Monday, April21, 2014 L-36.com

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Dedicated to the enjoyment of yachting, working with wood, and especially to Lapworth 36's everywhere



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High Strength Soft Shackle

Recient work by Brion Toss, Evans Starzinger, and myself has led to the development of a high strength soft shackle that Evens has tested to 230% of line strength. The secret to this added strength in primarily an increase in the strength of the knot, the weak point in conventional soft shackles. I should point out that Evans testing shows conventional soft shackles, with diamond knots, test at 170% of line strength, considerable above the "higher than line strength" number I have been using. While these two statements are consistant, the more percise number is considerably higher and higher than the testing I had done at NE Rope.
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L-36.com Forums Return

In honor of the April Fools prank by Sailing Anarchy, I am putting the Forum back online. Please feel free to post.

There are two forums, one is a general topic and the other is dedicated to rope, splices, and soft shackles.
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New and Improved Used Sails Listings

The "Used Sails" tab has been improved. It includes a new vendor, Second Wind Sails, and is easier to use. If you have ever looked for used sails for your boat I think you will like what we have to offer.

Find used sails that fit your boat from multiple vendors, North, Minney's, Pineapple, Beacon, and now Second Wind Sails. All presented in terms that relate to your boat. Just enter the brand of your boat, pick the specific boat from the list, and you will get a list of sails that will fit your boat. You can limit the results shown by filtering on sail type and, in the case of jibs, jib size. If you don't specify a sail type, all types are displayed. Previously, nothing was displayed and that was confusing some people. We filter the vendor results eliminating sails that we know will not fit.


This is a 93 % jib.
The clew is about 0 feet above the tack.
The luff is 91% of the forestay entered or estimated
Click HERE to get Contact information
ID#LUFFLEECHFOOTWEIGHT-MATERIALATTACHMAKERCONDITIONCOMMENTS - UPDATED LIST 10-3-2012NUMBERBINPRICE
H21439'37'13' 2"3 OZ DACRONLOOSE LUFFNORTHVERY GOOD 7LOOSE LUFF STAYSAIL, GOOD LIGHT JIB, COULD ADD HANKS11-570105$295.00
NOTE: We make no commission and are not selling any of these sails. This is just another FREE service from L-36.com
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Analysis of a Tack

Using GPS Tracking Data to Analyze Race Results
Regular readers of L-36.com know that I am writing an Android application for racing sailboats. I have had the pleasure this winter of collaborating with a Dutch sailor who is practicing this winter in hopes of winning his class in a major regatta this summer. With their 9th place finish two years ago and their 4th place last summer, we believe it is within reach.

This article is an analysis of a single tack. It uses GPS tracking data to calculate the current and from that to calculate the expected tacking angle.

The upwind leg is the leg of interest. We are analyzing the third from the last tack before the mark rounding. We want to know why the boat was not able to make the mark without the last two tacks. The ultimate goal is to come up with better on the water tools for calculating laylines when there is current.

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Small Things - Big Wins

Do you ever wonder what the big difference is between the boats that consistently finish in the front of the fleet and the boats that don't? Sure, sometimes it is just one or two big things; maybe a brand new set of sails while your struggle along with sails 5 or 6 years old, or maybe you think they have some uncanny way of always being on the correct side of the next shift. But after years of racing in all kinds of fleets I can tell you without a doubt that 95% of the time it is nothing so simple but yet something that can be easily attained. The magic factor is really a combination of a whole lot of small things that add up to a big difference and a big winning percentage.
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The First Bend

This bend has been tested. Sometimes it slips, sometimes it breaks. Either way it is stronger than a triple fisherman's. Amsteel is very slippery. It is difficult to test a knot that slips and even harder when it slips sometimes. If you pull and let it sit after it starts to slip, it recovers and ends up being strong, something above 40% of line strength by some tests. There are other knots that almost never slip, see the Last Bend but it is ugly and not near as simple or easy to tie as this knot. The standard for tying Amsteel or Dyneema together is the triple fisherman's knot. This knot slips less that a triple fisherman's so it is a step forward slipping or not. When it doesn't slip, it is stronger than the Last Bend. I present it here for your consideration.

