Contentious question-motor sailer

Discussion in 'Boat Design' started by wayne nicol, Aug 11, 2013.

  1. wayne nicol
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    wayne nicol Senior Member

    So here's a question for all the knowledgable folks out there,
    With roughly the same size parameters, could the new macgregor hull be improved upon, and still deliver the same kind of performance,or better, than it currently does.
    In that, I mean a higher top speed motoring, without compromising whatever sailing ability it has. Could both the motoring and sailing be improved upon??:D
    Thanks
    Wayne
     
  2. PAR
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    PAR Yacht Designer/Builder

    The boat you're referring to is a huge set of compromises in the first place. You can't have your cake and eat it too, though MacGregor has tried with the 26, it certainly is limited in both sailing and powering abilities. This is the whole point. They kissed off good sailing abilities, to offer much better powering. If you improve the sailing aspects of the design, you'll just be stealing from the power side of the coin. The reverse is true as well. Welcome to the convoluted concessions, that make up yacht design decisions.
     
  3. wayne nicol
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    wayne nicol Senior Member

    Absolutely, no argument there.
    But can the hull be improved in any way shape or form, so as to improve on both aspects of the performance, or is the macgregor at the pinnacle of such compromised design.
    Thanks
    Wayne
     
  4. PAR
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    PAR Yacht Designer/Builder

    Nothing is at a pinnacle, though typically, you'll trade one design aspect for another, so refinement to the 26D, is likely just more convolution. Simply put, improving power or sail ability is fairly easy, but both, though doable, is just a play in frustration, from a design point of view. In the end you need to define more precisely what you want. Broad, undefined goals aren't attainable. As far as the 26D, I wouldn't be interested in developing these lines out at all, though maybe someone would. I think as a ho-hum powerboat that sails as poorly as it does, she has room for improvement, but why. Knowing you can't have you cake and eat it too, suggests a futile exercise, even if some progress could be developed.
     
  5. Yobarnacle
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    Yobarnacle Senior Member

    My contention is an auxiliary sailboat is primarily designed to sail.
    A power cruiser with steadying sails is designed to power.

    A motorsailer SHOULD be designed to function best while sailing and motoring simultaneously. Motorsailing.

    I'm working on my motorsailer to achieve that.
     
  6. PAR
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    PAR Yacht Designer/Builder

    Motorsailors used to be divided into categories, 70/30, 60/40, 50/50, etc. which meant they were 70% one and 30% another. The 50/50's where about as good as you could ask for, sailing sort of okay and powering sort of well.

    A real motorsailor is a well powered sailboat, simply because it's "motorsailing". In reality, most cruisers find they do one or the other and not much of both. You'll never get a larger yacht to plane off, without huge power, so 2.0 S/L ratios or less is what you can expect, for speed. At these speeds, a well defined sailboat, with a big engine is all you can ask for. If looking at a light weight (small) boat, then yes, you can take the 26D approach, but no one is motorsailing with one of these. They're sailing or blasting along on power, rarely both.
     
  7. Yobarnacle
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    Yobarnacle Senior Member

    I believe times are changing. :)
    I have a trailer sailor. An Albin 25. I'm modifying.
    The designer, Pers Brohal, called it a trawler with sails.
    He said, it wouldn't sail well under sail alone, the rudder is too small.
    I've moved the rudder to transom hung. Bigger. Further aft. Deeper. More accessible.
    Using electric prop at low power, slightly faster than sail speed, the prop drag disappears. I have speed thru the winds eye on tacks. And instant reverse available.
    The boat is faster, more efficient, and more controllable under both power and sail, than just either.
    Synergy. :)
     
  8. rwatson
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    rwatson Senior Member

    Par is not the only NA loathe to bother with a successful design like the Mac. It has been a long process to locate qualified people to spend time on the exercise.

    In my little project, we spent a lot of time analyzing the Mac hulls.

    Not only have they compromised on sail/power ability, but also in accommodation. I was surprised to see how quickly the boat would round up in a gust. Formal analysis found that the boat was designed badly balanced - probably to get more room inside, and the placement of the centreboard.

    The other big consideration was their manufacturing method. This made it impractical to put in sharp edges for better planing chines, sharp transoms etc.

    Then, one of the big strengths (in my opinion) , the dimensions that had to fit into a container and be easily trailerable. This restriction in width is major performance impact factor.

    As Par so astutely points out, its all compromise. But how much compromise is acceptable ?

    Powering at speeds over 17 mph adds a sharply increasing motor and fuel cost, not to mention the discomfort of pounding along at over 25 mph. So, not a big incentive there.

