This blog is devoted to my John Welsford designed 15' Navigator yawl Ellie. I built her in my garage over a period of 18 months and launched her in 2011. She sports a sliding gunter main, roller furled jib and sprit-boomed mizzen. Her construction is glued-lapstrake over permanent bulkheads and stringers. This blog is a record of her construction and her voyages here in the Puget Sound area and (hopefully) a useful resource for fellow Navigator builders.

Tuesday, August 7, 2012

Navigator Tacking angles

On the JWBuilders forum, Robert asked a very good question about tacking angles.  More specifically, do the 120 degree tacking angles that he measured with his compass coincide with those experienced by other Navigator yawl owners.

I've often wondered the same thing.  It is widely accepted that yawls do not point quite as high as sloops, but make up for it on other points of sail.  So I uploaded the tracks stored in my Garmin GPS to have a closer look.

Looking at the tracks I quickly realized that I spend very little time tacking upwind.  This time of year the wind tends to come from the N or NW.  When I have a Northerly, I like to take a lap around Hat Island.  When I have a Northwesterly, I enjoy a reach down to Mukilteo and back rather than sail upwind to Hat.


But on closer inspection, I did find some good examples of Ellie tacking.  Here we're tacking North inside  Jetty Island back to the boat ramp.  The wind is from the NNW.
 
 And here's a bit of tacking into a Northwesterly.


And finally, tacking into a Northerly, while fighting a little bit of counter current from the outgoing tide.


I don't know what the tacking angles are in these examples.  I'll let you be the judge.  I know that if I try to pinch Ellie any tighter than the angles you see, her speed drops off dramatically.

I hope this helps answer your question Rob. Comments are always greatly appreciated.

6 comments:

  1. Opps, messed up on the math - here we go again:
    Joel,
    Using the first example (because it's the most consistent) you have tacking angles ranging from 106 degrees to 112 degrees. Of course there are other factors - are you being lifted by a tide for example. The average and the mean are very close, 108 /109 degrees, which is very consistent indeed.
    As we have discussed before, there is a difference between measuring tacking angles with a compass vs a GPS, so it's hard to tell if you and Robert are experiencing similar distance (to windward) over the ground.

    michael

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    Replies
    1. I'm very happy with ~110 degrees, which is about what I expected to see. If I were a competent sailor, and I had my jib fairleads located where they should, I've no doubt I could hit the 100 degree angle that JohnW says is achievable. In these examples, I wasn't making any effort to point as high as possible or sail efficiently. I was just sailing.

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  2. These are interesting discussions. It is a constant question, rarely answered any better than "Boat XYZ goes to windward well." I sail a small cat-ketch outrigger canoe with a leeboard (probably less efficient to windward than a good yawl), and my GPS tacking angles resemble the ones in the last screenload above, which seems to be around 60 to 70 degrees to windward.

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  3. Off topic, I know, but I saw that you and Ellie will be at the festival. I am so excited to see her in person!

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  4. It's going to be a great festival this year. I'm really looking forward to it. Jay is bringing his Welsford Pathfinder Gunvor to the festival from Oregon, which I'm excited to see. Glad you can make it. See you there!

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  5. Joel, I'm enjoying your blog very much. The photos are wonderful. Re tacking angles, I sail a Wayfarer dinghy (sloop). During my first cruises, my GPS tacking angles looked quite similar to yours:

    https://picasaweb.google.com/lh/photo/cU1zVkCtvFmyzZjO1a2tYroVwufp3T02gWbQBv6Lmr8?feat=directlink

    This summer I've discovered how to sail tighter:

    https://picasaweb.google.com/lh/photo/pLSyrQVtKirK6U8sUzB6TRXoqphoeWX9O8NtiNHcRGU?feat=directlink

    One of the main tricks was accepting the slower speed the boat makes through the water! Another one is: if you've got tell-tales (tickers) on the jib installed, let the windward ones stream upwards rather than straight back!

    There are many more little things about sail trim that can influence tacking angle, if you're interested google the "Wayfarer institute of technology" - there are plenty of great articles mostly written by Uncle Al, and some by an expert UK sail maker Mike McNamara.

    Cheers!
    Mato

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