Both the First Knot and the Last Bend can slip at about 35% of line strength. When they don't slip, they are about 40% of line strength with the First Knot just a little above this and the Last Bend below this. There is another variation that slips at about 40% that I will show here as well. You can untie the First Knot, but not the variation. This knot can also be untied even after being loaded up near breaking. Just put a spike through the center to loosen it up and remove the tails from the knot center. The rest is easy.

I am calling this knot the First Bend because by the time I was done testing dozens of variations on knots and never wanted to hear the word bend again, I called the final knot the Last Bend. It did well but upon considering this knot, the first one I considered, I came to appreciate it more. In fact, I am declaring it the winner of my search for the best bend for Dyneema. That said, the variation is stronger.

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Knives on a Boat

Are you still using an old worn out knife? When I found it time for a new knife, I was amazed how much knives have changed. I recently purchased about half a dozen new knives as I explored the field adding to the way too many knives I already had. I scored the Internet for recommendations. I read reviews on Amazon. I tried knives at the local WestMarine (none were acceptable). In the end there were 5 knives I liked and would recommend. There are also whole classes of knives I would stay away from. This article will take you through the thought process and hopefully help you find the perfect knife for your application.
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Automatic GPX File Marker and Route Generator

The set of tools that will generate a GPX file for your GPS has been recently fixed and I thought it time to make people aware of this valuable tool again. With two map clicks you can get a list of all the marks in that area, select the ones you are interested in, edit their names, and download a GPX file to your computer. These are USCG generated locations from the many volumes for all US territories. The search through all the volumes is done automatically. In just a couple of minutes, you can do what might take an hour to do previously. Please enjoy these tools.
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Boating Electrical ABCs

Many sailors I know find their boat's electrical system daunting. The very same people who will tinker with practically every mechanical device on their vessel, will for some reason, shy away from the electrical side of things. Perhaps this view is shaped by those salty-dog authors who dismiss electrical systems as new fangled, and prefer stinky kerosene instead. Or perhaps, sailors have forgotten their high-school science, although it is hardly more complicated than Ohm's Law. Regardless, you have nothing to fear, as electrical systems are very straightforward and equally reliable when properly maintained.
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StartLine Racing on Android

Here is some user input on the new features of StartLine:
"First of all, we had a great day. I got two really big compliments. One on the start and one on a tack. We had a down stream upwind leg. I made an early call for the tack, based on Startline's calulation of the layline. When we came out of that tack we saw that the upwind mark was still 50 meters upwind, but the current pushed us up wind. We were the only boat that had not over sailed that mark. Great."
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Basics of Sailboat Racing

This articles has been floating around the web and reprinted by some yacht clubs. It is an "introduction" to sailboat racing. It claims to be simple but is a bit more detailed than a typical introduction to racing. As far as I know, Captain Kangaroo is a fictional TV character from my youth but that is the author sited in the article. The pictures included in the article on the web are included but are enough to frighten anyone out of every trying racing. If you are new to racing, please do not assume these pictures are anything but the most extreme pictures the fictional Captain impersonator could come up with. If you are an experienced racer, they add humor to the article. See if you can pick out the bowman in the last picture. You can't see much of him, but he is in there. I hope you enjoy the article. Allen

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Velocity Headers

I don't think there is a subject so misunderstood than velocity headers. They can take an entire fleet and get them to all stop dead in the water where a boat that recognizes what it going on can sail right through them. I know because I have done it. We went from last to first to finish in a fleet where we were neither the biggest, fastest, or lightest boat and yet there they all were stopped as we went right by, sails luffing away.
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Unassisted Mast Climbing -- a review of 6 methods

There are many articles reviewing different ways of climbing a mast. There are also articles where people tell how they do it, their pet way. After frustration that none of the ways I have tried over the years or read about doing as complete a literature search as I could, would meet my goals, I went out and tried to come up with a new way, something that would meet my goals. This article reviews six ways of climbing a mast without help form anyone else. It talks about the pros and cons of each system and scores them on a set of criteria. The high score system is one I developed using some mountain climbing gear. I tried almost every mountain climbing mechanical and non mechanical assist that I could buy before settling on the system I like.

