Didi Mini Mk3 Plans

These views show the hull and cabin changes clearly.

Low budget performer

~ Economy of plywood

~ Modern radius chine hull with topside chine

~ Stitch & glue cabintop & topside chine

~ Developed from Didi Mini concept

~ Round bilge from sheet material

~ Amateur or pro builders

~ Fixed or canting keel

~ High performance racing on a tight budget

Detailing is based on the series of radius chine plywood designs that started with my DIDI 38 "Black Cat", and was followed by the DIDI 34, Mount Gay 30 and DIDI 26. The underbody has been reworked to allow a topside chine to be added to power-up the aft sections. The chine is formed by stitch & glue methods and fairs into the hull side just forward of the mast, with the bow sections remaining the same as the Didi Mini.

Design principle is simplicity and to the Mini 6.5 Class limits. The design includes options of a fixed keel with conventional port & starboard water ballast tanks or a canting keel with forward daggerboard and bow and stern water ballast tanks. For the fixed keel version the tanks increase sail-carrying power. For the canting keel version the tanks allow the bow to be trimmed down on windward legs for improved windward ability or the stern to be trimmed down for offwind performance in strong winds. The daggerboard can be tacked inside the casing for increased lift. Linked twin rudders are steered by central tiller.

Keels are hollow aluminum fabrications with through-bolted beaver tail ballast bulbs. The fixed keel has optional trim tab. Both keels are supported by the hull structure by means of an internal aluminum box frame. The fixed keel has an integral post to transfer some of the keel loads through to the deck structure.

The sections and waterlines on this view highlight the hull shape.

The deck layout is a fairly conventional 3-winch arrangement. The smaller headsails sheet to the top of the cabin and are led to the cabintop winch. The larger headsails and spinnakers sheet to the cockpit winches. Tweeker lines replace headsail tracks.

Drawings include full size Mylar patterns of the backbone, bulbs, rudders and daggerboard. Optional full size Mylar patterns for the bulkheads are also available.

We will continue to sell plans for the Didi Mini alongside the Didi Mini Mk3, in case there are builders who will prefer to build the older design.

Materials List:

CHIPBOARD (for setting out bulkheads if building from offsets)
1,83x2,74m (6'x9') 16mm (5/8") - 1 sheet

MARINE PLYWOOD 1,22x2,44m (4'x8') (preferably Gaboon or Okoume plywood)
3mm (1/8") - 7 sheets
6mm (1/4") - 20 sheets
9mm (3/8") - 15 sheets
12mm (1/2") - 2 sheets

SAWN PINE (for building stocks etc)
25X125mm (1"x5") (rails) - 18m (59')
50x50mm (2"x2") (bulkhead legs) - 20m (66')
75x75mm (3"x3") (posts) - 5m (17')

CEDAR or similar, selected, free of knots, shakes fractures etc
20x20 (3/4"x3/4") triangular fillet (joinery fillets) 20m (66')
19x23mm (3/4"x29/32") (tangent stringers) - 33m (108')
19x32mm (3/4"x1 1/4") (hull and deck stringers) - 166m (545')
22x32mm (7/8"x1 1/4") (bulkhead cleats) - 4m (14')
22x64mm (7/8"x2 1/2") (sheer clamps) - 16m (53')
32x32mm (1 1/4"x1 1/4") (toerails) - 10m (33')

RESIN & GLASS (for coatings and reinforced areas)
Epoxy resin (low viscosity 100% solids) - 40kg (90lb)
50mm (2") Wide woven tape - 60m (200')
75mm (3") Wide tape - 15m (50')
100mm (4") Wide tape - 75m (246')
450g/sq.m Biaxial fabric - 8sq.m (90sq.ft)

This design is dimensioned in both metric and imperial measurement systems.

Radius Chine Plywood Mini 6.5

LOA 6.50m (21'4")
LWL 6.45m (21'2")
Beam 3.00m (9'10")
Draft 2.0m (6'7")
Displ to DWL 1050kg (2315lb)
Displ light 850kg (1874lb)
Ballast 320kg (705lb)