Didi 40cr2 Kit at Exocetus Marine

 A few months ago I posted about the comprehensive kit being developed for the Didi 40cr2 by Exocetus Marine in UK. They are building a boat at the same time as developing the kit, to check everything for proper fit and assembly. Since my previous post the build has progressed to hull turn-over stage.

See captions under photos for explanations.

Side panel glued to hull framing.

First layer of pre-formed radius skin panels being installed.

This is how the radius skin panels are supplied in the kit, pre-formed in the Exocetus workshop.

Inside view of the radiused portion of the hull.

Second layer of radius fitted. A jigsaw joint on the side panel can also be seen.

Hardwood keel shoe, also cut by CNC. This forms a tough and flat surface onto which the keel root is bolted, removing compressive loads from the softer okoume plywood skin.

The gloss epoxy in this photo shows the fairness of the radius chine plywood hull. In the background is a Dix 470 catamaran that is also available as a kit, being built in the workshop.

High-build epoxy primer.

Outside, ready for hull-turning.

A novel way to turn a hull. I've not seen it done this way before.

The keel shoe is visible in this photo.

Steel frame on which the stern was supported during turn-over.

Turn-over completed.

The kit that Exocetus Marine is developing includes all plywood components plus all solid timber structure, pre-shaped and ready for installation. Their instruction manual is also very detailed, with interactive PDF 3D drawings that allow the builder to view in various formats and to zoom in to see finer detail.

To see our full design range, go to our main website or our mobile website.

Didi 40cr2 Kit from Exocetus Marine

Exocetus Marine in UK develops and supplies kits for our radius chine plywood catamarans, with kits produced for the Dix 470 and DH550 cats. A kit is currently in development for the new Dix 430 catamaran. The kits are very comprehensive and can be customized to each customer's needs, from basic bulkhead kits through to inclusion of whatever equipment and materials the particular builder would like to be delivered in the shipping container with the pre-cut plywood and other timber.

I have written about the Exocetus Marine kits in earlier posts on this blog, from when development first started in 2012. They have come a long way since then, under the expert hand of owner Kevin Bream.

CNC Kits for 47ft Plywood Catamaran
Dix 470 Catamaran Kit Build in UK
Kit-build Dix 470 Plywood Catamaran
Plywood Catamaran Kits
More About Plywood Catamaran Kits
DH550 Kit Shipped to Southern Africa
Dix 430 Catamaran

The DH550 catamaran "Valerie", built in Durban, South Africa, and in charter service in the Seychelles, was built from a very comprehensive kit supplied by Exocetus Marine, which included solid timbers, epoxies, engines, hardware, electronics, porthole frames etc.

DH550 charter catamaran "Valerie".

The Dix 470 catamaran "Marram", being built in Australia, is a big amateur project. The components have all been cut from CNC cutting files developed and supplied by Exocetus Marine.

Dix 470 "Marram", a husband and wife amateur project.

Exocetus Marine is now expanding their range in a new direction. This harkens back to my origins in radius chine plywood designs with my Didi 38 prototype "Black Cat", which has spawned a large and expanding range of designs from 15ft to 55ft, spanning both monohulls and multihulls. The Didi 38 design itself expanded to the Didi 40cr and, most recently, the Didi 40cr2. It is the Didi 40cr2 that is the newest project by Exocetus Marine.

"Passion X", prototype of the Didi 40cr2 design, built as an amateur project in Australia.

As with their catamaran kits, Exocetus is developing a very comprehensive kit for this first expedition into monohulls. In doing so they have transformed my CAD drawings into a complete 3D model before extracting the components for cutting by CNC then testing for accuracy of build. In doing this they are building the boat as well, enabling preparation of complete building instructions to guide those who will follow to build the Didi 40cr2 for themselves.

These photos are a few from the build record to date.

Bulkhead example, with jigsaw joints, doublers fitted around stringer slots.

