GPS Distance Errors

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Prolific posting day for me.  I saw this on Twitter,  An academic paper about system over estimate of distance by GPS devices.

WHY GPS MAKES DISTANCES BIGGER THAN THEY ARE

There is a lot of heavy duty math in the paper and if I manage to understand it, it will take a while.  But the basic gist is that the larger the error in the estimated positions along the route trajectory, the more cumulative distance errors occurs.

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In the pedestrian example they provided, the error peaked at 2.5 meters of over estimation at 45 minutes into the experiment.

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Not all that much error, but it gives you something to think about.

How it is supposed to look…Mahe Drysdale at the Head of the Charles

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I came across this over on Reddit.  I guess Mahe had a GoPro mounted on his boat during the head of the Charles.  Basically the same perspective as mine, but mounted a lot further away from the stern so you can’t see the finishes, which I am sure would have been even more impressive.

His row was at the end of the day on Saturday, when the winds had died down a bit from earlier in the day, but was still a factor.  The video shows him passing Andrew Campbell between the Western Avenue Bridge and the Weeks Footbridge.  Campbell is a lightweight and was effected by the headwind a lot more than the gigantic Drysdale.

Part 1:  Including a bit of his warm up, the start and the race through the Anderson Bridge

Part 2: Through the big turn, under the Eliot Street Bridge and to the finish.

Oh, what I’d give to be able to row like that.  It is interesting to have a video of the same race, under similar conditions, from the same perspective but with one of the finest scullers in the world doing the rowing.  It was particularly humanizing to see him take a lousy stroke now and then.

Merrimack Chase Videos

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Sorry about the shaky video.  I had to improvise a mount and it had a bit of wiggle to it. I decided that the videos would look better using the youtube stabilization.  I’m not entirely sure.  Also, for some reason, the heart rate sensor decided to not talk to my iphone yesterday.  It worked fine to the speedcoach, but that was using a polar receiver.  I suspect that the bluetooth connectivity is a bit squirrely.

Truth be told, it’s not all that exciting a video.  I go under a bridge at about 5 minutes into the first part.  And the water is nasty and rough, but since I had the first bow number for the event, I had no one to pass.  I had a close call with a buoy at 1:55 in the last part.  I almost got the last guy of the Master “C” group at the end of the race, but not quite.  I think the sprint from 2:00 into that video to the end was pretty good.

The pre-start and about the first 8 minutes or so of the race:

The middle of the race, from after the bridge around the big bend and into the flatter water.

The last few minutes of the race.

Not the prettiest rowing I have ever done, but for the state of the water, I’m OK with it.  Lots to work on for next season!

Merrimack Chase – I won.

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Weather:  Broken clouds.  Warm, nearly 60 degrees.  Windy.  It looks like some kind of a front went through during my race.  It was a WNW wind at about 10mph, with gusts up to 23mph.  This is a pure head wind through the first 2 km of the course.  The water as nasty.

Here is the weather underground almanac for today from a station right on the Andover side of the river in the middle of the course.  The cursor is about 5 minutes after my start.

Screen Shot 2015-11-07 at 4.33.21 PM

I was pleased with the race result.

results

I finished first among the Master D/E group.  And finished close to top guys in the Masters C group.  I know those guys and they are good scullers.

Looking at the map of my course, I am not all that happy with my line.  I messed up my approach to the bridge and it added about 30 meters to my course, or nearly 10 seconds to my time.  And I did not hug the big turn nearly close enough, that probably added another 30 to 50 meters of length to my course.  Having said that, I steered it bette rthan the guy behind me.  I think he could have beat me if he followed my line, but he went way wide around the turn.

