Didi 950 Projects

There appears to be considerable interest in my posts about the boats being built to our Didi 950 design. This is a radius chine plywood design with hard chine in the topsides, designed to fit into the Classe 950 box rule. In the past few days I have received a bunch of new photos that show the build process clearly, as well as some updated progress photos.

Before going into the new photos, you might like to read the article that I posted today on my Boatbuilder Tips for Amateurs blog about how to construct building stocks or beds, the foundation off which the skeleton of a wooden boat is built. It is illustrated with photos of the Didi 950 that is being built by Fred Grimminck in Australia. The photos below are mostly of that same project, being built from scratch without a kit.

The photo below shows the various backbone components, all of which slot eggcrate-fashion into the bulkheads. The slots help to locate the bulkheads and backbones correctly relative to each other. The bow and stern have single backbone on centreline and the mid-part of the hull as two backbones that run down each side of the keel support box. The two shorter pieces on the right are the paired double-backbone parts. Next toward the left is the aft backbone, which turns up at the far end to support the transom. Extreme left is the bow backbone, which turns up at the far end to form the stem and supports a bow bulkhead into which the forward ends of the stringers are located.

Didi 950 backbone components. Click on all photos to enlarge.

The photos below show a few of the forward bulkheads with the bow backbone dry-fitted in place. The backbone has doublers just below deck level for through-bolting the bow chainplate. The doublers can be seen at the forward lower end of the backbone.

Didi 950 bow backbone and forward bulkheads

Didi 950 bulkheads and backbones

In this next photo, the transom doubler has been set up as a doubler and the stringers etc run through, then are trimmed flush. When the transom is glued over the doubler the end-grain of the longitudinals will be covered and protected. Look through the 4th cutout from left through the doubler to see how the aft end of the aft backbone turns up against the inside face of the doubler. The backbone has locating tabs that slot through the doubler, seen as light-coloured marks on centreline of the doubler. In the lower photo the transom is being glued over the outside of the doubler.

Didi 950 transom doubler

Didi 950 transom being glued over doubler.

The sheer clamps on this design sit diagonally across the corner at the intersection between hull sides and decks. They are screwed and glued to cleats on the faces of all bulkheads. In this photo the sheer clamp is clamped to those cleats. You can also see how the stringers are slotted through the bulkheads. Once the hull skin has been glued on, these junctions become very strong and rigid

Didi 950 sheer clamp

Looking forward along the hull just prior to fitting the bottom skin. The wide stringers on both sides are the tangent stringers, with doublers to back up the joint between flat bottom panels and radius skin panels at the turn of the bilge.  The single aft backbone can be seen running through to the 3rd bulkhead from the bottom of the photo. The double backbone runs forward from the 2nd bulkhead from the bottom of the photo, then changes back to a single backbone further forward, also visible.

Didi 950 bottom stringers and backbones

Stringers in the forward part of the hull, mainly showing the radius area. The two broad stringers are at the tangents, joining the flat and radiused skins together. Between them are three radius stringers, over which the double-skin radius will be formed. Below the lower of the two tangent stringers are the stringers for the side skin panels.

Didi 950 stringers

This last photo shows Mike Vermeeschs boat, being built from a kit in Ohio. Mike has the side panels all dry-fitted to check for fit ahead of gluing in place. Looks like a nice fit. The bow will be capped with solid wood, which will cover and protect the end-grain of the stringers.

Didi 950 hull side panels

Thank you to both Fred Grimminck and Mike Vermeersch for taking the trouble to send me these photos and allowing their use.

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

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Update on Didi Sport 15 and Didi 950

I have recently added two new radius chine plywood designs to our range and wrote about them on this blog. Here are updates on both boats.

Yesterday I visited the prototype of the Didi Sport 15 (DS15) that is being built by Hunter Gall in Virginia Beach. I hadnt seen it in the flesh for a few weeks and wanted to see how the deck is looking as it comes together. Hunter is doing a really nice job of his project, working slowly but meticulously.

His boat, "Scallywag", is looking very pretty. He stained the hull surfaces blue and the deck surfaces red before doing the epoxy coatings and these colours will be highlighted by areas of clear-finished timber. It all entailed a tremendous amount of extra work to get it right than if he had painted it in the normal way. The final result is very attractive and she will be an eye-catcher when complete. Hunter can be pleased with the overall results.

The deck configuration that I designed is unusual, with a raised mast deck and wave-breaker above a flat foredeck and the open self-draining cockpit. It gives a decidedly retro image to the deck, over the thoroughly modern hull. It reminds me somewhat of the Lightweight Australian Sharpies that my Dad sailed in South Africa when I was a child. That makes it  somehow fitting that Hunter Gall is Australian, I am South African and we have ended up working together on this project in USA.

