deep rudder wanted
Printed From: Laser 28 International Class Association
Category: Laser 28 General
Forum Name: General Forum
Forum Description: All the topics that don't fit elsewhere
URL: http://www.laser28.org/forum/forum_posts.asp?TID=680
Printed Date: 03 May 2024 at 4:40am
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Topic: deep rudder wanted
Posted By: frfletch
Subject: deep rudder wanted
Date Posted: 19 September 2014 at 6:51pm
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Does anyone have have a Laser 28 deep rudder that they would like to sell? Please let me know if so.
Thanks. |
Replies:
Posted By: Mad Max
Date Posted: 21 September 2014 at 10:29am
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Many years ago I also looked for the deep rudder, found one but didn't want to part with the money. Talking to Bill he mentioned the cheap way would be extend the original which I did. I made a female mold of the tip and cast a new foot. The rudder was extended 4'5 inches and all lines fared to match the original. I don' know if this would be accepted as a class deep rudder but it made a major difference in the handling of the boat. Dick ------------- Dick #122 |
Posted By: frfletch
Date Posted: 21 September 2014 at 10:48am
| Ah yes! But was it faster? I remember it being said that the deep rudder option while deeper, provided no additional wetted surface or drag. To achieve that would require that it was either thinner, narrower, or both. |
Posted By: fatjohnz
Date Posted: 17 October 2014 at 9:59am
| Interesting; did you make any progress on this fletch? |
Posted By: frfletch
Date Posted: 22 October 2014 at 6:15pm
| No progress yet. I can modify, etc, but that would definitely increase the drag bucket. I have no trouble making the rudder if I can get the offsets. Farr provided me with offsets to the keel, but they would not release the rudder details. |
Posted By: WJRyan
Date Posted: 22 October 2014 at 8:59pm
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Silly question but what is an offset? ------------- Bill Ryan, Room4Crew, #155 |
Posted By: frfletch
Date Posted: 22 October 2014 at 11:00pm
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On any given foil, its shape is determined by specific numbers of the half section. Lets take a common foil (wing) that is a straight taper. If a straight taper, one only needs the exact shape of the base (say top of keel) and the shape of the bottom (say foot of keel). For fun, lets assign 10 measurement stations to each starting at the leading edge. Lets space each of them in 10% increments from the leading edge. Most of our sailing foils have their fullest sections about 40% back from the leading edge. If one drew s center line from the center of the leading edge to the center of the trailing edge, then the half values are the distance from the center line to the outside of the foil at each measurement station. So, when shaping a foil with a straight taper, one makes a template (female) that goes over the foil to be shaped with each measurement station marked on each side. He also makes a solid foil shape for the foot and attaches it to the foot of the foil to be shaped. Then one just trims the material between the measurement stations using a straight edge. I number each station say 1-10 or whatever, then use a piece of 1 1/2' x 1 1/2" aluminum angle as the straight edge. If it is hollow I fill it. If it is proud, one sands it off.
When making a foil from scratch, I use foam and a hot wire strung tight on a bow tensioned by Spanish windlass. This is attached to 12V DC or AC. A car battery with jumpers works fine. Then with one person each side of the bow, set the hot wire down on measurement station zero, and progress it. I call out the station from the leading edge position such as zero, one half, one, one and a half, two, etc, and ask the trailing edge person to keep up. When done, you have a near perfect foil. I first used this process is building model airplane wings. With a straight foil, or a straight tapered foil, one only needs two patterns. Top bottom, or with a wind, inside and wingtip. |
Posted By: frfletch
Date Posted: 22 October 2014 at 11:04pm
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sorry for the typos. Too many Margaritas. "Top and bottom, or with a wing, inside and wingtip."
Good grief! There should be a number one can call. :-( |
Posted By: Mad Max
Date Posted: 22 October 2014 at 11:56pm
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Page 663 will give an example of what fletch is talking about. The book can be found in some library's. In Buffalo your not allowed to borrow it, viewing only. http://books.google.com/books?id=lWe8AQAAQBAJ&pg=PA76&lpg=PA76&dq=Theory+of+wing+design&source=bl&ots=H-MckAjDGy&sig=PwibY9VQ-nAp078l1B3xla6f7i0&hl=en&sa=X&ei=xXlIVPalL8KIsQSEjIH4DA&ved=0CDgQ6AEwBTgK#v=onepage&q=Theory%20of%20wing%20design&f=false ------------- Dick #122 |
Posted By: WJRyan
Date Posted: 23 October 2014 at 6:34am
Thanks for the education gentlemen, Frank you are waaay more technical than I could ever plan to be! I still am trying to learn about the polars (that's where the Coke bear lives I think...)  ------------- Bill Ryan, Room4Crew, #155 |
Posted By: fatjohnz
Date Posted: 09 November 2014 at 8:51am
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For additional information, you could google 'NACA airfoil'. When I search, a wikpedia article for National Aviation Council of Aeronautics is first on the list and a airfoils tools website is second on the list.
