Sailing with Just Your Genny

[Dory Man]

I'm adding roller furling and a new 135 genoa to Dream Weaver this spring. I used a hanked on 130 last year but always in conjunction with the mainsail.

I heard more than a few sailors comment that they often sail with just their Genoa. 

Are there points of sail, sea conditions, wind strength, etc. that make it more useful? Are they any things to watch out for? Can it put undue strain on the rig in some circumstances? Does the type of boat (full keel, etc.) make a difference. 

What got me thinking is I heard a very experienced sailor comment that it's not always a good thing. Unfortunately he didn't elaborate and the conversation moved on.

It certainly makes it easier to take a quick sail, especially if you have roller furling.

Thanks for any ideas.

Dick

[Captain Smollett]

Some quick downsides off the top of my head:

1. Poor balance (tendency to fall off the wind)
2. Underpowered; mainsail and headsail work together (circulation or slot effect), and in any kind of seaway, speed through the water == stability (to a point, of course).  Aside from the balance issue, you may notice her hard to keep on course because you don't simply have enough power available to drive the boat through the seas (and it does not take a lot of "seas" for this).

Headsail only is a good tactic for downwind when the wind is a bit too much for all canvas;  you can point suprisingly high with headsail alone, but due to the helm balance issue you (a) probably won't like sailing like this and (b) may have trouble tacking.

I don't think it would cause any undo strain on a properly stayed rig.

[s/v Faith]

Laziness.. ;D

  That is my reason....

There are days when I only have a little bit to sail.  I often go out anyways.

  Sometimes when I carry not just my own cares out on the water, but those of others I just need to get underway

  I can sail out of my slip, and be under way with just the genny, in a minute or so.  Usually I can get out on the water with very little sound, or strain. 

  The drive is less then optimal, but sometimes you just don't care about making hull speed (although, sometimes it comes close).

  The man I bought the boat from had some health issues, and he used to go out like this some times.  It was the only way he could sail.  Maybe that is why 'Faith' understands, and just sails so well like this.   :)



 

[pogo2]

I've sailed my Newport 30 for the past 4 years with just the 150 Genny. I also heard that your not supose to sail this way, and I've read that this really only pertains to fractional rigs.  we've sailed with just the genny and a crew of 5 and hit 7.5 knots, it's a great way to sail when your single handed and just want to go for a few hours. But everyone has their own ideas on the subject, if it works for you then it might be right, and it does make a relaxing sail just 1 sail to work. My 2 cents.

[tigerregis]

I read an article some time ago that analysed several dismastings and it concluded that sailing under Genoa only was a poor choice with "modern rigs" that only had single lower shrouds. I stopped doing it after having read that and my rig is still up.

[Captain Smollett]

I stopped doing it after having read that and my rig is still up.

Ah, but you cannot prove a hypothesis by showing a negative.  You cannot say that your rig would have failed had you kept doing that. 

Sorry, it's a nitpick.  ;)

Sailing with headsail alone is a long established heavy air tactic; as is using twin headsails off the wind for 'trade wind' sailing.  There are countless instances of boats being sailed in this fashion without rig failures, so I think to assert causalilty is a bit of a reach.

Just what force is on the rig with headsail only that is not present with both main and headsail?  The weight of the mainsail itself?  I'd argue this is neglible compared to the forces produced by the sails from the wind.  The direction of the force produced by both sails from the wind is roughly the same (eg, both sails are pushing forward while close hauled).  Therefore, if the rig can handle main+genny, it can certainly handle genny alone.

I'd like to see a proper engineering analysis of those dismastings; I'd wager there's more to them than just sailing with genny alone.

[CapnK]

Just idle wondering, but...

Would having the mast be under tension from the forces of the main make the spar stiffer in some way, ie; less "flexy", more rigid? This wouldn't matter so much off the wind, but pounding to windward in a seaway it might...

[Captain Smollett]

Just idle wondering, but...

Would having the mast be under tension from the forces of the main make the spar stiffer in some way, ie; less "flexy", more rigid? This wouldn't matter so much off the wind, but pounding to windward in a seaway it might...

