[Public-List] Rudder Shape
Mike Meinhold via Public-List
public-list at lists.alberg30.org
Wed Feb 22 05:06:45 PST 2017
Greg
You might consider copying the original rudder as closely as possible. A lot of the value of an A30 is in her ability to race one-design. Any significant change to rudder profile or thickness of would compromise her eligibility.
Mike
Rinn Duin #272
Michael J. Meinhold
meinhold272 at gmail.com / 301 852 0619
> On Feb 22, 2017, at 7:42 AM, Gordon Laco via Public-List <public-list at lists.alberg30.org> wrote:
>
> Good morning Greg,
>
> Surprise, being an apres-400 boat, has a fiberglass rudder, and it’s port and starboard sides are parallel… there is no taper. The trailing edge is round, but I’ve not touched that for fear of grinding through the glass skin and exposing whatever is inside. I just live with it.
>
> With regard to the ¾” thickness you’ve remarked on below – strength is the issue and I don’t have advice on that.
>
> Gord Laco #426 Surprise
>
>
> On 2017-02-22, 2:41 AM, "Public-List on behalf of Greg Roberts via Public-List" <public-list-bounces at lists.alberg30.org on behalf of public-list at lists.alberg30.org> wrote:
>
> Thanks for all the responses! Gord, I had come to that conclusion
> myself but couldn't find anything online to back up my gut feel.(And
> fluid dynamics is not something I've ever studied so I didn't trust my
> gut...)
> So, no foil is confirmed. Do the factory fiberglass rudders have a
> taper or are the sides parallel?I'm tempted to copy the shape of the
> old rudder: Flat sides that taper to about 3/4" But perhaps the
> trailing edge should be a bit thicker?
> The current plan is to use a 1 1/8" bronze rudder post. Flat strips of
> bronze will be welded on to create the skeleton.Two strips will be
> used to create each spoke. See Jefa.comI'm not copying the pressed in
> rods that the factory used. Every bronze post failure I've heard of
> failed at the holes bored for the rods.
> Regards,
> Greg
> On 2/21/2017 at 9:28 AM, "via Public-List" wrote:Send Public-List
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> Today's Topics:
>
> 1. Re: Rudder Shape (Gordon Laco via Public-List)
> 2. Re: Rudder Shape (Bill Boyle via Public-List)
> 3. Re: Rudder Shape (Bill Boyle via Public-List)
> 4. Re: bottom paint (gordon white via Public-List)
> 5. Re: Rudder Shape (Bill Boyle via Public-List)
> 6. Re: Rudder Shape (Bill Boyle via Public-List)
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Tue, 21 Feb 2017 10:05:25 -0500
> From: Gordon Laco via Public-List
> To: Rod Symmes , Alberg 30 Public List --
> open to all
> Subject: Re: [Public-List] Rudder Shape
> Message-ID:
> Content-Type: text/plain; charset="UTF-8"
>
> Another interesting thing? in discussion with Steve Killing, the
> yacht designer who lives near us, and is the fellow who figured out
> how to make those huge America?s Cup catamarans fly by making their
> centre boards curved, I learned that the way to make certain a dinghy
> rudder or centerboard doesn?t vibrate is to make the trailing edge
> straight and squared with sharp corners. We make the servo blades of
> Voyager self steering vanes that way.
>
> Along the same lines? I?ve got an original Hasler self steering vane
> in our workshop. I bought it years ago for the Folkboat but never
> used it? I keep it to show where Voyagers came from. The Hasler is a
> fair bird cage of tubes, tiny blocks and lines, but it shows evidence
> of Hasler?s brilliant mind all over it.
>
> Now here?s the point of all this? Hasler?s servo blades, the part of
> the vane that?s in the water, is NOT foil shaped. It?s wedge shaped
> with a small radius parabolic leading edge, then steadily widens to a
> squared trailing edge about 1? thick. This is the same shape used by
> surface piercing hydrofoils of the 1960?s. interesting, isn?t it?