Hunter Galls DS15 project nearing completion

Other news on the DS15 is that work will start in the next few weeks on moulds to build a composite version in Europe. I will release more information about it after I return from the Cape to Rio Race, by which time the builder may be ready to start receiving enquiries.

The other boat was the Didi 950, for which the prototype kit has been cut and will be delivered to the builder in the next week or two. It appears that this is going to be a popular design because we have sold plan packages for another three boats since announcing the design.

Didi 950, bigger sister to the DS15

 One of those boats will result in a variation on the design, with a lifting keel. A lifting keel was part of the original concept for the builder of the prototype but he decided in the end on the simplicity of a fixed keel. The lifting keel proved to be a very viable option, using the same basic keel support arrangement as the fixed keel with no structural redesign. The major difference will be moving the motor aft to a position under the companionway, driving a saildrive rather than a shaft. This is to make room for the lifting keel to rise through the galley central locker unit.

The prototype of this design is to be built in Ohio, USA. The others that have been ordered will be built in Australia, Latvia and Greece. There is interest from other countries as well.

To see our full range of designs, please visit http://dixdesign.com/.

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Didi 950 Progress Lifting Keel Option

Mike Vermeersch in Ravenna Ohio turned over his Didi 950 hull a couple of weeks ago and sent me a video of the process.  He turned the hull with the help of a few friends, using the spit roast method and a pair of engine hoists.

With the hull settled in her new cradle, Mike has settled into doing the epoxy fillets and coatings, ahead of starting on the interior joinery.

Epoxy coatings progressing on Mikes Didi 950

While builders have been making material progress with their builds, I have been doing the drawings that detail the lifting keel version for Fred Grimminck. Fred is building his Didi 950 in Queensland, Australia. He has also turned his hull in the past fortnight.

The lifting keel version uses a keel support box of identical footprint to that of the fixed keel version. The difference is that the keel has to slide through where the motor sits in the fixed keel boat, so the motor has relocated to below the front of the cockpit and has a saildrive. The keel support box for this version has the casing built into it, with a flange at the top edge for bolting the keel securely in the down position. In the raised position, the keel is at approximately the same level as the bottom of the rudders. Draft is 2.35m (79") with the keel down and 1.15m (39") with the keel up.

The keel is lifted by means of a tackle, with the tail led to a dedicated winch that is recessed into the galley counter. This is a simple system, without the waterproofing and complication issues of leading it to a cabin roof winch.

Accommodation of the lifting keel version of the Didi 950

This lifting keel offers Didi 950 owners the possibility of having a racer or a performance cruiser, with deep draft, that can live on much shallower moorings or can access shallow anchorages.

To see our full range of designs to a wide range of concepts and materials, please go to http://dixdesign.com/.

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Didi 950 Construction Starts

Michael Vermeersch has started building his Didi 950 prototype in Ravenna, Ohio. This is the prototype of a very new design. Micheal is building from a pre-cut kit that we supplied and reports that the quality and fit have been excellent thus far.

Didi 950 Kit, ready for unpacking

 Yesterday Michael and a friend set up the bulkheads on the building stocks and he is now preparing to fit the backbone components to tie the bulkheads together.

Didi 950 Bulkheads set up and waiting for backbone.

This design has been drawn to comply with the Class 950 Class Rules. Watch this space for progress reports on this boat and the other Didi 950s being built in Australia, Latvia and Greece.

Please note that precut kits for our plywood designs supplied in USA must be ordered from Dudley Dix Yacht Design and not from the company that cuts them, Chesapeake Light Craft. For more info and pricing go to our plywood kits page.

To see our full range of designs please visit http://dixdesign.com/ .

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Radius Chine Plywood Class 950

The Didi 950 is our newest design and the plans are now nearing completion. They show a very modern boat that is designed to comply with the Class 950 Rules and which can be built by any reasonably competent amateur woodworker.

Sail plan of Didi 950

The Class 950 Rule produces a fast boat that is great for level boat-for-boat racing. The rule results in reasonable proportions and features, for a safe and strong boat with comfortable accommodation that is also good for a performance cruiser.

Class 950 accommodation

Construction is radius chine plywood with a hard chine aft in the topsides. This format produces a very modern hull that is built mostly from a very low-tech sheet material, yet looks as good as any moulded composite boat that can only be built with skills that most amateurs dont have. Most men are comfortable working with wood and this construction method allows them to use those skills to build a competitive boat.

