Fins on 8s seem to be getting longer and longer (I should say deeper) to the point that or standard 8 bay racking now seems not to work without damage between boats.

Someone told me there were 'summer' and 'winter' fins - though no idea what that meant.

Does someone that knows more about this than me know what the difference in handling would be between the standard (less tall) fin than the taller one.

I am on the tideway - and the steering portion of the fin dies not change in height, so presumably this is to keep the rear end from slewing?

I am trying to work out why we do not change back to the less deep design that neatly fits our current racking - or should we alter the spacing?

Empacher and Filippi

And I know an aerow would be the correct way to go :)

James
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On 01/11/2020 18:22, James HS wrote:

Fins on 8s seem to be getting longer and longer (I should say deeper) to the point that or standard 8 bay racking now seems not to work without damage between boats.

Someone told me there were 'summer' and 'winter' fins - though no idea what that meant.

Does someone that knows more about this than me know what the difference in handling would be between the standard (less tall) fin than the taller one.

I am on the tideway - and the steering portion of the fin dies not change in height, so presumably this is to keep the rear end from slewing?

I am trying to work out why we do not change back to the less deep design that neatly fits our current racking - or should we alter the spacing?

Empacher and Filippi

And I know an aerow would be the correct way to go :)

James

Hi James -

The summer/winter fin idea will be news to most of us. A deeper fin
will have more effect than a shallower one, & depth matters more than
area. But why you'd want different summer & winter depths is a puzzle.

The job of the conventional flat-plate main fin is to keep the stern
from slewing, which is its natural tendency (the hull's centre of drag
being well ahead of the boat's centre of gravity). The job of that
little rudder is to over-ride the natural action of the main fin but,
being small & operating within the boundary layer of slower & more
disturbed flow close to the hull, it is not very effective at the best
of times.

Unfortunately, the way the steering then works is that the main fin
resists the efforts of the little flat rudder until cox has applied
rather a lot of rotation (causing significantly increased drag), but
then stalls (loses a fair bit of the "lift" with which it had hitherto resisted the rudder's input), whereupon the stern swings. So when cox
seems to have difficulty in holding a good course, it might not be his
or her fault as they're having to ride a knife-edge between over- & under-steer.

And, yes, there is better kit

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: carl@carldouglasrowing.com Tel: +44(0)1932-570946 Fax: -563682
URLs: carldouglasrowing.com & now on Facebook @ CarlDouglasRacingShells

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On Monday, November 2, 2020 at 7:22:24 AM UTC+13, James HS wrote:

Fins on 8s seem to be getting longer and longer (I should say deeper) to the point that or standard 8 bay racking now seems not to work without damage between boats.

Someone told me there were 'summer' and 'winter' fins - though no idea what that meant.

Does someone that knows more about this than me know what the difference in handling would be between the standard (less tall) fin than the taller one.

I am on the tideway - and the steering portion of the fin dies not change in height, so presumably this is to keep the rear end from slewing?

I am trying to work out why we do not change back to the less deep design that neatly fits our current racking - or should we alter the spacing?

Empacher and Filippi

And I know an aerow would be the correct way to go :)

James

I'd hazard a guess that the less deep fin was named for 'summer' river depths...
I once saw a couple of aluminium skinned (yes, really!) 1x that had sprung, retracting fins.
Phil.
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On Sunday, 1 November 2020 at 19:10:51 UTC, carl wrote:

On 01/11/2020 18:22, James HS wrote:

Fins on 8s seem to be getting longer and longer (I should say deeper) to the point that or standard 8 bay racking now seems not to work without damage between boats.

Someone told me there were 'summer' and 'winter' fins - though no idea what that meant.

Does someone that knows more about this than me know what the difference in handling would be between the standard (less tall) fin than the taller one.

I am on the tideway - and the steering portion of the fin dies not change in height, so presumably this is to keep the rear end from slewing?

I am trying to work out why we do not change back to the less deep design that neatly fits our current racking - or should we alter the spacing?

Empacher and Filippi

And I know an aerow would be the correct way to go :)

James

Hi James -

The summer/winter fin idea will be news to most of us. A deeper fin
will have more effect than a shallower one, & depth matters more than
area. But why you'd want different summer & winter depths is a puzzle.

