Rocksolid Light

Welcome to novaBBS (click a section below)

mail  files  register  newsreader  groups  login

Message-ID:  

When in doubt, lead trump.


sport / rec.sport.rowing / Re: Boat speed improvements

SubjectAuthor
* Re: Boat speed improvementsIan Randall
`* Re: Boat speed improvementsJake Frith
 `* Re: Boat speed improvementsJohn E
  +- Re: Boat speed improvementsPeter
  `* Re: Boat speed improvementsJake Frith
   +- Re: Boat speed improvementsAndy McKenzie
   +- Re: Boat speed improvementsJake Frith
   `- Re: Boat speed improvementsAndy McKenzie

1
Re: Boat speed improvements

<99643aa5-ce96-4ed7-92bf-7e4ce60e60a4n@googlegroups.com>

 copy mid

https://www.novabbs.com/sport/article-flat.php?id=98&group=rec.sport.rowing#98

 copy link   Newsgroups: rec.sport.rowing
X-Received: by 2002:ac8:5142:: with SMTP id h2mr24889742qtn.266.1617084232565;
Mon, 29 Mar 2021 23:03:52 -0700 (PDT)
X-Received: by 2002:a25:cb03:: with SMTP id b3mr32978487ybg.321.1617084232341;
Mon, 29 Mar 2021 23:03:52 -0700 (PDT)
Path: i2pn2.org!i2pn.org!weretis.net!feeder8.news.weretis.net!proxad.net!feeder1-2.proxad.net!209.85.160.216.MISMATCH!news-out.google.com!nntp.google.com!postnews.google.com!google-groups.googlegroups.com!not-for-mail
Newsgroups: rec.sport.rowing
Date: Mon, 29 Mar 2021 23:03:52 -0700 (PDT)
In-Reply-To: <1c92ea4e-c74c-4c05-ad85-b0769dd6968en@googlegroups.com>
Injection-Info: google-groups.googlegroups.com; posting-host=1.129.104.170; posting-account=1JL7QgkAAADDCJCh5UHEAAXg696iwTJS
NNTP-Posting-Host: 1.129.104.170
References: <0b2ce247-5fe9-4451-81cb-13fd618c56cbn@googlegroups.com>
<rkil91$18a$1@dont-email.me> <rkkkr2$mfj$1@dont-email.me> <rkkq8m$s96$1@dont-email.me>
<4d5283ce-b986-4a06-9a3b-3b88ea12f06an@googlegroups.com> <rkq81b$fng$1@dont-email.me>
<9a1f3ad5-1ed0-444a-a571-7f27a110ded6n@googlegroups.com> <rtidqm$um3$1@dont-email.me>
<666cdb86-7edd-4eeb-acb8-490d4d7231e2n@googlegroups.com> <7f1b4d72-5d2e-4953-89f8-e47ecea75d9bn@googlegroups.com>
<7a3932dc-37d2-40d3-9585-cd1cb02ff501n@googlegroups.com> <1f0d3a75-4f87-44f6-8efe-ae4a59bed035n@googlegroups.com>
<4ff947dd-9fd9-466a-8f01-1866f770af08n@googlegroups.com> <0300c131-b77e-438b-bdf1-3c628fe201c0n@googlegroups.com>
<7945355b-3a88-4375-af4c-554ce75cc94cn@googlegroups.com> <1c92ea4e-c74c-4c05-ad85-b0769dd6968en@googlegroups.com>
User-Agent: G2/1.0
MIME-Version: 1.0
Message-ID: <99643aa5-ce96-4ed7-92bf-7e4ce60e60a4n@googlegroups.com>
Subject: Re: Boat speed improvements
From: lladnar...@gmail.com (Ian Randall)
Injection-Date: Tue, 30 Mar 2021 06:03:52 +0000
Content-Type: text/plain; charset="UTF-8"
 by: Ian Randall - Tue, 30 Mar 2021 06:03 UTC

Current FISA rules will not allow any moving parts on a rowing oar, thus an aerodynamic shroud as described above would be permitted on the shaft of an oar.

However, this design concept has been solved ... see images and plans here.... https://drive.google.com/drive/folders/1WIoVQkN4-5BA_QeSCtU1P7jL7yn1NDyN?usp=sharing

Test it yourself ... it noticeably reduces the wind resistance on an existing oar. Free speed.

The problem is not the effectiveness or legality of this design or a host of other speed advancements in our sport but the very nature of innovation and adoption of novel designs.

I made this presentation at an Australian STEM conference earlier in the year on the development of the RANDALLfoil ... you may find it interesting.

https://drive.google.com/file/d/1zmtLH02oDHZjOTd3vquX6AeknL1PiktV/view?usp=sharing

