High aspect sail ratio

Discussion in 'Sailboats' started by edik, Oct 13, 2011.

  1. edik
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    edik Junior Member

    I noticed that many moderately/heavy cruising sailboats sport a high aspect sail ratio. Makes me wander, why? I can see that on a racing boat this would make good sense. But on a moderately/heavy cruiser? It really doesn't add speed, makes sailing more uncomfortable and makes the boat more vulnerable to demasting. Unless I'm missing something, it's on a par with putting wide profile racing tires on your Suburban.
     
  2. CutOnce

    CutOnce Previous Member

    It is a slippery slope you are daring to question.

    The technologists amongst us will say the better pointing ability, possibly better speed potential and reduction of long, heavy booms are all good things. Our more radical technologists will promote lifting foils on anything that floats as well as high aspect ratio rigs. They will also say the logical conclusion of your anti-technology thesis is a return to square rigs, downwind-only travel and metal rimmed hats sporting horns and drinking grog.

    Surprising to few, people do buy 22" rims with low profile, expensive tires and put them on their V8 Sport Utility Vehicle (which is only city-driven in traffic). Spoilers and pseudo-aerodynamic frippery are required frosting on people's vehicular cake. Soccer moms regularly drive "mini" vans with 220 plus horsepower. So why shouldn't people buy boats selling the same dream?

    You seem to be expecting people to make sense. They don't. If people actually thought long and hard about what they really use and how they actually use it, Phil Bolger would have been a marketing genius. Jim Michalak and Michael Storer would be more popular than Phil Morrison.

    If you are contemplating a future in this industry, keep a thought in mind - Steve Jobs was heralded as a technology genius, while Steve Wozniak is a footnote in Apple's history. How something makes you look is a far more critical decision factor than how something makes you feel. And how something makes you feel is more important than if you actually use it. Actual use of technology is the lowest item on the decision making criteria.

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    CutOnce
     
  3. lewisboats
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    lewisboats Obsessed Member

    I know Jim personally and I have conversed with BoatMik on forums...Who's Phil Morrison?
     
  4. CutOnce

    CutOnce Previous Member

    Phil Morrison is the designer behind many of the last twenty or thirty years worth of high performance dinghies. I own a Phil Morrison designed boat.

    I would have also referred to the Bethwaite clan, but that could result in a severe thrashing from the peanut gallery. Basically, my point is that people designing for the highest performance and most elite sailors are far more popular than people who design for the real world usage 95% of the people sailing actually do.

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    CutOnce
     
  5. michael pierzga
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    michael pierzga Senior Member

    Low aspect sloops will have overlapping foresails.

    High aspect sloops will sail with a non overlapping foresail..... Self tacking, no chafe, easy to use. High aspect is user friendly
     
  6. edik
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    edik Junior Member

    Folks, sailing is a highly irrational activity. Again, I can somewhat understand the desire of a race boat owner to squeeze that very last half knot of speed out the boat, but to see that kind of sail on a boat with traditional lines? It simply doesn't look right. Alright, how about the golden middle: boom that doesn't protrude past the transom thus allowing for a backstay. The height of the mast can then easily ba calculated to achieve the desired square footage. No?
     
  7. michael pierzga
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    michael pierzga Senior Member

    Beautiful , pleasing to the eye, is when form matchs function.

    An oceangoing sailboat needs to be very powerful, plenty of sail area. This sail area is not intended to make you ' Fast", it is needed to best harness the light winds that are typical of ocean passages. If you cant keep her moving under sail, the motion of the yacht is uncomfortable and the engine will come on....you are no longer a sailboat

    I find high aspect ratio, non overlaping sails best for boats that need long legs..

    The same holds true with hull form. Inshore boats need superior windward performace ....long and thin. Offshore boats are beamy aft, with superior reaching and tracking abilty.

    A Twelve meter is beautiful, a Mini transat boat is beauitiful. Form and function.
     
  8. Petros
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    Petros Senior Member

    As pointed out, sailing is an irrational activity. I think many cruisers like their rigs to look like race boats, but to be comfortable. So you end up with fat heavy hulls with high tech looking sailing rigs. The racy appearance is a very real issue, if you can not sell the boat based on looks, you will soon be out of business. Your average consumer usually does not have a clue about how the stuff they buy works, let alone what works better, so slick looks is the only way you can get something sold. It is just the reality of the consumer market.
     
  9. michael pierzga
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    michael pierzga Senior Member

    "I think many cruisers like their rigs to look like race boats"

    I agree. Fashion. Marketing.

