weRow.com - Connecting Rowers | Rudern in Europa
Tragfähigkeit
(2002-12-15 13:40:48) Nachdem in Grossbritannien bereits seit einiger Zeit eine Kampagne für erhöhte Schwimmfähigkeit von vollgeschlagenen Ruderbooten läuft muss auch hierzulande mal etwas geschehen, bevor falsche Regelungen uns den Sport verderben.

Kurz gesagt: Die derzeitige Konstruktion von Mannschaftsbooten ist unzureichend, um nach Übernahme von Wasser der Besatzung die Möglichkeit zu geben, in sicheres Gewässer zu rudern.

Das bedeutet dass die Besatzung eines vollgeschlagenes Boot unweigerlich schwimmen muss, um zu überleben. Und das bei vermutlich rauhem Wasser. Dazu kommen folgende Gefahren:
1. Das eintauchen der warmen ruderer kann einen Kälteschock verursachen.
2. Da man aus Sicherheitsgründen am Boot bleiben sollte, ist es kaum möglich, sich aus dem Gefahrenbereich zu entfernen.
Ein Trainerboot kann kaum die Besatzung eines Achter aufnehmen.

Das vollschlagen eines Mannschaftsbootes ist keine Seltenheit und geschieht recht schnell... pützen ist sinnlos:
http://www.carldouglas.co.uk/leo/downloads/shell-swamping-1.jpg
http://www.carldouglas.co.uk/leo/downloads/shell-swamping-2.jpg

In Grossbritannien hat zuletzt der Tod von Leo Blockley zu der verstärkten Nachfrage nach Designvorschriften für Hersteller geführt.
Auf http://www.ourcs.org/leo/ gibt es detaillierte Unterlagen zu dem Unfall, den Forderungen und der Ignoranz des britischen Amateurruderverbandes.

Gerade am Wochenende gab es anscheinend beim Düsseldorfer Rudermarathon einen ähnlichen Fall, glücklicherweise ohne Todesfolge:

I've just come back from the Dusseldorf Marathon and I can tell you that
they do nothing for bouyancy in Germany. The boat we rowed in (a quad) was
a simple fibre-glass hull with an open wooden lattice frame inside. No
bulkheads, no canvasses, no enclosed chambers at all. It's built wider
(c.80cm) and higher than a fine racing four (like a coastal rowing boat).
This is quite typical of the boats they row there, though some do have
bulkheads and clip-on covers for the bow and stern sections. No-one wears
any bouyancy aids either.

Conditions on Saturday were fine, and we had a good start and first 42km.
Then, in the last 500m, a large wash broke over us. It filled the stern half
of the hull so that all the saxboard behind the cox was underwater. A few
seconds later another wave hit, and the whole boat sank from under us
leaving us floating freely in the Rhine. The boat bobbed back up, but only
the oars seemed to be keeping it up and it was no help at all to us - when
you tried to lean on it to keep your head up it just sank back under. The
DLRG (the German life-saving society) were on hand and effected a fast and
efficient rescue. This was a Good Thing, since having raced for 2hr 45mins
we didn't fancy trying to swim 100+m across a busy shipping lane with a 5mph
current. The DLRG are very fine chaps, but they aren't everywhere.

I have long been convinced of the need for inherent bouyancy, and there's
plenty of space for it in a Rhine boat. I shall be pointing my German
friends in the direction of the Leo Blockley Memorial web-site. Ironically,
they lost a member of their own club in the Rhine last year.

Die Änderung, die an Rennbooten durchgeführt werden muss, um die Tragfähigkeit in jedem Fall zu gewährleisten ist denkbar einfach:
Verkleidung und Versiegelung der Bereiche unter den Rollbahnen, vergleichbar mit der Konstruktion von Einern und manchen Zweiern.

Ein Gewichts- und Kostenproblem stellt sich dabei NICHT ein.

Noch ein Artikel von Carl Douglas zu dem Thema:
Von:Carl Douglas (carl@carldouglas.co.uk)
Betrifft:Re: Buoyancy once again.
Newsgroups:rec.sport.rowing
Datum:2002-06-16 13:11:01 PST

Lizwray writes>I am only worrying about the cost to certain clubs IF underseat buoyancy still>doesn't allow the boat to be rowed in the case of a total swaping.

The cost per boat should not be more than the cost of a few beers for
each rower and a few gins for the cox ;^)

Clearly we require standards as to how deep a fully-swamped boat should
float with its designated weight of crew. That's what the ARA has to
stipulate. Since it is evidently technical impotent, it has to obtain
advice. It has had 18 months to do so, but has shirked it. Playtime
over!> For if this>turns out to be the case, why mandate that clubs in areas (eg on the Cam) ->where even if you do sink, all you have to do is stand up and walk the 4 metres>to the shore, must comply to the same standard as crews in high risk areas?

