Measuring junk saling performance

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  • 14 May 2018 13:34
    Reply # 6159275 on 5682386
    Mark Mclauchlan wrote:

    Hello all.

     I happen to have a little 6.5m Monarch fin keel sailboat that I managed to dis mast last year. I am also in the process of trying to decide which would be the best rig (vs effort to achieve) on Stalemate which is a westerly konsort and would be pretty similar to Poppy. I would be interested in comparing cambered vs split junk rig. 

     The little boat could be on my mooring in Plymouth have two mast positions if needed to test different rigs. Would anybody be interested?

     

    Regards

    Mark


    Yes, Mark, I'm interested. let me know how your plans progress. We are hoping to have a testing session in Falmouth in September when David Tyler is planning to be there in Waeverbird, and KRKA lives there. We might be able to do some testing with you at the same time.
  • 14 May 2018 13:29
    Reply # 6159118 on 4913961

    Last week over a couple of days I tried out the JRA instruments on a friend's boat. Generally things went well, and the frame carrying the instruments did not break although it creaked and groaned a bit when the skipper tacked fast while we were creaming along at 7 knots, which generated maximum side force.

    Unfortunately we hit a snag that none of us had foreseen. We were trying to calibrate the water speed sensor in Ipswich dock where there is nice flat water and no current, as it has a locked entrance. We could run at above 5 knots for long enough, but we discovered the fatal flaw, which is that to calibrate the sensor, we have to use a Bluetooth connection, (to a phone with GPS), which worked fine when we were stationary, but stopped working once we got above 1 or 2 knots and the probe kicked up a bit of a bow wave.

    A bit of research on line led to the explanation - Bluetooth doesn't work through water. Apparently it uses a similar frequency to microwave ovens, so we were just trying to heat up the dock. I can see the system would work fine when the sensor is mounted in a boat, but it doesn't work in a probe.

    So we have gone back to the supplier to ask if there is another way to calibrate the sensor, or to get the Bluetooth signal out of the probe - an aerial maybe? No reply yet, but I guess they have their thinking caps on, or maybe they're just on holiday.

    If we can't make it work with the existing probe, I have a plan to change the probe so it sits on the water rather then in it, and has a spray rail like a fast motorboat to keep the bow wave low.

    Either way, it's going to be a while before we can sort this out, but one way or another we will sort it out. If all else fails we can change to an older simpler sensor. I will post an update when we know how we are going to proceed.

  • 14 May 2018 13:02
    Reply # 6158192 on 6120118
    Roy Denton wrote:

    Thanks for the update, Alan, it's looking promising.  If you need a 33' JR ketch with hinged battens for your portfolio I might be persuaded - once I get the RCD sorted.


    We might just take you up on that Roy! let me know when you have the RCD sorted.
  • 25 Apr 2018 20:26
    Reply # 6120118 on 4913961

    Thanks for the update, Alan, it's looking promising.  If you need a 33' JR ketch with hinged battens for your portfolio I might be persuaded - once I get the RCD sorted.

  • 24 Apr 2018 10:44
    Reply # 6117451 on 5681586
    Roy Denton wrote:
    Alan Boswell wrote:

    It may have been quiet on the surface, but we have been paddling like crazy underneath.

    Any chance of a short update on a further four months' paddling?


    I am pleased to report that as of yesterday we have got the electronics working together, so we are getting signals from the sensors to the multiplexer, and via wifi from the multiplexer to the laptop. We still have a glitch in getting the polar diagram software to accept the input via wifi, but I'm hopeful we'll get that sorted soon.

    It has taken a long time because both Chris and I have been super busy over the winter, but my 6 month contract is now finished so I have more time on my hands again. 

    The next step is to find a boat, preferably in East Anglia, that we can use to test the equipment out "in real life". It was going to be Rodney Whitworth's "Gung Ho", but sadly he has been taken ill. Tim Metcalfe has volunteered "Poppy", but she's not going afloat until 10th May, so if anybody knows of willing owner with a boat in the area (or close to it) available before then, please let me know.

