Flat Sails are Okay - mehitabel

  • 07 Jan 2011 22:31
    Reply # 491390 on 491310
    TONY AND SALLY SUMMERS wrote:

    David, having had a junk schooner and a catamaran before Ron Glas we were well used to easing sheets to get any real drive, however we are astonished at Ron Glas`s ability to drive to wind. 50` off the wind is her fastest and best point of sail, she will point higher but  not as fast with increasing leeway as one pinches, IM talking "normal" lumpy seaway not flat calm -- but this seems OK for 16.5 tons of floating home ,should I want better?

    again is this not down to hull form? Ron Glas has a few vices but sailing aint one of them!


    I'm not after a racing boat's speed to windward, that would certainly be uncomfortable. I'm happy with 5 knots at 30 degrees apparent wind, 45 on the compass, 50 on the GPS after leeway has been added in (that's what a good bermudan rigged boat of the same type and size should do).  I regulate speed off the wind to below 7 knots so that the self steering can manage.
    But what I do need in Tystie is power,  which a flat sail couldn't give me, to keep going solidly to windward against an awkward sea, in a shoal draft boat, 1 metre draft with bilgeboards. And what's more, I like doing it! Powering efficiently to weather in a responsive boat is fun, when the wind is fresh, the sun is shining, the sea is sparkling; and then I can forget I'm an OAP, un-latch the selfsteering, get hold of the tiller and enjoy the feel of a boat going at her best.
    It's all down to hull form and size and weight. Ron Glas is twice the size and weight of Tystie, with a deep keel. With cambered sails, Ron Glas should do 6 knots at 45 degrees, 8 to 9 knots on a reach.
    What it all boils down to is: different folks sail different boats in different ways, and if you don't want to sail that fast, and that close, you don't need more powerful sails.
    Last modified: 07 Jan 2011 22:31 | Anonymous member
  • 07 Jan 2011 22:07
    Reply # 491377 on 490687
    Deleted user

    Kurt, david, our rig is exactly as Jock handed on to us---- not sure yet whether we are sailing a grade one listed monument or should we refine it? weve only been voyaging in her for the last two years and still have much to learn and understand. So well carry on as "standard" forthe next year or two and then see!

    as for super light airs and that junk rig bane---slatting!---   my antidote is to get the fishin gear out and forget about forward progress! time for bed here in portugal , night! tony

  • 07 Jan 2011 22:00
    Reply # 491369 on 491304
    TONY AND SALLY SUMMERS wrote:

     I suspect that the modern rigs drive better to wind when deeply reefed--- is this true arne, david???---

    I don't think I'd put it like that. Cambered rigs drive better to windward - full stop. They drive better to windward under full sail, when the camber in the lower panels is more effective than flat panels would be. A well-shaped fanned top to the sail develops camber when deeply reefed, and also drives better than a 'Hasler' fanned top, which achieves something in developing camber, but isn't as powerful as it might be.

  • 07 Jan 2011 21:49
    Reply # 491348 on 490707
    David Tyler wrote:
    Kurt Jon Ulmer wrote:

    One thing I like about our flat junk sails is that they don't heel the boat nearly as much as the curvaceous Bermudan ones we used to have, (or the cambered junk ones we could have.)
    - At least the top third of the sail looks nicely, suitably curved anyways, when I look up from the deck, and I think it does to the wind also. It's definitely not flat.

    "Moderation in all things" - that's the key, I reckon. A flat sail is comfortable, but not fast. A well-cambered sail of any type is fast but not comfortable. I advocate a mildly cambered sail for offshore and voyaging use, maybe 4% to 6% designed camber. Arne advocates a camber of 8% to 10% for inshore sailing. We're both right.

