Home » General designs » Nimbus 9

Nimbus 9

Nimbus 9 is a single seat mini trimaran from the drawing board of Sailrocket designer Malcolm Barnsley. She is aimed at people with reduced mobility, but also learners and anyone seeking the thrill of a fast ride with greater comfort safety than the standard racing dinghies and beach cats.


The boat is extremely simple to sail from the fixed forward facing central seat, using a push/pull fore & aft tiller on one side for steering* and a single sheet for sail control.

Visibility is 360 degrees due to the high boom location. Speeds over 7 knots are readily achieved in windspeeds of 15 knots and above

With typical adult pilot mass of 75kg  operation in windspeeds up to 25 knots (force 6) is safe in sheltered waters, where speeds of 6 knots can be achieved reaching and 4 knots upwind. Significantly higher speeds are likely with lighter pilots .

Nimbus 9 is unsinkable in the event of serious collision damage, or capsize due to zero ballast and excess buoyancy of trapped air. A paddle (supplied) provides very effective auxiliary power if the wind dies.

*Adaption to foot steering is straightforward and is removable if both options need to be available on one boat.


The de-assembled boat can be easily be accommodated  on a standard size car roof rack, the heaviest item being the main hull at 18kg, and the longest being the the assembled platform (7 foot) is within the legal width limit (8 foot) and hence can be trailed


Allow 45 minutes for first time, 20 minutes once familiar. Only 2 tools needed 13mm spanner and mallet or light hammer


The rig is based on Optimist ‘School’ rig. The sail is wrapped around the mast/boom assembly and tied down on top of the boat  in between sailing.

Therefore it only requires stepping the mast, threading main sheet and mounting the sprit – approximately 10 minutes..

Launch & Recovery

Uses a very lightweight trolley based on the latest Optimist demountable trolley           

Main design features

  1. Single adjustable suspended fabric seat
  2. Free standing mast (one piece)
  3. Single Sprit rig sail   
  4. Swept forward stabiliser  floats
  5. Plywood dagger board
  • 2  straight Aluminium tubular crossbeams
  • Nylon split block crossbeam clamps (4)
  • Large dry storage locker plus hatch
  • Self draining cockpit
Dimensions Metric Imperial
Length overall 2.76m 9 foot
Length on waterline 2.43m 8.5 foot
Beam overall 1.98m 6.5 foot
Launching  draught 0.23m 9 in
Sailing draught 0.8m 2.5 foot  
Sailing mass (no pilot) 44kg 96lbs
Sail area 3.53 m^2 38.sq.ft


Nimbus 9 is built from Gaboon marine plywood by the stitch and glue method. The hull shells use 4mm ply with a full external sheathing of 250g/m^2  woven glass. Stringers and deck beams are from Meranti.

The bottom of the main hull is protected from abrasive damage by a bonded on Formica sheet which is sacrificial and can be replaced.


PLANS AND KIT OPTIONS                                                                                            £ POA