  • 14 Jan 2018 18:58
    Reply # 5682386 on 4913961

    Hello all.

     I happen to have a little 6.5m Monarch fin keel sailboat that I managed to dis mast last year. I am also in the process of trying to decide which would be the best rig (vs effort to achieve) on Stalemate which is a westerly konsort and would be pretty similar to Poppy. I would be interested in comparing cambered vs split junk rig. 

     The little boat could be on my mooring in Plymouth have two mast positions if needed to test different rigs. Would anybody be interested?


    Regards

    Mark

  • 13 Jan 2018 21:58
    Reply # 5681586 on 5065620
    Alan Boswell wrote:

    It may have been quiet on the surface, but we have been paddling like crazy underneath.

    Any chance of a short update on a further four months' paddling?
  • 07 Sep 2017 07:24
    Reply # 5066934 on 4913961

    A thought, if it hasn't already occurred to other members.  

    With regards to getting comparisons between different rigs on the same boat, what about the Coromandel/Corribee? 

    Tammy Norrie owns an original Hasler/McLeod junk rig on a Coromandel boat.  He is contemplating putting a different rig on.  Maybe just the same but with camber, or a Split-rig or Weaverbird style.  Another Coromandel owner already has a Split-rig fitted, albeit maybe not totally optimised for the boat/mast position.  

    The Corribee and Coromandel are supposed to have the same hull shape and dimensions and there are Corribee yachts out there with Junk Rigs fitted plus of course there are multitudes of Bermudan rigged Corribees which would make it possible to make a direct comparison with a Bermudan rig on the same boat.  

    I'm sure a friendly Corribee sailor wouldn't mind helping out.  Maybe contact the Corribee owner's association? A polar diagram of the Corribee's sailing performance might be a small incentive for them to assist.   

    Of course, there are different configurations underwater, like bilge or fin keels, and weights of individual hulls, (extra equipment, etc) but it might, over time, to be possible to  find hulls and owner's willing to help who all have the same configurations.  

    Dave D. 

    Last modified: 07 Sep 2017 08:26 | Anonymous member
  • 06 Sep 2017 21:16
    Reply # 5066332 on 4913961

    Well, you've got some pretty competent people helping you there, Alan.  There isn't any innovative idea that doesn't have some teething problems.  Best of luck with fitting and running it all - but keep the receipts for the guarantee!!

  • 06 Sep 2017 14:16
    Reply # 5065620 on 4913961

    It has been very quiet on this channel recently, but things have been happening behind the scenes. The working group of Rob Prince, Chris Gallienne, David Tyler, and myself have spent a lot of time and many emails discussing what equipment to buy, and concluded that ultrasonic speed detection was the most accurate. Consequently we have purchased a DX900 boat speed, leeway, and water temp sensor, from Airmar, and an LC7 wind and direction sensor from LJ Capteurs.

    The boat speed is said to be accurate to 0.01 knots, and the wind speed to 0.25 knots. Wind direction accuracy is to 1.5 degrees, which is the best we could find within the budget. We have developed an instrument mounting "rig" which can be moved from boat to boat and which has the boat speed sensor in a faired strut or "paddle" and the wind sensor on a mast, both of which can be "tacked" fairly easily - we hope.

    We have bought an HP X2 hybrid tablet/laptop for its extended battery capacity, and because we wanted a windows based system to use the free polar diagram software "Polauto".

    To get the data into the computer requires a multiplexer to receive the NMEA 0183 signals and combine them for feeding to the computer. Here we hit a snag because the first unit we tried, a Quark A031, we could not get to function properly. After Chris Gallienne and I both tried and failed, we sent it back, and we are now getting a unit from V-Boat, a Swedish company, which we hope will arrive this week.

    This has meant we have missed the opportunity to measure Weaverbird and KRKA in Falmouth which was scheduled for this week. We will reschedule when we have the system up and running.

    It may have been quiet on the surface, but we have been paddling like crazy underneath.

    Last modified: 06 Sep 2017 14:19 | Anonymous member
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