Re: Boat speed improvements

<281db009-b294-451e-9bff-5906b9fd9403n@googlegroups.com>

 copy mid

https://www.novabbs.com/sport/article-flat.php?id=100&group=rec.sport.rowing#100

 copy link   Newsgroups: rec.sport.rowing
X-Received: by 2002:ac8:5c8d:: with SMTP id r13mr4459813qta.366.1617229122800;
Wed, 31 Mar 2021 15:18:42 -0700 (PDT)
X-Received: by 2002:a25:9b07:: with SMTP id y7mr7448786ybn.505.1617229122502;
Wed, 31 Mar 2021 15:18:42 -0700 (PDT)
Path: i2pn2.org!i2pn.org!weretis.net!feeder8.news.weretis.net!proxad.net!feeder1-2.proxad.net!209.85.160.216.MISMATCH!news-out.google.com!nntp.google.com!postnews.google.com!google-groups.googlegroups.com!not-for-mail
Newsgroups: rec.sport.rowing
Date: Wed, 31 Mar 2021 15:18:42 -0700 (PDT)
In-Reply-To: <99643aa5-ce96-4ed7-92bf-7e4ce60e60a4n@googlegroups.com>
Injection-Info: google-groups.googlegroups.com; posting-host=92.25.23.104; posting-account=3fTEewoAAABdw9qx8uDw9Cp3JZoUXJDV
NNTP-Posting-Host: 92.25.23.104
References: <0b2ce247-5fe9-4451-81cb-13fd618c56cbn@googlegroups.com>
<rkil91$18a$1@dont-email.me> <rkkkr2$mfj$1@dont-email.me> <rkkq8m$s96$1@dont-email.me>
<4d5283ce-b986-4a06-9a3b-3b88ea12f06an@googlegroups.com> <rkq81b$fng$1@dont-email.me>
<9a1f3ad5-1ed0-444a-a571-7f27a110ded6n@googlegroups.com> <rtidqm$um3$1@dont-email.me>
<666cdb86-7edd-4eeb-acb8-490d4d7231e2n@googlegroups.com> <7f1b4d72-5d2e-4953-89f8-e47ecea75d9bn@googlegroups.com>
<7a3932dc-37d2-40d3-9585-cd1cb02ff501n@googlegroups.com> <1f0d3a75-4f87-44f6-8efe-ae4a59bed035n@googlegroups.com>
<4ff947dd-9fd9-466a-8f01-1866f770af08n@googlegroups.com> <0300c131-b77e-438b-bdf1-3c628fe201c0n@googlegroups.com>
<7945355b-3a88-4375-af4c-554ce75cc94cn@googlegroups.com> <1c92ea4e-c74c-4c05-ad85-b0769dd6968en@googlegroups.com>
<99643aa5-ce96-4ed7-92bf-7e4ce60e60a4n@googlegroups.com>
User-Agent: G2/1.0
MIME-Version: 1.0
Message-ID: <281db009-b294-451e-9bff-5906b9fd9403n@googlegroups.com>
Subject: Re: Boat speed improvements
From: frithj...@googlemail.com (Jake Frith)
Injection-Date: Wed, 31 Mar 2021 22:18:42 +0000
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
 by: Jake Frith - Wed, 31 Mar 2021 22:18 UTC

On Tuesday, March 30, 2021 at 7:03:53 AM UTC+1, lladn...@gmail.com wrote:
> Current FISA rules will not allow any moving parts on a rowing oar, thus an aerodynamic shroud as described above would be permitted on the shaft of an oar.
>
> However, this design concept has been solved ... see images and plans here.... https://drive.google.com/drive/folders/1WIoVQkN4-5BA_QeSCtU1P7jL7yn1NDyN?usp=sharing
>
> Test it yourself ... it noticeably reduces the wind resistance on an existing oar. Free speed.
>
> The problem is not the effectiveness or legality of this design or a host of other speed advancements in our sport but the very nature of innovation and adoption of novel designs.
>
> I made this presentation at an Australian STEM conference earlier in the year on the development of the RANDALLfoil ... you may find it interesting.
>
> https://drive.google.com/file/d/1zmtLH02oDHZjOTd3vquX6AeknL1PiktV/view?usp=sharing

If FISA doesnt allow any moving parts on a rowing oar, that's that, and does rather limit options aerodynamically. But the fixed shrouds linked above should see benefits that are worth crews looking at. If I was a serious rowing crew, I'd at least have a second set of oars fitted with shrouds like this that I'd pull out of the bag if there was a headwind.

Thanks for the Randall foil presentation. I found it quite interesting and inspiring especially the stuff about innovators having almost a duty to progress thier ideas. I've been sitting on and (far too) slowly developing a few novel, patentable ideas (outside of rowing) and feel the same sort of responsibility/ guilt. Indeed to the point that the frustration of not having developed any of them has made me sometimes regret conceiving them in the first place, especially every time inferior products enter the market.

My thoughts about the Randall Foil itself (which I accept nobody has asked for) are:
Has diving of oars been proven to be a problem? I can see how a novice rower diving a blade 18 inches underwater is clearly an issue (alters the gearing, oar has to be dragged back out again at the end of the stroke, upper part of the loom is a brake against the oncoming flow). But the difference at elite level between an athlete burying an oar 3 inches under versus another burying 1 inch under. Is that even measureable? The oar and that first foot of loom isn't moving very far through the water, and it's mainly twisting in its own stationary puddle isn't it?

Also the leading edge of the oar (if we are considering it a foil) at the catch, which from experience is where the diving tends to be an issue, is its far end, surely. Does this mean that the behavior of a Randall foil is very dependent on the angle of the top edge of the blade onto which it is fixed? If diving one's oars or sculls is as costly as your presentation suggests, wouldn't an alternative design be a shorter wing shaped surface riding foil fitted at an upward angle to the outboard quarter or third of the blade face, so that the rower could only bury the blade at the catch by massively forcing the hands upwards? Not sure whether a penalty would be paid at blade extraction though... While the surface riding foils would stay at the surface at the catch, when the flow over them reversed later in the stroke, would they get forced back under again and then be a pain to extract, or would the much more turbulent water the blades are working in later in the stroke mean that it's not an issue? Maybe you'd need to have a larger upward kick at the end of the blade top to accomodate it although that's likely a whole blade design rather than an additive component. So maybe something like your shelf type design but fitted to a blade top the shape of a shallow smile, that way the leading edge has rocker keeping it above the water like the front of a surfboard at the catch, and then again from the other end when the flow reverses later in the stroke.

I thought about this stuff quite a bit a few years ago when I was doing a lot of sculling- at one point I double sided taped pieces of 2 inch deep by 3/4 inch thick closed cell foam strip to the top of my blade faces- my thought being that even a small amount of buoyancy so far away from the boat would help with diving at the catch and also help with balance in rough water (coastal sculler). In some ways similar in sentiment to the Randall Foil. It was not really noticeable in either aspect whether they were on or off the blades and I took them off when something started eating the foam (rats perhaps? - I used to store my blades in the garden). I went for buoyancy rather than a 'foil' type device as it was my belief that for much ot the stroke the blades shunt back and forth a bit and twist in a stationary puddle, but I finally concluded that the volume of buoyancy you'd need to actually make a difference to the diving would be unmanageable out on the blades. I managed to cure my diving with the tried and tested tricks of technique changes and stern pitch.

I liked the benefits that the Italian sculler found and appreciated that the commentary picked up on the device. Looking at his strokes on the video though he didn't seem to be rowing in a particulary shallow fashion. The foils didn't appear to be sitting at the water surface (if that is their intention?), but hard to tell for sure unless you had a following camera.