I don't THINK so; if you draw a simplified force vector diagram (the easy way, assuming the sails are triangular, and that the force vectors are applied to points at the geometric metacenters of each sail), you get that the forces are roughly parallel in roughly the direction of the wind, right?

For clarification: Tension is "pulling."  If you pull on a cleated line, you are placing the line under tension.  The mast is not under any tension since nothing is pulling "up" on it.  In fact, a mast is generally under tremendous compression load from the downward components of all the supporting rigging.

If I understand your hypothesis correctly, you are suggesting that the sail (full of wind) essentially keeps the mast from bending.  Most masts have some bend in them (intentionally) that is concave aft, so that the any force produced by the main, behind the mast, would tend to add to that bend.  At least that's the way the force vectors in my mind are working out.

The best I could consider as a difference is the torque on the mast; with both sails up, the torques cancel to some degree; with only one, there is a larger net torque tending to spin the mast about its axis.  I doubt this has much of an effect on rig stability, though.

I just don't see how sailing genoa alone can be the sole cause of a rig failure.  Perhaps if I could see that original article and gain access to some of the analysis it would help.

[CapnK]

This is interesting theoretimical stuff. I hope no expert happens along soon to ruin all this good non-expert thinking... ;)

A mast is bendy (to a degree), right? The rigging is designed to hold it in column, keeping it straight. An adjustable backstay, like that fitted to many racing boats, can exert enough backwards force on the top of the mast to make the *middle* of the mast bow forward, right? You can see that effect in what happens to the mainsail shape. That's the whole point of a tensionable backstay.

So, a genny flying alone would in effect be a *forestay* tensioner, bowing the middle of the mast backwards, right?

Put a main on the mast, tensioned up with halyards, along the boom, and wind, and it seems that the mast would be held more in column.

I'm not attempting to forward the theory that "genny-alone sailing" causes rig failure, in fact I have sailed that way many times (my boats have had double lowers, though). I'm basically just musing aloud over morning coffee. :) However, stresses on an aluminum spar would be cumulative, right?

A single lower shroud keeps the mast in column *athwartships* quite well, but would not be so effective at stopping mast bend in the fore and aft plane of movement, which is where the effects of genny-alone rig stresses would most be felt. At least, that's what it seems like to me. So I'd be more hesitant to sail that way if I didn't have a rig designed to countereffect the mast bending forces from the pull of a foresail.

Does any of this make sense? It does to me, but that may not be saying much. ;D

[CharlieJ]

one thing that must be taken into consideration in this discussion. There is a huge difference in mast loadings when you have a mast head rig sailing with just a headsail, as opposed to a fractional rig sailing with just a headsail.

The fractional rig headsail is applying a force forward to the mast BELOW the backstay. You run a real risk of over bending the mast at the headstay attachment point with that sort of rig.

NOt as big a deal in a mast head rig since the load is directly opposite the back stay.

Offshore cutter rigs usually have running backstays to oppose the staysail stay and in heavy weather they sail under staysail alone- but the force is carried by the running back.

Just  something to consider.

[Solace]

Whew! A lot of fancy theories - and I'm sure some of it may be on the money.

Fact is a lot of boats sail under headsail only. Myself included. While I might agree that a fractional rig may suffer more than a conventional rig, surely there are more strenuous points of sail with both sails up.

Quite often when you sail with just the headsail you are not concerned with making top speeds - tho depending on the winds and your point of sail, you might just achieve it. The reason is usually more one of convenience, or as described above, laziness. Cuts out hauling a mainsail up (removing and stowing the cover) and putting it away again. To me, that's reason enough. Especially if I'm just out sailing the bay.

The bottom line is - it probably is okay, but it depends on lots of things - sail rig, your boat, winds etc. If you are thinking of sailing like that on those lazy days and you are only doing 3 or 4 knots (and its not blowing 7 bastards out) I wouldn't give it a second thought.

Cheers!

John

[CharlieJ]

on your conclusions- sailing on a lazy day- yup, totally agree.

There is one point I saw in your post though.

Tehani away from the dock will NEVER have a mainsail covered or the main halyard unhooked. In fact, the halyard is tied to the head of the sail- there is no shackle.

