Didi 950 Build Stringers going on

Earlier this month I posted about the start of construction of the Didi 950 of Micheal Vermeersch in Ohio. Construction is progressing nicely.

The backbone components have all been fitted and glued. They have slotted connections, egg-crate fashion, with all of the bulkheads. Further into the project all of those junctions will be strengthened with structural epoxy fillets.

The sheer clamps have been scarphed into lengths sufficient to span the full length of the boat, from available shorter lengths. Before that they were also bevelled along both edges to remove excess material to save time later planing them to shape.  The sheer clamps are the major strength members along the deck edge. Normally they would sit flat against the inside of the hull skin but with these designs I turn them diagonally across the corner for a cleaner and lighter detail that also has a better balance of gluing area between the components that are being joined.

Now Michael is fitting the hull stringers. With this method of construction the stringers are arranged to suit the different regions of the hull skin. In the photo below you can see the sheer clamp, spanning the bottom corners of the bulkheads. Just above that is a topside stringer. There will be another similar stringer close to the chine that will accurately align the upper side panel.

The other full-length stringer that is in place is the tangent stringer that defines the edge of the curved portion of the hull that is laminated from thinner plywood. On top of the hull there is a stringer partially slotted in, defining the other edge of the curved panel.

Below the tangent stringer is a short stringer at the right in the photo. This is an additional stringer needed to fill in the space where the side panel increases in width due to the tightening of the radius toward the bow.

In the foreground are stringer lengths that will be scarphed together into the long lengths required. The angles have been planed and are ready for gluing.

 

 

 

 

 

Didi 950 with hull stringers being fitted.

To see more of this and our other designs, go to http://dixdesign.com/

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How to build a roller furler for under 40

Ellies home-made sub-$40 roller furler

Introduction:

There are many different types of roller furling systems. This furler is a "Wykeham Martin" or "wire luff" type.  This popular design has been in continuous use worldwide for over 100 years.  It requires a jib that has a stainless steel wire sewn into the luff, or has a "jib set flying" (a jib that does not attach to a stay).  If your jib hanks onto a fixed forestay or needs to wind around a forestay this furler wont work for you. The furler you need would be more like this one.

This furler, as illustrated below, is sized for my 15 Welsford Navigator, or any similar sized small sailboat. It is comparable to a Ronstan RF76 or a Harken 434 dinghy furler.  It can be scaled up in size and strength for larger boats by substituting a stronger eye-bolt, stronger u-bolt, upper swivel, and ball bearing thrust bearing.

Here is a test run of the furler

Origin

In issue #58 of Small Craft Advisor magazine, Kirk Gresham wrote an excellent article on how he designed and built two roller furlers for his 17 cutter Eider for a mere $40 each using bits of scrap and a few bits and pieces of hardware from a local hardware store. This saved Kirk a whopping $670 off the $750 price tag he was quoted for two furler units from a local Port Townsend chandlery. I knew from the moment I read Kirks article that I wanted to build one of his furlers too. I love building things. Id much rather build something than buy it, even if it ends up costing me more. But in this case building it saved me a bundle too. Thats a two-fer for me!

I had some questions after reading the article, but I knew Kirk attends the Port Townsend Wooden Boat Festival every year, so I met Captain Kirk at the festival. He answered all of my questions and allowed me to take some close up photos of his furlers.

Being a mechanical designer by trade, naturally I couldnt resist making some improvements to the design.  I used bronze thrust washers in place of the steel radial bearings Kirk used, and I made the spool with a core of solid hardwood instead of using a section of PVC pipe.  These two changes significantly increase the strength of the furler, make it operate more smoothly and increase corrosion resistance. I also used an ABS end cap instead of the bent aluminum strap used to contain the furling line. It looks better and does a much better job of containing the line.

So, here I present my improved version of Kirks $40 roller furler.

Click to enlarge

Making the Drum Assembly

The drum is made from an inexpensive 3" ABS drain pipe end cap available at any home center that sells indoor plumbing supplies, like Home Depot, Lowes, Grainger, etc.  The cap I used is a Mueller 2979H.  (Note: a 3" cap is actually 4" in diameter.  It caps a 3" inside diameter drain pipe).  Caps are available in a variety of sizes if you want a larger or smaller furler. You will also need a stainless steel eye-bolt. I used a 1/4" x 4" Stanley V2161, but welded eye bolts are a better choice as they are much stronger. To make the drum assembly, drill a 1/4" hole in the center of the end cap for the eye-bolt. Drill 7/8" diameter holes every 45 degrees around the outside for access to the furling line. Locate these holes so they are 1/4" below the open end of the cap.