Re: Boat speed improvements

<876a87c0-d600-43b4-af3a-957c48a7c135n@googlegroups.com>

 copy mid

https://www.novabbs.com/sport/article-flat.php?id=110&group=rec.sport.rowing#110

 copy link   Newsgroups: rec.sport.rowing
X-Received: by 2002:a37:8c1:: with SMTP id 184mr2208756qki.472.1617786028658;
Wed, 07 Apr 2021 02:00:28 -0700 (PDT)
X-Received: by 2002:a25:4646:: with SMTP id t67mr3004668yba.495.1617786028454;
Wed, 07 Apr 2021 02:00:28 -0700 (PDT)
Path: i2pn2.org!i2pn.org!weretis.net!feeder8.news.weretis.net!proxad.net!feeder1-2.proxad.net!209.85.160.216.MISMATCH!news-out.google.com!nntp.google.com!postnews.google.com!google-groups.googlegroups.com!not-for-mail
Newsgroups: rec.sport.rowing
Date: Wed, 7 Apr 2021 02:00:28 -0700 (PDT)
In-Reply-To: <281db009-b294-451e-9bff-5906b9fd9403n@googlegroups.com>
Injection-Info: google-groups.googlegroups.com; posting-host=188.122.50.23; posting-account=9vH-jAkAAACmOEThO4LaQm5wt_tnLbun
NNTP-Posting-Host: 188.122.50.23
References: <0b2ce247-5fe9-4451-81cb-13fd618c56cbn@googlegroups.com>
<rkil91$18a$1@dont-email.me> <rkkkr2$mfj$1@dont-email.me> <rkkq8m$s96$1@dont-email.me>
<4d5283ce-b986-4a06-9a3b-3b88ea12f06an@googlegroups.com> <rkq81b$fng$1@dont-email.me>
<9a1f3ad5-1ed0-444a-a571-7f27a110ded6n@googlegroups.com> <rtidqm$um3$1@dont-email.me>
<666cdb86-7edd-4eeb-acb8-490d4d7231e2n@googlegroups.com> <7f1b4d72-5d2e-4953-89f8-e47ecea75d9bn@googlegroups.com>
<7a3932dc-37d2-40d3-9585-cd1cb02ff501n@googlegroups.com> <1f0d3a75-4f87-44f6-8efe-ae4a59bed035n@googlegroups.com>
<4ff947dd-9fd9-466a-8f01-1866f770af08n@googlegroups.com> <0300c131-b77e-438b-bdf1-3c628fe201c0n@googlegroups.com>
<7945355b-3a88-4375-af4c-554ce75cc94cn@googlegroups.com> <1c92ea4e-c74c-4c05-ad85-b0769dd6968en@googlegroups.com>
<99643aa5-ce96-4ed7-92bf-7e4ce60e60a4n@googlegroups.com> <281db009-b294-451e-9bff-5906b9fd9403n@googlegroups.com>
User-Agent: G2/1.0
MIME-Version: 1.0
Message-ID: <876a87c0-d600-43b4-af3a-957c48a7c135n@googlegroups.com>
Subject: Re: Boat speed improvements
From: joh...@john-ewans-design.co.uk (John E)
Injection-Date: Wed, 07 Apr 2021 09:00:28 +0000
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
 by: John E - Wed, 7 Apr 2021 09:00 UTC

I've just seen this discussion and found it interesting as we have kept ourselves motivated during lockdown by developing a few products to add to our (Active Tools) product range, one of which gives an aerodynamic drag reduction. We started looking at Height Spacers to try and solve the issue of swapping them one handed when out on the water and the answer to that seemed to be a ‘pull tab’ and as that inevitably elongates the design we then wondered whether making the nose of that tab ‘aero’ (as the cycling fraternity say) and adding a Kamm tail (again, very common on bike frames https://www.trekbikes.com/gb/en_GB/inside_trek/kammtail_virtual_foil/) might give a small drag reduction.

What we found, using CFD analysis, was that a short stack of these had a drag of only 19% of that of randomly orientated conventional spacers and that that would give a top flight Eight a 0.4 metre advantage over a 2K race... The caveats on this are that we did not look at cross wind performance, although the is no reason to believe that will be poor, and forward mounted riggers, or riggers with C cups that shield the Oarlock/Swivel, would not benefit from using these.

This is what the device looks like and we have initial samples from the tool on the way to us now https://drive.google.com/file/d/1GkUtmQcqGHZydN4QO5n1TIOqhh8bSrU_/view?usp=sharing

The 0.4 metre figure makes one wonder what gains you would get by extruding aerodynamically profiled backstays, or adding thin Carbon Fibre covers to standard ones, and also whether a profile with a Kamm tail might work well for oar shafts?

On another point, in response to a comment in the thread, I believe that all the major manufacturers make their oar shafts from Pre-preg material? The spiral lines you see are the witness lines left after the Nylon tape they wrap them with before curing is removed.

