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.

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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.

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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.

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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.

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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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