ROUNDING UP

[Mark]

Whats pre-bend?

So pre-bend is how much curve is in the mast prior to stepping.If a sail is laid on the ground it will not lay flat. It has a billow depending on the cut.So if the mast is perfectly straight the billow for want of terms will be at its max.If you then induce bend in the mast it takes the shape out of the sail and makes it flatter.Sailing in consistantly high winds would mean that mast pre-bend may be essetial so as to depower the main. But by the same token sailing in very very light breezes is assisted by a flat sail. Anyway back to pre-bend.With a mast laying down on supports (prior to stepping) you can bend the mast (on a 260 B&R rigg) by tightening up the reverse diagonals. Because of the nature of swept back spreaders the more you tighten the reverse diagonals it pushes the mast forward.So as a rule of thumb ( that I have always used) about 2-2.5% is suitable for most mainsail cuts. This is the % of the P measurement.Down here on the South coast of Western Australia where the wind really howles more pre-bend is required than perhaps sailing around on a protected lake.If I was to have the mast on my 260 straight I would be reefing a lot earlier.So in my instance I have about 3%.Then when you step the mast and adjust the shrouds the effect on the mast bend is minimal.Hope this is as clear as mud??

 

[Brian]

Balance

One thing I haven't heard anyone mention is the relative balance of the jib vs the main. If you were to sail your boat with just the jib you would notice that the boat wants to fall off because most of the lateral force for the sail is in front of the keel. Sailing with just the main will increase the tendency to round up because most of the force is behind the keel. In either case the rudder has to compensate for the unbalanced sail load. By letting the main out more in relation to jib you will dramatically reduce the tendency to round up. On my previous boat, a Catalina 22, I could keep the boat balanced with the railings in the water by letting the main out enough to balance the boat so the rudder was not needed (a slower but still interesting way to sail). The Hunter carries a much higher percentage of its total sail area in the main but the principal is the same. To be honest I think the manufacturers intentionally design in some tendency to round up because it helps prevent knockdowns with novice sailers. If they have too much sail up for the conditions or if a sudden gust hits the boat will point head to wind and flatten out. More experienced sailors can balance the boat. I can see some benefit in overheeling the boat occasionally to learn more about it's balance and how it handles various conditions but in general I would be hesitant to treat a boat as nice as the Hunter in that way.

 

[Ron Mehringer]

Reverse diagonals?

I didn't realize that the 260 had reverse diagonals. The 26 doesn't, and thus precludes setting pre-bend.Ron MehringerHydro-Therapy

 

[Jeff Peltier]

Re-reverse diagonals

I'm pretty sure you do, as I have seen them on other 26s. They are the stay that starts at the spreader and end up at the mast, right above the struts. This is where the turnbuckel is located for making tension adjustments. Because of the angle of the spreader, as you tighten these, they create a bend in the mast.Jeff Peltier

 

[alan]

Nooooooooooo, the 260 has the struts and...

...reverse diagonals, not the 26 which is an older boat but shares the same hull. alan

 

[Mark]

Well thats interesting

So you rely on the shrouds to put bend in the mast on a 26??

 

[Ron Mehringer]

Bending the 26

Yup. On the 26, bend in the mast is created/controlled by the stays.Ron MehringerHydro-Therapy

 

[Mark]

Stays or

Shrouds Ron?

 

[Ron Mehringer]

...or shrouds

Mark you caught me in a slip of the tongue (or should I say "finger" since I'm typing). You are correct. Bend is adjusted via the shrouds, not stays, on the 26's B&R rig.Ron MehringerHydro-Therapy

 

[Dick]

Shrouds crossed

Seams like it might be important to note that shrouds that pass throught the spreaders are attached forward of the others. At least that is the way it is in the manual. Works for me.

 

[Kevin Flanagan]

Been living this conversation

all Summer. I also believe this boat/rig is very sensitive to tuning adjustments and "sail plan"(more so than a "big boat"). You guys made some similar comments to me when I asked about rig tuning in a previous post. I re-checked my shroud tensions and realized I was using incorrect numbers. I bumbed up tensions to 700 and 600 on uppers and lowers respectively. Pretty sure mast rake is good (plumb bob is somewwhere btw 4-6 inches aft of mast base). Sails are in good condition (not "blown out"). Difference in heel and reduced weather helm is amazing. That being said, the boat is still pretty tender. Rudder is inneffective when sailing with a a full main and no head sail. I reef and carry a full head sail at windspeeds of 10 kts to maintain 15 degree heel. I reduce headsail and sometimes take it all in at winds between 13-15 kts. Wind speeds above 15 kts make boat control a little difficult. Wish I knew what you guys were doing to keep heel and boat control comfortable (15-20 degrees) in heavier winds. I'd like to take the boat to the Cape, Block Island or Cutty Hunk. Will not do it until I'm more comfortable with the rig.