I also drilled a series of small drain holes in the bottom of the drum.

Use locktite to secure the two nuts on the eyebolt.

Making the Spool Assembly

To make the spool assembly, first I cut two plywood disks from 1/4" plywood. The outer diameter of the disks should be just slightly less than the inner diameter of the ABS cap. We dont want the furling line to slip through the gap and jam the furler. Sandwiched between the disks is a piece of oak (or any other hard wood) that is 2" in diameter and 7/8" thick. Glue these three pieces together taking care to align them accurately. Drill a 1/4" hole through the center for the eye-bolt. Drill two more holes to match the stainless steel U-bolt legs. The U-bolt I used is a 1/4" x 1-1/8" x 3-1/2" Stanley V2193. Drill one extra hole in the upper disk for the stop knot of the furling line. Paint the spool with several coats of enamel paint. Cut and file the legs of the U-bolt flush with the nuts. Use locktite to secure all four nuts.

Assembling the unit

To assemble the unit, place the spool onto the eyebolt of the drum assembly. Then add a 1/4" stainless steel washer, your thrust bearing, and a locknut. Additionally secure this locknut by drilling a tiny hole near the end of the eyebolt and adding a cotter pin, or use Locktite (blue not red).  The thrust bearing is simply two or three 1/4" I.D. sintered bronze thrust washers. These strong, inexpensive corrosion resistant self-lubricating washers should be readily available at any good hardware store, or you can order them here. Once in a great while, apply a drop of motor oil to the thrust washers. It will soak into the porous metal and lubricate them for a long time.

A ball bearing can be used instead of the thrust washers if you prefer. They are more expensive but may operate more smoothly under high tension.  The exact size you need will depend on the diameter of your eyebolt and the space available inside your u-bolt. The style of bearing you would want is shown below, and a source for stainless steel thrust bearings in many sizes is here.  Ive tested both the thrust washers and the ball bearings on my boat and there was no noticeable difference.

Tie a stop knot in the end of your furling line, feed it through the hole in the upper disk and out through one of the holes in the drum. Spin the spool to wind up the line.

Upper Swivel

A swivel is required at the head of your jib to allow the wire luff to spin and roll up the jib.  With this type of furler you want a swivel that spins easily. I have tested three different swivels on my boat that have worked well for me.

This anchor swivel, is a good choice provided your luff tension is not too tight.  If your jib uses a jib halyard, this swivel will work for you. It is extremely strong, very inexpensive, and spins well under moderate tension.  However, since its not a ball bearing swivel, it can stick when tensioned too much.

Ball bearing swivels are a better choice.  The Ronstan RF75 swivel is considerably more expensive, but is an excellent choice for larger sailboats with higher luff tensions.  And this jumbo sized (size 10) fishing swivel is an excellent choice for smaller sailboats and sailing dinghys.  It is the largest ball bearing fishing swivel Ive been able to find and works very well on my Navigator. It is rated to support up to 810 lbs.  Do not rely on this fishing swivel to hold up a mast on anything larger than a sailing dinghy.

A word about strength

Make sure you select components that are strong enough for your application. An easy and conservative way to do this is to look at the diameter of the stainless steel cable used to make your jibs luff wire.  My jib uses 1/8" cable, which has a Safe Working Load (SWL) of 352 lbs.  3/16" cable has a SWL of 740 lbs, and so on.  The SWL of each one of your components (eye-bolt, u-bolt, swivel, thrust bearing, shackles, etc) should be at least as high as that of your cables.  Youll be able to find the SWLs on the products packaging, at the manufacturers website, or with a bit of Googling. That way youll know your furler is stronger than your luff wire.

$40 furlers around the world

Click here to see Barrys UK version of this furler.
These young folks are enjoying their furler on their homebuilt catamaran
John Hows Fulmar
SailCanoeFan in Montreal  

Conclusion

This furler has performed flawlessly on my Navigator Ellie for over 5 years now, and I couldnt be more pleased with it.  If you have any feedback or if you build one of these furlers for yourself, Id love to hear about it.  Please leave a comment below.

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First Build Day Building Form

After months of hemming and hawing over plans and possibilities and uncertainties and even driving to the Middle of Nowhere to get a trailer, finally we start building the boat.  Or at least we build something that is essential for building the boat.

The Glen-L plans call for making a building form upon which to build the boat.  With the building form you get the boat at a height you can work on it, as well as have a level, plum, and square form upon which to assemble the individual pieces.