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Since the wind was from the WNW, the first half of the course until you were completely through the turn was straight into it, and the chop was pretty nasty, so the pace was really slow.  Once around the corner, it was a lot smoother and much less wind.  Still a few gusts to contend with, but much nicer water.  The splits reflect that

In the last 1000m I was coming up behind one of the boats from the Master C group.  I wanted to take the line along the buoys on the western shore, but he didn’t really give me a good line and I ended up nearly hitting one of the course buoys.  That pissed me off enough that I cut across his stern and spinted my guts out to the finish.  I nearly caught him at the line.  I can thank him for probably a 10 second better thime than I would have other wise had.  🙂

Screen Shot 2015-11-07 at 3.03.42 PM Screen Shot 2015-11-07 at 3.03.23 PM

Start_|_Dist_|_Split_|_Pace_|_Strks__|_Rate_|_DPS_|_AvgHR_|_Remarks
00020_|_4320_|_24:38_|_2:51.1_|_456___|_18.5_|_09.5_|_141___|_warmup
Start_|_Dist_|_Split_|_Pace_|_Strks__|_Rate_|_DPS_|_AvgHR_|_Remarks
00020_|_0340_|_03:17_|_4:49.3_|_038___|_11.6_|_08.9_|_126___|_in the chute
00360_|_4700_|_21:34_|_2:17.7_|_594___|_27.5_|_07.9_|_175___|_Race!
05060_|_1480_|_09:36_|_3:14.6_|_160___|_16.7_|_09.3_|_124___|_back to the dock

Dist__|_Time__|_Pace___|_Strks_|_SPM__|_DPS__|_AvgHR_|_Remarks
00340_|_03:17_|_4:49.3_|_038___|_11.6_|_08.9_|_126___|_warmup
04700_|_21:34_|_2:17.7_|_594___|_27.5_|_07.9_|_175___|_Main set
01480_|_09:36_|_3:14.6_|_160___|_16.7_|_09.3_|_124___|_rest meters
06520_|_34:27_|_2:38.5_|_792___|_23.0_|_08.2_|_156___|_Total

Video will be coming a bit later.

Thursday: Taper Day 2 –> 2 x 2′ / 5′ rest (on the erg)

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Early meeting, so I missed a beautiful morning on the river.  I looked at the glassy smooth water as I drove past.

Plan:  Taper day 2.

  1. 20 minute warmup
  2. 2 x 2′ / 5′ rest
    1. rate: >30
    2. pace:  faster than 2K race pace (1:40ish)
    3. on slides
  3. Cool down

2x500 Screen Shot 2015-11-05 at 9.02.04 AM

It was mercifully brief, but each interval really stung.  I pushed a lot faster than 2k race pace and let the rate really climb on the theory that the whole point is to provide sufficient stimulus to avoid any fitness loss during the taper.  No evidence that this is the right thing to do, but it made me feel like I was giving it my all.

Tomorrow:  Back on the river.  A nice warmup, a single 500m interval, and an easy cool down focusing on technique.  Then load up the boat for the race.

Wednesday: Taper day 1 – 3 x 500 / 500m rest

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This has been the nicest stretch of weather this week.  Today was mirror flat water, temps in the 50s, and bright sunshine.

Plan:  Implementing a short 3 day taper for the race on Saturday.  This is based on this paper.

  1. Nice long warmup
  2. 3 x 500m / 500m rest
  3. Rate: >30
  4. Pace: faster than 2:00
  5. Work on keeping the rate up and technically clean.

Screen Shot 2015-11-04 at 11.15.45 AM Screen Shot 2015-11-04 at 11.15.15 AM

Start_|_Dist_|_Split_|_Pace_|_Strks__|_Rate_|_DPS_|_AvgHR_|_Remarks
00020_|_3980_|_19:58_|_2:30.6_|_402___|_20.1_|_09.9_|_141___|_w
04000_|_0500_|_01:59_|_1:58.9_|_063___|_31.8_|_07.9_|_166___|_Int #1
04500_|_0500_|_02:53_|_2:52.9_|_052___|_18.0_|_09.6_|_141___|_r
05000_|_0500_|_01:59_|_1:59.3_|_066___|_33.2_|_07.6_|_168___|_Int #2
05500_|_0500_|_03:04_|_3:03.8_|_059___|_19.3_|_08.5_|_144___|_r
06000_|_0500_|_01:58_|_1:58.2_|_062___|_31.5_|_08.1_|_170___|_Int #3
06500_|_1260_|_07:22_|_2:55.4_|_140___|_19.0_|_09.0_|_132___|_c