Re: Boat speed improvements

<ca76a78c-4c71-4fcd-b308-8e97f8c957f3n@googlegroups.com>

 copy mid

https://www.novabbs.com/sport/article-flat.php?id=112&group=rec.sport.rowing#112

 copy link   Newsgroups: rec.sport.rowing
X-Received: by 2002:a05:620a:12f6:: with SMTP id f22mr2244539qkl.3.1617788241468;
Wed, 07 Apr 2021 02:37:21 -0700 (PDT)
X-Received: by 2002:a25:1f82:: with SMTP id f124mr3210313ybf.198.1617788241163;
Wed, 07 Apr 2021 02:37:21 -0700 (PDT)
Path: i2pn2.org!i2pn.org!weretis.net!feeder8.news.weretis.net!proxad.net!feeder1-2.proxad.net!209.85.160.216.MISMATCH!news-out.google.com!nntp.google.com!postnews.google.com!google-groups.googlegroups.com!not-for-mail
Newsgroups: rec.sport.rowing
Date: Wed, 7 Apr 2021 02:37:20 -0700 (PDT)
In-Reply-To: <876a87c0-d600-43b4-af3a-957c48a7c135n@googlegroups.com>
Injection-Info: google-groups.googlegroups.com; posting-host=82.69.62.89; posting-account=BeP6PgkAAAAEmJv0M-ZLMbe9k9wk6CvJ
NNTP-Posting-Host: 82.69.62.89
References: <0b2ce247-5fe9-4451-81cb-13fd618c56cbn@googlegroups.com>
<rkil91$18a$1@dont-email.me> <rkkkr2$mfj$1@dont-email.me> <rkkq8m$s96$1@dont-email.me>
<4d5283ce-b986-4a06-9a3b-3b88ea12f06an@googlegroups.com> <rkq81b$fng$1@dont-email.me>
<9a1f3ad5-1ed0-444a-a571-7f27a110ded6n@googlegroups.com> <rtidqm$um3$1@dont-email.me>
<666cdb86-7edd-4eeb-acb8-490d4d7231e2n@googlegroups.com> <7f1b4d72-5d2e-4953-89f8-e47ecea75d9bn@googlegroups.com>
<7a3932dc-37d2-40d3-9585-cd1cb02ff501n@googlegroups.com> <1f0d3a75-4f87-44f6-8efe-ae4a59bed035n@googlegroups.com>
<4ff947dd-9fd9-466a-8f01-1866f770af08n@googlegroups.com> <0300c131-b77e-438b-bdf1-3c628fe201c0n@googlegroups.com>
<7945355b-3a88-4375-af4c-554ce75cc94cn@googlegroups.com> <1c92ea4e-c74c-4c05-ad85-b0769dd6968en@googlegroups.com>
<99643aa5-ce96-4ed7-92bf-7e4ce60e60a4n@googlegroups.com> <281db009-b294-451e-9bff-5906b9fd9403n@googlegroups.com>
<876a87c0-d600-43b4-af3a-957c48a7c135n@googlegroups.com>
User-Agent: G2/1.0
MIME-Version: 1.0
Message-ID: <ca76a78c-4c71-4fcd-b308-8e97f8c957f3n@googlegroups.com>
Subject: Re: Boat speed improvements
From: pgke...@yahoo.com (Peter)
Injection-Date: Wed, 07 Apr 2021 09:37:21 +0000
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
 by: Peter - Wed, 7 Apr 2021 09:37 UTC

On Wednesday, 7 April 2021 at 10:00:29 UTC+1, John E wrote:
> I've just seen this discussion and found it interesting as we have kept ourselves motivated during lockdown by developing a few products to add to our (Active Tools) product range, one of which gives an aerodynamic drag reduction. We started looking at Height Spacers to try and solve the issue of swapping them one handed when out on the water and the answer to that seemed to be a ‘pull tab’ and as that inevitably elongates the design we then wondered whether making the nose of that tab ‘aero’ (as the cycling fraternity say) and adding a Kamm tail (again, very common on bike frames https://www.trekbikes.com/gb/en_GB/inside_trek/kammtail_virtual_foil/) might give a small drag reduction.
>
> What we found, using CFD analysis, was that a short stack of these had a drag of only 19% of that of randomly orientated conventional spacers and that that would give a top flight Eight a 0.4 metre advantage over a 2K race.... The caveats on this are that we did not look at cross wind performance, although the is no reason to believe that will be poor, and forward mounted riggers, or riggers with C cups that shield the Oarlock/Swivel, would not benefit from using these.
>
> This is what the device looks like and we have initial samples from the tool on the way to us now https://drive.google.com/file/d/1GkUtmQcqGHZydN4QO5n1TIOqhh8bSrU_/view?usp=sharing
>
> The 0.4 metre figure makes one wonder what gains you would get by extruding aerodynamically profiled backstays, or adding thin Carbon Fibre covers to standard ones, and also whether a profile with a Kamm tail might work well for oar shafts?
>
> On another point, in response to a comment in the thread, I believe that all the major manufacturers make their oar shafts from Pre-preg material? The spiral lines you see are the witness lines left after the Nylon tape they wrap them with before curing is removed.

I assume someone has looked at the drag factors of the crew themselves? - Hair, clothing, sunglasses and hats and cox positions - particulary in cross-winds...
pgk

Re: Boat speed improvements

<de002874-0343-4b51-a71b-99ba181acdffn@googlegroups.com>

 copy mid

https://www.novabbs.com/sport/article-flat.php?id=114&group=rec.sport.rowing#114

 copy link   Newsgroups: rec.sport.rowing
X-Received: by 2002:ad4:4a6f:: with SMTP id cn15mr3685672qvb.56.1617806797983;
Wed, 07 Apr 2021 07:46:37 -0700 (PDT)
X-Received: by 2002:a25:d942:: with SMTP id q63mr4987518ybg.261.1617806797620;
Wed, 07 Apr 2021 07:46:37 -0700 (PDT)
Path: i2pn2.org!i2pn.org!weretis.net!feeder8.news.weretis.net!proxad.net!feeder1-2.proxad.net!209.85.160.216.MISMATCH!news-out.google.com!nntp.google.com!postnews.google.com!google-groups.googlegroups.com!not-for-mail
Newsgroups: rec.sport.rowing
Date: Wed, 7 Apr 2021 07:46:37 -0700 (PDT)
In-Reply-To: <876a87c0-d600-43b4-af3a-957c48a7c135n@googlegroups.com>
Injection-Info: google-groups.googlegroups.com; posting-host=92.25.23.104; posting-account=3fTEewoAAABdw9qx8uDw9Cp3JZoUXJDV
NNTP-Posting-Host: 92.25.23.104
References: <0b2ce247-5fe9-4451-81cb-13fd618c56cbn@googlegroups.com>
<rkil91$18a$1@dont-email.me> <rkkkr2$mfj$1@dont-email.me> <rkkq8m$s96$1@dont-email.me>
<4d5283ce-b986-4a06-9a3b-3b88ea12f06an@googlegroups.com> <rkq81b$fng$1@dont-email.me>
<9a1f3ad5-1ed0-444a-a571-7f27a110ded6n@googlegroups.com> <rtidqm$um3$1@dont-email.me>
<666cdb86-7edd-4eeb-acb8-490d4d7231e2n@googlegroups.com> <7f1b4d72-5d2e-4953-89f8-e47ecea75d9bn@googlegroups.com>
<7a3932dc-37d2-40d3-9585-cd1cb02ff501n@googlegroups.com> <1f0d3a75-4f87-44f6-8efe-ae4a59bed035n@googlegroups.com>
<4ff947dd-9fd9-466a-8f01-1866f770af08n@googlegroups.com> <0300c131-b77e-438b-bdf1-3c628fe201c0n@googlegroups.com>
<7945355b-3a88-4375-af4c-554ce75cc94cn@googlegroups.com> <1c92ea4e-c74c-4c05-ad85-b0769dd6968en@googlegroups.com>
<99643aa5-ce96-4ed7-92bf-7e4ce60e60a4n@googlegroups.com> <281db009-b294-451e-9bff-5906b9fd9403n@googlegroups.com>
<876a87c0-d600-43b4-af3a-957c48a7c135n@googlegroups.com>
User-Agent: G2/1.0
MIME-Version: 1.0
Message-ID: <de002874-0343-4b51-a71b-99ba181acdffn@googlegroups.com>
Subject: Re: Boat speed improvements
From: frithj...@googlemail.com (Jake Frith)
Injection-Date: Wed, 07 Apr 2021 14:46:37 +0000
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
 by: Jake Frith - Wed, 7 Apr 2021 14:46 UTC

