Converting Fractional Rig to Masthead

[mitiempo]

If the rig is 3/4 fractional and has an extrusion that relies on the runners they cannot be eliminated by moving the forestay and uppers to the masthead. They will still be needed to support the upper part of the mast. Also if the forestay is moved to the top of the mast there will not be any forward support of the mast section below the masthead as originally designed. Without the support the forestay now provides and without runners (which the op wishes to eliminate) the mast, being a section designed to be tweaked, will probably invert.

I think these changes will require a new stiffer extrusion - either during the re-rig or when the mast goes over the side if not done properly. And the damage that does can easily exceed the cost of a new extrusion.

If the boat is as bad as the op states currently, it may have been created (not properly engineered) by someone who didn't have the proper skills. To re-do the rig without expert advice (as opposed to internet advice which is often worthless) is likely to end badly - maybe worse than the current rig.

Hire an expert for at least a look and consultation. Rig design is not a simple exercise.

 

[Wanderer138]

Whatfiero may have something here . I have found that if I reef the main down to the first reef(Slab Reefing) the weather helm is reduced quite considerably and the boat is much better balanced. Only problem is that the big main produces great thrust in light winds.

Greetings Fox, I think you solved your own problem!

I sailed a fractional-rigged Hunter 23 for years. The fractional rig allows you to depower the mainsail in several ways when sailing to weather, especially when closehauled:

1) reef to reduce sail area. Reducing sail area reduces weather helm, so you don't need as much rudder angle to maintain course, which means LESS DRAG - and more boatspeed.

2) don't worry too much about the running backstays. By the way, if they're attached at the same height on the mast as the upper shrouds and forestay they're not really backstays. The real backstay is attached at the masthead. It should be set up so it can be tensioned or eased easily while under way. Tensioning does two things at once:

a) bends the mast by pulling the masthead back and pushing the center section (between the upper shroud tangs and the boom) forward like a bow. The point where the shrouds and forestay are attached to the mast doesn't move. This flattens the middle of the mainsail, which not only reduces its power, but also

b) reduces tension on ("opens") the leech - also known increasing mainsail "twist". This spills air off the upper portion of the sail while maintaining power on the lower portion. The boat heels less (less wetted surface, more comfortable), has less weather helm, needs less rudder angle, which means less drag...and more boatspeed.

3) if you have a traveler, try pulling it above the centerline of the track and then ease the mainsheet until the boom is back on the centerline. The sail will be at the same angle of attack as before but the mainsheet won't be pulling down on the boom as hard. This reduces tension on the leech, wihich opens the mainsail and...well, you know the rest.

4) Before going out in heavy air, you can "pre-bend' the mast in port by loosening the lower shrouds (to reduce mast stiffness) and increase tension in the upper shrouds to "pre-bend" the mast. It works just like using the backstay but takes more effort. Once you get the amount of pre-bend you want, retighten the lowers to restore mast stiffness and that's it. The amount of pre-bend in the mast can be measured by marking the sail in increments along a line from the leech aft for a foot or two midway between the tack and the upper shroud tangs. Attach the main halyard to the mainsail tack and tension it by hand to provide a visual reference. If you lie on the deck at the foot of the mast and look up at the masthead you will clearly see the bend. Pictures of the pre-bend in my H23 mast may still be in the forum archives. Search under "H23 Raven"

These mainsail trim techniques are widely used in racing. They can also be combined to depower the main even further. I was never much of a racer but I'll happily trim my mainsail to gain half a knot when cruising. Sailiing at 5.5 kt instead of 5 kt means I can turn a ten-day passage into nine. That's 10 percent saving in food and water.

Others advantages have also been mentioned above, such as easier maneuvering under mainsail alone in tight quarters and the working jib is usually all you need. Happy sailing.

Peter

 

[centerline]

Whatfiero may have something here . I have found that if I reef the main down to the first reef(Slab Reefing) the weather helm is reduced quite considerably and the boat is much better balanced. Only problem is that the big main produces great thrust in light winds.