For example, my Merit25 keel/rudder profiles were NACA 0010; a predefined profile. So at the locations were I wanted a template, I would measure the chord length and pop that number in a tool that would generate offsets of the foil vs.increment from the leading edge (as fletch said). If I make templates for the Laser28, I might see if I can back into one of the NACA profiles to get more data points for the template |
Posted By: fatjohnz
Date Posted: 05 February 2018 at 7:23am
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Once or twice a season we find ourselves racing to the windward mark in 20 knots gusting to 25+ As we go to round the mark the boom is eased to the shroud and ... it's not enough release of pressure to turn the boat. The boat continues to sail upwind and will not respond to the rudder. Is there some trick I'm not aware of to force the boat around? Do I need to consider an extension to the rudder? |
Posted By: WJRyan
Date Posted: 05 February 2018 at 7:38am
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As I reread the thread I wanted to share some new information about obtaining a standard or a long rudder. I recently had to obtain a new one (underwater obstruction bent post) and found both available from: Rudder Craft Inc. PO Box 9667 Boise, ID 83707 866-400-2204 https://ruddercraft.com/index.php?route=product/product&path=181_151&product_id=780 They have obtained the drawings from Farr for the long rudder. Great service, nice people, let you know more this summer. - bill ------------- Bill Ryan, Room4Crew, #155 |
Posted By: Bill Layton
Date Posted: 05 February 2018 at 7:43am
| The longer rudder is only helpful in really big seas. Don't get caught with too much vang on as that will keep the main powered. And be sure you let the jib out lots before you start easing the main. Both have to be eased off big time in those winds. I used to use the large rudder but I went back to the original rudder because it has much better feel. And it feels feather light. Whereas the longer rudder feel heavy, like an old chevy with power steering. I sail in big seas and big breeze with the original rudder all the time and I've found it's just a matter of learning to depower enough before you start bearing off. |
Posted By: khardy
Date Posted: 05 February 2018 at 9:21am
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also keep your crew on the rail until after you round the mark. Crew tends to get off the rail in preparation for kite hoisting. In heavy air its much better to keep the entire crew on the rail until you are turned down even though your kite may not get up as quickly. |
Posted By: Bill Layton
Date Posted: 05 February 2018 at 10:14am
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That looks great Bill, thanks for sharing that!
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WJRyan wrote:Posted By: fatjohnz
Date Posted: 12 May 2019 at 7:45am
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I wish I wasn't reading this post but I grounded the rudder on something hard yesterday. When she came off it felt like the the rudder top is binding firmly on the hull especially as the tiller comes through center. I assume that is bent rudder post? I was going to haul to inspect but I suppose I can just reach under the water and feel if the rudder top is in contact with the hull. Anyone have a spare rudder ... ? The construction materials listed for the new rudder have epoxy upgrade and fabric upgrade. Are either of these important? Thanks in advance as always, john |
Posted By: Bill Layton
Date Posted: 12 May 2019 at 9:04am
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Some bent shafts can be straightened and some can't. You won't know until you remove it and have some shop look at it. Epoxy and fabric upgrades are a good idea particularly when manufacturing a rudder using the standard method of cored fiberglass.
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Posted By: WJRyan
Date Posted: 12 May 2019 at 11:03am
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If you are having to "pull" the tiller and you hear a scraping sound the odds are pretty good it is bent. I have one of those! When we dropped it the local experts shared others experiences with trying to straighten a post and the recommendation was to trim the top trailing edge instead and to leave the post alone. I have pictures of the repair and glass work done before I decided to get a new rudder instead, let me know and I will share. Sorry for the hit, I know how scary it was for me! - bill ------------- Bill Ryan, Room4Crew, #155 |
Posted By: fatjohnz
Date Posted: 20 May 2019 at 6:09am
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Hello, I called the rudder shop to confirm they were making a standard (not deep) rudder. He said it their layout measures 48". Can you confirm that is correct? thx, john |
Posted By: WJRyan
Date Posted: 20 May 2019 at 10:51am
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Hi John, I'm traveling this week and will measure when I get home but in my rough notes I have the standard rudder as 43 5/8" and the longer rudder as 48 1/8". - bill ------------- Bill Ryan, Room4Crew, #155 |
Posted By: Bill Layton
Date Posted: 20 May 2019 at 10:53am
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The Bruce Farr designed longer rudder is 47.6 inches on the trailing edge. As I recall the original short rudder was 4.5 inches shorter.. measured on the trailing edge. |
Posted By: WJRyan
Date Posted: 20 May 2019 at 11:33am
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My notes are from the leading edge and the longer rudder is built from the Farr drawings, the RudderCraft folks obtained original ones. ------------- Bill Ryan, Room4Crew, #155 |
Posted By: Winner
Date Posted: 20 May 2019 at 9:12pm
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48" would be the long rudder. Mine is 47.5" at the trailing edge and 47" at the leading edge. ------------- Chris Eclipse #240 Thunder Bay, ON |
Posted By: Bill Layton
Date Posted: 20 May 2019 at 9:26pm
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Bill do you have any pics of that new rudder? It would be interesting to see them. |
Posted By: Comet
Date Posted: 21 May 2019 at 11:21am
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I'm interested in the longer rudder, too. So any pix or details much appreciated. |
Posted By: fatjohnz
Date Posted: 22 May 2019 at 10:38am
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Here is a pic of the deep rudder on the RudderCraft website. https://store.ruddercraft.com/index.php?route=product/product&path=181_151&product_id=780 RudderCraft does not have a template for the original/standard rudder. If anyone wants to part with their standard rudder, let me know. john |