Monday, April 7, 2014

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 Vermeesch's 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.

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