All parts are referenced for identification and assembly instructions.

Bulkheads set up on the building stocks.

Cockpit structure installed, bracing the whole structure.

Backbone with bevels and scarphs pre-cut.

Pre-cut opening for propeller shaft log.

Laminated keel floors.

Keel floors installed through backbone structure.

Stringers being installed. This is a tangent stringer, with a doubler on the outer face for joining the radiused skin above the stringer to the flat skin below.

Hull side panels jigsaw-jointed at ends of sheets.

Example from the interactive building manual for the DH550 catamaran. A similar manual will be supplied with the Didi 40cr2 kit.

Check back to this blog occasionally. I will update here on progress of the kit development and the construction of their boat.

For more information on our designs go to our main website or our mobile website.

Road Trip to Sail the Didi 29 Retro "Arabella"

It was my 70th birthday 2 weeks ago and I was surprised by my family with a totally unexpected visit by my sister Dorothy and her daughter Robynne from across the Atlantic, come to participate in the festivities and to help make it a very special occasion. Winding down Dorothy's trip, she and I made a brief road trip to North Carolina. We started off down the Outer banks, where I hoped to find some decent surf. The weather stymied that one with strong onshore winds, so we wasted little time feeling sand between our toes, visited the Graveyard of the Atlantic Museum in Hatteras and arrived at the ferry dock to board for Ocracoke to find rows and rows of cars waiting ahead of us.

Innocent us, we did not expect a flood of people to be visiting this tiny barrier island. I expected to arrive at the ferry dock and be boarded 15-30 minutes later, then a short crossing, time to get lunch on the tiny island before boarding our reserved ferry to Cedar Island. Wrong. After sitting in the queue for a long time, the very accommodating NC Ferry staff let us jump the line to catch the next ferry, or we were not going to make out 4pm ferry. That short crossing to Ocracoke is actually about 4 or 5 times the straight-line distance because the ferry has to wind back-and-forth through the channels.

Satellite view of Ocracoke Inlet, Courtesy Google Earth. The Hatteras ferry dock at extreme right, Ocracoke ferry dock at extreme left. The sand banks and channels move around and the ferries have to zig-zag through them. 

So, we had a drive-through tour that really didn't do justice to the very cute little town of Ocracoke, arriving in time to check in for our next ferry, without lunch. The ferry route to Cedar Island was more direct and parallel to the barrier islands, in deep water.The main entertainment was a variety of seabirds soaring behind us and looking for food to be churned up by the propellers or tossed in the air by passengers.

Once on land we saw the results of the coastal areas that were devastated by Hurricanes Florence and Michael last year. Homes destroyed, most that survived now being jacked up 6-8ft to get them above future flooding.Trees still on top of some homes, no longer habitable. And our hotel still undergoing reconstruction, with water service disrupted at times and cold water coming out of the hot taps. But the beds were new and very comfortable, so we got a good night's sleep. In the morning, a short ferry ride and drive to a marina in Oriental.

"Arabella" is very pretty. She was built by professional boatbuilder Bruce Mierke as his personal sailboat, to our Didi 29 Retro design. He customised his build to suit his own needs, so she has a shorter cabin and some different detailing.

"Arabella" in her dock, retractable bowsprit withdrawn

Lifting keel in raised position, hauled up by a tackle system led to the cabintop winch.

Lifting rudder in a casette. Bruce modified this from my original design, to give some steering when the rudder is partially raised. There is an outboard motor well but Bruce has an electric pod drive installed.

With the short cabin, Bruce has kept his halliards at the mast .

The bowsprit retracts and pivots on an inboard traveller on the foredeck, with control lines led aft to the cockpit.

"Arabella" hard on the wind.

Very neat high-peaked gaff rig with nicely-shaped mainsail. All spars are carbon.

