Conventional wing rigger with a stay?

[Henry Law]

(I thought we'd discussed this but I searched for threads with "stay" in
their title and couldn't find anything about "conventional" wing riggers
with stays, rather than the odd-looking "reverse" wing rigger.)

Coming back from my first 2016 outing this morning I encountered one of
our student members in the boat house, cleaning and polishing her
newly-acquired 1x. It's a Fillipi (hooray, not a Chinese import) and of
course I admired it; she was pleased to have someone happen by to admire
her pride and joy, and in any case it's plainly a nice piece of kit,
well made and well finished.

But it's got a wing-rigger, the conventional kind which mounts above
your feet, which additionally has a stay running from the end of the
wing to a point at the for'ard end of the cockpit. (Which I think is
called a "backstay" despite the fact that it runs forward; why?).

I've not taken much notice of wing riggers; I just don't like them and
can't entirely explain the reasons (it's partly because the one club 1x
with a wing that I rowed weighed a ton and I wasn't happy that I could
get my feet out from under the wing, given where the stretcher was).

I was given to wonder, though: if wing riggers are so wonderfully rigid
and light and all that stuff, why on earth did it need a stay? To my
eye it looked odd, and on top of that I could see that getting back into
it after a ditching was going to be really hard.

--

Henry Law Manchester, England

[s...@ku.edu]

Henry,

I row a 2002 Filippi with a carbon wing. When I bought the boat, backstays were not recommended. They are now, and I've been using them for 3 years. As Carl has pointed out, wings put more load on a smaller area, so, perhaps, the backstay is a way of spreading the load. As for getting back in after flipping, there is lots of open space to "mantle" onto the cockpit, much more than with a 3-stay rigger.

I prefer a wing (bow or stern) rigger, but this has nothing to do with the rigger per se. I prefer a 1x without ribs because they allow wider tracks. I set my work through and seat and shoe height in such a way that my calves hit the tracks in a 1x with ribs. (I even have this problem in my 1976 Stampfli 2x. I also have to "warn" even slender women with average hips that my 2x is "narrow" because of the ribs.) My calves go between the tracks in my Filippi. With modern tracks this is less a matter of open sores and more just comfort in fully extending my legs.

Steven M-M

[don Vickers]

Henry,

Calling that brace a backstay is consistent with the bass ackward naming of many objects in rowing. The naming of most components is from the perspective of the rower rather than the boat. Another example is that the frontstops on the slide are toward the stern.

I have sometimes wondered if we should refer to the stern as the front of the boat to be consistent with the rather inconsistent naming.

don Vickers

[Henry Law]

On 02/01/16 15:18, don Vickers wrote:
> I have sometimes wondered if we should refer to the stern as the front of the boat to be consistent with the rather inconsistent naming.

I love it! Thus bow-loaders become stern-loaders again ...

I've been thinking about that backstay (or what you very sensibly call a
"brace"). It's only going to take load if the wing flexes in a
horizontal direction, that is it gives under the strain of the rower's
drive. The thing is made of carbon fibre (known for its stiffness);
it's a box structure, which must confer some additional rigidity; and
its cross-section is at least five inches from front to back at the
point where it's bolted onto the hull. Surely it's not going to flex
under the load applied by any normal mortal?

If that wing needs stiffening in the horizontal plane then it's a weak
design; if it doesn't (which is what I suspect) then the backstay is
nothing more than a source of weight.

[Alexander Lindsay]

I am not so sure. I am no sculler, so correct me if I am talking rubbish (I often do), but it has always seemed to me that the "backstay" has a very useful safety function. In the case of a nearly head-on collision with anther boat (yes, yes, I know it should never happen, but it does, and I have done it), if I were the bow man in the other boat I would much rather have a glancing blow from a flexible back stay than have my spine snapped by the end of the rigid wing. Similarly, in the absence of back stays, I would much rather be hit by a bow mounted rigger than a stern mounted one. Better chance of survival.

But that said, I have not enjoyed rowing in an eight with wing riggers. I prefer more freeboard and uncrushed knuckles.

