Uncrossable Marshes

[geomorph]

I wasn't there so this is all theoretical.

When looking at the Routegadget map for GG's run I didn't even see the black line delimiting the uncrossable - there were too many other black lines adjacent.

The route round is +130 m.

If the constraints of juxtapositioned features necessitate the removal of a part of the defining symbol is the symbol employed the right one. My preference would be for uncrossable marshes to be defined by a cross-hash blue as this stands out better in feature-rich zones, and it avoids the implied static spatial dimensions a solid line suggests - marshes are spatially dynamic as we all know.

The preceding week had been relatively dry. This may have lessened the extent of uncrossability as many of you mentioned using the tussocks.

[alcumbria]

I went straight through the uncrossable marsh followed immediately by an uncrossable gorsh bush then later on when straight through all the dark green Rhododendrons,maybe one day I will learn to go around

[King Penguin]

In the individual event, for class M50L, the purple line went close to an 'uncrossable' marsh just before control 160. I was slightly unsure of my position at that point, and attempted to relocate off the uncrossable marsh. I couldn't find it, and in retrospect I conclude that I was standing in the middle of it at the time. It was only ankle deep, and not as bad as the 'normal' marsh by the control.

I'm reassured. I too lost time there on M50L when I could not find the uncrossable marsh and started to doubt my position. The linear wet ditch alongide was far, far worse.

[King Penguin]

Is it mapped as uncrossable? Well, it should have a black line round it, but in fact it only has a black line on one side. Uncrossable in one direction maybe?

A new convention ? From all the maps I saw afterwards I believe the courses were designed such that no-one should have been anywhere near it when going from east to west on the way back. Is this why it did not need to be uncrossable east to west ?
I was alone when I hit it on leg 3. I did not register it was mapped as uncrossable, but did not like the look of where I first saw it so went north to an easier point. In retrospect I still crossed in the "uncrossable" section, but I too had far worse "crossable" marshes on Saturday.

[graeme]

I'm reassured. I too lost time there

Me too. BigJon wondered if the two sides of the track were mapped separately and didn't quite join up properly.

[openadventure]

Now you will have excuse my ignorance - but its hardly surprising that some people struggle to get to grips with orienteering when uncrossable marshes are actually crossable.

Makes it tricky to say an area is "out of bounds" or you can't cross that wall. Guess you guys understand the rules so what does it matter..

Umm strange world.

[Roger]

On my first-ever visit to the New Forest (November Classic 1984, a month after I'd started orienteering), I lost about 20 minutes by crossing an uncrossable marsh and failing to believe that I could be where I in fact was: "that marsh is uncrossable so I can't possibly have crossed it".

Which makes my excursions into two uncrossable marshes on Saturday and one on Sunday about par for the area. I hadn't realised that the Beaulieu marsh was marked as uncrossable until I read it here.

But how does such a marsh actually get mapped as uncrossable? If the surveyor lives to tell the tale then mustn't it be crossable? Or does SOC have access to some expendable creatures? Weren't there more ponies around last time I went to the New Forest?

Requiring mappers to venture at least waist-deep into the mire to test for crossability, when they may have a further five hours or more to spend in the field, is of course a quick way to deter the people on whom our sport depends. So as competitors we've surely got to take the mapped crossability of marshes as an indication only, trust our judgement when we get there on whether or not to take it on (unless it's 'may not cross' on a sprint map), and appreciate that water levels can vary quite a lot. I've got no complaints about the maps for either day.

[soc123]

As DavidJ said there were notes about the marshes in the final details.

As the mapper for that area, firstly I would like to say that it is not easy to map a completely new area for a Championship event as its first use.
Perhaps some of you would like to try?