If we are underway, or at anchor out away someplace, that mainsail is uncovered and READY to hoist. Now should we be in a long term anchorage where I've a couple of hooks well sunk, then it gets covered up, but for an overnight, it's always ready. And if the weather is iffy, it'll have the first reef tied in belore we go to bed.

[Adam]

I don't THINK so; if you draw a simplified force vector diagram (the easy way, assuming the sails are triangular, and that the force vectors are applied to points at the geometric metacenters of each sail), you get that the forces are roughly parallel in roughly the direction of the wind, right?

I would disagree. You're neglecting to take into account that on many points of sail, the wind isn't pushing you. The sail is forming an airfoil shape, and the lower air pressure on the convex side of the sail is actually "sucking" the sail, and hence the boat, along.

For clarification: Tension is "pulling."  If you pull on a cleated line, you are placing the line under tension.  The mast is not under any tension since nothing is pulling "up" on it.  In fact, a mast is generally under tremendous compression load from the downward components of all the supporting rigging.

The way I muddled through it, three forces should be acting upon the mast. Simplified, they're "axial", "tangential", and "normal (or perpendicular)".

axial - imagine grabbing the top and bottom of the mast and pulling apart (tension) or pushing together (compression). Of course, due to the tension in the rigging, the mast is always going to be in a state of compression. This isn't significant when all of the forces on the mast are parallel to the mast itself. The sails themselves shouldn't produce a significant axial strain on the mast, and in every instance I can picture it, it would be in a direction the would relieve some small percentage of the compression due to the rigging.

Tangential - again, imagine grabbing the mast at both ends, this time twisting it like you're wringing out a rag. With all sails up, you're going to have unequal loading tangental to the mast. The main (unless it's loose footed) will distribute (unevenly, but still distributed) the force of the wind/sail/"suction" along the length of the aft portion of the mast. The jib, spinnaker, whatever, in front of the mast will generally place this force on the top of the mast, the only point at which it's attached to the mast.  One will usually counter the other (ie - if the main is exerting a clockwise moment on the mast, the jib will probably be producing a counter clockwise moment). Of course, chances are astronomically small that these forces will cancel each other, just one will mitigate the effect of the other, if only by a tiny amount. Worded better by you, below:

The best I could consider as a difference is the torque on the mast; with both sails up, the torques cancel to some degree; with only one, there is a larger net torque tending to spin the mast about its axis.  I doubt this has much of an effect on rig stability, though.

But in a wing on wing sailing condition, I'm picturing the genny and main to be acting in the same direction, moment wise. In this condition, their forces would be additive, meaning that you're putting more of a tangential strain on the mast with both sails than either sail could create alone.

Normal forces - This is the easiest one to picture. Imagine being a giant, grabbing the top of the mast, and pushing or pulling it. This puts a bending moment on the mast, along the entire length of the mast. The rigging and the deck (on a keel-stepped mast) will resist this bending moment, but some deflection is going to occur. Things like a screw hole or a crack in the mast, or even just a nick, create a stress concentration point. Stresses (axial, tangential, and normal) within the material are multiplied at these locations, due to the geometry of the material. This is why you often see the ocean racing sailboats have a mast broken at a point where something attaches to the mast (radar mount, spreaders, etc..).

Remember that all of these forces act concurrently. So when your normal forces bend the mast from its usual geometry, the loading on the mast changes. The compression force from the rigging is now exerting a part of itself as a bending moment.

I just don't see how sailing genoa alone can be the sole cause of a rig failure.  Perhaps if I could see that original article and gain access to some of the analysis it would help.

I agree with you there Smollett.  In my opinion, and from my experience, sailing under either sail by itself shouldn't hurt your rig if the wind/weather conditions are such that you could safely use both. Maybe a better way of saying it is, if the wind picks up and you need to shorted sail, don't just drop your main. That will probably mean you're in more wind than that sail can handle. But if you just don't  feel like monkeying with putting the main up, I'd go ahead and leave it down.

sorry, I had to finish this post up quick... and no time to go into fatigue failure!!! dang!  IT'S QUITTIN' TIME!!!!!  ;D  ME1201 Statics/Dynamics is dismissed for the day. Pop quiz tomorrow!