 

[Michael]

Shrouds Foreward or Aft

We had this discussion before -- (shrouds through the spreaders foreward or aft) -- but the manual I have for my 94 clearly shows the upper shrouds going aft. For what it is worth. I'm not sure it makes a whole lot of difference one way or the other.

 

[Jeff Peltier]

To answer Kevin's question

If you loosen the lowers a little, you should get some prebend, which would flatten your sail and allow you to keep full sails in more wind.

 

[Rick Macdonald]

How tight is tight?

I hope this doesn't sound lame...When I tighten my lower shrouds enough so they at least have some tension (maybe a bit less than or equal to the uppers) most of my prebend disappears. This might indicate that my uppers are nowhere near tight enough?I've seen shroud tightness discussed a little here recently. Before I found this forum I had no idea so I called the factory about my H23.5 and was told 20 percent of the breaking strength.OK, I should buy a guage...The Hunter fellow also said "guitar string tight". Well, I've played the guitar for 30 years so I do know about that, but the strings on a guitar cover more than two octaves.Can anybody describe the taughtness in terms of how clear the sound should be if I "pluck" the shrouds at shoulder height? Others have said they should just thunk and not be audible, but others yet refer to a nice clean tone that is generated. It seemed like the Hunter fellow was wanting a clear and perhaps even sustained tone.

 

[Ron Mehringer]

Get the guage Rick

Rick, you really should get the Loos guage. The rule of thumb is 20% of shroud breaking strength for the uppers, 10% for the lowers. But, on my 26 I don't go quite that tight. Guess I'm chicken or lazy.Until you get the guage, there is a technique that Crazy Dave described using your fingers. He posted it sometime this summer. Try a search.Ron MehringerHydro-Therapy

 

[Wanderer138]

Get the gauge Rick - Part II

The Loos gauge will eliminate the guesswork. I'm not exactly sure how the sequence works with a B&R rig, but on the H23 you tension the uppers until you get the amount of prebend you need, tighten the lowers to stiffen the mast and then fine tune the uppers so that the leeward shroud stays tight when sailing close-hauled in 15 to 18 kt of wind. That's it.To measure prebend, lay the mainsail on the grass. Put some marks near the middle of the luff spaced an inch apart and perpendicular to luff rope to create a scale. Six or seven marks is plenty.Now, raise the sail with a piece of light line or bungee tied to the halyard shackle. With no load on the sail, stretch the line to the tack of the sail and sight up it to the head of the sail. The line will cross the scale and you can read the prebend quite easily.Unfortunately, the B&R rig has no backstay so you're stuck with the prebend you dialed in at the dock. The H23 backstay can be rigged so that the tension can be adjusted under way, so prebend can be changed in an instant depending on wind conditions and point of sail. Tally ho!PeterH23 "Raven"

 

[Wanderer138]

Where prebend comes from

The B&R rig has swept-back spreaders and shrouds mounted aft of the mast base. As the upper shrouds are tensioned, they act like a bowstring and push the middle of the mast forward...voila, prebend. The lower spreaders resist this bowing action, so they have to be kept loose until you get the amount of prebend you need.The H23 rig is similar except it has a backstay but no diagonal shrouds.PeterH23 "Raven"

 

[Rick Macdonald]

Ron - may the gauge be with you

OK, time to order a Loos gauge. There seems to be two: the more expensive "Pro" stand-alone model (clips on and stays on the wire) and the cheaper "finger-pull" model shaped like an upside-down "L". Any preference?I think I found Dave's method: 1 to 1 1/2 inch deflection when you pull the shroud with two fingers. He doesn't say but I assume he means to pull as hard as you comfortably can. He also doesn't say but I assume he means somewhere between elbow and shoulder height.Judging by several posts where people are surprised to find that their shrouds were not tight enough when properly measured, I'd guess mine too are too loose.

 

[Ron Mehringer]

Which guage

I bought the standard Loos guage. But, as all to often happens, I wish I had gotten the Pro. Loos claimes the Pro has, "Higher accuracy and easier to use than standard models. The cable can be adjusted while the gauge remains on the cable. Just watch the pointer move." The standard works just fine, but I like to make my life easier whenever possible.Both the standard and the "Pro" models come in multiple sizes, so be sure to get the right one for your boat.See link below for Loos site.Ron MehringerHydro-Therapy

 

[Rick Macdonald]

OK, gauge is ordered

Thanks, Ron, I now have a PT-1 (Pro) on order!