> At low speeds it likely makes more drag resistance than a pure foil?
> but at high speed much less, and especially at angles of incidence.
> Whatever turbulence it ?feels? is swept off the wedge and tumbles in
> futile frustration aft of the squared edge where there?s no blade.
>
> As a maker of vanes I was also interested to note that Hasler resolved
> the issue of making the vane fit various freeboard heights by simply
> making the blade way too long. The spruce is cheap, and the owner can
> trim it to whatever is required. Genius.
>
> Gord #426 Surprise
>
> On 2017-02-21, 9:24 AM, "Public-List on behalf of Rod Symmes via
> Public-List" wrote:
>
> What I remember from aerodynamics in that time period was that
> European car rally drivers prefered the Volvo station wagon over the
> sedan because, in spite of the extra pounds of glass, they were 2 or
> 3 mph faster with that square back end.
> Go figger ?
> Cheers, Rod
> -------- Original message --------
> From: Michael via Public-List
> Date:21-02-2017 7:37 AM (GMT-05:00)
> To: Gordon Laco , Greg Roberts , Alberg 30 Public List -- open to
> all
> Subject: Re: [Public-List] Rudder Shape
> I always think of Kamm back cars of the late '70's on this
> subject. Kamm
> was an aerodynamic scientist who calculated the drag of building
> in a
> tear drop shape was more than just cutting off the back of the car
> square. Made for a bunch of ugly little cars.
> Michael Grosh
> #220
> ------ Original Message ------
> From: "Gordon Laco via Public-List"
> To: "Greg Roberts" ; "Alberg 30 Public List --
> open to all"
> Sent: 2/21/2017 3:27:50 AM
> Subject: Re: [Public-List] Rudder Shape
>> Good day Greg,
>>
>> A foil shaped rudder would do you no good at all? one must
> consider,
>> with our sorts of boats, that the ?foil? has it?s leading edge at
> the
>> forward part of the keel and the rudder is a sort of flap or trim
> tab
>> on that structure, not something on it?s own.
>>
>> The only improvements one could give our rudders would be to
> minimize
>> the ?leaking? of flow from the leeward side to the windward
> between the
>> rudder post and the after part of the keel (already a pretty good
> fit
>> in Alberg 30?s except of course for the troublesome propeller
> aperture)
>> and perhaps a narrower and more squared trailing edge. The
> thicker
>> rounded trailing edge (when considered in cross section) is not
> so good
>> for minimizing turbulence at the trailing edge.
>>
>> Gord #426 Surprise
>>
>> On 2017-02-21, 12:32 AM, "Public-List on behalf of Greg Roberts
> via
>> Public-List" public-list at lists.alberg30.org> wrote:
>>
>> Did any of our boats come with a foil shaped rudder?My wood
> rudder
>> has
>> flat sides and a gentle taper..I'm not sure how much one
> would gain
>> with a foil given the 3/4 keel,I'm having a hard time
> picturing how
>> you would handle the tilt when defining the profile.
>> Regards,
>> Greg
>> _______________________________________________
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>>
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> ------------------------------
>
> Message: 2
> Date: Tue, 21 Feb 2017 15:51:14 +0000 (UTC)
> From: Bill Boyle via Public-List
> To: Greg Roberts ,
> "public-list at lists.alberg30.org" ,
> "public-list-request at lists.alberg30.org"
> , Alberg 30 Public List --
> open to all
> Subject: Re: [Public-List] Rudder Shape
> Message-ID:
> Content-Type: text/plain; charset=UTF-8
> If you want to close the gap between the keel and the rudder this is
> the product to use.Hawk Marine Products, SlotStrip
> |
> | |
> Hawk Marine Products, SlotStrip
> Manufactures of Marine Products | |
>
> |
> I use this on my Classic Moth to close up the dagger board slot.? They
> also have it in bigger sheets to close bigger gaps.? Any keel hung
> rudder would benefit from this.?
