Choosing a Sail Plan: Balanced Lug Yawl

After choosing a boat to build, I needed to decide on the sail plan.  The Welsford Pathfinder has at least three configurations available: Bermudian sloop, gaff yawl, and lug yawl.  I had considered the gaff yawl plan, and still think of it as the ideal plan for sailing given the flexibility of depowering the boat in heavy winds with either jib and mizzen or main alone.  But the idea of sitting at the boat ramp and setting up shrouds, forestay, and jib with roller furler and associated sheets every time I wanted to sail made me pause.  The lug yawl is a simple plan, unstayed, and the idea of a more relaxed plan without a tensioned, stayed mast was appealing.  Everything in sailing is a compromise, and most advise that the tradeoff here is in upwind performance.

Credit: Watertribe.com “DekesRaceReport”

I was sold after reading about the lug yawl Welsford Pathfinder “First Flight” completing the Everglades Challenge (http://watertribe.com/PDF/Florida2018/DekesRaceReport.pdf ) with decent upwind performance after tuning the main of the lug yawl.  CLC boats also describes advantages of a lug in small boats (https://www.clcboats.com/life-of-boats-blog/lug-nuts-lug-rigs.html  ).

I decided to build the lug yawl version of Pathfinder, and ordered the “Lug Yawl” plans as an add-on to the main plan set from Duckworks.  The Lug Yawl plans consist of  one page, specifying a 145 sq ft main and other details, but it was clear that something was amiss.  There is no mizzen drawn on the plan sheet.  It seemed very unusual for a designer to draw a plan sheet for a sail plan and not include one of the two sails.  Online searching confirmed others had altered the lug yawl plans after raising similar concerns, with the decision made to move the main mast location up to aft of bulkhead #1 (http://forum.woodenboat.com/showthread.php?188315-Pathfinder-Build-In-FL-Keys&p=5006887#post5006887 ).  “Gardens of Fenwick” is the other lug yawl Pathfinder I am aware of that has been completed (https://prep4texas.blogspot.com/2018/03/healing-thinking-and-projects.html#comment-form ), and he also placed his main mast just aft of B#1, specified in what I understand is a different set of lug yawl plans from what I have, drawn by JW specifying a smaller, 105 sq ft main.

Why does it matter where the main mast is placed?  Well, the center of effort describes the central point of force on the sails of a boat, and its location in relation to the center of lateral resistance (determined by the keel and hull size/location) affects the balance of the boat.  If the COE is too far forward of the CLR, there is a tendency to lee helm, and the opposite is true (weather helm) if COE is too far aft of CLR. Most sources suggest that it is ideal to have to COE just aft of the CLR to create a mild weather helm.  I found out as well that the COE tends to move aft as the boat is underway, so the calculated values often place COE farther forward to adjust for this.

Anyway, the COE on the “lug yawl” sail plan-- without any mizzen drawn in -- was exactly where it is located on both the gaff yawl plan and the sloop plan, which suggests that is the ideal place.  But I still wondered - is the COE on my plans accounting for the phantom mizzen, or is there a mistake in the plans and this is actually a lug (non-yawl) plan set?

I contacted a respected authority, who sent a short note recommending sticking with the plans, and using the mizzen location shown on the gaff yawl plan.  It still didn’t feel right, so I went about finding how to calculate a center of effort to double check the plans.  I found an old reddit post linking to a much older article in “The Rudder” circa 1902:

It describes the simple geometry needed to calculate a center of effort.  Scribbled arithmetic decorates the sides.  It’s a reminder that in 1902 you couldn’t simply pull up a calculator for solving math problems.  I found a certain satisfaction in plugging in numbers and getting the answer for the center of effort.  Once I got there, I was able to confirm my doubts.  The sail plan I received was for a balanced lug rig (ie., single lug sail without any mizzen), not a yawl.  That explains why there is no mizzen drawn on the “lug yawl” plan.  So the main mast will need to move forward to just behind B#1 to account for the mizzen and maintain a balanced helm.  The goal is to have the final COE -- including the mizzen -- in the same place as the other Pathfinder sail plans.  Placing the mast in this location is the same conclusion drawn by another builder who has completed his Pathfinder and has youtube videos showing a nicely balanced boat, so I feel comfortable with the decision.  

Welcome: Choosing a Boat Design

Welcome to my story about building a sailboat at home. I am underway on a project to build a Welsford Pathfinder, and although there are many excellent blogs already published with far more details about the build than I would be able to write, along the way I have learned things that may be helpful for the next builder.

First, I wanted to mention a couple of the other designs I looked at because, frankly, they are all incredible and I wish I had time to build them all.

After reading online about various boats that can be built from plans at home, I narrowed my choices to three designs.  My requirements were:

• Approximately 17 feet in length. This is the largest I can fit in my garage during the build. 