The job of the conventional flat-plate main fin is to keep the stern
from slewing, which is its natural tendency (the hull's centre of drag
being well ahead of the boat's centre of gravity). The job of that
little rudder is to over-ride the natural action of the main fin but,
being small & operating within the boundary layer of slower & more
disturbed flow close to the hull, it is not very effective at the best
of times.

Unfortunately, the way the steering then works is that the main fin
resists the efforts of the little flat rudder until cox has applied
rather a lot of rotation (causing significantly increased drag), but
then stalls (loses a fair bit of the "lift" with which it had hitherto resisted the rudder's input), whereupon the stern swings. So when cox
seems to have difficulty in holding a good course, it might not be his
or her fault as they're having to ride a knife-edge between over- & under-steer.

And, yes, there is better kit

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

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Carl,
Would there be a dis-benefit to reverting to the 'shorter' fins - they are still substantially longer than the steering rudder (and so I understand bad) as it seems strange that all the manufacturers have suddenly switched to this longer fin when we only used to total our 8s through bad judgement - now we do it every time we rack them!
The longer fins also make a more regular visit to the bottom of the river as careless coxes mis-judge the 'shallows'. The fact that it becomes 'shallow' on the tideway twice a day seems to leave them bemused!
James
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On Monday, 2 November 2020 at 08:09:58 UTC, James HS wrote:

On Sunday, 1 November 2020 at 19:10:51 UTC, carl wrote:

On 01/11/2020 18:22, James HS wrote:

Fins on 8s seem to be getting longer and longer (I should say deeper) to the point that or standard 8 bay racking now seems not to work without damage between boats.

Someone told me there were 'summer' and 'winter' fins - though no idea what that meant.

Does someone that knows more about this than me know what the difference in handling would be between the standard (less tall) fin than the taller one.

I am on the tideway - and the steering portion of the fin dies not change in height, so presumably this is to keep the rear end from slewing?

I am trying to work out why we do not change back to the less deep design that neatly fits our current racking - or should we alter the spacing?

Empacher and Filippi

And I know an aerow would be the correct way to go :)

James

Hi James -

The summer/winter fin idea will be news to most of us. A deeper fin
will have more effect than a shallower one, & depth matters more than area. But why you'd want different summer & winter depths is a puzzle.

The job of the conventional flat-plate main fin is to keep the stern
from slewing, which is its natural tendency (the hull's centre of drag being well ahead of the boat's centre of gravity). The job of that
little rudder is to over-ride the natural action of the main fin but, being small & operating within the boundary layer of slower & more disturbed flow close to the hull, it is not very effective at the best
of times.

Unfortunately, the way the steering then works is that the main fin resists the efforts of the little flat rudder until cox has applied
rather a lot of rotation (causing significantly increased drag), but
then stalls (loses a fair bit of the "lift" with which it had hitherto resisted the rudder's input), whereupon the stern swings. So when cox seems to have difficulty in holding a good course, it might not be his
or her fault as they're having to ride a knife-edge between over- & under-steer.

And, yes, there is better kit

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

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Carl,

Would there be a dis-benefit to reverting to the 'shorter' fins - they are still substantially longer than the steering rudder (and so I understand bad) as it seems strange that all the manufacturers have suddenly switched to this longer fin when we only used to total our 8s through bad judgement - now we do it every time we rack them!

The longer fins also make a more regular visit to the bottom of the river as careless coxes mis-judge the 'shallows'. The fact that it becomes 'shallow' on the tideway twice a day seems to leave them bemused!

James

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On Monday, 2 November 2020 at 08:09:58 UTC, James HS wrote:

On Sunday, 1 November 2020 at 19:10:51 UTC, carl wrote:

On 01/11/2020 18:22, James HS wrote:

Fins on 8s seem to be getting longer and longer (I should say deeper) to the point that or standard 8 bay racking now seems not to work without damage between boats.

Someone told me there were 'summer' and 'winter' fins - though no idea what that meant.

Does someone that knows more about this than me know what the difference in handling would be between the standard (less tall) fin than the taller one.

I am on the tideway - and the steering portion of the fin dies not change in height, so presumably this is to keep the rear end from slewing?

I am trying to work out why we do not change back to the less deep design that neatly fits our current racking - or should we alter the spacing?

Empacher and Filippi

And I know an aerow would be the correct way to go :)

James

Hi James -

The summer/winter fin idea will be news to most of us. A deeper fin
will have more effect than a shallower one, & depth matters more than area. But why you'd want different summer & winter depths is a puzzle.