    The camber that develops in a flat-cut, but fanned, sail is the "fiendishly-clever Chinese" way of getting camber for nothing. That's why I don't think anyone should make a purely Hasler-style sail nowadays, but should look at the later planforms.
    My main modification to the recommended Hasler-McLeod sail form was to 'fan' the two battens nearest the yard, raising their leech ends above the parallelogram ones below. I think this may roughly match the 'transitional panel' idea presented in an old JRA newsletter and mentioned by Arne K since. 
    I also increased panel heights up high and decreased that (P) dimension down low. So early full-panel reefs are 'balancing' size. Sheet geometry (Dmin) also benefitted. 
    My favourite planform in PJR was figure 2.24, but I wanted equal battens and a larger top panel.
    Fanned sails are both much earlier, and later.
    Thanks,
    Kurt
  • 07 Jan 2011 21:30
    Reply # 491342 on 491304
    TONY AND SALLY SUMMERS wrote:

    Kurt,yes I agree--[and am I alone in thinking 5 knots passage speed makes the maths easy!!]   we have a total mix of battens---   some aluminium, some heavy ,some light , some wooden, the net effect is a good sail shape WHEN FULL SAIL IS HOIST--- howevever I do think the  flat rig starts to loose its efficiency if one reefs too early- but as you say ,the flat sail allows you to carry more sail with less heeling for longer--- typically we start to reef in 20knots plus. by then the reefed sail is fine in terms of drive. I suspect that the modern rigs drive better to wind when deeply reefed--- is this true arne, david???--- but is hull form not the real limiter?

    as to light weather sails --no we dont use them, despite her weight to sail area Ron Glas just keeps sailing-----albeit quite slowly in very light airs.  as to sheets fouling-- no problem  despite the fact that the distance between main and foresail is less than the minimum that Jock specifies in PJR!!

    (It seems you're awake and right next door... you'll notice another question nearby.)

    I do like 5 knots. And we reef in about the same wind. We have ~75 sqm of sail on 11 tonnes of boat with a 9.8 m waterline.

    Hull form - I think it is a limiter, and all a boat's ambitions should line up for the best result. 

    mehitabel has a pretty good hull form for moderate speed, and I've improved the keel's foil, moved the ballast lower, moved the rudder aft and lightened the boat. Not for speed, but rather for comfort and against leeway.

    I like the way full sail steadies the motion at sea, and in typical trade winds with a typical swell and typical not-too-close reach and typical speed (avoiding any more numbers here) all is very well. 

    If our sails had camber, that situation wouldn't benefit.

    I asked about auxiliary sails because for very light conditions, where our sails don't flop about but don't work either, and a little progress would be useful, I have had daydreams about them flying all billowy, pulling. Azores, Mediterranean daydreams... (aim to be there in a couple of years.)

    Cheers,
    Kurt
  • 07 Jan 2011 21:03
    Reply # 491310 on 490687
    Deleted user

    David, having had a junk schooner and a catamaran before Ron Glas we were well used to easing sheets to get any real drive, however we are astonished at Ron Glas`s ability to drive to wind. 50` off the wind is her fastest and best point of sail, she will point higher but  not as fast with increasing leeway as one pinches, IM talking "normal" lumpy seaway not flat calm -- but this seems OK for 16.5 tons of floating home ,should I want better?

    again is this not down to hull form? Ron Glas has a few vices but sailing aint one of them!

    Last modified: 07 Jan 2011 21:03 | Anonymous member
  • 07 Jan 2011 20:53
    Reply # 491307 on 491233
    David Tyler wrote:
    TONY AND SALLY SUMMERS wrote: Nothing wrong with flat sails in our opinion---  We are still sailing Ron Glas on Jock`s second set of sails--1987-- still going fine. In fact we still have the original 1971 sails on board and short of a bit of restitching they  are OK !! We dont find the sails "slow"-- certainly comfortable but the boat is fast enough-- we are often reefing to keep the speed down below 7knots --- personally I find any faster becomes uncomfortable.The latest sailforms are very interesting and all power to those of you that are pushing new ideas----  when the time comes to replace Ron Glas`s sails we will probably stick to the original flat design!
    I'm sure you're reaching 7 knots easily once the sheets are eased, but what speed does Ron Glas achieve hard on the wind? This is where a bit of camber comes in useful.
    Anyway, it's good to hear that you're satisfied with the rig as it is - "if it ain't broke, don't fix it!".
    Easing the sheets is where it's at.
    Mehitabel tacks with pleasure through about 120 degrees on the compass, to be honest, so I could say she's unlikely to ever sail hard on the wind. Right up to that angle she maintains good trustworthy progress if there's over ~10 knots of wind and only a chop to climb. With a little more wind, she becomes lively and keeps 5 knots on, but likes to sail no closer to the arrow.
    With much more of a sea, well, she becomes slow unless there's more wind, and then we'd soon rather be doing something else than sailing to windward. 
    I couldn't happily plan a passage in any boat, sailing closer to the wind than mehitabel's best close reach, especially sailing fast. I could, however, enjoy rounding a point without doubt in a fickle 5 knot headwind. 
    I wouldn't ask any other boat to admit to mehitabel's numbers, which she was reluctant to let me publish. (She's indignant now.) But otherwise, is Ron Glas in agreement?
    Cheers,
    Kurt
  • 07 Jan 2011 20:43
    Reply # 491304 on 490687
    Deleted user