Why? There is never a safe time for a rower to find themselves in the
drink, because although a water-borne sport it takes place *on* the
water, is not a sport normally involving immersion, and its participants
(crew boats) have not the slightest expectation of an involuntary swim:
1. A member of a club I once rowed for was drowned when his 4+ rowed
over a pram, got a hole & swamped. Study the Irwell at Prestwich,
Manchester, where this happened. Even the Cam looks big & deep in
comparison. If that boat had had inbuilt buoyancy to the required
standards, it would not have sunk.
2. As I've said before in answer to you, boats do not 'belong' to any
one sheltered stretch of water but (as the trailer traffic & the odd
trailer smash show) travel all around the country & even from the
sheltered Isis to the river in Spain where Leo died. How many clubs
don't use a trailer>(i agree there may still be good reason to promote under seat buoyancy if this>is the case - but that is a different arguement)>>I am more than willing to help with sink tests because I simply do not at this>point believe there is sufficient proof that it will do what you say (note I>would love to be proved wrong).

Why? Do you think that ship designers only guess at what their vessels
will carry? Do you really think that naval architects don't know what
they are talking about when they design yachts, cruisers, battleships,
etc.? Are you really saying that, although surrounded by a myriad
technologically-based artefacts, you think that these all happened by
accident, guesswork & a bit of rubbing of the magic ju-ju stick I know of at least one (brand new) Janousek 8 that was swamped at Putney (jan>2000) in freak conditions, and sank - the crew couldn't row and had to be>rescued by launch. (I do not believe the hull was comprimised but may be wrong)

Without an authentic accident report (the ARA doesn't do such things),
we can't know to what extent this is true. Do you have more details?
Nor do we know if the crew was the correct weight for the boat, the
buoyancy compartments were properly sealed, or the hatches were fixed &
had functioning seals. How much water was later found under bow & stern
canvases & inside the under-seat compartments? Was any damage done?

Still the wealth of evidence is that Janouseks tend to allow their crews
to row home after a swamping when others do not. And the amount of
under-seat buoyancy in a Jano is a lot less than it could be.>>As you correctly summerise it's all down to archimedes... weight vs volume>displaced.>>So if you sit an open 8 next to an enclosed 8 and pour 6 buckets of water into>each - they will sit at the same level in the water - (archimedes doesn't care>if the air's at the bottom and the water at the top or vice versa) it is ONLY>once the water has reached the top of the saxboards that the compartments>limits the amount of water thatgoes in ( do you agree??)

You are correct about the simple buoyancy situation, & once full of
water the boat with greater enclosed volume will then float higher than
the boat with less. The real mechanics of swamping are better
understood by reference to the diagrams at:
http://www.carldouglas.co.uk/leo/downloads/shell-swamping-1.jpg
http://www.carldouglas.co.uk/leo/downloads/shell-swamping-2.jpg

Under-seat buoyancy creates dams which limit length-wise flow of water.
In real life the inevitable flow to one end (see diagrams) of boats
without under-seat buoyancy greatly accelerates the swamping rate. So
even if a supposedly-buoyant shell has an overweight crew it has a much
greater chance of reaching safety before dangerously swamping than one
without under-seat buoyancy.

Everything favours under-seat buoyancy and in a few years we'll wonder
why the desirability of swamped boats being able to float their seated
crews was ever in doubt.>>Problem is - the sax boards on an 8 are usually around 5 inches deep, the boat>at seat level can be over 2 foot wide and the footwells are deeper than in>smaller boats -that's still a lot of water even with enclosed compartments>under seat.
It's not the volume the boat can hold that's at issue. That can be as
large as you like. It is the volume of water the boat (enclosed
compartments, structure, fittings & all) can displace when flooded that
matters.>>If the critical point (weight of water in the boat which results in the riggers>being under water and therefore unrowable) is reached before the water inside>the boat reaches the top of the saxboards - then it's still going to be>unrowable - yes it will be sitting higher in the water but the crew will still>have to ditch.

Which is why you must enclose enough volume to ensure that the boat will
always, however 'full', remain afloat with its seated crew. Then who
would wish to ditch>Maybe it's because I'm still an engineer at heart but I want to see proof in>the form of sink tests... and the sooner the better.

By all means.>>liz

Cheers -
Carl

Carl Douglas Racing Shells -
Fine Small-Boats/AeRoWing low-drag Riggers/Advanced Accessories
Write: The Boathouse, Timsway, Chertsey Lane, Staines TW18 3JZ, UK
Email: carl@carldouglas.co.uk Tel: +44(0)1784-456344 Fax: -466550
URLs: www.carldouglas.co.uk (boats) & www.aerowing.co.uk (riggers)


Was tut der deutsche Ruderverband, um diese Gefahr einzudämmen?
Verbieten von Rudern bei schlechtem Wetter ist ein netter Ansatz, aber die Bedingungen können schneller wechseln als einem Lieb ist und das einfache Verbot von Schlechtwetterrudern ist NICHT die passende Lösung. Die Boote schwimmen einfach nicht. Nicht das Wetter war zu schlecht. Es wäre, als würde man sich darüber beklagen, dass man im Winter friert. Lösung: Nicht mehr rausgehen oder einen Mantel anziehen?

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