I think you are on track here to solving the problem.....

if the boat is heeling too much it will have weather helm.... if you reef you can reduce the heel.
you mention the "big main produces great thrust in light winds"....this is good. but in the case that you are still getting a bit of weather helm, you will have to ease off on the mainsheet to spill more wind to keep her on her feet.... heeling more doesnt mean you are going to go faster... it actually has the opposite effect, the more she lays over, the more wind she needs to maintain that speed,.... and the more wind she has when she is laid over, the greater your problems become, the least of which is weather helm which may be a saving grace before the next greater problem arises reefing is the answer to this problem.
it will allow the boat to stand upright and still catch the necessary wind to drive the boat to its potential.

the boat will move easiest thru the water when she is mostly upright, and that is where you should generally try to keep it, but there is a sweetspot somewhere between the driving force of the wind on the sails causing the heeling action, and water resistance against the hull, that is a perfect balance for the boat... it sails best with the least amount of work right there.
once you exceed this sweetspot and allow it to heel over more, you are putting more stress on the boat and rigging for very little more, if any, gain in speed. but you will have significantly more weather helm and have a harder time of sailing her.

and when the wind lightens, trim in the sheets or shake out a reef to keep her where she likes to be....

 

[mitiempo]

I have a Fractional Rigged Cole 43. I would like to convert her from Fractional Rig To Masthead for 2 reasons. 1. Having to continually adjust running backstays is a pain...

Note the original poster's first complaint. With a 3/4 fractional rig they can't be eliminated. A 3/4 fractional rig with slender extrusion needs runners to keep the rig in the boat, the backstay to the masthead mainly used for mast bend/mainsail flattening.

 

[RichH]

Looking at the pics of your boat in the "sailboat data" website I see two potential problems with this boat being rigged as a 3/4 fractional boat.
1. The mast appears to be at 40% back from the bow, sloops generally have their masts at 30% station.
2. When I estimate the CE of each sail via their 'centroid of area', (100% headsail) and the centroid of area of the main, the combined CE of the combined sail plan (100%) is WELL AFT of the mast and well AFT of the (my) estimated CLR of the hull.
Therefore, this boat is going to have LOTS of 'weather helm' and you probably have to drag the rudder at an angle considerably sideways to keep a straight course while on a beat.

As regards to runners, you can install 'intermediate stays' running from the aft lower chainplate to the hounds of the current frac. headstay. Intermediate stays are inefficient strengthwise because of the small angle that the wire will intercept at the hounds (trigonometry), so you will need to strengthen the chainplate system of the aft lower if 'intermediates' can be a solution to avoiding the use of runners. You will have to examine if the position of an intermediate stay will allow sufficient boom travel off of the centerline (for downwind sailing). Intermediates do somewhat interfere with how far the boom can swing, but you dont have to readjust on every tack/gybe.

As other posters have stated, messing around with the CLR/combined CE relationship on a sailboat is a fairly critical relationship. If serious about this change (change back to masthead) Id suggest that you turn over such decisions to a sailboat designer/architect. My first recommendation for this would be Robert H. Perry (www.perryboat.com / 360-652-7771) as he does such 'consulting services' (for fee) to be sure that you get this correction 'right' the first time. Not only are the CLR / combined CE relationships important but also too the hull shape which develops the dynamic forces that influence 'helm pressure'. Bob Perry is probably 'the world's premier' designer of cruising boats. Id contact Bob directly by phone, state your case as well as you know it, and get an 'estimate' from him of the cost for correction. He'll probably require that you verify all the boat's rigging and spar dimensions plus pics and dimensions of the chainplate, etc. system. Id suggest also to him about installing added 'intermediates' to be a substitute for the runners, although Id keep the runners in addition to any intermediate shroud additions for when that mast starts 'a pumping' and to assist with forestay tension during stink weather.

If this boat was OEM designed as a masthead, you probably already have all the hardware mounted on the mast, etc. to convert back to a masthead (if the mast is OEM).

Good luck, nice boat !!!!!!

 

[Wanderer138]

Note the original poster's first complaint. With a 3/4 fractional rig they can't be eliminated. A 3/4 fractional rig with slender extrusion needs runners to keep the rig in the boat, the backstay to the masthead mainly used for mast bend/mainsail flattening.

Agreed. A true fractional rig should also have the chainplates aft of the foot of the mast and swept-back spreaders. The mast is then supported by the shrouds (which are also pulling aft) and the forestay. I've often sailed my H23 with the backstay slack. The B&R rig is similar and it has no backstay at all.

I looked up the Cole 43 online. If it's the same boat, somebody either went to some trouble and expense to convert to the fractional rig... or maybe the original mast was damaged beyond repair and was replaced with the closest thing available.