3D Profile of Didi 950

The more that I look at this boat the more that I would like to be on it for offshore or ocean racing. This would be a great boat for sailing trans-Atlantic in the Cape to Rio Race or going across the Pacific in the Trans-Pac Race. Close-reaching to broad-reaching under asymmetrical and powered up by water ballast tanks, she will be a thrilling boat, reeling off the miles like few others in this size range can do.

3D View with contours to highlight hull shape.

Someone close by, please build one of these boats. I need to sail on this one.

For more info go to http://dixdesign.com/didi950.htm and visit our website at http://dixdesign.com/ to see our other designs.

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Didi 950 Build Started

Michael Vermeersch of Ohio commissioned the Didi 950 design and has now started construction of his boat. He is building from a pre-cut plywood kit that was supplied by Chesapeake Light Craft in Annapolis. The kit arrived as 61 sheets of plywood with all components accurately cut by CNC router and packed on 2 pallets.

Michael reports that he is progressing well with the assembly of the backbone and bulkheads and that everything is fitting together beautifully. A few more bulkheads to go, then he will be ready to start setting up on the building stocks.

Michael with wife Pat & daughter Catherine.

Since adding this design to our stock design list, another three boats have been started. They are in Australia, Greece and Latvia.

The Didi 950 is drawn to the Class 950 Rule and detailed for building by the radius chine plywood construction method. It can be built from plans only or from a kit. Kits are currently available in USA but can be supplied by most of our international kit suppliers as well. Enquire with the supplier in your area and I will send the files to them for pricing. Note that for USA you must order from us, you cannot order it directly from Chesapeake Light Craft.

For our full range of designs, please visit http://dixdesign.com/.

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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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Didi 950 Up and Over

This seems to be a period of hull-turning. About 10 days ago I posted about the Didi 26 being turned in Hood River, OR. Now I am doing the same for Mike Vermeerschs  Didi 950 in Ohio.

Mike turned his hull this weekend and it went very smoothly and safely. It is a much bigger boat, with more weight that can potentially get out of control and more height needed to successfully accommodate the hull on its side as it goes through the process. Bigger and heavier boats need more care, preparation and equipment than is the case with smaller boats.

Mike chose to turn it using the spit-roast method. This is only one of many methods that I describe in my book "Shaped by Wind & Wave".

Turning by this method is done by attaching axles to both ends of the hull to suspend it on supports (Mike used engine hoists) while it is rotated on the axles. Care must be taken to get the axles on centreline and close to the vertical centre of gravity of the hull, to keep the rotational forces small. In this case Mike asked me for the position of the VCG, which he says proved to be spot-on. Once lifted, he turned it by himself, exerting about 20lb of force to rotate the hull. These photos tell the story.

Spit-roast axles ready to be fitted.

Axle bolted to transom.

Axle bolted to bow.

Axle in chain sling attached to boom of engine hoist.

Lifted on engine hoists and turn started.

Almost over.

Cradle ready for the hull, on castors for easy moving.

Safely settled in her new cradle and ready for interior work.

Thanks Mike Vermeersch for the great photo series.

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

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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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Didi 950 Hull Skin Completed

Over the last few months we have watched as two builders on opposite sides of the world have worked on their Didi 950 projects. Mike Vermeersch in Ohio, USA, is building his boat from a kit and Fred Grimminck in Queensland, Australia, is building his from scratch.

Fred has taken a break from his boat for a couple of weeks while delivering his recently sold Didi Mini clear across Australia by road, a formidable road trip.

Fred Grimminck delivering his Didi Mini Mk2 across Australia.

Mike has been able to continue and has now completed the fairing and sanding of the radius as well as fitting the bow capping and shaping of the forefoot. His boat is looking very nice, with the final hull shape now clear.

Radius skin completed but still to be faired.

Radius faired and sanded. The jigsaw joints of the side panels are seen below the radiused panel.

Completed stern sections.

Bow capping fitted, ready for shaping.

Bow capping and forefoot shaped and sanded.

Completed bow shape. Clean and shaped from plywood.

Faired and ready for epoxy and the fibreglass reinforced areas to be done.

There are also builds of the Didi 950 progressing in Greece and Latvia.

To browse our full range of designs, please visit http://dixdesign.com/.

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Didi 950 in Australia

Fred Grimminck in Queensland, Australia, has previously built a boat to our Didi Mini design. Now he is building a Didi 950. In contrast to the boat of Mike Vermeersch that I showed yesterday, Fred is building his boat from scratch, marking and cutting the plywood panels himself from our drawings.

Today I have received photos from Fred of his project. He is at the same stage as Mike but the different perspective of his photos shows the details from different angles to help visualise how it all goes together. Click on the photos to enlarge.