>
> Bill BoyleSlainte #129
> From: Greg Roberts via Public-List
> To: public-list at lists.alberg30.org;
> public-list-request at lists.alberg30.org
> Sent: Tuesday, February 21, 2017 12:32 AM
> Subject: [Public-List] Rudder Shape
> Did any of our boats come with a foil shaped rudder?My wood rudder has
> flat sides and a gentle taper..I'm not sure how much one would gain
> with a foil given the 3/4 keel,I'm having a hard time picturing how
> you would handle the tilt when defining the profile.
> Regards,
> Greg
> _______________________________________________
> These businesses support your Association:
> http://www.alberg30.org/store/A30supporters.html
> Please support them.
> _______________________________________________
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> Public-List at lists.alberg30.org
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> ------------------------------
>
> Message: 3
> Date: Tue, 21 Feb 2017 15:51:14 +0000 (UTC)
> From: Bill Boyle via Public-List
> To: Greg Roberts ,
> "public-list at lists.alberg30.org" ,
> "public-list-request at lists.alberg30.org"
> , Alberg 30 Public List --
> open to all
> Subject: Re: [Public-List] Rudder Shape
> Message-ID:
> Content-Type: text/plain; charset=UTF-8
> If you want to close the gap between the keel and the rudder this is
> the product to use.Hawk Marine Products, SlotStrip
> |
> | |
> Hawk Marine Products, SlotStrip
> Manufactures of Marine Products | |
>
> |
> I use this on my Classic Moth to close up the dagger board slot.? They
> also have it in bigger sheets to close bigger gaps.? Any keel hung
> rudder would benefit from this.?
>
> Bill BoyleSlainte #129
> From: Greg Roberts via Public-List
> To: public-list at lists.alberg30.org;
> public-list-request at lists.alberg30.org
> Sent: Tuesday, February 21, 2017 12:32 AM
> Subject: [Public-List] Rudder Shape
> Did any of our boats come with a foil shaped rudder?My wood rudder has
> flat sides and a gentle taper..I'm not sure how much one would gain
> with a foil given the 3/4 keel,I'm having a hard time picturing how
> you would handle the tilt when defining the profile.
> Regards,
> Greg
> _______________________________________________
> These businesses support your Association:
> http://www.alberg30.org/store/A30supporters.html
> Please support them.
> _______________________________________________
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> Public-List at lists.alberg30.org
> http://lists.alberg30.org/listinfo.cgi/public-list-alberg30.org
> ------------------------------
>
> Message: 4
> Date: Tue, 21 Feb 2017 11:00:44 -0500
> From: gordon white via Public-List
> To: public-list at lists.alberg30.org,
> public-list-request at lists.alberg30.org
> Subject: Re: [Public-List] bottom paint
> Message-ID:
> Content-Type: text/plain; charset=windows-1252; format=flowed
>
> There was discussion at last Saturday's maintenance seminar of bottom
> paint and I believe prices quoted were between $160 and $200 per
> gallon.
> I just bought a gallon of Woolsey copper ablative bottom paint at my
> nearby Tru-Value hardware store for $99.
> - Gordon White, BRIGADOON II (#275)
> ------------------------------
>
> Message: 5
> Date: Tue, 21 Feb 2017 17:28:19 +0000 (UTC)
> From: Bill Boyle via Public-List
> To: Bill Boyle , Greg Roberts
> , "public-list at lists.alberg30.org"
> ,
> "public-list-request at lists.alberg30.org"
> , Alberg 30 Public List --
> open to all
> Subject: Re: [Public-List] Rudder Shape
> Message-ID:
> Content-Type: text/plain; charset=UTF-8
>
> Well, that didn't stick.?? I'll post the reference to the SlotStrip
> over on the facebook page.