The job of the conventional flat-plate main fin is to keep the stern
from slewing, which is its natural tendency (the hull's centre of drag being well ahead of the boat's centre of gravity). The job of that
little rudder is to over-ride the natural action of the main fin but, being small & operating within the boundary layer of slower & more disturbed flow close to the hull, it is not very effective at the best
of times.

Unfortunately, the way the steering then works is that the main fin resists the efforts of the little flat rudder until cox has applied
rather a lot of rotation (causing significantly increased drag), but
then stalls (loses a fair bit of the "lift" with which it had hitherto resisted the rudder's input), whereupon the stern swings. So when cox seems to have difficulty in holding a good course, it might not be his
or her fault as they're having to ride a knife-edge between over- & under-steer.

And, yes, there is better kit

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

---
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Carl,

Would there be a dis-benefit to reverting to the 'shorter' fins - they are still substantially longer than the steering rudder (and so I understand bad) as it seems strange that all the manufacturers have suddenly switched to this longer fin when we only used to total our 8s through bad judgement - now we do it every time we rack them!

The longer fins also make a more regular visit to the bottom of the river as careless coxes mis-judge the 'shallows'. The fact that it becomes 'shallow' on the tideway twice a day seems to leave them bemused!

James

I thought that the variants of fins were about weed? A long thin fin presumably has less drag and slightly more stabilising effect, but is more likely to collect weed, and summer rivers are weedier!
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On 02/11/2020 10:20, Andy McKenzie wrote:

On Monday, 2 November 2020 at 08:09:58 UTC, James HS wrote:

On Sunday, 1 November 2020 at 19:10:51 UTC, carl wrote:

On 01/11/2020 18:22, James HS wrote:

Fins on 8s seem to be getting longer and longer (I should say deeper) to the point that or standard 8 bay racking now seems not to work without damage between boats.

Someone told me there were 'summer' and 'winter' fins - though no idea what that meant.

Does someone that knows more about this than me know what the difference in handling would be between the standard (less tall) fin than the taller one.

I am on the tideway - and the steering portion of the fin dies not change in height, so presumably this is to keep the rear end from slewing?

I am trying to work out why we do not change back to the less deep design that neatly fits our current racking - or should we alter the spacing?

Empacher and Filippi

And I know an aerow would be the correct way to go :)

James

Hi James -

The summer/winter fin idea will be news to most of us. A deeper fin
will have more effect than a shallower one, & depth matters more than
area. But why you'd want different summer & winter depths is a puzzle.

The job of the conventional flat-plate main fin is to keep the stern
from slewing, which is its natural tendency (the hull's centre of drag
being well ahead of the boat's centre of gravity). The job of that
little rudder is to over-ride the natural action of the main fin but,
being small & operating within the boundary layer of slower & more
disturbed flow close to the hull, it is not very effective at the best
of times.

Unfortunately, the way the steering then works is that the main fin
resists the efforts of the little flat rudder until cox has applied
rather a lot of rotation (causing significantly increased drag), but
then stalls (loses a fair bit of the "lift" with which it had hitherto
resisted the rudder's input), whereupon the stern swings. So when cox
seems to have difficulty in holding a good course, it might not be his
or her fault as they're having to ride a knife-edge between over- &
under-steer.

And, yes, there is better kit

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

---
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Carl,

Would there be a dis-benefit to reverting to the 'shorter' fins - they are still substantially longer than the steering rudder (and so I understand bad) as it seems strange that all the manufacturers have suddenly switched to this longer fin when we only used to total our 8s through bad judgement - now we do it every time we rack them!

The longer fins also make a more regular visit to the bottom of the river as careless coxes mis-judge the 'shallows'. The fact that it becomes 'shallow' on the tideway twice a day seems to leave them bemused!

James

I thought that the variants of fins were about weed? A long thin fin presumably has less drag and slightly more stabilising effect, but is more likely to collect weed, and summer rivers are weedier!

Andy -
I take your point on weeds, but don't understand why fins should be
getting deeper - which is what James says is happening.
A more sweptback shape, without the sharpening (it's pointless - it
doesn't reduce drag but does impair performance) of the leading edge,
would be better at shedding weeds, not to mention the polythene bags &
other detritus

James -
There's a solid case for a deeper rudder, but that's hard to arrange
with a plate fin.

Good steering gear, by keeping the boat under better control & inducing
less steering drag, is likely to give a crew more speed than any other
change you might make (say 1 to 5 seconds over 2k, depending on crew,
coxing skills & conditions).