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How to Fly a Spinnaker - Updated 8/30/2013

Spinnaker This 8 page tutorial covers all the terms, positions, and tasks of flying a symmetric spinnaker using the end for end gybe technique.

I have had Papoose for 23 years and never used a spinnaker on her. Last two seasons we won the local beer can series using a free flying jib downwind sometimes along with our normal jib. But we always had to play catch up to the boats that used spinnakers. I decided to learn to fly a spinnaker so we could move to the next level.

I joined the crew of a very successful Tarten-10 for the winter series. I used a GoPro camera to document as much as I could. This training series of articles is the result.

Lazy Lightning (the T-10) uses end for end gybes which are said to be appropriate for boats up to 35 feet. It is much simpler to rig and execute than a dip pole gybe so is the preferred method for boats such as mine which fly smaller spinnakers.
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Tide Page


This new tide page will show tide chart, table, and hourly tide or current. Search for a tide station by entering part of the name. Select from the list of possible stations. There is a list box that shows nearby stations if you want to switch locations. A map shows where the station is registered.
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Using Bluetooth GPS Receivers with Android - UPDATED 7-13-2013

To get the most accuracy from GPS based applications it is not enough to use the built in GPS in your phone or tablet because they do not have differential (WAAS) mode. Some applications can take advantage of higher update rates available in external GPS devices as well. In this article, I will explain why you might want an external GPS receiver, what the various Android drivers do, and why I picked "Bluetooth GPS Provider" as my preferred app. Finally, I will explain all of the Preferences in Bluetooth GPS Provider, something you will not find anywhere else.

Note that as of Android 4.1 it is a little tricky to get these devices to work. Read on and find out what you need to do.

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How to Point Higher

NOTE: This is an article I wrote for our local yacht club newsletter. For background, so far this season I have come in first 6 times and second once. Last race we won by 4 minutes in a 6 mile race.

Resource id #11
I have been racing at SPYC for 5 years and that represents almost all my racing experience. I am thankful to the club for this experience and it has helped me a great deal to become a better racer. I am also grateful to other skippers who are far better racers than I will ever be for sharing many insights and tips on sailing. While I do not consider myself an expert racer, I would like to continue the tradition of sharing what I have learned in hopes of making other boats faster as well. In my case, there are two things that help Papoose win races. One is having lots of wind when racing against much lighter boats. The other is pointing ability. It is my hope that this article might help other people discover new pointing ability in their boats.
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More Low Friction Rings

In the first article of this series we gave results on using fairleads and showed how the added friction is not significant with low deflection angles. In this article we consider using low friction and other standard rings with high deflections and analyze how these can be used in systems to provide simple and inexpensive mechanical advantage. Again we used the digital scale shown on the right to make the measurements. This scale reads up to 220 pounds with 1/2 pound resolution.

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Fairlead Friction Uncovered

Have you ever wondered hom much, if anything, you are giving up by using fairleads instead of blocks? How much friction is there. How does this compare with a block? Does the style of the fairlead matter? This article attempts to answer these questions.

Using a digital scale, I was able to compare the no fairlead force required to just move my weight against the turning block that I had on the test bench to the force required to move the weight when there was a bend through one of two types of fairleads. I took data at many angles with both fairleads. I also took some data with different line types, specifically Samson XLS and Amsteel.

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Jibsheet Fairleads

Do you find that you get wraps on your jib winches or just want give a better lead angle to the winch? In the last race we did, a new crew member got a wrap so tight that the only way to release it was to cut the sheet with a knife. We strung the lazy sheet to the secondary winch and took the pressure off but that was not enough to free the wrap, that is when the knife came out. The winch manufacturer recommends between 3 and 8 degrees as the ideal sheeting angle.