 

[mitiempo]

As regards to runners, you can install 'intermediate stays' running from the aft lower chainplate to the hounds of the current frac. headstay. Intermediate stays are inefficient strengthwise because of the small angle that the wire will intercept at the hounds (trigonometry), so you will need to strengthen the chainplate system of the aft lower if 'intermediates' can be a solution to avoiding the use of runners. You will have to examine if the position of an intermediate stay will allow sufficient boom travel off of the centerline (for downwind sailing). Intermediates do somewhat interfere with how far the boom can swing, but you dont have to readjust on every tack/gybe.


If this boat was OEM designed as a masthead, you probably already have all the hardware mounted on the mast, etc. to convert back to a masthead (if the mast is OEM).

The mast was changed when it was converted to fractional as the op has stated that the upper section is tapered. That makes it more flexible, which a racer would want with a 3/4 fractional rig. The intermediate stays you recommend are not very effective, causing both more rig compression and less aft pull at the same time. The Valiant 40 was originally rigged this way and Bob Perry has stated that it was a mistake, runners being a much better choice. And this was with a masthead rig with a stiffer extrusion. I believe later Valiants were changed to runners to alleviate this issue.

The op also states "By removing the running backstays, I can reduce the amount of trimming AND WEAR ON THE MAIN."
There should never be any wear on the main from the runners as only one is set at any time - the windward one.

I see nothing wrong with having running backstays on a rig that requires them. Set up properly even on a double headsail masthead sloop they are easy to deal with. Anything that helps keep the mast in column is a good thing and I would look at them as added security. Many offshore sloops that install an inner forestay between the spreaders and masthead have runners as they should to counteract the staysail stay's forward pull. And this is with the stiffer (fore and aft) mast of a masthead rigged boat. A 3/4 rigged fractional as I posted is designed so that the runners are effectively the main aft force to keep the mast in column - the backstay is there mainly to create mast bend and not act as a conventional backstay as on a masthead rigged boat. On a performance cruiser, as opposed to a racer, the fractional is most often 7/8 and doesn't require runners until the wind gets into the high 20's or 30's.

Bob Perry would also be my number one choice for a consultation and/or a re-rig.

From the op's description I don't see how changes to masthead can be made without a new mast - a large expense.

 

[RichH]

Intermediate can indeed be applied to alleviate the extra induced stress caused by the narrow (less than 10°) intercept angle with the forestay hounds. All one has to do is add a suitable spreader to each intermediate so that the intercept angle of the wire AT the mast is 'reasonable' ... that will also relieve and lessen the induced stresses in the chainplate system of the aft lower to where such intermediates are usually attached. Such is simply 'statics' design ;-)

I too have a Perry-design (Ty 37 with essentially the same rig geometry as the Valiant) and have left the inefficient intermediates in place ... but still additionally use the runners for both headstay tension and to change the oscilation natural frequency of the mast during 'stink'.

 

[The Fox]

Great Idea Rufus1138 by adding a bowsprit and running the forestay all the way to the masthead and turning her in to a cutter rig it would certainly move the COE forward. Unfortunately Heinzir is correct, the upper shrouds only go as far as the forestay so there would be no side support above the original forestay attachment. I could, however, see a balance benefit in adding a bowsprit and moving the forestay lower attachment out to the bowsprit and keeping the original fractional rig upper attachment. Could still possibly use the original jib as well.

 

[Sunbird22358]

One further possibility...... Excessive weather helm can be the result of the sails being old and too "full" ie: stretched out. A stretched out sail will have more "belly" in it to catch the wind, not so bad in light winds, but as wind strength increases..that belly produces more heeling force and less driving force, it also may increase weather helm. The suggestion to try reefing the main may give some answer to this.... reefing may flatten the sail and take out the "belly".... reducing the weather helm effect. Also try tightening the outhaul to flatten the sail. Not sure how old your sails are, but these tests may provide clues?
Tightening the forestay and losening the backstay will tend to move the masthead forward reducing any aft rake. This will also help to dial out some of the weather helm.

PS: To the owner of CHICITA, the Mac 23 (Venture of Newport), I remember reading about your boat in SMALL BOAT JOURNAL many years ago, especially with that modification of moving hte outer forestay up to the masthead, she has to be one of the best looking "Venture of Newports" around!