Uncrossable marsh

[Duncan]

Suppose you are running at a regular orienteering event (not sprint or urban). On one of the legs the line goes straight through an uncrossable marsh (ISOM symbol 309). The marsh looks feasible and safe to cross, and that route looks faster than the alternatives of going round one side or other. May you cross it, or is it forbidden?

I believe under ISOM 2000 you may cross, as it only says "A marsh which is uncrossable or dangerous for the runner." But this is something that is changing with the revised ISOM 201x, whose draft text says "Crossing an uncrossable marsh is forbidden for safety and fairness reasons". And it is the sort of thing that has always been forbidden with ISSOM (sprint / urban maps).

Which raises an interesting question - when ISOM 201x is published, there will still be tons of maps still being used that were drawn with ISOM 2000. When you race, how will you know whether the map was drawn with ISOM 2000 or ISOM 201x, and hence whether you may cross things like this? BOF rules say you shall/should have tons of dull information on the map, and whether it is ISOM or ISSOM is a "should", but the version of ISOM is not mentioned.

[AndyC]

Final details / instructions in the start lane?

Planning at Ray Demense earlier in the year I found the crossability of the marshes varied with the time of day: in the mornings they were frozen and fairly safe/easy to cross, in the afternoons they thawed and became treacherous. Therefore a blanket "not to be crossed" makes sense as the mapper won't be able to know the exact state on the day and it may be different for an early or a late starter

[Duncan]

Let's suppose it was a real event, and there was no indication in the final details or the start lane.

[graeme]

If there's no definitive source of information about what the map means, you can cross it.

Also, events are run under national rules not ISOM specs. So I believe that in some countries its legal to cross solid blue water, in others not. I think I went round the solid blue water at the October Odyssey - but since there wasn't any water to be seen it was hard to tell.

I think you're right to anticipate a period where this will be an issue. I would recommend that during this time any organising club who doesn't want anyone crossing a marsh uses the OOB screen. It may be technically redundant, but it is unambiguous which is more important.