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Unique Mainsheet System Analyzed

It isn't often you see a completely new way to rig a mainsheet. I saw this posting on Sailing Anarchy and though I would share an analysis of what they are doing and why. Here is a picture of the boat


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More on Rings as Twings, Inhaulers, and Fairleads

I have several articles on using rings as inhaulers and twings. This can be taken to extremes and the jib car can be eliminated and just the twing and inhauler used. It not only can be, that is how the TP-52 fleet is rigged. Here are some pictures to show it. This is a picture I took a couple of years ago at the Big Boat Series in San Francisco of the TP-52 Mayham
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Calibrating a Marine Compass

Everyone understands that a marine compass needs to be calibrated. I am not an expert on compass calibration but got interested in the question when a club member asked me if I had an article on the subject on this web site. It is easy enough to find articles on how to calibrate a marine compass but I found them lacking in two areas. First, they did not explain what was really going on such that I could understand why things were being done. Second, they all recommended you don't actually do the calibration yourself but rather hire an expert. Of course, because I only was presented with a how and a recommendation not to do it, I did not have the knowledge to judge if the procedure was going to be error prone if I did it without some of the fancy tools the professionals have. I kept thinking about it and doing a few experiments until I felt I understood what the goal of all these measurements was and how accurate they needed to be. Of course, I would be a fool if I didn't give the same advice, have an expert do the job for you. But after reading this you might at least understand what is going on and be able to judge for yourself if you think you know enough to calibrate your own compass.
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7-Day Tide and Current Forecast

Improved 2/27/2013 - Graph now goes midnight to midnight. Added title to each section.

Tables and graphs for selected tide or current station for the week ahead.
Table shows high and low times for tide, slack and peak for current. Also shows sun and moon events. Graph is as shown below. The final table shows the hourly values.

Sorry tide depth graphs only, please select another station.
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Low Friction Rings Mechanical Advantage

Using Low Friction Rings instead of Blocks
I recently saw a picture of a three stage cascaded block system using low friction ring instead of blocks. This article analyzes such a cascade and shows how to calculate its effective mechanical advantage. The techniques shown can easily be extended to other systems. I will discuss one such system that I use on my boat.

Mechanical Advantage
To analyze a system like this you need to know the efficiency of a single stage, extend that to the the efficiency of the entire system, and translate that to mechanical advantage. For reference lets consider the following sketch.

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Make Your Own Telltails

By: Ed Sinofsky

I admit it, this is sailing nerdiness at its extreme. When I was a teenager I was a sailmaker at Spencer sails in Huntington New York. That was almost 40 years ago! I used to make the telltales when I worked there. It was always fun bringing pockets full out to customer's boats and giving them away like bringing cake or wine to a visit.

I'm no longer a sailmaker, but over the years I have fine-tuned the design. As winter sets in, I always like to make a nice big batch just to keep myself occupied. I thought some of you might be interested to see how I do it.
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2013 Racing Rules of Sailing -- When Boats Meet

With a new year comes new rules. Nothing major changed this year, just clarifications and a few changes to keep people from "working the rules". If you sailed to the intent of the old rules, nothing changes. Here is a link to just the definitions and section 2, When Boats Meet. This is the part every racer needs to know and the source of most discussion of the rules.

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GPX and CSV Waypoint Editor and File Converter

  • Input GPX or CSV Files
  • Add any number of additional waypoints
  • Edit any name, location, or symbol
  • View location of waypoints on map
  • Download as either GPX or CSV The file at the left is an example of the map view of a file about to be edited.

    This tool can be used to convert any Garmin gpx file to a StartLine csv file. In addition, you can use this to read your gpx files into Excel or Word processor for analysis, viewing, or editing.
    GPX -> EDIT -> CSV
    GPX -> EDIT -> GPX
    CSV -> EDIT -> CSV
    CSV -> EDIT -> GPX

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    Buying New Sails?

    by Harry Pattison

    New sails represent one of the biggest investments you make in your boat. So when getting ready to make that purchase what things should you consider to make sure you get the product that best fits your needs and to insure you spend your money wisely?

