop? I'm sure the reason is very technical and the position of the mast is different, but I'd love to hear what is the advantage of 2 foresails for far forward.

Thanks,
Not on boats with no bowsprit. Which usually exists to power a slow, heavy hull.

Our Liberty 458, no bowsprit, has the inner forestay mounted well aft of the bow.

The staysail is our dedicated stormsail. That's the advantage.

Disadvantageis tacking the genoa.

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Old 23-11-2016, 18:20   #10
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Re: Cutter theory

Thanks everyone, really interesting stuff.
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Old 23-11-2016, 18:23   #11
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Re: Cutter theory

We too have a true cutter (mast aft, smaller main, larger jib, properly rigged inner forestay). LOVE IT. Very versatile sailplan, easy to balance, quick to adapt to changing weather. Only issue is tacking when we have the big (135) gennie in light air (but that's when we have it hoisted). Both foresails are on furlers, so we do not have a removable inner forestay. That is the only annoyance, and frankly would not give up anything to remove that irritant.

Winter with gustier winds, we hoist the 98% Yankee. Summer the 135. We use the stays'l a LOT, even motor sailing, as it will help reduce roll even if not giving any lift.
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Old 23-11-2016, 18:54   #12
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Re: Cutter theory

One of the problems in discussing 'cutters' is that the meaning of the term has shifted. There are those who still (rightly) contend that to be a cutter a boat must be gaff-rigged, with a staysail on the forestay, and a jib at the bowsprit end. There are no such things as "Staysail stays", or "Inner Forestays" on a cutter. With this rig, the mast is well forward, with a long boom that sometimes extends over the transom. The staysail is small, and is almost always in play, and the working jib is not large--certainly not genoa sized. With my cutter, the first step to reducing sail area is one reef in the main, then the jib comes in, then reef 2 in the main, then storm try'sl, then reef in the stay'sl. The nice thing about a cutter with a big gaff main is that the mainsail is the driver, so there's no need for vulgar big headsails or spinnakers or rubbish of that sort.

Once you start having boats with triangular mains and no bowsprits, all the terms get wonky, since whatever a boat like that is, it absolutely cannot be described as a cutter without doing violence to the term. I think there should be a special name for such things, just like there is only one thing that's a schooner, one that's a sloop, one that's a ketch, etc. Then, and only then, can the sailing merits of a cutter be compared to the sailing merits of other sorts of rigs.
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Old 23-11-2016, 19:27   #13
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Re: Cutter theory

You guys realize that many of you are sounding more than a little Cult'ish, right? Or even bordering on the Occult. Secret handshake & all. https://en.wikipedia.org/wiki/Occult Which seems more than a bit silly, & does little to assist the OP with his question(s).

Defining what a cutter is, & even sighting a reference for such, makes sense in the context that you then go on to describe why those aspects which make up a Cutter work, why, & how. Which perhaps is what he's asking for. Along with (hopefully) doing things such as reading The Rigger's Apprentice, & other works which (one would hope) do exactly what I just described.

It's what I tried to do earlier to some degree, but I'm not a historical rigging expert. Though I've more than a fair understanding of how rigs, keels, & hulls interact together.

Sometimes the cult of the cutter gets in the way of it's realities. Such as that flying 2 small headsails in the same patch of real estate can create quite a bit of aerodynamic interference if not done exactly right. Both in terms of where each corner of the sail is anchored, & the same for their sheets. Especially as compared to one big jib. And the fact that the main is then operating in the bad air created by 2 sails, not one. A point which some folks take irrational offense to, despite it's truth.

Ditto on the fact that it takes a lot more work to keep 2 headsails optimally tuned vs. one large one. Especially when the wind is variable, or the seas make keeping an arrow straight course difficult.
BTW, poor trim, & more drag, equals slower speeds, more heeling, less pointing, & more leeway.

Also, when reaching & running most of the above is also true, even if the fore most sail is a spinnaker instead of a jib. A thing proven by the fact that racing boats spend huge amounts of money, & time, optimizing the placement of their staysail's tack, head, & sheet position (ditto on it's shape). Since if a staysail used on a reach is properly setup, it can add 0.5 - 1kt to boat speed. But done wrong, it's a drag, again adding no speed, & increasing heeling, etc.

Don't get me wrong, I like the rig. But dogma has to give way to common sense, science, & advances in materials, hardware (esp. furling gear), sail design, & rigging. So that if the design of, & techniques for using cutter rigs gets altered, & it's for their betterment, perhaps it makes sense? Maybe?

BTW, Solent's rock too (the rig, & the sails), as do Code 0's (true 0's). Though none of them are anywhere near new either. But all add to a boat's versatility. Even Cutters.


Edit: I owned one for a number of years, before my seeming bias is called into question.
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Old 23-11-2016, 19:59   #14
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Re: Cutter theory

Here's a short video of our cutter rigged Oyster sailing off Croatia last season. My wife's taking a nap while I wonder around the deck shooting video as the boat basically sails itself. 8-9 knots of wind, 6 knots of boat speed. Skip ahead to around 1:30 to see the two jibs in action.
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Old 23-11-2016, 20:09   #15
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Re: Cutter theory

Here's another video of our cutter rigged Oyster in very different conditions. 30-35 knots with an 8-10ft swell at times sailing along very comfortably using only the staysail making 7 knots. A well-balanced sail plan for all conditions. My only complaint is that the running backstays can be a PITA if you need to tack often.

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