Adding sail trim controls

[Roadking Larry]

I've been real happy with the boat so far. The A4 on mine shows no signs that it has ever been apart. It's a little cold natured when the Temps hit the low 50s and below but not terribly so. It was rigged pretty much like it came from the builder. I've added the hardware to run everything to the cockpit, updated the main winches and redone some of the electrical (with more to do). It'll never be finished or perfect but what boat ever is?

 

[Pyewacket]

I raced a C&C 34, masthead boat. We used a baby stay to secure the middle of the mast, then cranked on a lot of hydraulic backstay pressure (up to 3400#) in a breeze. That pulled the head of the mast back, straightened the forestay, and also bent the mast. In effect the mast "got shorter" because of the bend. We never bent that mast more than 3/4 of the mast chord out of plumb. But every mast is different. The bend in the mast also flattened the main quite a bit, and that was very valuable as wind velocity increased.

About Cunninghams: On that large boat we only used 2:1 mechanical advantage and it was always enough. But we had good racing mainsails. We fixed the Cunningham to the mast with a padeye, then threaded the line up and through the cringle on the main, then down to a turning block and through a halyard organizer to a rope clutch on the after edge of the cabin. The cringle served as the upper turning block, giving us 2:1 at the cost of some friction. Cheap, fast and easy to do. The purpose of the Cunningham is to keep the maximum draft of the main forward to about the middle of the sail as the wind increases. If you find you need a whole lot of Cunningham because the sail is always draft-aft, then the sail may need to be recut or replaced.

Can you explain to me how that happens?? To bend the mast the masthead has to move backwards. That is impossible on a boat where the forestay is attached to the same part of the mast as the backstay. Like the masthead.

Fractional boats bend the mast by having the mast bend around the forestay attach point. Anything above that points bends aft, anything below bends forward.

I've owned racy masthead boats; we bent that mast with an adjustable babystay.

Regarding folding the boat.. ask someone that owns a big masthead rigged racing boat. Often when they crank on the backstay hard, you cannot open or close doors downstairs. One guess why.

 

[Windward6120]

Bending a masthead rig (intentionally)

[Edit: I obviously failed to read all the other posts that said substantially the same thing, so forgive the lapse and live through the "me to" nature of the content]

If the mast is sufficiently flexible and has some forward prebend along it's length, cranking the backstay can increase that forward bend, flattening the main somewhat. Believe that's the same effect you get from the baby stay, yes?

My Chrysler 26, while masthead rigged with dual lowers, has a very flexible mast. When tuning, I usually set it up with about 1/2" to 1" of prebend (forward bow) at the spreaders. I then crank the backstay bridle adjuster down to about the top of the pushpit. This increases the forward bend considerably. I then tension the aft lowers to limit that bend to less than half of the mast's longitudinal section - max of maybe 2.5" in my case.

The adjuster lets me point a bit better by tensioning the headstay, and helps depower the rig somewhat in heavier air. The C-26 does well in fairly heavy conditions but is tender, so easy depowering is a big thing for me.

 

[Jackdaw]

I raced a C&C 34, masthead boat. We used a baby stay to secure the middle of the mast, then cranked on a lot of hydraulic backstay pressure (up to 3400#) in a breeze. That pulled the head of the mast back, straightened the forestay, and also bent the mast. In effect the mast "got shorter" because of the bend. We never bent that mast more than 3/4 of the mast chord out of plumb. But every mast is different. The bend in the mast also flattened the main quite a bit, and that was very valuable as wind velocity increased.

You at Pikes?? Us too, on Kestrel (Blue 36.7). I used to own a C&C 34 and what you say rings true. I agree that baby-stay primary to bend mast/flatten main, While backstay used to control sag.

Its also clear that if the mast has bend induced, that adding more backstay may increase the bend in a meaningful amount. But to me that is a 2nd order effect, and makes the forestay rod tight in order to add any extra bend. Its also very hard on the boat.

 

[Jackdaw]

Hi Jackdaw,

First time post (I think) on the forum, but quite a bit of sailing and some rigging work under my belt.

If the mast is sufficiently flexible and has some forward prebend along it's length, cranking the backstay can increase that forward bend, flattening the main somewhat. Believe that's the same effect you get from the baby stay, yes?

My Chrysler 26, while masthead rigged with dual lowers, has a very flexible mast. When tuning, I usually set it up with about 1/2" to 1" of prebend (forward bow) at the spreaders. I then crank the backstay bridle adjuster down to about the top of the pushpit. This increases the forward bend considerably. I then tension the aft lowers to limit that bend to less than half of the mast's longitudinal section - max of maybe 2.5" in my case.

The adjuster lets me point a bit better by tensioning the headstay, and helps depower the rig somewhat in heavier air.

Does this make sense?

Regards,
Jeff
Windward

Hi Jeff,

Yes that makes sense. See my last post (just about this one). I agree that depending on a boat and setup, adding backstay tension can have an effect on bend. Normally it is slight, but that again is boat dependent. Like most with the same rig you are correctly using your lowers to preset (and limit) the bend. You're right, a babystay will have the same effect on bend, but without the huge effect on forestay tension.

Clay

 

[bigpapaporsche]

Kiss Principal

The OP was discussing "Sail Trim Controls," In my experience to many Sailors forget the basics of Sail-Trim, i.e. the requirement adjust all Three Sides of the sail, Luff-Leech-Foot, not to leave a simple Reefing System out! The main idea is to change the Shape/Size of the sails to fit the conditions to provide the best possible sail. Sometimes a smaller or de-powered sail can produce the most pleasurable sail, depending on conditions, i.e. smooth, safer, and even faster! For example, nobody mentioned the Outhaul or Genoa Cars. The OP mentioned the addition of a Traveller, this should be fun to play with to change the sail shape and improve performance and control. Its away been hard for me to see the "Draft of a Sail," so this year I added Black Trim Stripes to both sails so I will be able to read my sails better.

 

[Roadking Larry]

Added the Cunningham over the weekend but time and weather were against me so I didn't get to try it out. Racing again Saturday weather permitting, (thunderstorms in the forecast) so I might get a chance to see if it makes a noticeable difference.

I pretty well duplicated the set up in the diagram Jackdaw posted on the first page using 1/4" line, a couple of Ronstan blocks and a 150 cam cleat.