    First make an honest assessment of what kind of sailing you will be doing. Broadly sailing falls into four categories; offshore cruising, local cruising and recreational sailing, cruise/race, and racing. The type of sail material, type of construction, and the price to some extent will be determined by this decision.

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    Stray Current Can Drop your Mast

    You would think that having researched and witting an article on galvanic corsion that I would know better. But when I installed my antenna on the pulpit thus grounding it, I was only thinking about the VSWR and antenna performance. Little did I know I was going to cause a failure that not only could have but probably should have taken my rig down.

    The coorsion was caused by a 20mA current that was sourced by the potential difference between my newly cleaned (after inspection) bronze chainplate and the zinc on my prop shaft. The path was the bolts holding in my chainplates to the chainplate to the shroud to the bronze ring around my lifeline to the lifeline to the stern pulpit to the antenna ground to boat ground and finally to the zinc on the prop shaft. The connection between the shround and the lifeline was the same as it had been for 50 years but I guess this time it make electrical connection or perhaps it was the different type of twine I used to lash it. That could have held water where the old twine didn't. In any event, in just a few months (May to September) this damage occurred. It is truly amazing that during the race we did the day before ...


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    Rock Box Blue - First Look

    It will not come as a surprise to readers of L-36.com that I was a little disappointed to see that there was no "time to line" function (yet) in the new Rock Box Blue. But if you watched any of the Olympics or the America's Cup you see that the vast majority of starts today have boats lining up at a distance from the line and starting their accelerated run seconds before the gun. For those kind of starts, the Rock Box is a perfect match. Having a 50+ year old 12,000 pound boat, I want more than that and the developer of the Rock Box points out that there is more to come on this really solid platform.

    That said, the new Rock Box is an impressive product. The waterproof case, O-ring sealed looks solid and well made. There is more to this product than just the start function as I will explain below.

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    Buying Used Sails

    by William Posner

    sail Given the cost of purchasing new sails for your boat these days, some are turning to the used sail market. Here at Pacific Sail Trader we wish to give you the lowdown on how best to do it. Purchasing a sail without seeing it in person is the greatest concern of most buyers. Not being able to actually touch it seems to be the missing sense.

    Will it fit correctly? Of course a seller that will provide not only accurate measurements with the sail pulled taught, but showing photos of the good and the bad can help as well. If there are patches or repairs, are they shown? Seeing the corners is key. Often the original owner, especially if a racer will have written the luff , leech and foot measurements as well as the date those measurement were taken. Getting the build date is a plus! Let's say you see that the corner rings are reinforced with leather.Well that's a clue as to the age as it has been many years since that was a standard feature seen on sails.

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    Phone or Tablet On Board?

    Using phones and tablets for marine applications is very attractive. Applications are a fraction of the cost of dedicated marine products that seem to perform the same function. But the marine environment is very difficult and there are problems with both phone and tablet applications. There are many articles on the Internet showing you which 10 apps are the best. This is not one of those articles. This article explores some of the problems people don't talk about and points out what to look for to get the best experience with your phone or tablet. The things that turned out to be important onboard were not the things that seemed important checking out the application at my desk.

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    Starting Line Apps

    I had intended to review both iRegatta and BC Racer. Both are excellent well done apps for smart phones and tablets.

    After testing both, I decided not to review the programs themselves, but to talk about limitations on this class of device. Perhaps you can overcome these limitations but after reading this you will at least you will know what they are.

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    Starting on Time with GPS -- Getting to the line at the gun going fast

    This is the first of a series of articles on using GPS devices to get to the line on time going fast.

    Wouldn't it be great to have an application or device that would get you to the starting line right at the gun going fast. There are several phone/tablet apps that say they will help you do that and a few dedicated boxes that say they will do it better.