• Easy to trailer, which to me means under about 1200 lbs and a shallow draft given my vehicle towing capacity.  

• Option for a small cabin or cuddy, both to create a dry area to escape the cold SF bay spray, and for an enclosed area for “biobreaks” during a daylong sail.  

• I initially had a requirement to have an orderable CNC plywood kit to jumpstart the build, but eventually abandoned that idea.

Here was the shortlist:

• B and B Yachts Core Sound 17 mark III

• Kees Prins / Iain Oughtred modified Fulmar, “FarFetch”

• John Welsford Pathfinder

The others I considered included “Able” by Selway-Fisher, “Ebihen 16” or "Ilur" by Francois Vivier, the Willow Bay “Shilling”, and JW’s smaller Navigator. Able and Ebihen do not have cabin plans available, Shilling’s listed weight is more than I was planning and there is limited information about builds available online, and the Navigator vs Pathfinder decision came down to having enough space forward for a small cabin and possibly a drier boat with the larger size of the Pathfinder.

1. B and B Yachts Core Sound 17 mark III

Image: B&B Yacht Designs http://bandbyachtdesigns.com

This is a wonderfully engineered boat in my opinion, a cat ketch design which is well suited to singlehanded sailors.  Use of the 17 foot space is close to ideal with a decent cockpit and roomy enough cabin for sleeping.  The boat is self-righting (check out this test: https://www.youtube.com/watch?v=ObO_0BdYeMU ), mast tabernacles are part of the plans for quick launching from a trailer, solar panel and battery placement are already indicated on the plans, and there is even a windvane design.  I was an email away from ordering the kit, and I still think this would be a fantastic choice meeting all of my needs.  But there was one problem I couldn’t overcome.  I just couldn’t get used to some aspects of what I saw as a boxy appearance.  Coming home to see my boat on the trailer every night, it has to be an emotional connection that wasn’t there.

I even used a CAD program to draw some alternate deck shapes and considered making alterations on my own (see below for an example), but after realizing that the mast support is integral to the deck shape because of the thoughtful engineering in the CS 17 mk3, I realized I was in over my head and decided to move on.

2. Kees Prins / Iain Oughtred modified Fulmar, “FarFetch”

Image: Wooden Boat Magazine, Kees Prins in the original Fetch https://www.facebook.com/WoodenBoatPub/posts/fetch-adapting-a-small-daysailer-for-cruising-read-tom-jacksons-article-in-wb-no/10153618587220603/

I am really taken by the lines of this boat, based on Iain Oughtred’s Fulmar, a 16’7” clinker plywood planing dinghy.  Kees Prins created his own cabin cruiser adaptation which, by all reports, is seaworthy and comfortable.  At the request of a prospective builder he drafted plans for FarFetch, a widened Fulmar with drawings for a cabin similar to Fetch.  If I were an expert builder, this would be my ideal boat.  A couple of slight drawbacks for my needs were the stayed cutter design of FarFetch (different from the original Fetch, which is a yawl), as it would be slower to rig on the boatramp.  The projected weight of around 1500-1600 lbs would push it over the towing capacity of my small crossover vehicle.  But more important was that a combination of Oughtred’s and Prins’ designs are needed to complete the build, adding to the complexity of an already years+ long project, and I wasn’t confident enough to be the first builder to undertake this one.

3. John Welsford / Pathfinder

   

   Image: duckworks.com 
   

   
   

I came to the Pathfinder next.  Frankly, I started out with the Pathfinder and was initially put off by the lack of availability of a CNC kit. It is described as relatively easy to build, trailerable, with cabin modifications available online.  Great traditional lines with a plucky curve to the sheer and just enough coaming to keep out some spray and define the active area of the cockpit.  People have sailed Pathfinders in quite varied conditions, so although it will be challenging to sail a flat bottom design on San Francisco bay, I believe the boat--  well-sailed -- will be suitable.

For those of us new boatbuilders, the extensive community available online (numerous builds well-documented in blogs and forum threads and JW’s active Facebook group) provides reassurance that if I get stuck, I can find someone else who has solved the same problem.

I decided on the Welsford Pathfinder.  I’d be happy to hear about other similar choices others have faced and what factors tipped their decision - especially from anyone who has undertaken the beautiful FarFetch.

My perspective in writing this is after having started the project (sourced key materials, cut out the frames and starting gluing them).  Having initially planned to jumpstart my build with a CNC kit, I would suggest to any prospective builders not to limit yourself to kit-available plans.  The Welsford plans have a series of drawings of the frames with measured setbacks for the curves, so it isn’t necessary to do the start-to-finish full lofting process I was worried about.  And it did not take as much time as I feared - working only on weekends and one day during the week, I had the frames cut out (ie., the starting point of a CNC kit) in about 8 weeks.  And I’m slow.  It takes that long to order a CNC kit and have it dropped on your driveway anyway.