Adam

[starcrest]

in all of my offshore sailing only one time did I use any more than a working jib and main.there was one time on the triton on the way home that I actually was brave enuff to put up a 160 jenny.it wasnt up for long .I will swear by working jibs they can be used in a blow or lite stuff.when you feel the mast start to pump the boat its time to shorten sail area before it catastrophically shortens itself.it only has to happen once...and those things dont only happen on TV.

[starcrest]

let me say one more thing as per the above.thetime to shorten sail can be anywhere at any time.I remember many times having to go up on deck at absurd hours of the nite in all sorts of sea conditions....complete with skydiver harness as life harness and all. I mean with the vane steering,not changing course(heading up ) to do so....the bow pitching up and cown,the wind and spray blowing....it aint fun.did you ever try reefing the main at 3am from the lee side in 35 kt wind and associated sea conditiop,,,,,on both of my ariel and triton I rigged so it could be reefed from either side.I have a conservative attitude so as to take it easy on the rig.

[kingfish]

hello all,
My 2 cents .... I sail with my headsail only all the time, Or I should say I sail with my big genny and my mizzen sail. My boat has perfect balence like this. She never really gets allot of weather helm but with the head and mizzen up I easly do hull speed, and even better I am not walking on the walls. I say go for it. Especially with a furler, If it really starts to blow, roll it up a littel and off you go.
Cheers
D

[CapnK]

Kingfish -

Sailing like that seems to me to be one of, if not the best, advantage to a ketch rig. My next door-slip neighbor has a Dickerson 35 ketch, and he says he gets underway, then trims sails until she is on course without him touching the helm at all. He doesn't even lash the wheel - just lets the rudder trail, and the sails do the sailing. I'll have to try that sometime, I've yet to sail on a 2-master... :)

[kingfish]

Its funny. The whole time I sailed a sloop, I always thought that having the second mast would be a pain in the neck, especially cause I am always by myself. Now that I sail a yawl, I could never go back to a sloop. It tends to get in the way allot. But it is well worth it in stability under sail. If you ever get a chance to sail one. Try it out, I think you will like it...
Cheers
D

[starcrest]

there was a time I sailed with jussa working jib only---to avoid excess weatherhelm.aplace called the  "slot" jussoutha molokai----that was very strong wind----it drove the boat allthe way to oahu-----

[Fortis]

My take on it is that it is more practical with a masthead rig then a fractional.

Our headsail does about 70-80% of the work depending on what point of sail we are on, so going out with just the heady makes sense sometimes. In fact when we were learning our boat, we started with headsail only, then main only, then both.

Even though when we had learnt a H28 previously it was the exact opposite order (except you can add the second mast and all the combinations to the list).

I think that a foil keeled boat would need both main and genoa to balance properly. We have a medium fin and balance pretty well on the genny alone when we choose to do it that way (it is actually less balanced on main alone).

The full keeled H28 with its smaller jibs (despite being a masthead rig and having a bowsprit) would just not balance on its heady alone. Did fine on main only, but if you were going to want to run heady and no main, you needed to have at least a reefed down sail on the mizzen mast.) Of course the steering on the H28 involved a dead whale being towed off the transom and prodded with a small twig to change directions.
(big ugly transom-hung rudder that was like trying to close/open a barn door in a hurricane) .

One early morning we were sailing back form Queenscliffe, perfect sunlight, about 10 knots of breeze to just ghost along. The entire bay to ourselves...and we nearly got run down by a Benetsnail 45 coming out of Geelong, with a heady only, and the bimini set up OVER the boom, towing three fenders through the water on each side, with both people on board totally oblivous to everything as the music blared out and the guy attempted to get the griller on the aft deck lit.

The girlfriend was sunbathing topless on the cabintop...I presume there was an autopilot steering.

Thye missed us by about 12 feet. If I had not given up on notions of knowing I had right of way and thrown an emergency tack, they would have hit.

It is in no way fair...but when I think of sailing on genny alone, for some reason my mind flashes back to that moment....


Alex.

P.S about three hours later we heard on Channel 16 that a boat that we are 99% was them had continued on and run aground on a sandbank (that was directly in front of the course they had been sailing on when we encountered them) and they were looking for a rescue tow.

The area is magnificently well marked with bouys and clear chanels etc. And at that time of day you could just see the mud and sand banks in that area. Oh well.