    As far a s sailing goes - any sailing is just plan slow. A comparable size pure sailing boat might have 3 or 4 knots on a Mac, which in a race is bad news, but on a sunny, relaxing day - hardly a dealbreaker. Especially since the Mac can stay out on the water another 2 hours a day, as it can do a quick powered run back to the marina at least twice the speed of any sailing yacht.

    A lot of 'mac improvers' have goals of making it better - but as Par says, the reasons WHY are the clue to the whole process.

    I will be happy to get
    1) significant extra performance
    2) an interior nav station
    3) be able to build it myself without having to pay exorbitant import and freight costs.

    http://www.boatdesign.net/forums/bo...sailer-power-cruiser-water-ballast-21999.html
     
  9. PAR
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    PAR Yacht Designer/Builder

    The Vega 27 isn't quite a trawler, though it is a bit of a pig as a sailboat, which is likely what Pers was referring. Speed improvements will be quite modest, even with all new appendages (keel and rudder), as the hull is quite burdened and there's only so much you can get from it. I'm glad your improvements have pleased you, but it's hard to think of her having much more speed than say 9 MPH, which is 1.5 S/L. I would imagine 8 MPH would be her usual speed.

    The 26D has considerably better power potential then your boat and even motorsailing she's got a lot more potential. Sailing, you'll get about the same, though she might get lucky enough, in a stiff breeze to see 1.8 to 2.0 S/L, which is just a dream for the Vega 27.

    If you remove some of the restrictions and some of the SOR motivated elements of the design, sure you can get more from a 26D like design. I still think it's a cake and eat it too thing. A nav station is an easy to satisfy requirement, as any galley counter top of settee table can serve double duty. Edges can be "hardened up" after she's popped from a mold or as a home build, though not such an easy thing in manufacturing. As far as "significant extra performance", well this will need some defining, but sure there's room. As to who wants a job like this, well again, good luck with that. Most sailors find the SOR compromises on the 26D unacceptable. Most powerboaters, would just leave the mast as home and wish she had more balls. Americans (a lots of Australians from my experience) would likely just replace the 50 HP outboard with a 140 HP unit and use it for what it really is.
     
  10. Yobarnacle
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    Yobarnacle Senior Member

    So how does the mac compare with the Albin?
     

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  11. Yobarnacle
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    Yobarnacle Senior Member

    8kts? Hahaha! 7kts is good.

    But I'm a deep sea tug captain. 7 knots is GOOD on tow! Towed all over the world at 7 kts. I LIKE 7 knts. :)
     
  12. Yobarnacle
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    Yobarnacle Senior Member

    Looking at the drawing, and it's not lines, it appears the mac has a crossed metacentric shelf.
    as she heels, the stern will rise and bow depress.
    Root hog.

    The Albin is a more seaworthy form in my estimation.
     

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  13. rwatson
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    rwatson Senior Member

    Yes, you are correct. That is a Mac 'feature'

    It was important in my design to not have parallel sides like the Mac, so that the stern wouldn't force the bow under when heeled.

    Considering the Macs recommended heeling angle was around 8 degrees, it theoretically wouldnt be a huge drama, but you cant tell sudden gusts to give you time to let the sheets out.
     
  14. Yobarnacle
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    Yobarnacle Senior Member

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  15. rwatson
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    rwatson Senior Member

    Well no, its not that easy. For a start, you get totally new requirements for visibility, which has a big impact on cabin top shapes, which affects foredeck access over the cabin top. There are a whole lot of issues that occur with inside nav station, funnily enough, the most significant one from a business point of view is 'style'. People want to have that sleek, yachty image without thinking about the practicality.

    Cost of build was always a big priority in the Macs design

    As far as SEP, I would be happy with another 2-3 mph, or equivalent fuel savings under power, being able to sail comfortably in heavy gusts, be rated at Class B in the ISO ratings ( potential for commercial hire ).

    Doing this while retaining the trailering ability, containering ability with superior to class accommodation and comparatively low cost approach will be the aim.


    Sure, and they have a total right to do that - though their insurance wouldn't cover any problems while using 150 HP.

    From my point of view, I wont invest another 100% on the bigger motor ( $18,000 compared to $9000 ), nor will I spend the money on the fuel for the privilege of having my ears and bum assaulted by the high speeds. Most of all, I wont impact my sense of security of not having sails as a fallback propulsion system, in case of mechanical failure.

    Peoples motivations for boats varies wildly, from speed crazed offshore powerboats to timber only, traditional gaff rigged replicas, to foiling supersailers.

    Their inner motivation is a constant source of debate. I cant justify the expense on my budget, nor can I summon up the enthusiasm for 'ultimate' boating solutions that are basically just 'money pits'.
     
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