A happy new year to any readers. And to me, as I now rejoice in being in masters category J.

Alexander Lindsay

[carl]

Interesting discussion.

A wing rigger is a long cantilever, under complex loadings which include
bending in the vertical & horizontal planes, plus torsion.

The bending deflexion from loads of the end of any given cantilever is
proportional to the applied load & to the cube of its length. The
rigger's deflexion is substantially increased by any flexibility in its
attachment to the boat, where the boat may be less well-built than the
rigger. The mechanical advantage exerted by the load applied at the
outer end of the rigger puts the stiffness of that rather small
attachment region between rigger & boat under considerable test.

A stern-mounted wing encounters 2 forms of torsion-generating load:
1. the vertical loads tend to bend the stay in its less-stiff direction
(for a flat or oval stay section) but also apply a substantial torque
across the boat where the rigger is mounted:
https://www.facebook.com/CarlDouglasRacingShells/videos/877142705639602/?video_source=pages_finch_main_video

2. the horizontal loads on the pin tend to twist the stay while the fact
of those loads being applied above the transverse axis of the mountings
on the boat also apply a torsional input which rigger & boat must resist.

Which takes us to the use of backstays on such installations.

Near the catch, the backstay will somewhat counter the tendency of the
rigger to twist about its stay's axis & to rotate at the boat. It will
also, thanks to its rising axis, somewhat diminish the vertical movement
of the rigger end.

But forgive me if I'm somewhat under-impressed.

A bow-mounted wing has the disadvantage of a substantially longer stay -
remember that vertical & horizontal bending deflexions are proportional
to the cube of stay length, so the stay needs to be significantly more
solid to resist the main pulling load, which occurs near mid-stroke,
where the load is no longer aligned with the stay axis. And, since the
pulling load is again applied above the mounting point, & if anything is
angled slightly upwards, the stay & its mounting have to be more
substantial in order to diminish work height & pitch variation under load.

Cheers -
Carl

--
Carl Douglas Racing Shells -
Fine Small-Boats/AeRoWing Low-drag Riggers/Advanced Accessories
Write: Harris Boatyard, Laleham Reach, Chertsey KT16 8RP, UK
Find: tinyurl.com/2tqujf
Email: ca...@carldouglasrowing.com Tel: +44(0)1932-570946 Fax: -563682
URLs: carldouglasrowing.com & now on Facebook @ CarlDouglasRacingShells

[Henry Law]

On 02/01/16 17:28, Alexander Lindsay wrote:
> I am no sculler, so correct me if I am talking rubbish (I often do),
> but it has always seemed to me that the "backstay" has a very useful
> safety function. In the case of a nearly head-on collision with anther
> boat (yes, yes, I know it should never happen, but it does, and I
> have done it)

Well, that's a different matter. If what I'm looking at is a "safety
deflector" then let's call it that.

But being hit by the rigger is only part of the story. I happened
across this today ...

http://www.row2k.com/blogs/post/7/400/Top-Images-of-2015---12-26--Prepare-to-be-Boarded/#.VogVzV5TtZ5

... it's terrifying.

[Jim Dwyer]

So Carl:

Can you imply that a stern wing rigger is better than a bow wing rigger?

Jim

"carl" wrote in message news:n692fp$j6u$1...@dont-email.me...

[Kit Davies]

I agree with Alexander that the safety function of backstays is worth
the extra weight.

One other point though: I assume these backstays were attached to the
tops of the pins? If so, maybe she prefers pins supported top and bottom.

Kit

[carl]

On 02/01/2016 18:26, Henry Law wrote:

A very neat bit of steering but, in view of the small speed difference
the 2 boats, perhaps less dangerous than most other modes of collision

Mind you, a Filippi quad just like that in the picture collided a
head-on a week ago with one of our clients in a beautiful CD Special
single. The quad now needs new bows while I'm hear that our client's
boat has only slight damage.

