Lake Accotink

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September 23

Lake Accotink – Run, Bike or Walk, but please no Swimming

NOTE: The MTBO portion of the event has been CANCELLED due to rain. Foot orienteering will continue as planned.

On September 23rd 1806, Lewis and Clark returned to St. Louis after two years of exploring the Pacific Northwest. Now exactly 212 years later, channel your inner explorer in the wilderness of Northern Virginia!

Please join us for this season's Lake Accotink orienteering meet which will have several exploration/racing opportunities:

  • Mountain biking orienteering (MTBO) will, weather permitting, be available in short, medium, and long courses.  Registration opens at 8:30 am, starts are immediately thereafter, last start is at 10:00.
  • Traditional white, yellow and orange classic orienteering courses will be offered for with registration beginning at 10:45 and starts allowed from 11:00 to 1:30. All participants in the foot orienteering races must be completed by 3:00.
  • For foot orienteering, the piece de resistance will be a variation on score-O imported from Ontario called a "Thomass" event. Registration and start window will be as for the classic courses but for added excitement the Thomass will have an optional mass start at 12 noon.  This course is intended for advanced orienteers and for intermediates interested in a change from point-to-point courses. Shortly after the start, the course will enter a single large score-O window.  Orienteers may tackle the points within the window in any order they choose and are allowed to skip a certain number of controls according to an age/gender/skill based handicapping system.  After completing the score-O window, conventional point-to-point orienteering regains its sway with a series of mandatory controls leading to the finish.

    Lake Accotink is a beautiful park in Springfield, VA with a train trestle, tangled trails and of course a sparkling lake. Don’t miss this second orienteering meet of the fall.

    Lewis and Clark were tasked to explore and map newly acquired territory and were out for two years, four months and ten days, your task is to use your map skill, have fun, and be back by 3pm.

    For any youth or large groups planning to attend this event, please contact the event director so that we can coordinate pre-registration for the group. The group registration and waiver forms are part of the information on our Group Leaders page.

    Note that registration for both events will be at the McLaren-Sargent Pavilion, accessed from the parking lot off Heming Ave rather than through the southern park entrance most navigation apps will lead you to if you search for Lake Accotink Park.

    Mountain Biking Notes:

    MTBO is navigational racing on mountain bikes, in which each participant is given a map showing a series of checkpoints to be found in a designated order in the shortest possible time, with the choice of route between checkpoints left up to the racer. Success therefore depends on raw speed, of course, but also on the ability to read the map, make good route choices and execute them efficiently.

    Rules for the MTBO event:

    NOTE: The railway bed/track is out of bounds. Stay away from it.

  • Helmet use is mandatory.
  • Participants are required to stay within 10 feet of their bikes at all times while racing.
  • Participants are required to stay on trails, tracks, roads and fields. No short cuts through the forest.
  • Be aware that all courses require some degree of technical MTB riding skills and may involve quite narrow, steep and rocky sections.
  • Participants must yield to horses and pedestrians, in accordance with park rules.
  • Alternative parking is available at the lower parking lot (7500 Accotink Park Rd,, Springfield), which is a short walk from the pavilion where registration will be.

    Note: in case of rain and therefore poor trail conditions we may be required to cancel the MTBO event; make sure to check this website the day before the event for news. The foot-O in the afternoon will take place rain or shine.


    Lake Accotink Park, McLaren-Sargent Pavilion, Springfield, VA (Classic)

    RegistrationNo advance registration required. Just show up and have fun!
    Start TimesStart on a foot orienteering course any time between 11am - 1:30pm. [MTBO starts have been cancelled.]
    ScheduleSunday, September 23
    11:00 am - 1:30 pmClassic: Classic Orienteering Start Window
    3:00 pmClassic: Classic Course Closing Time
    Event Director:DennisAndHelen Doherty
    Course Designer:Jon Torrance
    Location Details

    Classic, Classic
    Lake Accotink Park
    McLaren-Sargent Pavilion
    Springfield, VA
    Google Map

    From the North or South: use I-495/Beltway exit 54AB/Braddock Rd/Rt 620, heading east on Rt 620/Braddock Rd as you exit. In ~0.8 miles, turn right on Heming Ave. In ~1.3 miles, turn right at the Lake Accotink Park sign and follow the park road to the parking area. The pavilion is up a small path starting at the far (west) end of the parking lot.

    Alternative parking is available in the lower parking lot (7500 Accotink Park Rd,, Springfield). It's a short walk from there to the pavilion where registration is located; follow signs or ask someone how to get to the McLaren-Sargent pavilion.
    Links to Lower Parking Lot:
    Google Maps Link
    Apple/iPhone Link

    Course DetailsClassic
    Course NameLength (km)Climb (m)No. Controls
    White 2.91159
    Yellow 3.11659
    Orange 4.121012
    Score 28
    Course NotesClassic

    Our second full spectrum event of the season will in fact be, weather permitting, more than full spectrum, offering mountain bike orienteering in the morning before the usual pedestrian orienteering. MTBO courses will be available in short, medium, and long versions. There will be classic point-to-point white, yellow, and orange courses and, for advanced (and adventurous intermediate) orienteers, another Canadian import to follow on last season's dogbones score-O - a Thomass event.