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    Weather Page Updates

    It has been about a year since I reported on the L-36.com Marine Weather page. There have been many improvements to the page in that time that I want to share. The page has been well received and has hundreds of users. I thought it would be useful to point out some of the improvements for those of you who have not tried it recently.
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    Wind Map

    wind map This is an experimental page that will show the wind for nearby reporting stations. There are three sources of reports: Local and regional Airports, NOAA Buoy Data Center, and Local weather stations. The local version of this page uses all three. The wide area only the official stations which are from the first two. Please check out this site and give feedback. What do you like and what do you want to see added or changed?
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    No Shackle Toggle Halyard
    UPDATE:

    UPDATE: New configuration shown!
    This article shows how to make a simple extremely light and easy to use no shackle integrated toggle for attaching a halyard to the mainsail. This method works with HM line such as Amsteel. There are several articles elsewhere on the site that show how to make Amsteel to Line halyards. This article is the finishing touch.
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    8:1 and 20:1 Cascade Vang Systems (and link to 16 more vang systems)

    A 8:1 Vang system that is cheaper than using two fiddle blocks, lighter, and stronger. What is not to like? You just run the control line back to the cockpit where you put a cam cleat. You will likely need a turning block on deck but then you have the vang where you want it when it needs to be released quickly before you round up.

    The second vang system shown is the 20:1 vang on Papoose. This is a unique system with some advantages that are discussed.

    This page also has a link to 16 standard variations on vang systems.

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    Eventide Sails Again

    I am happy to report that the L-36 Eventide returned to the Bay on New Year's Day 2012. After our very well photographed adventures at the 2011 Master Mariners Race I faced a tough decision about whether to restore Eventide. Her hull had basically been sawed through from deck to just above the water line by the other boat's chain link bobstay, and her spruce mast and boom were shattered into multiple pieces beyond repair. Eventide had been so thoroughly restored by her previous owner "Chairman" Bob Griffith and given me so many good times that I decided that if I could find a used and affordable mast and boom that the hull was worth repairing.

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    Creating the Easy to Use Waypoint and Route Program

    This winter I am racing on a Tartan-10, not my L-36. We are racing the winter series out of South Beach Yacht Club and another one out of the Golden Gate Yacht Club. The skipper doesn't use a GPS and as I find them indispensable in sailing to a mark and in calling the layline, I brought my wrist version along. But first I needed to program in the waypoints and routes. What a pain. I used OpenCPN and plunked a waypoint down over the marks on the map. Entering the routes was the most difficult. That led me to build the waypoint and route editor. Then I thought, wouldn't it be great to just have a list of all the marks in the area and just check them off, rename them to match the names the race committee uses, import them into a program, copy and paste the race committee routes onto a page and press a button (after a little editing perhaps) and have a file you could download into your GPS? So I built just that.
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    Lazy Lightning racing toward the Bay Bridge

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    Disclaimer:
    The information on this web site has not been checked for accuracy. It is for entertainment purposes only and should be independently verified before using for any other reason. There are five sources. 1) Documents and manuals from a variety of sources. These have not been checked for accuracy and in many cases have not even been read by anyone associated with L-36.com. I have no idea of they are useful or accurate, I leave that to the reader. 2) Articles others have written and submitted. If you have questions on these, please contact the author. 3) Articles that represent my personal opinions. These are intended to promote thought and for entertainment. These are not intended to be fact, they are my opinions. 4) Small programs that generate result presented on a web page. Like any computer program, these may and in some cases do have errors. Almost all of these also make simplifying assumptions so they are not totally accurate even if there are no errors. Please verify all results. 5) Weather information is from numerious of sources and is presented automatically. It is not checked for accuracy either by anyone at L-36.com or by the source which is typically the US Government. See the NOAA web site for their disclaimer. Finally, tide and current data on this site is from 2007 and 2008 data bases, which may contain even older data. Changes in harbors due to building or dredging change tides and currents and for that reason many of the locations presented are no longer supported by newer data bases. For example, there is very little tidal current data in newer data bases so current data is likely wrong to some extent. This data is NOT FOR NAVIGATION. See the XTide disclaimer for details. In addition, tide and current are influenced by storms, river flow, and other factors beyond the ability of any predictive program.