From these photos you also get an idea of just how beautiful a location we have to build the Shantyboat  Thanks to Lawrence and his family for their generosity, and perhaps their healthy curiosity as they watch the project slowly come together from a pile of lumber to a boat.

I actually found an error on Glen-Ls otherwise flawless building plans.  The plans called for the cross spalls to be 97", which is one inch over 8 (a frustrating waste of conventional length lumber).  Another measurement in an end view gave half the measurement of the cross spall as 3-11 1/2", or 95 inches. As usual after a little back and forth clarification, I got a message from Gayle:

Wes,

I had Glen take a look at the plans and heres his
response:

Seems to be an error. The cross palls should
extend 3 11-1/2" each side of CL or 95" long. You
have thickness of side planking, plus FG plus rub
rail to obtain beam of 8 2". This will make an 8
width on the bottom to match the two 4 wide PW
panels. 

Gayle Brantuk

This building form was mostly made of scrap lumber.  The stringers (the frames of the boat that run longitudinally) will sit on top of and perpendicular to these cross spalls on top of the building form. 

I actually built the form wrong, at least according to the plans (the side pieces are reversed inside out).  And though it didnt hurt anything, it set me off on a cascade of self-recrimination at my carelessness.  If I assembled the boat with as little attention to detail, I would be wasting material, causing undue frustration, and making an ugly boat.

This made me rethink ways I could balance my eagerness with my sense of precision.  The next week I switched gears from my cavalier construction of the building form to a slower more careful approach.

Jen and Kai both helped me make the building form.  And after Kai and I had a pretty pointless conflict, I realized one very important boatbuilding need that I hadnt taken into account for people working hard in the hot sun all day:  Snacks!

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Didi 950 Build Bottom Skin Panels

Mike Vermeerschs amateur boatbuilding project of a Didi 950 is moving on to the next stage, with bottom panels fitted and work starting on the side panels. Mike is building from a plywood kit that we supplied to him and reports that the fit is good. The kit has jigsaw joints on all large panels, making them easy to assemble either on the floor or on the boat.

Didi 950 with all stringers installed.

Two of the stringers each side, at the junctions between flat and radiused skin areas, have plywood doublers attached to serve as backing pads to the joint. I call these the tangent stringers. The doubler on the upper tangent stringer is in process of being fitted and can be seen running forward from the transom through to the third bulkhead from aft.

In the photo below, the transom has been fitted, followed by the bottom panels. These panels each have two transverse jigsaw joints and join each other at a centreline butt joint over the plywood backbone. In the photo the jigsaw joints have temporary battens over them to secure them while the glue is setting.

Bottom panels fitted.

Mike has also started to dry-fit the side panels ahead of gluing in place. At the right of the photo the forward lower panel can be seen and which will continue through to the transom. The lower edge, as seen upside-down like this, forms one half of the chine. The other half of the chine will be formed by the upper side panel.

Today Mikes 300lb brother decided to test the hull stiffness of this partially-built Didi 950 . He climbed onto the bottom of the boat and jumped on the bottom panels. They passed his improvised test but I think that I would have recommended that he wait until the whole hull was skinned before doing such a test.

Mikes 300lb brother tests the Didi 950 hull stiffness.

The broad stringer that shows on this photo is the upper tangent that will join the lower side panel to the radius.

To see our other designs, visit http://dixdesign.com/ .

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Build your own Scamp with John Welsford himself!

Big news in the SCAMP world. The Northwest School of Wooden Boatbuilding is launching a very special "Build a SCAMP" course this summer (August 6th) here in Port Townsend, WA.

What will make the two-week-long course especially notable is that the instructor is SCAMP designer, John Welsford, who is flying in from New Zealand especially to teach 12 students to build 12 SCAMPs.

If that wasnt enough, the NWSWBB has partnered with the Northwest Maritime Center on the course, so all 12 SCAMPs will be built at the NW Maritime facility down on the water in Port Townsend—the birthplace of SCAMP #1.

Students will spend two weeks with John Welsford and two shop assistants building their own SCAMP from the Small Craft Advisor kit made by Turnpoint Design. Students can trailer home their mostly completed SCAMP at the end of two weeks, or opt to extend their stay for as long as two additional weeks.

Details are just being finalized. For more information check the SCA magazine message board or contact the NWSWBB at: (360) 385-4948 or http://www.nwboatschool.org

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Why Would Anyone Build a Boat

Why would anyone build a boat? What kind of question is that for a boat designer to ask? I ask it because there are so many people who ask it in all seriousness. They ask it because they really cant understand why anybody would build a boat instead of buying one. There are so many boats out there that are available and can be acquired with so much less effort, new boats, good used boats, boats that have been damaged in weather events, tired boats that can be rejuvenated and almost dead boats that can be resuscitated.

