Main only

[Quoddy]

Is sailing with the main only on a fractional rig (130 sq ft jib /188 sq ft main) a viable way to sail or would you just be constantly struggling with bad balance?
The boat has a forward hinged centerboard, would raising it some have enough of an effect to counter potential balance problems?

 

[sailingdog]

It really depends a lot on the design of the boat and the sails. If the center of effort is too far aft, when compared with the center of lateral resistance, yes, you'll have a lot of balance issues. Raising the centerboard will help some, but not a whole lot. If the main has a large roach, it will exacerbate the problem, since that tends to move the center of effort of the mainsail aft.

 

[BobM]

It is probably only viable if you have good wind (10+ knots). Raising the centerboard would probably hurt you in light wind when tacking as you won't have a headsail to push the bow over. Raising the board would reduce the boats directionality and make it more vulnerable to being pushed off the tack by wind and waves, especially given lower boat speed if winds are light.

 

[Ross]

I often sail under main only and balance is a problem even with a full keel. Balance is even more a problem under jib only. Much depends on the point of sail.

 

[Clark]

IMHO, sailingdog nailed it. Behavior is dictated by the rig and hull/keel design.
Understand this though about raising the board. That will work with main only but it'll make jib only balance worse. Raising the board will move the center-of-lateral-resistance AFT and will want to make your boat fall off even more. Raising the board a bit DOES work with main only on boats like ours (large-roached mains and small genoas).
Remember how your boat wants to round up in higher winds? That is the main putting the center of effort rearward and overpowering the rudder/keel location. Just experiment some and you'll get it!!

 

[RichH]

Is sailing with the main only on a fractional rig (130 sq ft jib /188 sq ft main) a viable way to sail or would you just be constantly struggling with bad balance?
The boat has a forward hinged centerboard, would raising it some have enough of an effect to counter potential balance problems?

With a frac. rig it is usually a viable way to sail.

To enhance/remedy any 'helm balance' problems you can:

1. apply 'heavy' mainsail halyard (and/or cunningham - if you have one) tension to relocate the position of 'maximum draft' more forward in the sail (changing the dynamic center of effort to be more forward). Applying 'hard' luff tension via the halyard (and/or cunningham) will also 'trip the leech' (leech falls off to leeward) and will somewhat depower the aft section of the sail - also helping to relocate the 'dynamic' center of effort.

2. drop/ease the traveller a bit .... essentially does the same as above by (slightly) moving the CE more forward - not as efficient at #1 but is 'additive' to #1.

3. Raise the (front pivoting) centerboard which changes the 'center of later resistance' to be more 'aft' ... but if you raise the board too much you can begin to 'slip to leeward' and make considerable leeway, when sailing above a beam reach. When on a beat or high close reach, watch the wake that is coming out from the aft centerline of the boat - if its coming off the stern at a noticeable angle (boat is slipping to leeward) rather than straight, then you need to adjust the board a bit 'deeper'. If you're cognizant of the 'slip to leeward' and 'helm balance', you can balance between board position and leeward slip.

Note: if boat is slipping to leeward, you will develop a lot of pressure on the rudder and may erroneously think this is 'weather helm'. If the wake is coming off the stern at any noticeable angle what you will feel on the helm is NOT weather helm but the boat 'slipping off to leeward' - if so, drop the centerboard more !!!!!

On most frac. rigs (with jib furled/doused) you 'can' have an almost perfectly 'helm balanced' boat if you do the above - depends of sail SHAPE and board position.

 

[kenkindy1]

We do it all the time on our 240. We've run reefed main alone as well when it gets snotty.

 

[Joe]

smaller headsail with self-tack is one option.

Sailing with mainsail only is really personal preference... and whether your boat likes it will decide that. I'm not aware of any rules or general conditions that would restrict you.... Some folks like jib only, but others claim that stresses the rig. Others like main only but the jib only sailors object to control issues... But you must get out there and experiment.

One suggestion I can make is that you consider changing to a smaller headsail... say 90 to 110 % jib you'll find it much easier to handle than a large genoa but it will still maintain a good aerodynamic relationship with the main.

A huge benefit in going smaller up front is that it would allow you to rig a self-tacking jib... that would give you the convenience of sailing with main only, coupled with the effeciency and performance of the sloop rig.

 

[Joseph Shirley]

After 45 years sailing Thunderbirds (fractional rigs) I'd say that you'll never get the boat to perform well with just the main, although it will be less noticeable well off the wind. There are times when it is easier and desirable to sail on just the main like if you got caught in a squall. Then you might not cate so much about inefficiency.

Joe S

 

[Rick D]

Memories Once Again, Joe

After 45 years sailing Thunderbirds....
Joe S

Joe, the one I sailed for 19 years was sail no. 538. I have a large watercolor of her in my living room. I just went to look.

Oh, yea, sailing on the main. I have to agree. The only time I do it is for cocktail cruising. The jib just gives the main so much more power and pointing. Even on my Vision 32 which was a near cat rig, it was remarkable what the little blade added to performance.

 

[Stu Jackson]

Been here, discussed that, but always something new.

The general consensus here, over the years on this topic, has been:

masthead sloop: jib drives, main only is slower

fractional sloop: main drives, only jib is slower

So, other than comfort and personal preference, "where's the beef?", like what more is there to say, other than "keep em comin'!"

 

[cephius (Dave)]

The H260 sails very poorly under main alone. You have a hard time going beyond a reach in strong winds. I always add enough jib, just under the amount that over powers the rig, so I can point better.

Even so, I see it done all the time.

Note that this specific boat is designed as Family Safe. It lacks many of the sail shaping controls we've come to expect, like travelers.

 

[catsailor]

And always drop the traveller WAY down when you tack...

until the boat is back up to speed. Unless you like slamming into irons.