On Wednesday, April 7, 2021 at 10:00:29 AM UTC+1, John E wrote:
> I've just seen this discussion and found it interesting as we have kept ourselves motivated during lockdown by developing a few products to add to our (Active Tools) product range, one of which gives an aerodynamic drag reduction. We started looking at Height Spacers to try and solve the issue of swapping them one handed when out on the water and the answer to that seemed to be a ‘pull tab’ and as that inevitably elongates the design we then wondered whether making the nose of that tab ‘aero’ (as the cycling fraternity say) and adding a Kamm tail (again, very common on bike frames https://www.trekbikes.com/gb/en_GB/inside_trek/kammtail_virtual_foil/) might give a small drag reduction.
>
> What we found, using CFD analysis, was that a short stack of these had a drag of only 19% of that of randomly orientated conventional spacers and that that would give a top flight Eight a 0.4 metre advantage over a 2K race.... The caveats on this are that we did not look at cross wind performance, although the is no reason to believe that will be poor, and forward mounted riggers, or riggers with C cups that shield the Oarlock/Swivel, would not benefit from using these.
>
> This is what the device looks like and we have initial samples from the tool on the way to us now https://drive.google.com/file/d/1GkUtmQcqGHZydN4QO5n1TIOqhh8bSrU_/view?usp=sharing
>
> The 0.4 metre figure makes one wonder what gains you would get by extruding aerodynamically profiled backstays, or adding thin Carbon Fibre covers to standard ones, and also whether a profile with a Kamm tail might work well for oar shafts?
>
> On another point, in response to a comment in the thread, I believe that all the major manufacturers make their oar shafts from Pre-preg material? The spiral lines you see are the witness lines left after the Nylon tape they wrap them with before curing is removed.

John,
I would imagine a Kamm tail profile could work very well indeed for oar shafts if Trek's claim of comparable drag to a 1:8 foil is correct.
In fact I think you, or perhaps Trek, or whoever they got the idea off might have stumbled upon the next generation of rowing oar.

Think of the advantages:
1) You could get the correct orientation of stiffness on the drive from an oarshaft of that profile without a large weight penalty. (It might even be lighter than a round shaft - The flat could actually help your drive phase stiffness- like it does Trek's lateral frame stiffness)
2) The penalty in the water of burying the loom would be much smaller, so you might be able to extend the aero section all the way down to the blade. (Not have to end it a foot early and lose all the aero where you actually need it most like in the fixed arero shroud shown somewhere above)
3) Similarly the shorter tail would mean you would not have to worry about contact with the riggers like you would with a long foil section, so you could continue your aero right up to the collar. (and upwards of the collar as far as the handle if you wanted). More of the potential issues of conventional foil shrouds neutralised.
4) The fact that these types of foil have better performance in misaligned flow suggests you might be able to do things like deliberately arrange it slighly misaligned on the recovery, so it's less badly aligned on the drive. Depends on what misalignment these Kamm profiles would absorb before the drag starts climbing. Because it's a short foil profile, even squared (90 degrees out of whack), it's going to be way better than a conventional long tail foil profile.
5) It will work as a fixed part of the oar shaft (so within FISA rules)
6) The technology is not IP protected and not patentable (been around for years- such as on Kamm tail sports racing cars of the 1960s). Plus I note Trek did not try to patent it- which suggests someone else thought of it for bikes first. For FISA, this is an advantage- they do not allow patented technologies. If there was a Rowing specific IP to be had (unlikely), its been blown by this thread anyway (publication- prior art).
7) In the way that Trek has found out that this is less of a 'wing' than a full length foil (so it does not get moved as much in sidewinds), any problematic behaviour of the looms of the oars catching the wrong bit of air, creating lift and trying to take off, or plumet into the water might be usefully reduced.

It's a known fact that fatter foils will take a larger angle of attack than thinner ones before stalling (hence sailing dinghies having a relatively skinny centreboard and a fat rudder profile). In combination with this I remember reading somewhere that at certain flow speeds, truncating a foil like this sometimes does not majorly increase drag, as the air pretty much describes the same path it would have if the back half of the foil was present. In a wind tunnel the upper and lower air streams desribe a foil shape, coming back together in much the same place it would if the back of the foil was present. Reading between the lines of their marketing waffle it looks like what Trek has found out is if you have a fat foil and get rid of the back of that foil, the air will then describe its own foil type shape, only aligned better to the flow than when a full foil is redirecting the flow in a direction it doesn't necessarily want to go- so for them better in crosswinds. So in the context of a bike in a crosswind the Kamm profile effectively provides a 'virtual foil' correctly aligned to the aparent wind. But similarly an oar is not always perfectly aligned with the oncoming air flow- particularly when alternating between squared and feathered.

If your profiled height washers buy 40cm over 2K, try riggers and 8x oar shafts in a CFD package!