There is no single answer to that question, there are many reasons why people build boats for themselves and each builder no doubt has a bunch of these reasons rolled up inside whatever it is that drives him to build his boat.

A reason that is common to all of the builders is passion. They have a passion to create a boat, to create something that would never have existed were it not for them and their desire to do this. Having been there myself many times, I can attest to the fantastic feelings that flood through when we first put that new boat into the water and then to give it life by hoisting sail or opening the throttle for the first time. If you think about how wonderful you felt when you first used a new boat that you had bought, doing the same in a boat that you have created with your own hands intensifies those feelings in ways that cant be described.

Petr Muzik built his Shearwater 39 then circumnavigated in his 70s.

It is that passion that also drives many of the decisions that are made during the build project. It drives them to do quality work because they want to feel pride in the final product. They want their creation to show well when seen by others, to be seen as a thing of beauty. Those who have never thought to build a boat themselves look at it and say "Wow, did you build that?".

Financial restraints are behind many amateur boatbuilding projects. If you need or want a new (as in not pre-owned) boat that costs double the money that you can afford to put into it, then the only route to get it is to build it yourself. I have never calculated ahead of my boatbuilding projects how much they are going to cost. Each time I have just dived right in and started, then kept going to the end. That was when I found out what the total cost was and was able to compare with what it would have cost me to buy an equivalent new pop-out production boat. Each time the cost of my fully-equipped boat was around 45% of the cost of a base-package for a production boat of similar size and concept.

Those who dont get it say "It cost you a lot more, you havent priced in your labour hours, which must be priced at your professional rate of pay". No, we dont price our labour into the project and no, we should not price it at the rate that we receive in our paying jobs, whatever they may be. The project serves as a hobby, as recreation that helps us to recover from a tough week working for someone else. It helps to keep us motivated and able to take on the world. The alternative of working very extended hours at our paying jobs to generate the funds to pay someone else to build our boat brings with it a risk of getting burned out in the process.

Andrew Morkel built his Argie 15. Now he and his family are learning to sail in it.

Many people who build big boats for long distance cruising want to build it themselves to give them confidence in the strength of the boat. They know that they will be sailing their boat on very remote waters, far from rescue services and possibly with their beloved family aboard. The safety of all depends on the quality of the build and they dont want to leave that to people whom they dont know. They have vested interest in doing everything in the best manner possible, so they want to do it themselves. In the process they garner the side benefit of knowing intimately how the boat works, where all of the important parts are, how to get to every seacock or filter in a hurry when dictated by some emergency that may develop onboard. They know exactly how to repair everything onboard because they installed it in the first place. They are likely to lay out all aspects in a very sensible and logical manner because they will have to maintain it themselves. At sea in a storm is not the best time to be trying to track down plumbing or electrical faults in systems that are overly obscure because the person who installed them before the hull liners or lockers were installed didnt consider the problems of working on them in the completed boat.

Others build their own boats because they want something different,  a boat that will stand out from the crowd on marinas, at sea and in distant anchorages. They add personal styling features to fit their own characters and they choose joinery detailing such as is not available from production boatbuilders.

Sergey Federov built his Hout Bay 33 to a very high standard.

Some people choose to build a boat purely for the hobby benefit. They enjoy the build more than using the boat, so the project will be drawn out interminably. They produce exceptional quality in the process but will probably sell the boat when completed or soon after.

It has been said many times that the happiest days of a boatowners life are when he buys and when he sells the boat. The exception to that cliche is the boatowner who has built his boat himself. There is so much of the builder wrapped up in that boat, in the form of blood, sweat and tears, to say nothing of chunks of skin and body hair, that he and the boat have an affinity and  intimacy that is unknown to those who buy their boats. I have felt very sad when selling each of the boats that I have built, far from the happiest days of my life.

It has also been said many times that boatbuilding is a disease and when you have had it, you will experience periodic relapses. I have to agree with this one, I have had numerous relapses. I cant say that I have suffered relapses, as would apply to most diseases, I have enjoyed those relapses too much to convince my wife that I have suffered in any way. And this is the way that most amateur boatbuilders feel. Visit any of the many boat shows that cater for amateur boatbuilders and you will see for yourself how much they love what they do and just how much passion they build into their projects.

To see our range of designs, for amateur or professional boatbuilding, please go to http://dixdesign.com.

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