    Many completely unsuitable details from race boats are carried over to cruisers. The present trend of "Plumb bow" narrow entry, cruisers makes me laugh. They have to add folding anchor contraptions with huge opening hatches in the foredeck and beefy chafe guards to protect the stem. Anchoring with ease is the primary mission of a cruiser.

    I regularly see head stay roller furler drums located below deck on cruisers to achieve max luff length on the head sail.
     
  10. CatBuilder

    CatBuilder Previous Member

    You would be amazed at how many people do not understand this concept. :confused: :(

    The vast majority sees a powerful rig and thinks it's to sail dangerously.

    They don't stop to consider that it's to sail (instead of motor) in light winds and to reef in heavy weather.
     
  11. philSweet
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    philSweet Senior Member

    I have a habit of looking at things from a weird perspective, and this is going to be one of those times. Cruiser or racer, I want a rig that uses all of the hull's available stability. Excess stabilty is very expensive underway. The cruiser's hull is optimsed for liveability and will often have a shape and displacement giving it a great deal of stability. So it can carry a tall mast with ease. The main difference in rig choice for a cruiser should be the amount of effort and attention needed to achieve good performance. Exactly how this translates into aspect ratio isn't obvious. Cruisers will have a larger gap between the deck and the foot of the sails than racers. This lowers the actual span of of the sailplan and lowers the effective span even more (for a given mast height). Determining at what minimum speed the owners will switch on the engine also affects the design. Coastal cruisers and offshore cruisers might have very different answers to that question.

    What I personally want in a cruiser is the tallest rig that she can carry, a sailplan and fins that will work on autopilot down to two knot boat speeds, a boom on a track that can be set real low in light air and is reefed up as a first reef or when guests are aboard, highcut headsails with long leads and mast steps. At least one selftacking headsail arrangement with good performance for coastal waterway work. The rig would be much easier and cheaper to build if the motor was turned on at three knots instead of two.
    I want the rig pushed far forward on the hull so she will behave at anchor. The rig height of a cruiser with a beam much over 12 feet will likely be constrained by the ICW's 65' bridge clearance rather than by stability. I run 58' clearance on 16000 pounds and 30'lwl.
     
  12. michael pierzga
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    michael pierzga Senior Member

    There it is....Normal Ocean weather Gibraltar to the Caribbean. 10 to 15 knots downwind.

    If you expect to enjoy yourself, enjoy sailing and make a deliberate passage under sail , you must have a powerful sail plan.

    Designers know this. Listen to what they say.
     

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  13. daiquiri
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    daiquiri Engineering and Design

    Did you perhaps mean to say "aft"? To get an action similar to hoisting a mizzen sail?
     
  14. philSweet
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    philSweet Senior Member

    daiquiri, that wasn't very clear, was it?

    In the context of aspect ratio- If you set the hull up so that it will hang at anchor on a short leash and not tack and turtle on its mooring when storms hit then you must locate the CLR rather far forward relative to the windage of the hull. Cruisers should be this way. Racers aren't. I don't know any formal metrics for this, I just know which boats behave and which don't. Big tanks under the vee berth kept full shift CLR forward and windage aft while at anchor. Turning a big barndoor rudder 90 deg can help, but not as much as I would have guessed. Now the rig. If you're going to get enough lead with the rig you need either a high aspect rig, or a fixed bowsprit, and bowsprits aren't real popular. Figuring out when, exactly, the rig grows to the point that you have to start shifting the CLR aft again is probably a reasonable limit to the aspect ratio of a cruiser. Keel fins which have a CE at 25% chord when hooked up and a CE of 50% cord when stalled don't help matters (causing the CLR to shift aft at anchor). I think aft loaded fins should be preferred on cruisers. I would love to see some formal reports on this stuff, it seems to be closely held info. With modern materials and gadgetry, I don't think there is as much of a cost premium for the high aspect rig as there used to be. Folks will put the same gadgets on the low ratio rigs and sail cloth holds its shape so well now.
     

  15. michael pierzga
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    michael pierzga Senior Member

    I dont see any cost issue with high aspect, its certainly cheaper than a ketch. High aspect rigging is technical so the mast tube , rigging and the yachts structure will need to be professionally crafted.

    Low aspect sail plans also have advantages. For instance a ketch is a lovely rig for inshore cruisers. The small sails promote crew involvement, family style. Sail handling gear can be non technical. They anchor well. The mizzen is a great location for antenna and a split rig is fantastic for sun awnings. They also sail just fine.

    In the end you will get the best result by communicating with your naval architect Naval architects need a mission statement. Avoid the term " all purpose " sailing vessel. I find that they do a poor job at everything.
     
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