Some potential there I'd say...

Re: Boat speed improvements

<adf687eb-93bb-4df1-8e09-2b38706ccba2n@googlegroups.com>

 copy mid

https://www.novabbs.com/sport/article-flat.php?id=118&group=rec.sport.rowing#118

 copy link   Newsgroups: rec.sport.rowing
X-Received: by 2002:a0c:a425:: with SMTP id w34mr7807299qvw.2.1617872038981;
Thu, 08 Apr 2021 01:53:58 -0700 (PDT)
X-Received: by 2002:a25:1287:: with SMTP id 129mr4383306ybs.117.1617872038662;
Thu, 08 Apr 2021 01:53:58 -0700 (PDT)
Path: i2pn2.org!i2pn.org!weretis.net!feeder8.news.weretis.net!feeder1.feed.usenet.farm!feed.usenet.farm!border1.nntp.ams1.giganews.com!nntp.giganews.com!news-out.google.com!nntp.google.com!postnews.google.com!google-groups.googlegroups.com!not-for-mail
Newsgroups: rec.sport.rowing
Date: Thu, 8 Apr 2021 01:53:58 -0700 (PDT)
In-Reply-To: <de002874-0343-4b51-a71b-99ba181acdffn@googlegroups.com>
Injection-Info: google-groups.googlegroups.com; posting-host=209.93.48.61; posting-account=qIPzYwoAAABDnTk7ke4pgXHHgpDK1lsY
NNTP-Posting-Host: 209.93.48.61
References: <0b2ce247-5fe9-4451-81cb-13fd618c56cbn@googlegroups.com>
<rkil91$18a$1@dont-email.me> <rkkkr2$mfj$1@dont-email.me> <rkkq8m$s96$1@dont-email.me>
<4d5283ce-b986-4a06-9a3b-3b88ea12f06an@googlegroups.com> <rkq81b$fng$1@dont-email.me>
<9a1f3ad5-1ed0-444a-a571-7f27a110ded6n@googlegroups.com> <rtidqm$um3$1@dont-email.me>
<666cdb86-7edd-4eeb-acb8-490d4d7231e2n@googlegroups.com> <7f1b4d72-5d2e-4953-89f8-e47ecea75d9bn@googlegroups.com>
<7a3932dc-37d2-40d3-9585-cd1cb02ff501n@googlegroups.com> <1f0d3a75-4f87-44f6-8efe-ae4a59bed035n@googlegroups.com>
<4ff947dd-9fd9-466a-8f01-1866f770af08n@googlegroups.com> <0300c131-b77e-438b-bdf1-3c628fe201c0n@googlegroups.com>
<7945355b-3a88-4375-af4c-554ce75cc94cn@googlegroups.com> <1c92ea4e-c74c-4c05-ad85-b0769dd6968en@googlegroups.com>
<99643aa5-ce96-4ed7-92bf-7e4ce60e60a4n@googlegroups.com> <281db009-b294-451e-9bff-5906b9fd9403n@googlegroups.com>
<876a87c0-d600-43b4-af3a-957c48a7c135n@googlegroups.com> <de002874-0343-4b51-a71b-99ba181acdffn@googlegroups.com>
User-Agent: G2/1.0
MIME-Version: 1.0
Message-ID: <adf687eb-93bb-4df1-8e09-2b38706ccba2n@googlegroups.com>
Subject: Re: Boat speed improvements
From: andymcke...@gmail.com (Andy McKenzie)
Injection-Date: Thu, 08 Apr 2021 08:53:58 +0000
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
Lines: 102
 by: Andy McKenzie - Thu, 8 Apr 2021 08:53 UTC