In the summer the same winning combination had a warm-up collision with
Filippi 2- in Copenhagen, resulting again in only slight damage to his
single (& without leaving the water he went on to win his event) but
disabling damage to the pair.

A poke in the eye for those who like to think that carbon must be
tougher than our wood-composite laminates - The Empire Strikes Back!

[s...@ku.edu]

Carl, 2 questions:

1) What I see in your video of the vertical rocking of the bow wing Empacher is the rigger and boat all moving together. I'm assuming that a similar video of one of your shells would show the same overall connection or stiffness. The take-away point for me is that these vertical forces on the bow wing are "translated" onto the shell over a relatively shorter area than would be the case with a triangular 2-stay rigger (stern or bow). Am I interpreting this correctly?
2) I'm not sure I follow your argument re "pulling load." Throughout the drive aren't you pushing against the stern face of the pin?

Steven M-M

[James]

On Friday, January 1, 2016 at 12:36:42 PM UTC-5, Henry Law wrote:

Here's one that was discussed a few weeks back... A bow-mounted Fluid wing with a fore-stay?!

http://www.row2k.com/hocr/photo.cfm?action=pf&dir=2015Fall/HOCR/1017R07SenMast1x&start=7&label=Event%2012%20and%2013%20-%20Senior%20Master%20Singles&hi=yes#.VohGRRFlxjl

I think the consensus was that the set-up was for "optics" i.e. getting used to all the room of a bow rigger.

I just upgraded my Italian 3-stay with a set of Carl's Aeros and I have to admit that it took some time for my eyes to get used to the lack of a back stay...

[gsl...@gmail.com]

>.... It's only going to take load if the wing flexes in a

> horizontal direction, that is it gives under the strain of the rower's

> drive. ....
> --

Not exactly. The force applied by the oar is is above the plane of the wing so it will apply some torsion resulting in a change of pitch. That (and an insignificant amount of pin flex) is what the back stay will resist. I would hope that the torsion is negligible for any reasonably designed rigger but I haven't done the measurement.

[carl]

> Carl, 2 questions:
>
> 1) What I see in your video of the vertical rocking of the bow wing Empacher is the rigger and boat all moving together. I'm assuming that a similar video of one of your shells would show the same overall connection or stiffness. The take-away point for me is that these vertical forces on the bow wing are "translated" onto the shell over a relatively shorter area than would be the case with a triangular 2-stay rigger (stern or bow). Am I interpreting this correctly?
> 2) I'm not sure I follow your argument re "pulling load." Throughout the drive aren't you pushing against the stern face of the pin?
>
> Steven M-M
>

Hi Steven -

1. We show that video because it demonstrates the significant
flexibility of both boat & rigger mounting. Someone is very gently
moving the end of the rigger both up & down, applying insufficient force
to do more than marginally displace the ~14kg boat from its position on
the rack despite the ~100cm lateral distance (leverage between the far
saxboard & the rigger end.

Taking boat width at the racking point as 40cm:
the maximum up-force on the rigger is 14x20/100 = 2.8kg
& the maximum down-force can't exceed 14x20/60 = 4.7kg

It is precisely because those forces are so low that this demonstrated
amount of torsional flexibility between a fixed point & the line from
pin to pin - a mere ~65cm distance, merits comment.

I think, too, that the angle of rotation of the rigger end about the
boat's axis is greater than that of the boat it the rigger's mounting.

2. The difference between pull & push is one of viewpoint only. If I
pull on the handle & the oar pivots somewhere near the blade, then I see
the oar pulling against the oarlock & pin while you see it pushing - a
matter of words, not meanings. The net effect is a force applied at a
point some distance up the pin which, being applied in a roughly
horizontal plane & some distance above the rigger's mounting point,
generates a rotational couple about a horizontal axis perpendicular to
the line of the boat at the rigger's attachment to the boat.

[s...@ku.edu]

On Sunday, January 3, 2016 at 9:35:53 AM UTC-6, carl wrote:

Thanks, Carl. Got it on push/pull. On a similar vid with a 2-stay or 3-stay rigged shell, what difference would we see? Steven M-M