So, how did she sail? Wind was very light, around 4-5 knots most of the time. On the flat water that we had, she sailed close to the wind at 3.5-4 knots, with little wake and an easy helm. She cut through the occasional powerboat wakes of the ICW with little fuss or loss of speed. Once cracked off, we pushed out the bowsprit, set the top-down roller-furled asymmetrical off the end and rolled away the jib to allow the spinnaker to breathe.

She powered up and reached at just a touch under the apparent wind speed, topping out at more than 8 knots boat speed in 9 knots of apparent wind. That put her boat speed at well above the true wind speed in which we were sailing. She did this with no fuss and very easy control. The speed gave the feeling that the wind had picked up but with the bag stowed and back on the wind under main and jib, we still had the same light breeze as before. She just gets up and goes. She will reel off the miles if used as a small cruiser.

"Arabella" has the smaller of the two gaff rigs that I drew. This one is suitable for most small crews, for racing or cruising. The other gaff rig is larger and will need a larger and more experienced crew. We also have a Marconi rig with square-top mainsail.

See our full range of designs on our main website or our mobile website.

Dix 430 Catamaran

A long time ago I drew the basics of a design for a 43ft wood/epoxy catamaran for a professional builder. He didn't have the resources to build the boat, so the design went no further. Ever since it has remained on our website as a teaser, hoping to entice another builder to commission the completion of the design. A few people did ask me to carry on but those requests somehow never coincided with a gap in my design schedule, so it went no further.

I did get to design the bigger Dix 470 and DH550 cats for radius chine plywood construction. A few of the 55 footers have been launched and others are in build to both designs. Both boats are also offered as comprehensive CNC-cut kits of all plywood components, by Exocetus Marine in UK.

Exocetus Marine wanted to expand their kit range down to smaller cats as well, so they commissioned a new 43ft cat with a similar aesthetic to the bigger boats. This has replaced the design that has been languishing on our web pages for so long. Exocetus Marine will have the programming for cutting the Dix 430 completed during the second quarter of this year.

Dix 430 sail plan

As with the bigger sisters, the new design is also radius chine plywood construction, the build method that I developed for my Didi 38 prototype "Black Cat". That boat is now 23 years old and is still racing competitive. That design has been followed by a stream of smaller and larger designs of similar or derivative construction.

In addition to the kit option, the Dix 430 can also be built from plans or from plans plus Mylar bulkhead patterns. They can be ordered through our stock plan pricelist.

The new boat is a good size for family distance cruising and lazing around the islands. Initially available with cruising keels, a daggerboard option may be added later if there is demand for it.

Dix 430 accommodation

Dix 430 cross-section

See more of this and our other designs on our main website or our mobile website.

Argie 15 Framing

It has been pretty cold here the past few days, with winter starting to bite. Today the high temperature was just on freezing. As it grows colder over the next few weeks, a snug workshop is a good place to be spending productive time.

Kevin Agee is spending most evenings in his workshop, working on the Argie 15. Current tasks are fitting the framing for the seats and the transom doubler.

If you are fortunate enough to source timber longer than the hull, you can do the side stringers each in a single length. For the rest of us, it is necessary to join two pieces together to get the full length. This is done by scarphing (or scarfing or scarph-jointing) them. Each joint is done by cutting or planing the ends to be joined at an angle to form sloping mating surfaces. For an application like this and using modern adhesives, the slope angle need not be more than 1:6, so for timber 20mm thick the joint would be 120mm long.

One half of the scarph joint. This was cut on a saw but it could also be done with a jack plane.

The two pieces to be joined, dry-fitted to check accuracy.

The joint has been glued and here is shown being glued into the hull with temporary screws to hold the stringer until the glue has cured.

Stringers are glued in along both sides to form landings for the seats against the hull sides. Edge frames are also glued to the bulkheads to support the transverse seat edges.

Stringers fitted full length of both sides to form landings for the seats.

Edge framing being glued in for transverse seats.

Working neatly all the time will ensure a good finished product. This joint is an example, no scrappy edges, nicely filleted internal angle, all contact surfaces glued for a solid joint. 