    The start for all courses, including MTBO and THOMASS, will be in the grassy area below the Lake Accotink dam, a few hundred meters walk west of parking and registration for the event. The finish for all courses will be at the west end of the dam, just off the main trail heading west from the start.

    A Thomass is a form of handicapped score-O, traditionally mass started, bearing some resemblance to the familiar Stumble/Bumble formats. It features a single score-O window, in which everyone has their own handicap based on age/gender/experience entitling them to skip a certain number of controls. After the score-O window, it's a straightforward race to the finish with low handicap speedsters gunning to see how many of the people with higher handicaps they can overhaul and canny high handicappers doing their best to hold on to whatever advantage they built up in the score-O window.

    For this event, a mass start will be offered at noon. The course will also be available throughout the classic start window, for those to whom the timing or nature of the mass start isn't congenial. Please, if taking part in the mass start, gather at the start by 11:50am for map distribution and a pre-race briefing. Participants will be allowed to turn over their maps and plan how to attack the course for a minute prior to the mass start. People starting the Thomass on their own are asked to give themselves no more time than that to study the map prior to starting, in the interest of fairness.

    The handicapping system will work as follows:

  • within the score-O window, everyone will be allowed to skip 3 controls
  • if, as of Dec 31, 2018, you'll be over 35 or under 18, you may skip another 2 controls
  • if you'll be over 50 or under 16, you may skip an additional 2 controls
  • if you'll be over 65 or under 13, you may skip a further 2 controls
  • if you expect to be some gender other than male on that date, you may skip 2 more controls

    All Thomass participants should add all that up and come up with a number of controls they're allowed to skip between 3 and 11. For convenience during registration, the various possible levels of handicap will correspond to our usual assortment of course colours as follows:

  • handicap of 3 skips = blue
  • handicap of 5 skips = red
  • handicap of 7 skips = green
  • handicap of 9 skips = brown
  • handicap of 11 skips = beige

    All course maps will be printed at 1:7,500 scale. The contour interval is 5 meters.

    Note for all courses: the map is now, ignoring some updating of the trail network over the years, the most elderly QOC map in regular use and its age shows. Unmapped newer rootstocks probably outnumber the mapped ones. Some vanished trails have been removed from the map for this event but not necessarily all that ideally should have been. There are also a few new trails or rerouted sections of mapped trails not reflected on the map. The vegetation mapping is also not to be absolutely relied on - this will be most noticeable in a fairly consistent failure when it comes to indicating what on much newer maps would be the difference between open woods (white) and slow running (light green). Control 114 in particular, on the yellow, orange, and Thomass courses, is in the middle of a patch of unmapped light green, verging on thick enough in places to rate medium green (Update: in fact, a large tree has fallen into the center of the reentrant in the few weeks since control locations were vetted. The control is now hung a little higher in the reentrant than planned/indicated on the map, immediately to the WSW of the fallen tree.). Darker shades of green, where mapped, tend to still more or less correspond to reality and should generally be avoided, as should marshes.

  • Entry FeesIndividual Entries

    Note: juniors = under 21

    Club Member, adult Club Member, junior Non-Member, adult Non-Member, junior
    Epunch Owner $5 $5 $10 $5
    Epunch Borrower $10 $5 $15 $10

    Team or Group Entries

    Participants are welcome to compete together as a single team entry. Teams containing one or more nonmembers are charged the nonmember individual rate. Teams containing one or more adults are charged the adult individual rate. For teams to receive member or junior rates, all members of the team must be members or juniors, respectively. Each extra team map beyond the first is an additional $2. Individuals or teams desiring to compete on a second course can do so for a reduced fee of $2/map.

    Important Notes
    • If you wish to become a QOC member you should join online in advance via this webpage (which also explains the member benefits). Membership is completely optional.
    • Most of our events use an 'epunch' timing chip for electronic timing. Individuals or groups without their own epunch pay a higher entry fee (see above), which includes the loan of an epunch for that event. Loaned epunches that are lost incur a $40 replacement fee. Epunches (also known as SI-cards or finger sticks) can be purchased from online vendors as described here.
    • Former QOC members who have let their membership lapse pay non-member fees.
    • Compasses are available at no charge, but if lost incur a $15 replacement fee.
    • Please provide collateral (driver's license or car keys) when borrowing a compass or epunch.
    • For additional safety, whistles are available for sale at $1/each.
    • Free beginner instruction is always available - just ask at the registration table.