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: carl@carldouglasrowing.com Tel: +44(0)1932-570946 Fax: -563682
URLs: carldouglasrowing.com & now on Facebook @ CarlDouglasRacingShells
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Is the summer/winter thing perhaps related to straight line racing in summer, where a deep fin might be helpful, vs. head racing in winter, with more bends?
On Monday, November 2, 2020 at 12:37:52 PM UTC, carl wrote:

On 02/11/2020 10:20, Andy McKenzie wrote:

On Monday, 2 November 2020 at 08:09:58 UTC, James HS wrote:

On Sunday, 1 November 2020 at 19:10:51 UTC, carl wrote:

On 01/11/2020 18:22, James HS wrote:

Fins on 8s seem to be getting longer and longer (I should say deeper) to the point that or standard 8 bay racking now seems not to work without damage between boats.

Someone told me there were 'summer' and 'winter' fins - though no idea what that meant.

Does someone that knows more about this than me know what the difference in handling would be between the standard (less tall) fin than the taller one.

I am on the tideway - and the steering portion of the fin dies not change in height, so presumably this is to keep the rear end from slewing?

I am trying to work out why we do not change back to the less deep design that neatly fits our current racking - or should we alter the spacing?

Empacher and Filippi

And I know an aerow would be the correct way to go :)

James

Hi James -

The summer/winter fin idea will be news to most of us. A deeper fin
will have more effect than a shallower one, & depth matters more than >>> area. But why you'd want different summer & winter depths is a puzzle. >>>
The job of the conventional flat-plate main fin is to keep the stern
from slewing, which is its natural tendency (the hull's centre of drag >>> being well ahead of the boat's centre of gravity). The job of that
little rudder is to over-ride the natural action of the main fin but, >>> being small & operating within the boundary layer of slower & more
disturbed flow close to the hull, it is not very effective at the best >>> of times.

Unfortunately, the way the steering then works is that the main fin
resists the efforts of the little flat rudder until cox has applied
rather a lot of rotation (causing significantly increased drag), but
then stalls (loses a fair bit of the "lift" with which it had hitherto >>> resisted the rudder's input), whereupon the stern swings. So when cox >>> seems to have difficulty in holding a good course, it might not be his >>> or her fault as they're having to ride a knife-edge between over- &
under-steer.

And, yes, there is better kit

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 >>>
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Carl,

Would there be a dis-benefit to reverting to the 'shorter' fins - they are still substantially longer than the steering rudder (and so I understand bad) as it seems strange that all the manufacturers have suddenly switched to this longer fin when we only used to total our 8s through bad judgement - now we do it every time we rack them!

The longer fins also make a more regular visit to the bottom of the river as careless coxes mis-judge the 'shallows'. The fact that it becomes 'shallow' on the tideway twice a day seems to leave them bemused!

James

I thought that the variants of fins were about weed? A long thin fin presumably has less drag and slightly more stabilising effect, but is more likely to collect weed, and summer rivers are weedier!

Andy -
I take your point on weeds, but don't understand why fins should be
getting deeper - which is what James says is happening.
A more sweptback shape, without the sharpening (it's pointless - it
doesn't reduce drag but does impair performance) of the leading edge,
would be better at shedding weeds, not to mention the polythene bags &
other detritus

James -
There's a solid case for a deeper rudder, but that's hard to arrange
with a plate fin.

Good steering gear, by keeping the boat under better control & inducing
less steering drag, is likely to give a crew more speed than any other change you might make (say 1 to 5 seconds over 2k, depending on crew,
coxing skills & conditions).
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

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On Monday, 2 November 2020 at 05:37:52 UTC-7, carl wrote:

I take your point on weeds, but don't understand why fins should be
getting deeper - which is what James says is happening.
A more sweptback shape, without the sharpening (it's pointless - it
doesn't reduce drag but does impair performance) of the leading edge,
would be better at shedding weeds, not to mention the polythene bags &
other detritus

I recall one day on the Avon in Christchurch, NZ, when one 8+, rowed by the OURC men, shredded three coxswains' hands right to the tendons when they reached under the boat to clear weeds off the sharpened fin. Not my program but I went over with a file and took the edge off the fin. Oddly nobody else cut their hands. The crew still won their race if I remember correctly (it was pre-2000). One of the stupidest things I've ever seen is people sharpening a fin on a boat.
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