View into the structure at the stern. The extra plywood layer on the centre of the transom is a doubler to strengthen it for the rudder pintle fittings. The notches in the tops of the transverse frames are for half-jointing the seat stiffeners. Those will be added in a future post.

You can see in all of these photos just how neat Kevin's work is. This is important if you are to have a really nice boat at the end of the project. If you don't think that you can't work to this standard, consider that Kevin is an amateur boatbuilder, not a professional. He is working with normal hobbyist woodworking tools. He has only built one previous boat, his own Inlet Runner 16.

To see more of our designs, go to our main website, our mobile website or our Flickr albums.

Argie 15 Hull Glued together

The stitch-&-glue boatbuilding method is also known as stitch-&-tape. Our Argie 15 build being done by Kevin Agee has now reached that stage where both of these names can be seen in the process.

The hull skin has been stitched together with electrical ties, with a few copper wire ties at high-load points where the electrical ties are not strong enough to hold the panels close together. In the photo below, the bulkheads have been secured in their correct positions, changing the floppy panels into a hull shell of the proper shape. At this stage it is still somewhat flexible and can still be adjusted to remove any twist that may have occurred when tying the panels together. Get behind the boat and sight over the top of the transom, lining up the tops of the bulkheads with the top of the transom in your sight-line. Any twist will be obvious and must be pulled out before starting on the gluing process. You can see the ties holding the joints together.

The next step is to glue the outside joints of the panels between the ties. For this boat we are using MAS Epoxy products throughout and the glue that we are using is MAS Gluzilla in the 185ml cartridges, applied with a standard caulking gun. The glue comes out pre-mixed from the mixing nozzle and can be applied directly into the V-shaped joints between the panels, filling the joints flush between the ties. In the photo below the ties have been left in place to hold the joints until the epoxy has cured. Epoxy can stretch for days after it has hardened, so don't be in a rush to pull the ties out.

While the epoxy in the joints is curing you can glue the bulkheads in place. This is done with epoxy fillets, which we have chosen to also do with the MAS Gluzilla. It is applied in a large bead on each side along the perimeter of each bulkhead against the hull. They are finished smooth to a cove-shape using a tongue depressor or similar tool. In the photo below, there are two semi-circular cutouts in the bottom edge of the aft bulkhead of the middle seat. There is a matching pair in the forward bulkhead of that seat. These are to take PVC half-pipe drains that bring water from the forward compartment of the cockpit into the aft area where crew can bail it more easily or it can be drained through dinghy self-bailers.

 Next step is to pull out the ties and fibreglass the insides of the joints. The epoxy glue on the outside will hold the joint while the inside of the joint is taped. All of the seams must be taped, taking care to finish neatly against the bulkheads. When the epoxy has set and started to cure you can feather the edges with a small block plane with a very sharp blade set fine. If the epoxy has already cured then it may be better to feather the edges with a small finishing sander.

Close-up of taped seam before feathering the edges

Taped seams in the bow. The centreline seam has first been epoxy-filleted to form a good surface to receive the glass tape.

In areas where the taped seams won't be seen, like inside the seats, they don't have to be feathered but must be sanded smooth and the weave filled with epoxy to give a smooth surface. If you don't do this then there will be rough surfaces and jagged edges that will rip your knuckles when cleaning those places in the completed boat.

When that has all been done, lightly sand all of the internal surfaces of the boat and remove all dust, then apply three coats of low viscosity epoxy. The first coat will soak into the wood to create a good bond. By the third coat you should have a full coating of epoxy that can be sanded smooth to prepare for paint. Try not to leave more than 12 hours between epoxy coats, so that they can bond chemically to each other. If more than 12 hours has passed then lightly sand the epoxy before applying the next coat.

Three coats of epoxy on all inside surfaces.

To see more of this and our other designs, go to our main website, mobile website and Flickr photo albums.