Bottom panels fitted, bow view

In this photo you can see how the bottom panels are slightly Veed aft but the V increases toward the bow and the flat panels become very fine, both features to soften the ride when the boat is planing fast in lumpy water and slamming over short waves can become uncomfortable. The edges of the panels land on the doublers of the tangent stringers at the intersections of flat and radiused skin panels. The edges are rebated to half-thickness, with the first layer of radius plywood landing on the doubler and the second layer landing on the rebate, forming a Z-shape joint detail.

Ready for side panels to start

 In the photo above, the doubler at the upper tangent is in place and part of the lower side panel is clamped in place, seen at bottom right. The left edge of this panel has been planed to form the sloping surface for the scarph joint to the next piece, the main difference from the jigsaw joints of Mikes kit. Also visible in this photo, are scarph joints in some of the stringers. These appear to have been glued in place on the hull. The alternative is to pre-glue them into long lengths before installing in the boat.

Interior view of transom and cockpit area

The photo above shows some of the interior detail. The transom is 9mm plywood but has doublers to strengthen it around the perimeter, at the backbone and at the rudder hardware. You can see the plywood backbone passing through the bulkhead ahead of the transom. These intersections are self-locating egg-crate detailing to assist with accuracy during setting up the skeleton. The backbone is on centreline in bow and stern but changes to a pair of backbones offset from centreline from forward of the mast through to the cockpit.

A major difference between the two boats of Mike and Fred is in the keel detailing. Mikes boat has a fixed bulb keel that hangs from an internal support box that is bolted between the two components of the double backbone. The support box also holds the engine beds and bearers, sited directly over the keel. Freds boat will have a lifting keel. It will be housed in a modified keel support box of identical footprint but with integrated casing for the lifting keel and without the engine beds. Freds engine will be a saildrive unit located under the companionway and front of the cockpit.

There are also boats to the Didi 950 design beign built in Greece and Latvia. Watch this blog for news on all of them.

Go to http://dixdesign.com/ to see our full range of designs.

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Didi 950 Hulls Taking Shape

The Didi 950 projects of Fred Grimminck in Australia and Mike Vermeersch in USA continue in parallel. Freds build is from plans only and Mikes is from a kit that was cut by CNC router. Both have completed the flat sheet panels of the sides and bottom and are now skinning the radiused parts of their hulls. This is the stage that the hull shape really starts to show.

Some of the photos that I show of these two projects show minor differences, due to building from a pre-cut kit or with the builder cutting all components. Both produce the same boat at the end of the process but they may look a little different at times while being built.

Side and bottom panels all completed, ready for radius to start.

The photo above is of Mikes kit boat, with neat edges at the sheer (where hull and deck will meet). The photo below is of Freds boat with irregular edges at the sheer. This is because the kit panels are supplied with a uniform strip of waste to be trimmed off to the final line after turning the hull over, while the boat built without a kit has the panels inividually cut by the builder and the waste width may vary.

Same stage, Freds boat. Backbone still to be trimmed at forefoot.

The radius is skinned in two layers, made with narrow transverse strips. The first layer lies on the stringers and the doublers of the tangent stringers, fitted between the edges of the side and bottom panels. These edges have rebates pre-cut into them and onto which the second layer will be laid.

First layer of radius being fitted to Mikes boat.

The rebate along the edge of the side panel can be seen in this photo.

Final hull shape starting to become clear.

Construction of the boat in Latvia has now started and the boat in Greece will soon follow. To see more of this design and others in our stock design range, please visit http://dixdesign.com.

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Didi 950 Downunder

I have shown the Didi 950 project of Fred Grimminck in Queensland, Australia, in previous posts. Since then he has progressed nicely and is now well into the fitting-out phase. This, of course, had to start with turning the hull right-way up. Fred used a similar method to the hull turning that I showed recently in Ohio, except that he replaced one of the engine hoists with a tractor-mounted forklift, to lift the hull and pull it out of the building shed, then push it back in. Here is Freds video of the operation.

The fitting out is moving along, as can be seen in these photos.

Starboard water ballast tanks

Port water ballast tanks and double quarter berth.

Building the saloon settees.

Same area, from above. The open area where the vacuum cleaner is
standing is where the engine is located in the fixed keel version.
This boat has a lifting keel, which will pass through this area.

Looking forward at the foredeck, with deck beam flange being laminated.

This is the second boat of our design that Fred has built. Five years ago he built a Didi Cruise-Mini that he sailed for a few years, then sold recently. Watch this space for more photos of the progress of Freds project.

See more of this design and others in our portfolio, at http://dixdesign.com/.

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