Dist__|_Time__|_Pace___|_Strks_|_SPM__|_DPS__|_AvgHR_|_Remarks
03980_|_19:58_|_2:30.6_|_402___|_20.1_|_09.9_|_141___|_warmup
01500_|_05:56_|_1:58.8_|_191___|_32.2_|_07.9_|_168___|_Main set
01000_|_05:57_|_2:58.4_|_111___|_18.7_|_09.0_|_143___|_rest meters
01260_|_07:22_|_2:55.4_|_140___|_19.0_|_09.0_|_132___|_cool down
07740_|_39:14_|_2:32.0_|_844___|_21.5_|_09.2_|_144___|_Total

The intervals stung, but only for a very short while after finishing each.  I really like to see a pace below 2:00 on the speed coach.  It’s fun to row fast.

I’m probably going to need to do tomorrow on the erg because I have an early meeting at work.  Pity.  The weather is supposed perfect again.

Tuesday: 5×1500 / 5′ rest

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Many cultures have named winds that have an important impact on daily life.  In Southern California, the Santa Ana winds blow hard in afternoons as hot air rises above the mountains and draws air from the Pacific Ocean.  In the Rocky Mountains, the Chinook is a warming wind which in Native American Legend is the “snow eater”.  In Europe the Mistral blows from the Mediterranean to the Alps.  Today, I experienced a wind that I think needs a name.

The “Finale”…a wind, always a head wind, that occurs only during the final 1000 meters of a head race, or during the last rep of a workout.  It comes quietly, barely rippling the surface of the water, but you feel it on the back of your neck as you watch your splits slow down, despite your best efforts.  Then as you enter the last 5 strokes, the “Finale” disappears as mysteriously as it came, leaving the river glassy smooth. In ancient time, it was believed the that “Finale” was caused by playful rowing god who took great joy in tormenting scullers.  But with the introduction of modern metrology, the mystery has only deepened because this wind is not detectable by normal anemometers.

Sorry for the digression.  The weather this morning was perfect.  I mean really perfect.  High 40s, into the low 50s by the time I finished.  Bright sunshine, now that the clocks have changed.  And except for the mysterious Finale, no wind at all.

Plan:

  1. 5 x 1500 / 5′ rest
  2. rate: r28
  3. pace: 2:10
  4. Technique: Experiment with trying to hold my hands higher going into the finish to avoid washing out and stop “rowing over a barrel”

Screen Shot 2015-11-03 at 10.41.28 AM

The spikes in the rate are from when I go around the s-turn.  There is a peak to come into the turn, then about 10 strokes straight, then a peak to come out of the turn.  Going upriver, the turn starts about 700m in.  Going down river, around 1000m.