On Wednesday, 7 April 2021 at 15:46:38 UTC+1, frit...@googlemail.com wrote:
> On Wednesday, April 7, 2021 at 10:00:29 AM UTC+1, John E wrote:
> > I've just seen this discussion and found it interesting as we have kept ourselves motivated during lockdown by developing a few products to add to our (Active Tools) product range, one of which gives an aerodynamic drag reduction. We started looking at Height Spacers to try and solve the issue of swapping them one handed when out on the water and the answer to that seemed to be a ‘pull tab’ and as that inevitably elongates the design we then wondered whether making the nose of that tab ‘aero’ (as the cycling fraternity say) and adding a Kamm tail (again, very common on bike frames https://www.trekbikes.com/gb/en_GB/inside_trek/kammtail_virtual_foil/) might give a small drag reduction.
> >
> > What we found, using CFD analysis, was that a short stack of these had a drag of only 19% of that of randomly orientated conventional spacers and that that would give a top flight Eight a 0.4 metre advantage over a 2K race... The caveats on this are that we did not look at cross wind performance, although the is no reason to believe that will be poor, and forward mounted riggers, or riggers with C cups that shield the Oarlock/Swivel, would not benefit from using these.
> >
> > This is what the device looks like and we have initial samples from the tool on the way to us now https://drive.google.com/file/d/1GkUtmQcqGHZydN4QO5n1TIOqhh8bSrU_/view?usp=sharing
> >
> > The 0.4 metre figure makes one wonder what gains you would get by extruding aerodynamically profiled backstays, or adding thin Carbon Fibre covers to standard ones, and also whether a profile with a Kamm tail might work well for oar shafts?
> >
> > On another point, in response to a comment in the thread, I believe that all the major manufacturers make their oar shafts from Pre-preg material? The spiral lines you see are the witness lines left after the Nylon tape they wrap them with before curing is removed.
> John,
> I would imagine a Kamm tail profile could work very well indeed for oar shafts if Trek's claim of comparable drag to a 1:8 foil is correct.
> In fact I think you, or perhaps Trek, or whoever they got the idea off might have stumbled upon the next generation of rowing oar.
>
> Think of the advantages:
> 1) You could get the correct orientation of stiffness on the drive from an oarshaft of that profile without a large weight penalty. (It might even be lighter than a round shaft - The flat could actually help your drive phase stiffness- like it does Trek's lateral frame stiffness)
> 2) The penalty in the water of burying the loom would be much smaller, so you might be able to extend the aero section all the way down to the blade.. (Not have to end it a foot early and lose all the aero where you actually need it most like in the fixed arero shroud shown somewhere above)
> 3) Similarly the shorter tail would mean you would not have to worry about contact with the riggers like you would with a long foil section, so you could continue your aero right up to the collar. (and upwards of the collar as far as the handle if you wanted). More of the potential issues of conventional foil shrouds neutralised.
> 4) The fact that these types of foil have better performance in misaligned flow suggests you might be able to do things like deliberately arrange it slighly misaligned on the recovery, so it's less badly aligned on the drive. Depends on what misalignment these Kamm profiles would absorb before the drag starts climbing. Because it's a short foil profile, even squared (90 degrees out of whack), it's going to be way better than a conventional long tail foil profile.
> 5) It will work as a fixed part of the oar shaft (so within FISA rules)
> 6) The technology is not IP protected and not patentable (been around for years- such as on Kamm tail sports racing cars of the 1960s). Plus I note Trek did not try to patent it- which suggests someone else thought of it for bikes first. For FISA, this is an advantage- they do not allow patented technologies. If there was a Rowing specific IP to be had (unlikely), its been blown by this thread anyway (publication- prior art).
> 7) In the way that Trek has found out that this is less of a 'wing' than a full length foil (so it does not get moved as much in sidewinds), any problematic behaviour of the looms of the oars catching the wrong bit of air, creating lift and trying to take off, or plumet into the water might be usefully reduced.
>
> It's a known fact that fatter foils will take a larger angle of attack than thinner ones before stalling (hence sailing dinghies having a relatively skinny centreboard and a fat rudder profile). In combination with this I remember reading somewhere that at certain flow speeds, truncating a foil like this sometimes does not majorly increase drag, as the air pretty much describes the same path it would have if the back half of the foil was present. In a wind tunnel the upper and lower air streams desribe a foil shape, coming back together in much the same place it would if the back of the foil was present. Reading between the lines of their marketing waffle it looks like what Trek has found out is if you have a fat foil and get rid of the back of that foil, the air will then describe its own foil type shape, only aligned better to the flow than when a full foil is redirecting the flow in a direction it doesn't necessarily want to go- so for them better in crosswinds. So in the context of a bike in a crosswind the Kamm profile effectively provides a 'virtual foil' correctly aligned to the aparent wind. But similarly an oar is not always perfectly aligned with the oncoming air flow- particularly when alternating between squared and feathered.
>
> If your profiled height washers buy 40cm over 2K, try riggers and 8x oar shafts in a CFD package!
>
> Some potential there I'd say...
I had to look up 'Kamm Tail Profile' and when I did I sort of had to laugh, because I thought 'I'm sure I've seen these in the back of the boathouse'. Old wooden hollow blades have almost exactly this profile, although from an aerodynamic viewpoint 90 degrees out of phase, as the flat back is orientated sternwards during the drive, and towards the water on the recovery. Still - should deal with the 'prior art' element of the patent lawsuit.

Re: Boat speed improvements

<5e59759c-2a25-4b8c-9222-cc4cd490d89an@googlegroups.com>

 copy mid

https://www.novabbs.com/sport/article-flat.php?id=119&group=rec.sport.rowing#119

 copy link   Newsgroups: rec.sport.rowing
X-Received: by 2002:a05:620a:40d:: with SMTP id 13mr7698977qkp.369.1617877490244;
Thu, 08 Apr 2021 03:24:50 -0700 (PDT)
X-Received: by 2002:a25:910:: with SMTP id 16mr10778562ybj.472.1617877489975;
Thu, 08 Apr 2021 03:24:49 -0700 (PDT)
Path: i2pn2.org!i2pn.org!weretis.net!feeder8.news.weretis.net!proxad.net!feeder1-2.proxad.net!209.85.160.216.MISMATCH!news-out.google.com!nntp.google.com!postnews.google.com!google-groups.googlegroups.com!not-for-mail
Newsgroups: rec.sport.rowing
Date: Thu, 8 Apr 2021 03:24:49 -0700 (PDT)
In-Reply-To: <adf687eb-93bb-4df1-8e09-2b38706ccba2n@googlegroups.com>
Injection-Info: google-groups.googlegroups.com; posting-host=92.25.23.104; posting-account=3fTEewoAAABdw9qx8uDw9Cp3JZoUXJDV
NNTP-Posting-Host: 92.25.23.104
References: <0b2ce247-5fe9-4451-81cb-13fd618c56cbn@googlegroups.com>
<rkil91$18a$1@dont-email.me> <rkkkr2$mfj$1@dont-email.me> <rkkq8m$s96$1@dont-email.me>
<4d5283ce-b986-4a06-9a3b-3b88ea12f06an@googlegroups.com> <rkq81b$fng$1@dont-email.me>
<9a1f3ad5-1ed0-444a-a571-7f27a110ded6n@googlegroups.com> <rtidqm$um3$1@dont-email.me>
<666cdb86-7edd-4eeb-acb8-490d4d7231e2n@googlegroups.com> <7f1b4d72-5d2e-4953-89f8-e47ecea75d9bn@googlegroups.com>
<7a3932dc-37d2-40d3-9585-cd1cb02ff501n@googlegroups.com> <1f0d3a75-4f87-44f6-8efe-ae4a59bed035n@googlegroups.com>
<4ff947dd-9fd9-466a-8f01-1866f770af08n@googlegroups.com> <0300c131-b77e-438b-bdf1-3c628fe201c0n@googlegroups.com>
<7945355b-3a88-4375-af4c-554ce75cc94cn@googlegroups.com> <1c92ea4e-c74c-4c05-ad85-b0769dd6968en@googlegroups.com>
<99643aa5-ce96-4ed7-92bf-7e4ce60e60a4n@googlegroups.com> <281db009-b294-451e-9bff-5906b9fd9403n@googlegroups.com>
<876a87c0-d600-43b4-af3a-957c48a7c135n@googlegroups.com> <de002874-0343-4b51-a71b-99ba181acdffn@googlegroups.com>
<adf687eb-93bb-4df1-8e09-2b38706ccba2n@googlegroups.com>
User-Agent: G2/1.0
MIME-Version: 1.0
Message-ID: <5e59759c-2a25-4b8c-9222-cc4cd490d89an@googlegroups.com>
Subject: Re: Boat speed improvements
From: frithj...@googlemail.com (Jake Frith)
Injection-Date: Thu, 08 Apr 2021 10:24:50 +0000
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
 by: Jake Frith - Thu, 8 Apr 2021 10:24 UTC

> I had to look up 'Kamm Tail Profile' and when I did I sort of had to laugh, because I thought 'I'm sure I've seen these in the back of the boathouse'. Old wooden hollow blades have almost exactly this profile, although from an aerodynamic viewpoint 90 degrees out of phase, as the flat back is orientated sternwards during the drive, and towards the water on the recovery. Still - should deal with the 'prior art' element of the patent lawsuit.

