To jibe or not to jibe

[contrail]

Originally Posted by StuM

That's not pre-bend. Pre-bend is adjusting the tension on standing rigging to put a degree of bend in the mast before sails are set.

According to our OTB racer, that's what us cruising cat owners should be doing. Breaking out the rigging tools and adjusting the standing rigging depending on wind strength.

Adjusting the mast bend while sailing using backstay tension, running backstays, leech/mainsheet tension is a different thing entirely.

Actually, I do realize that (and it is certainly doable) but thought he must be referring to the running rigging. Couldn't see many folks, mono or multi, playing much with the standing rigging! Many don't have it quite right, in the first place....too much tension on cats. Sorry to have caused confusion.

[thomm225]

Originally Posted by contrail

Whether they do or not, they certainly can adjust the pre-bend. I doubt that many cruising monohullers do it, either. One of the reasons for a fractional rig is so that it can be more flexible than a masthead rig.

Many don't realize it, but the mainsheet and mainsail leech on a tripod rig, like most cats have, acts, in some ways, like a backstay. So, easing the traveller and tightening the mainsheet, in addition to trimming the sail, can also act somewhat like tightening a backstay to bend the mast and flatten the sail.

Yep, then consider what cranking in more prebend along with that would do to flatten your sail.

Stewy in the mean time is still stuck on making adjustments while sailing. That's what racers do Stu not cruisers unless they get close then .... it's on!

Then if you could rotate the mast a bit and rake some more you could really increase efficiency on the upwind leg be it a mile or 100 miles.

Then there's downhaul on racing cats. Some guys have 8 to 1 downhaul and set it as hard as possible in heavy winds.

[Oliver L.]

OK, one more from a cat cruiser (currently Nuku Hiva...)

1. We always reef on the course we're at. I found out you need to keep the batten cars well lubed with Teflon spray, but if that's done it is easy and safe. On our boat I am at the mast and I release the halyard bit by bit alternating with pulling down the rear. That avoids overbending the battens.

2. We gybe when we have to - which is usually once a week, regardless of the wind. Since we reef often, reef early, the size of the main is in tune with the wind and the rest is timing. Get the traveller centered and locked on both sides, bring the sheet in and then while your s.o. is turning the wheel keep pressure on the winch handle to pick up whatever slack is left.

3. I have never touched my diamonds for the purpose of adjusting. It would take a damn big wrench...

Greetings from Paradise

Oliver

[mark_morwood]

It strikes me that this theoretical discussion of applying beach cat tuning techniques to 45'+ cruising catamarans makes about as much sense as taking a Laser tuning manual and using it to adjust the rig on a 45' monohull. Yes they both use the wind to drive the boat, and general principles like sail shape etc apply, but the loads, hardware, and characteristics of the boat and rig are so dramatically different, that it is probably best to start with the manual and standard practices for 45+ cruising cats, rather than hobie cats when learning how to sail one better.

Just because us "cruisers" don't recommend adjusting the diamond stays to get pre-bend for the forecast conditions, doesn't mean that we are just lazy or ignorant. It also doesn't mean we haven't raced other boats where these adjustments are important or relevant.

[thomm225]

Originally Posted by mark_morwood

It strikes me that this theoretical discussion of applying beach cat tuning techniques to 45'+ cruising catamarans makes about as much sense as taking a Laser tuning manual and using it to adjust the rig on a 45' monohull. Yes they both use the wind to drive the boat, and general principles like sail shape etc apply, but the loads, hardware, and characteristics of the boat and rig are so dramatically different, that it is probably best to start with the manual and standard practices for 45+ cruising cats, rather than hobie cats when learning how to sail one better.

Just because us "cruisers" don't recommend adjusting the diamond stays to get pre-bend for the forecast conditions, doesn't mean that we are just lazy or ignorant. It also doesn't mean we haven't raced other boats where these adjustments are important or relevant.

No one said cruisers were lazy and ignorant.

I was just pointing out to another poster that you could set mast prebend on a cruising cat similar to the way it is done on a small racing catamaran.

And if you do have beach cat racing/sailing experience it will most definitely help you get up to speed faster on a large/heavy cruising catamaran.

As for the tuning techniques of beach cats, they apply. It's the reason America's Cup syndicates many times start out with models or smaller versions of their final boat.

Your big cat is still catamaran. But maybe your mast doesn't rotate, and you don't care about the amount of downhaul you have on your main, or the amount of rake on the mast that day etc. It's all good. But if you want more speed, a beach cat racing book can give you many ideas...............

[monte]

We gybe in around 25KT with full main as described above, centre the main etc. never had the main go over with anything approaching a worrying force, just gently flicking through the wind and filling in the new tack. That said wind strength is never consistent, it's either 20-25 or 25-30 or whatever, so we wait for a slight lull and gybe then. If it's rising or getting close to 30K consistently we would throw a couple of reefs in the main for sure, although more likely we would be flying a parasailor with no main at that stage anyway. Would likely drop the main or parasailor at 30K+ consistently altogether and putt along under jib.
I'd much rather gybe with 25K TWS, 17K AWS , than turn beam on to sea and wind and chicken gybe through close to 30 AWS. Not gybing in over 15K TWS on a helia, probably around 8K TWS, I doubt that is a FP recommendation and doubt anyone would worry about gybing with 8K AWS.

[UNCIVILIZED]

Just as an FYI, there are a few types & models of cruising cats out there, which use hydraulic rams in lieu of turnbuckles. At which point, all you have to do to tune things, is switch the selector knob on the hydraulic panel, & either ease off some of the pressure in cylinder X. Or pump half a dozen/ten times on the lever. And poof, you can even cant the rigs on some.

Of course such boats are usually owned by folks with a racing background. And likely they had their hands in, in terms of selecting performance sailing options when she was built or refitted. Both custom cats, & factory.

But when you start getting dialed in on stuff like that. In this case (above), & optimize you lift to drag ratio. Paying attention to the little things, The miles come a lot easier, & the boat's much better behaved when Neptune gets a bit ornery. Or you get an extra 25-50 miles/day to just circumvent the distasteful weather.
Just a thought.

[SwissMocha]

Originally Posted by monte

We gybe in around 25KT with full main as described above, centre the main etc. never had the main go over with anything approaching a worrying force, just gently flicking through the wind and filling in the new tack. That said wind strength is never consistent, it's either 20-25 or 25-30 or whatever, so we wait for a slight lull and gybe then. If it's rising or getting close to 30K consistently we would throw a couple of reefs in the main for sure, although more likely we would be flying a parasailor with no main at that stage anyway. Would likely drop the main or parasailor at 30K+ consistently altogether and putt along under jib.
I'd much rather gybe with 25K TWS, 17K AWS , than turn beam on to sea and wind and chicken gybe through close to 30 AWS. Not gybing in over 15K TWS on a helia, probably around 8K TWS, I doubt that is a FP recommendation and doubt anyone would worry about gybing with 8K AWS.

Prooves my assumption, thank you Atoll!


Gesendet von meinem iPhone mit Cruisers Sailing Forum

[Svan]

I too would welcome suggestions on downwind reefing when caught with full sails up. I'm going to try the topping lift trick sometime.

A word of advice if you're running the boat single handed and you need to talk a lubber through steering you through a gybe. Make crystal clear that the when the sail comes over the boat will want to round up, and they will have to reverse their rudder input to hold course. Sailors just know to do it. We fumbled a gybe that way, ended up in irons with the jib sheets all twisted. Not fun, shoulda furled for the turn.