    Kurt,yes I agree--[and am I alone in thinking 5 knots passage speed makes the maths easy!!]   we have a total mix of battens---   some aluminium, some heavy ,some light , some wooden, the net effect is a good sail shape WHEN FULL SAIL IS HOIST--- howevever I do think the  flat rig starts to loose its efficiency if one reefs too early- but as you say ,the flat sail allows you to carry more sail with less heeling for longer--- typically we start to reef in 20knots plus. by then the reefed sail is fine in terms of drive. I suspect that the modern rigs drive better to wind when deeply reefed--- is this true arne, david???--- but is hull form not the real limiter?

    as to light weather sails --no we dont use them, despite her weight to sail area Ron Glas just keeps sailing-----albeit quite slowly in very light airs.  as to sheets fouling-- no problem  despite the fact that the distance between main and foresail is less than the minimum that Jock specifies in PJR!!

    Last modified: 07 Jan 2011 20:43 | Deleted user
  • 07 Jan 2011 20:10
    Reply # 491282 on 491115
    TONY AND SALLY SUMMERS wrote: Nothing wrong with flat sails in our opinion---  We are still sailing Ron Glas on Jock`s second set of sails--1987-- still going fine. In fact we still have the original 1971 sails on board and short of a bit of restitching they  are OK !! We dont find the sails "slow"-- certainly comfortable but the boat is fast enough-- we are often reefing to keep the speed down below 7knots --- personally I find any faster becomes uncomfortable.The latest sailforms are very interesting and all power to those of you that are pushing new ideas----  when the time comes to replace Ron Glas`s sails we will probably stick to the original flat design!
    Everything in your reply rhymes with our experience. I too prefer 5 or 6 knots to 7. And like you, I have a great deal of respect for the current inventors' work. 
    I even have a little file of sketches, of batten designs that would give smooth camber to the lower part of our flat-cut sails, which should improve their ability to sail to windward with authority in light air. (Not racing, just going a little better with a little less breeze.) But how necessary? So far, not very.
    Do you make use of auxiliary sails at all?
    And, do your fore-sheets foul the main's luff when you're short-tacking, if you ever do? (Mehitabel has similar geometry to Ron Glas there, and they do snag, and I usually ignore it and keep going.)
    Regards,
    Kurt
  • 07 Jan 2011 19:27
    Reply # 491233 on 491115
    TONY AND SALLY SUMMERS wrote: Nothing wrong with flat sails in our opinion---  We are still sailing Ron Glas on Jock`s second set of sails--1987-- still going fine. In fact we still have the original 1971 sails on board and short of a bit of restitching they  are OK !! We dont find the sails "slow"-- certainly comfortable but the boat is fast enough-- we are often reefing to keep the speed down below 7knots --- personally I find any faster becomes uncomfortable.The latest sailforms are very interesting and all power to those of you that are pushing new ideas----  when the time comes to replace Ron Glas`s sails we will probably stick to the original flat design!
    I'm sure you're reaching 7 knots easily once the sheets are eased, but what speed does Ron Glas achieve hard on the wind? This is where a bit of camber comes in useful.
    Anyway, it's good to hear that you're satisfied with the rig as it is - "if it ain't broke, don't fix it!".
       " ...there is nothing - absolutely nothing - half so much worth doing as simply messing about in junk-rigged boats" 
                                                               - the Chinese Water Rat

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