"Naturally you will be able to learn to optimize your boat, whith it's own characteristics." True, but maybe not so true. Especially to weather a 35 foot cruising boat (30'wl) being sailed to its optimum might sail lets say at anywhere from 27-35 degrees into the wind, apparent and maybe achieve 6.5 knots speed. To weather a roller furling main can greatly reduce that potential because it's not possible to shape the sail to get that performance. The guy ends up losing interest because he can't make his boat go.
The modern vertical batten sails are built with thin battens between the layers of the sail to reduce exactly this effect.If you get a furling main it will not be possible to learn to optimize boat and sail performance because the vertical battens will create bumps that interfere with laminar flow of air over the lee side of the sail.
We treated our main with Sailcote and had teflon tape on both edges of the mainmast slot. Never had a problem until our last Bermuda race with her when some highly edumacated racing sailors were playing with it while I was off watch. Someone got me up and I 'splained it again to the guys with multiple, advanced science degrees and fancy sailing CVs.2. Chafe going in and out of the slot. There's a lot of drag through these slots. The batten pockets stand proud of the rest of the leech, and will take the brunt of the abuse.
Having sailed offshore quite a bit on an Oyster 53 with this vertical batten arrangement, they do work, to some extent. You can definitely build a better main with these than without them, provided the sailmaker knows what he/she is doing.The modern vertical batten sails are built with thin battens between the layers of the sail to reduce exactly this effect.
In sailing there is the tortoise and the hareVertical battens are great if your sailmaker has experience with them.
In my experience the downsides are that the angle the battens are furled at is critical which means they must be a) properly installed on the sail and b) be furled properly and the same way every time. As an example, I've heard of some mast-furling boats having issues with their vertical battens if the drag/load on the outhaul wasn't kept under control while furling, since it could cause the bottom of the sail to furl tighter than the top meaning the battens were no longer aligned with the mandrel in the mast.
My experience is that there is usually a good amount of room inside the mast for the battens, it's the slot that may cause some issues since sail+batten pocket+batten can create quite a thick section of sail to pull in and out of the slot. Make sure your sailmaker measures this carefully.
With regards to the type of batten I would highly recommend using stiff rectangular battens as opposed to the run-of-the-mill, cheaper, round pultruded battens which seem to feature on most cheaper in-mast furling mains. The round battens don't resist compression forces nearly as well and just "S" in the batten pocket, causing the roach to collapse and the sail to look awful. Normally you could upsize the round batten to compensate for this but in the case of in-mast furlers that would cause issues with the aforementioned slot in the mast. RBS and Bluestreak are good examples of high quality battens depending on where you are in the world.
Vertical battens means you can get away from a hollow/concave roach which in turn gives you a lot more sail area (like 15-20% more depending on the sail design and batten layout) in a place where it matters a lot (high up) and a much more aerodynamically efficient sail. These things greatly benefit the light air performance of the sail.
That being said, many long-distance cruisers swear by non-battened furling mains for their simplicity and reliability. They appreciate having one less thing that could go wrong and aren't too worried about losing the sail area mentioned above.
For stop and go sailing a furling mainsail is heavenThink I’ll stick with a flaking system, Dutchman or lazy jacks. Boat I’ve offered on has the latter, last boat had the former. They all have compromises, just have to pick my personal poison.
The Dutchman system we have on the 40 footer with a fully battened main is a joy.Think I’ll stick with a flaking system, Dutchman or lazy jacks. Boat I’ve offered on has the latter, last boat had the former. They all have compromises, just have to pick my personal poison.
On a well cut mainsail, it lets you manage power by just modulating sheet tension to twist/untwist the sail.Roach is highly over-rated. Open up the wallet and spring for a fresh joint.
Luff tape And Full battens are the issueBased on a lot of offshore miles on a lot of differrent kind of boats as well as a few years of working as a sailmaker/sail designer for North. I'd prefer the newer in-boom furling mains over in-mast furling any day of the week.
The older in-boom furling systems certainly had their issues, but in the modern hi-end systems they have been pretty much all resolved. The pro's for inboom over in-mast are easier sail handling, in case of a jam your sail can always come down, no extra weight aloft, lower cost, installing and removing sail can be done in pretty much any weather, sail shape is much nicer and last but not least, there is less wear on the mainsail.
Than they used the wrong luff tape and batten ends. The last boat that I sailed on with in-boom furling had around 35.000 miles on the main. Mostly in the North Atlantic including a winter crossing. It has never been off the boom during those miles.batten compression erodes the luff and tape ..it could happen in one day if the wind goes soft and the sea state cause the sail to start talking
not good for offshore work .
What ever you sayThan they used the wrong luff tape and batten ends. The last boat that I sailed on with in-boom furling had around 35.000 miles on the main. Mostly in the North Atlantic including a winter crossing. It has never been off the boom during those miles.
I am fully aware of the issues that you mention, but it is almost always due to poor workmanship or wrong choice of materials by the sailmaker. That is no different than excessive wear on the batten ends and batten joints in an in-mast furling system.