Yes, I thought that too. I have an old pair of Suttons sweeps as bannisters in my house. Apart from being 90 degrees out of whack, they are a bit too rounded at the edges, but there is a similarity there. I guess they did it for ease of construction, and like a laminated wooden longbow, the wood on the flat back section is a darker, harder and presumably stiffer/ whippier wood. I guess it also helped in that they didn't have to have a complex seperate moulding for the collar- they were just a section of white heat shrunk plastic that conformed to the shape, mainly held in place by the bolt on collar and a bit of electrical tape top and bottom.

Re: Boat speed improvements

<4127b205-7141-4930-8611-d4dd9177c071n@googlegroups.com>

 copy mid

https://www.novabbs.com/sport/article-flat.php?id=120&group=rec.sport.rowing#120

 copy link   Newsgroups: rec.sport.rowing
X-Received: by 2002:a37:9e56:: with SMTP id h83mr8405326qke.38.1617886372238;
Thu, 08 Apr 2021 05:52:52 -0700 (PDT)
X-Received: by 2002:a25:bb08:: with SMTP id z8mr11076519ybg.188.1617886371932;
Thu, 08 Apr 2021 05:52:51 -0700 (PDT)
Path: i2pn2.org!i2pn.org!weretis.net!feeder8.news.weretis.net!proxad.net!feeder1-2.proxad.net!209.85.160.216.MISMATCH!news-out.google.com!nntp.google.com!postnews.google.com!google-groups.googlegroups.com!not-for-mail
Newsgroups: rec.sport.rowing
Date: Thu, 8 Apr 2021 05:52:51 -0700 (PDT)
In-Reply-To: <5e59759c-2a25-4b8c-9222-cc4cd490d89an@googlegroups.com>
Injection-Info: google-groups.googlegroups.com; posting-host=209.93.48.61; posting-account=qIPzYwoAAABDnTk7ke4pgXHHgpDK1lsY
NNTP-Posting-Host: 209.93.48.61
References: <0b2ce247-5fe9-4451-81cb-13fd618c56cbn@googlegroups.com>
<rkil91$18a$1@dont-email.me> <rkkkr2$mfj$1@dont-email.me> <rkkq8m$s96$1@dont-email.me>
<4d5283ce-b986-4a06-9a3b-3b88ea12f06an@googlegroups.com> <rkq81b$fng$1@dont-email.me>
<9a1f3ad5-1ed0-444a-a571-7f27a110ded6n@googlegroups.com> <rtidqm$um3$1@dont-email.me>
<666cdb86-7edd-4eeb-acb8-490d4d7231e2n@googlegroups.com> <7f1b4d72-5d2e-4953-89f8-e47ecea75d9bn@googlegroups.com>
<7a3932dc-37d2-40d3-9585-cd1cb02ff501n@googlegroups.com> <1f0d3a75-4f87-44f6-8efe-ae4a59bed035n@googlegroups.com>
<4ff947dd-9fd9-466a-8f01-1866f770af08n@googlegroups.com> <0300c131-b77e-438b-bdf1-3c628fe201c0n@googlegroups.com>
<7945355b-3a88-4375-af4c-554ce75cc94cn@googlegroups.com> <1c92ea4e-c74c-4c05-ad85-b0769dd6968en@googlegroups.com>
<99643aa5-ce96-4ed7-92bf-7e4ce60e60a4n@googlegroups.com> <281db009-b294-451e-9bff-5906b9fd9403n@googlegroups.com>
<876a87c0-d600-43b4-af3a-957c48a7c135n@googlegroups.com> <de002874-0343-4b51-a71b-99ba181acdffn@googlegroups.com>
<adf687eb-93bb-4df1-8e09-2b38706ccba2n@googlegroups.com> <5e59759c-2a25-4b8c-9222-cc4cd490d89an@googlegroups.com>
User-Agent: G2/1.0
MIME-Version: 1.0
Message-ID: <4127b205-7141-4930-8611-d4dd9177c071n@googlegroups.com>
Subject: Re: Boat speed improvements
From: andymcke...@gmail.com (Andy McKenzie)
Injection-Date: Thu, 08 Apr 2021 12:52:52 +0000
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
 by: Andy McKenzie - Thu, 8 Apr 2021 12:52 UTC

On Thursday, 8 April 2021 at 11:24:51 UTC+1, frit...@googlemail.com wrote:
> > I had to look up 'Kamm Tail Profile' and when I did I sort of had to laugh, because I thought 'I'm sure I've seen these in the back of the boathouse'. Old wooden hollow blades have almost exactly this profile, although from an aerodynamic viewpoint 90 degrees out of phase, as the flat back is orientated sternwards during the drive, and towards the water on the recovery.. Still - should deal with the 'prior art' element of the patent lawsuit.
> Yes, I thought that too. I have an old pair of Suttons sweeps as bannisters in my house. Apart from being 90 degrees out of whack, they are a bit too rounded at the edges, but there is a similarity there. I guess they did it for ease of construction, and like a laminated wooden longbow, the wood on the flat back section is a darker, harder and presumably stiffer/ whippier wood. I guess it also helped in that they didn't have to have a complex seperate moulding for the collar- they were just a section of white heat shrunk plastic that conformed to the shape, mainly held in place by the bolt on collar and a bit of electrical tape top and bottom.

Remember that prior to heatshrunk plastic the collar would be riveted leather.

1
server_pubkey.txt

rocksolid light 0.9.7
clearnet tor