> From: Bill Boyle via Public-List
> To: Greg Roberts ; "public-list at lists.alberg30.org" ;
> "public-list-request at lists.alberg30.org" ; Alberg 30 Public List --
> open to all
> Sent: Tuesday, February 21, 2017 10:51 AM
> Subject: Re: [Public-List] Rudder Shape
> If you want to close the gap between the keel and the rudder this is
> the product to use.Hawk Marine Products, SlotStrip
>
> ?
> |?
> |? |?
> Hawk Marine Products, SlotStrip
> Manufactures of Marine Products? |? |
>
> ? |
> I use this on my Classic Moth to close up the dagger board slot.? They
> also have it in bigger sheets to close bigger gaps.? Any keel hung
> rudder would benefit from this.?
>
> Bill BoyleSlainte #129
> ? ? ? From: Greg Roberts via Public-List
> To: public-list at lists.alberg30.org;
> public-list-request at lists.alberg30.org
> Sent: Tuesday, February 21, 2017 12:32 AM
> Subject: [Public-List] Rudder Shape
> ?
> Did any of our boats come with a foil shaped rudder?My wood rudder has
> flat sides and a gentle taper..I'm not sure how much one would gain
> with a foil given the 3/4 keel,I'm having a hard time picturing how
> you would handle the tilt when defining the profile.
> Regards,
> Greg
> _______________________________________________
> These businesses support your Association:
> http://www.alberg30.org/store/A30supporters.html
> Please support them.
> _______________________________________________
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> Public-List at lists.alberg30.org
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> ?
> _______________________________________________
> These businesses support your Association:
> http://www.alberg30.org/store/A30supporters.html
> Please support them.
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> Public-List at lists.alberg30.org
> http://lists.alberg30.org/listinfo.cgi/public-list-alberg30.org
> ------------------------------
>
> Message: 6
> Date: Tue, 21 Feb 2017 17:28:19 +0000 (UTC)
> From: Bill Boyle via Public-List
> To: Bill Boyle , Greg Roberts
> , "public-list at lists.alberg30.org"
> ,
> "public-list-request at lists.alberg30.org"
> , Alberg 30 Public List --
> open to all
> Subject: Re: [Public-List] Rudder Shape
> Message-ID:
> Content-Type: text/plain; charset=UTF-8
>
> Well, that didn't stick.?? I'll post the reference to the SlotStrip
> over on the facebook page.
> From: Bill Boyle via Public-List
> To: Greg Roberts ; "public-list at lists.alberg30.org" ;
> "public-list-request at lists.alberg30.org" ; Alberg 30 Public List --
> open to all
> Sent: Tuesday, February 21, 2017 10:51 AM
> Subject: Re: [Public-List] Rudder Shape
> If you want to close the gap between the keel and the rudder this is
> the product to use.Hawk Marine Products, SlotStrip
>
> ?
> |?
> |? |?
> Hawk Marine Products, SlotStrip
> Manufactures of Marine Products? |? |
>
> ? |
> I use this on my Classic Moth to close up the dagger board slot.? They
> also have it in bigger sheets to close bigger gaps.? Any keel hung
> rudder would benefit from this.?
>
> Bill BoyleSlainte #129
> ? ? ? From: Greg Roberts via Public-List
> To: public-list at lists.alberg30.org;
> public-list-request at lists.alberg30.org
> Sent: Tuesday, February 21, 2017 12:32 AM
> Subject: [Public-List] Rudder Shape
> ?
> Did any of our boats come with a foil shaped rudder?My wood rudder has
> flat sides and a gentle taper..I'm not sure how much one would gain
> with a foil given the 3/4 keel,I'm having a hard time picturing how
> you would handle the tilt when defining the profile.
> Regards,
> Greg
> _______________________________________________
> These businesses support your Association:
> http://www.alberg30.org/store/A30supporters.html
> Please support them.
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> ?
> _______________________________________________
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> Please support them.
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