Secondly, as regards showing the feature as uncrossable, it was borderline, sometimes when visited water was out over the path, and others it was not as waterlogged as it is at present. With a wide stream running down the east side that negated being able to show a black line surrounding the feature, advice was sought from the map advisor.
As the approach was always going to be from the west (for this event) then it was important to have a black line on the west side.
The planners could have broken the magenta line, to draw attention to the feature, as someone has mentioned that total rational thought does not necessarily exist in the mind of the competitor en route to control 1 on a relay!

[soc123]

As regards uncrossable marshes on Day I area Eddie H was unfortunate - there are hidden bomb craters in the marshes - very difficult to spot when mapping without doing what Eddie did!
The uncrossable marsh en route to control 160 did not require visiting as the attack point for the control was the north end of the fight just north of the bend in the forest road about 50m north of the marsh - the planner's idea was to get competitors to run through the very nice piece of woodland on that slope - not to go bog snorkeling in the uncrossable marsh! - the extent of which by the way I think should go further westwards towards the control site

[mappingmum]

Fact: Crossability of a marsh is a subjective assessment.
Fact: Crossability of marshes may vary over time and with weather conditions.

Similar subjective assessments are made when mapping other features eg is a boulder/cliff/tree big enough to be mapped, fences adjacent to walls, pavements next to buildings, green/light green/white depiction etc.

Even if the mapper had a crystal ball and knew what the weather pattern was going to be in the days preceeding BOC 2009, s/he would still not satisfy everyone with his or her depiction of the marsh because as has been quoted here already; some are headcases, some don't like getting wet and muddy feet/knees/thighs (personally I don't blame them) and some aren't skilled in tussock-hopping. The point being that you will never satisfy everyone.

The remit of the mapper is to depict the current ground features in 2 dimensions as best they can. Using this information as a base, orienteers are free to make their own judgements regarding route choice.

If, on multiple visits to the site, the event officials have seen a marsh in a swampy or flooded state, then I would suggest it is a very responsible and professional decision to map the marsh in it's worse case scenario as "uncrossable".

For the avoidance of doubt, I have no allegiance with the mapper!

[gg]

Until my route was mentioned - I hadn't even noticed! Had to get my map out to look. Now I think about it, I do remember getting wet to the first control...

Certainly didn't spot the 'uncrossability' at high speed, and I crossed with at least 3/4 other guys

[EddieH]

Regarding the real danger of marshes I believe the whole idea of quicksand type marshes to be fallacious. I don't believe that a marsh can "suck you down" we are less dense than the marsh and therefore reach a point of balance and can only drown through panic (although on a colder day I might have died from shock ).
This is not the first time I have been in a similar marsh, although the first time it was totally unexpected.
It is a serious effort to swim out and get the legs moreorless horizontal but it can be done.
At Littlemill in a Scottish relays I crossed about 100m of uncrossable marsh - this time it wasn't really marshy, simply chest deep water amongst the trees - I've been similarly deep in a Tasmanian marsh where the really frightening thing was dodging a snake that was swimming through it

[Gross]

I've been similarly deep in a Tasmanian marsh where the really frightening thing was dodging a snake that was swimming through it

It wasn't a snake.... it was Dr Palmer

[King Penguin]

I believe the whole idea of quicksand type marshes to be fallacious. I don't believe that a marsh can "suck you down"

In 1974, when walking the Pennine Way with a friend, we joined up with a third person for a day when all his mates had opted to go round by bus. At one point he disappeared immediately up to his waist. By the time we got his rucksack off him and started to drag him out he was up to his chest and still going down. That peat bog was most definitely a man-eater. Had he been on his own I fear he would not have been seen again until someone dug him up perfectly preserved 5,000 years later.
For anyone thinking of doing the Pennine Way - the official route as hown on maps has since been changed and now avoids that section, but beware if you are using an original Wainwright as your bible.

[EddieH]

I'm still not convinced unless of course he has very dense stuff in his pack. As you say "still going down" - who's to stay he would not have stopped with his head out.

Horses now - they definitely disappear but I guess they are much denser than us, and no doubt panic as well.