A MINI SPORTBOAT
The Didi Sport 15 design was commissioned by an Australian living in the same city as me in USA. A South African designing for an Australian, for building in USA. He built his boat with exquisite workmanship, taking his time with the project over a few years. When completed he took it to the Wooden Boat Show in Mystic Seaport, Connecticut, where it took first prize in the sailboat division of the Concourse d’Elegance.
This design started as a 16ft bigger sister to my Paper Jet design. The Paper Jet is a very light high performance skiff, 4.1m (13’5”) long and weighing 95lb without the rig. It has an efficient planing hull of hard chine plywood, with hollow wings and trapeze. I have sailed mine at more than 20kts in 25+kts of wind, single-handed on trapeze. I drew it primarily for two teenagers but it has found more demand from men wanting to sail a single-handed trapeze boat.
My client loved the Paper Jet concept and what he wanted was the same but bigger, at 16ft long and with twin trapezes for two adults. It was to be named the Paper Falcon for the F16 Fighting Falcon aircraft.
That design didn’t progress beyond early work on 3D modelling. At that time he told me that he also planned to use it as a picnic boat, to sail to his favourite isolated island beach, carrying four adults with cooler boxes full of food and Fosters. That came as a shock because it had never been mentioned that he wanted the boat for anything other than mixed fleet racing. I told him that the Paper Jet concept really had no chance to serve that aspect of his needs/wants; a more robust and stable boat was needed.
The Paper Jet, with narrow waterline beam, wide deck beam and very quick reactions to wind and wave, is a sensitive boat that needs fast reflexes and the ability for the sailor to become one with the boat, adjusting to wind changes at the same time that the boat reacts to those changes. If you have to think between the gust arriving and hiking out further or easing the mainsheet then you will spend a lot of time swimming. After the first swim and retrieving cooler boxes and other gear he will have lost the enthusiasm of his wife for picnic outings to their private spot.
The concept immediately changed to what you see in the Didi Sport 15, as a ballasted little sportboat. Aside from his liking for the Paper Jet, he also liked the Mini-Transat boats that I had drawn over a few decades. He particularly liked the newer generation of that design series, the Didi Mini Mk3. This has the modern trend of a chine in the topsides aft of the mast to help shape a flatter and more powerful planing stern. He asked if I could develop what he wanted from that little trans-ocean racer.
So, the concept changed from being a big sister for a trapeze skiff to a little sister for a trans-ocean racer. The Didi Sport 15 hull is a direct development from the Didi Mini Mk3, with the waterline beam and stability to serve the picnic purpose that the builder wanted. A ballast bulb on the daggerboard adds capsize security and increases sail-carrying power for stronger winds. It is able to carry load in a relatively docile manner if reefed down to suit the breeze of the time. In this mode she is really a sportboat with a modern and powerful rig that can be reduced to be as docile as needed for the situation or conditions. With her full rig of squaretop mainsail, self-tacking jib and asymetrical spinnaker on a retractable bowsprit and launched from a chute, she can be a spirited racer for club Olympic triangle and point-to-point racing. Or just blast back-and-forth across the bay or lake until you wear yourself out from fun and excitement.
She has a covered foredeck above a full-length sealed self-draining wet deck. That creates a small cuddy cabin, a safe and dry storage area for those cooler boxes, as well as shelter or play area for small crew to get out of rain or sun if needed. These features make her a good option for raid-type racing events that require carrying one’s own stores, camping equipment etc over long distances between camping stops. Hanging a tarp or the mainsail over the boom turns her into a camp cruiser, with a cockpit long and wide enough for a couple of airbeds for a comfortable night anchored or nudged up onto the beach in a sheltered private cove.
This is a DS15 but the DS15A has the same hull, with different cockpit and rig. Photo Glen Meyburgh
But this boat is schizophrenic, it has a very different alternative personality for those who want to have some high-performance fun. Remove the ballast bulb from the daggerboard and she morphs to what I originally intended with this design. She becomes a high performance skiff with one or two trapezes for adults.
