Monday, 30 October 2017

40' racing trimaran for shorthanded sailing designed by Kurt Hughes

One of my long term projects has been to build a 40' trimaran that is capable of demounting to a high cube container for transport.  Initially I was going to build Kurt's F40 trimaran stock plan but since that time my requirements have evolved somewhat. 

The new design allows for a little more space onboard and has standing room in the main hull.  Displacement at DWL is about 200kgs greater which has necessitated one more inch beam in the main hull and one inch greater depth, worth it we think for the extra payload which is needed to meet the offshore requirements for fuel load and water tankage.  It uses an outboard which is mounted up near the cockpit for easy access.  Length of the main hull has been shortened to 39'4 to allow it to fit into the slightly less stringent Cat 1 requirements for offshore sailing.  All hulls now have reverse bows and the main hull is now going to be foam sandwich rather than cylinder molded to allow for compound curves.  Floats may be cylinder mold or foam sandwich (not settled at the moment).

Rig is going to be a secondhand 18 metre aluminium mast that was salvaged off a Malcolm Tennant Bladerunner 43' catamaran it will be made into a two piece for container transport, sails were salvaged too and are reusable for my trimaran platform.

It's a relatively simple boat overall which should help with it's shorthanded brief.  We have gone with a single deep daggerboard to stay with that theme rather than float lifting foils.  Float rudders are being fitted in addition to the main hull rudder.  A little more complication but helpful if we find ourselves in main hull flying mode.  Float volumes are 200% of displacement so large but not massive. Not shown in the renders is the bow nets and bow rail which are necessary for safety when working the foredeck.

The other concern was budget so we are not going for a full carbon build.  There will however be carbon on the 0 degree axis on the beams which are deflection driven parts and possibly on the 0 degree axis of the floats if we go with cylinder mold construction.  Daggerboard, rudders on the floats and main hull are made to be able to retract for shoal draft and beaching if need be.

Kurt goes into detail on some features of the design in his post on his multihullblog:
http://multihullblog.com/2017/10/40-foot-performance-shorthanded-trimaran-for-owen/












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