Bow/Prow Design
richard pratt
Filippi bow (or is that prow) design that resembles what I can only
describe as an inverted chisel rather than the gentle upward curve we
are used to seeing. It is especially noticeable on the 8 but also
seems to appear on their new smaller boats. I also thought I saw
something not too different on a couple of Empachers as well, but it
could have been the Pimms.
As the very front part of the boat seems to make very little contact,
if any, with the water can anyone (Carl?) enlighten me as to the
thinking behind this design? I am certain of one thing: aesthetics
were not in the equation.
Richard
Tinus
For what it's worth:
An image of the particular bow design: http://www.nlroei.nl/Fotoboek-display-86489.html
A similar design (and explanation) for yachts:
http://www.marin.nl/web/News/News-items/MY-Predator-cuttingedge-yacht-design.htm
Carl Douglas
The wave-piercing bow on the predator, & on a number of other yachts &
powered vessels (including the Ady Gil, deliberately mown down by
Japanese whalers), is a design which allows & encourages submarining as
a way of handling waves higher than the normal freeboard with reduced
pitching. This is not the situation in a typical flat-water rowing
event, since rowing would itself be impossible in such conditions.
The bows shown on the nlroei photo are not reversed or wave-piercing
designs of that kind but result from a manufacturer's decision to have
vertical hull sides right down from the deck to the waterline. It is
important to know that you do not get a bow profile independent of a
hull form, & a vertical bow cannot come without a vertical sheer.
A reason for not having a vertical sheer is that, where a boat needs to
ride comfortably over smaller waves, the effect of flare is to gently &
smoothly lift the bow without immersing the deck, & the veed shape that
goes with this bow flare both prevents slamming on waves & improves
directional stability.
Sailboats often have vertical bows so they fit within a class overall
length rule while maximising their waterline length. This is not
relevant in rowing.
The other reason why sailboats have upright stems is that is makes sense
for a hull which will normally sail heeled over to have a distinct chine
on each side, close to the waterline. This gives a more effective hull
shape when the boat is heeled, & has the coincidental effect of
generating a steep stem. Since rowing shells do not travel heeled at 30
degrees, there is no obvious reason to design them as if they did.
HTH
Carl
--
Carl Douglas Racing Shells -
Fine Small-Boats/AeRoWing Low-drag Riggers/Advanced Accessories
Write: Harris Boatyard, Laleham Reach, Chertsey KT16 8RP, UK
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Stamps
Those bowballs look like they would adequately protect you if you were
hit by them, don't they?
The manufacturers should be ashamed, what are they thinking???
Carl Douglas
The ball on #4 is probably the most dangerous. That boat has a pointed
bow, with the ball entirely above the deck. That bow will fracture
upwards on impact, into long, piercing carbon shards, leaving the rest
of the bow to drive forward unprotected & the target with a wound full
of carbon fibres hard to detect by X-ray, the devil to extract & readily
fracturing into ever smaller pieces as the surgeon tries to get them out.
How do I know all this? Because I've had to inspect the results of a
human injury collision involving just such a bow. And I work with
carbon, as well as a range of other fibres
In that photo we see how the vital human protection function of the
bowball has been made subordinate to the FISA photo-finish imperative.
Not one of those balls give significant protection against bow
penetration of a target rower. As long as you have a visible 4cm ball,
anything goes. Can you imagine such madness being accepted in today's F1?
However, if I was to be hit by any of those bows I'd prefer it to be one
of the upright ones. In structural terms these have less chance of a
piece of boat being snapped off & driven into the body, & it would
always be better to come up against a slightly radiused vertical edge
that's ~10cm tall than a spike. It's the choice between the end of
plank & a javelin - give me the plank.
That said, I'd still prefer intelligently designed bow protection - e.g.
provide a larger radius & bring that back over the deck.
Cheers -
Richard du P
>
> Those bowballs look like they would adequately protect you if you were
> hit by them, don't they?
> The manufacturers should be ashamed, what are they thinking???
The point has been made [not by me] in another exchange, that this
chisel-type edge won't concentrate the impact as acutely as would an
old-fashioned spike bow.
That said, I think I'd like to see more protection before three
quarters of a ton of fully manned VIII rides up and hits some young
person's abdomen at race pace
..... and the sight of that little orthodox bowball, perched at a
jaunty angle, does it give anyone but me, a slight impression of
pithtaking?
If this sort of bow is anything more than a fashion statement, maybe
its maker could develop an appropriate quasi-ball.
For "British" [ie English and Welsh] readers, did I hear many months
ago that this question is under review, in the corridors of power?
Anyone know what the answer is?
Richard du P
Paul
design? The boats we row in today are basically the same that we were
rowing in 40 years ago. Yes the material has changed but the shape has
not. 2KV tried something different, but foundered almost before they
got going due to poor build quality? Is it conservative boat builders,
conservative boat buyers or are the hull shapes we row in really the
very best possible?
Paul
Kit
There are certainly better qualified people on this board than me, but
I suspect it is down to diminishing returns. The small amount of money
in rowing and current the level of satisfaction people have with their
hulls does not warrant spending vast sums on small improvements. If WC/
Oly winners received 100k prizes, you can bet your bottom dollar there
would be CFD servers being thrown at the problem by the dozen.
Andy McKenzie
I found a site, http://www.epickayaks.com/news/news/epic-kayaks--why-a-plumb-bow
, that has a little more information on why a designer might choose a
plumb bow, citing some arguments in terms of lowered resistance in
waves, and better handling in some waves. Although there is no class
limit on the length of an 8 I guess there are practical considerations
in terms of transport and storage why a designer who wants to increase
length in the water might not want to increase the overall length of
the boat - or we would end up with boats poking out of boat houses
like planes sometimes do out of hangars (http://www.life.com/image/
50400177).
Andy
Sarah A Harbour
They're the same shape that Resolute have been making for a while.
You're right about aesthetics though, they look pretty ugly to me -
but maybe I'm biased because Oxford were racing us in a Resolute with
a squashed nose... ;-)
Sarah
Henry Law
> Since rowing shells do not travel heeled at 30
> degrees,
And the last time you saw novices was when, exactly?
--
Henry Law Manchester, England
Jonny
> On 12/07/10 19:24, Carl Douglas wrote:
>
> > Since rowing shells do not travel heeled at 30
> > degrees,
>
> And the last time you saw novices was when, exactly?
>
> --
ah, but Henry, they are only at that angle for a short time while the
continue on their merry way towards a watery end to the training
session.
Andrew Hunt
Weitnauer (WM) singles, which I think has been in the club since at
least 2006 when I started rowing. It's only the heavyweight one that
I've seen the vertical bow on, a new lightweight one that recently
arrived has a "normal" bow as do all our other (lightweight) Weitnauer
singles and doubles, so I'm not sure if it's an option, or if only
some shell sizes that have it. (I've also noticed a few other
Weitnauers around Switzerland with the vertical bow, only in use by
heavyweight rowers.)