An owner in Port Elizabeth, South Africa, justifiably nicknamed ‘The Windy City’, has proven his boat in strong winds. He has sailed her in 35kts with the ballast bulb and with his crew on trapeze. In winds under 20kts he is happy with trapezing crew and no bulb. He has been caught out on the bay by 40+kts, which they managed but described as ‘survival conditions’. Construction is over permanent bulkheads and a ladder-frame backbone, with stringers. Most of the hull is 6mm sheet plywood, the exception being the radius area that is done with two layers of 3mm. The topside chine uses a stitch-and-glue joint and increases the power from the stern when power-reaching. The deck and cockpit are all 6mm sheet plywood using stitch-and-glue detailing.
Hull shape is radius chine with a partial hard chine in the topsides. The radius chine runs from the transom through to the forefoot and produces a shape close to round bilge, with a shallow V-bottom. The hard chine runs from the transom through to the mast, where it fairs out into the topsides. The resulting shape is fine in the bow, with a broad, clean and powerful stern. Low drag and fine bow for wave penetration and upwind sailing, powerful aft for planing downwind in the strong stuff.
When the daggerboard has the ballast bulb attached then raising and lowering is by means of a tackle attached to the mast below the spreaders. It is basically a lifting keel in this configuration and must be locked down with a locking pin in case of capsize. When the bulb is not fitted, it operates like a normal daggerboard, no tackle required.
A further development of this design was commissioned by a client in California. He was deeply committed to handicapped sailing and commissioned an adaptive version of the DS15. This became the DS15A, for Didi Sport 15 Adaptive. I modified the design and construction started on the prototype, with the client financing the build and a friend doing the work. Construction progressed to the stage where the hull needed only the upper side panels to be fitted before deck construction could start. Unfortunately, the client succumbed to cancer before the work progressed any further. As far as I know it remains at that stage, waiting for completion.
His vision for the boat was for it to be very versatile in what could be done with it in terms of crewing by able-bodied crew/instructors and handicapped crew. To this end, the design has two removable seats with seat belts and mounted on tracks. It can also be rigged with a single trapeze. Steering is via a tiller that is linked by cables to a whip staff tiller mounted on a pedestal in front of each seat.
Mainsheet traveller controls are led to the aft seat. The mainsheet is double-ended, each end going to a block with cam-cleat on top of the pedestal at each seat. The sheet for the self-tacking jib is double-ended and led to the front seat. The halliard for the asymmetrical spinnaker is led around the perimeter of the cockpit past both seats then up through the spinnaker chute to a patch in the middle of the sail, as a retrieval line. The cleat is operated from the front seat. The spinnaker sheets can be led to either seat. Most of these sail controls are led to camcleats on the raised coamings of the side decks.
This arrangement allows the boat to be adapted to a very wide range of crewing options by using both seats or replacing one or other of the seats with an able-bodied crew or skipper.
The plan with the DS15A was to build the plywood boat, then take moulds off it for fibreglass construction. Fibreglass detailing has been drawn for the DS15A that can be used for either boat if a series builder wants to take it on.
The standard plans packages for these boats include all detailing and full-size paper patterns of all bulkheads and the backbone. We also offer optional full size Mylar patterns for all plywood components to help with drawing the skin panels and speed up construction.
Plywood kits are also available, comprising all of the plywood components except for the radiused hull skin. In Australia our kit supplier is Stainless Boatworks, with website at www.stainlessboatworks.com.au
These boats were drawn for amateur builders of moderate skill, with no need for hi-tech products and equipment. Most of our plywood designs are built in garages or back gardens, with little smell or noise beyond what is normal for an active DIY woodworker. My own boatbuilding and design origins are in amateur wooden boats and I have carried that experience through to the wooden boat designs that I draw. The standard of detail on the drawings and the build methods used have proven good for relatively inexperienced boatbuilders, to develop confidence in their own abilities and the boats that they create.