Screen Shot 2015-11-03 at 10.41.16 AM

Start_|_Dist_|_Split_|_Pace_|_Strks__|_Rate_|_DPS_|_AvgHR_|_Remarks
00020_|_2980_|_15:01_|_2:31.1_|_307___|_20.5_|_09.7_|_137___|_w
03000_|_1500_|_06:23_|_2:07.6_|_178___|_27.9_|_08.4_|_164___|_Int #1
04500_|_0500_|_03:47_|_3:47.2_|_070___|_18.5_|_07.1_|_129___|_r
05000_|_1500_|_06:27_|_2:08.9_|_180___|_27.9_|_08.3_|_168___|_Int #2
06500_|_0500_|_03:02_|_3:02.0_|_058___|_19.1_|_08.6_|_139___|_r
07000_|_1500_|_06:29_|_2:09.5_|_181___|_28.0_|_08.3_|_170___|_Int #3
08500_|_0500_|_03:05_|_3:04.9_|_059___|_19.1_|_08.5_|_142___|_r
09000_|_1500_|_06:30_|_2:10.0_|_182___|_28.0_|_08.2_|_168___|_Int #4
10500_|_0500_|_03:07_|_3:06.6_|_062___|_19.9_|_08.1_|_140___|_r
11000_|_1500_|_06:38_|_2:12.6_|_189___|_28.5_|_07.9_|_169___|_Int #5
12500_|_1680_|_09:49_|_2:55.2_|_194___|_19.8_|_08.7_|_128___|_cool down

Dist__|_Time__|_Pace___|_Strks_|_SPM__|_DPS__|_AvgHR_|_Remarks
02980_|_15:01_|_2:31.1_|_307___|_20.5_|_09.7_|_137___|_warmup
07500_|_32:26_|_2:09.7_|_910___|_28.1_|_08.2_|_168___|_Main set
02000_|_13:01_|_3:15.2_|_249___|_19.1_|_08.0_|_137___|_rest meters
01680_|_09:49_|_2:55.2_|_194___|_19.8_|_08.7_|_128___|_cool down
14160_|_10:16_|_2:28.9_|_1660___|_23.6_|_08.5_|_150___|_Total

That was awesome.  Hard, but awesome.  Seriously, a bit of wind picked up while I was resting before my last interval and I think that slowed me down a bit.  But I was also really tired by that point.  The big win was just hanging in with that rep when I felt like I was going to blow up.

Tomorrow:  3 x 500 / 500m rest (start of taper for Saturday’s race)

Monday: 14K steady state

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Forgot my HR monitor at home.  It was cold at first, but sunny and it warmed up nicely by the end.

Plan:

  1. 4 x 3000m / 1′
  2. rate: 18-20
  3. pace: 2:25 ish

chart (2)

This is from the RIM log file.  I didn’t bother downloading the data from the Speedcoach.

I ended up pushing the first 3000m a bit too hard, so for the rest of the workout, I basically alternated 500m of square blade, 500m of slow roll ups, and 500m of “normal rowing”

It was a beautiful morning for a row and a nice session.

Sunday: 4×20′ / 1′ rest

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Static erg.  Core perform seat. PC running rowpro died while I was rowing.  Very sad.  Need a new beater PC to sweat all over.  Good thing I had my iphone going as a redundant HR monitor!  How’s that for obsessive!

Plan:

  1. 4 x 20′ / 1′ rest
  2. slow start: 5′ at 2:15. 5′ at 2:10, then 2:04 the rest of the way
  3. rate: r19
  4. mechanics:  Work on controlling handle height and easing into the catch.

11-1 Screen Shot 2015-11-01 at 7.22.06 PM

So, my HR was way higher than last session.  But the lactates were fine, delightful in fact.  So, I am definitely at the right training power, and I will push just a little bit faster next time.

lac

Just goes to show you that HR is not very well correlated with lactate level, even over the short term.

Side Video of Rowing Drills

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Square Blade rowing

Flaws to fix:

  • Touching water
  • Slightly feathered from square

Square at pause:  Feather at the finish normally, then pause at half slide, then square the blades, then continue to catch.

Flaws to fix:

  • Pausing too early.  I am pausing at 1/4 slide, right when my hands go over my knees.
  • Touching water.  This is mainly caused by a sloppy finish leaving me slightly off balance

Alternating Strokes:  This video starts with a few strokes of slow roll ups, then goes into a 3 stroke alternating sequence.  First is a stroke on the square, then a stroke with a slow roll up, then a normal stroke.  The idea is to extract the blades the same way for each, and then change what is done on the recovery.  I find that the norma strokes feel so good when I do this drill