Malcolm Tennant Multihull Design Ltd - Sienna

Sienna - 38

Sienna - 38
11.5 m[37.7'] ocean cruising cat

This design was introduced in 1997 and there are two currently under construction. This is a serious cruising boat and the difference between the light ship displacement and the full load/overload displacements are a reflection of this. It generally epitomises what we look for in a cruising boat. The full-bodied hulls mean that the vessel will not have the top end speed of the finer vessel but nor will its performance be degraded by a full cruising load. Our usual "underwing girder" eases the transition from the wing to the hulls. There are no right angle joins in the bulkheads to allow stress concentrations. The hulls are cut away on the inboard side down aft to maximise the size of the boarding platforms and aid in boarding the vessel from a dinghy or the water.The interior layout is that of a typical "English Style" cruising cat. The lack of wing berths in the cockpit area means that we can have a walk through transom on a vessel much shorter than is usual for this feature.The helm is mounted on a plinth that also serves to provide extra headroom over the double hull berths down aft. The diesel tanks are inboard of here and the platforms also make it easy to operate the cabin top mounted winches to which most of the sailing controls are led.Saildrives are the auxiliary of choice with the stock two bladed folding propeller replaced with three bladed feathering propellers to give more "bite" in adverse conditions and reverse.The rig is a simple, non-rotating, aft swept spreader rig. This is lighter and more stable than a diamond supported mast but it does restrict the overlap of the headsails. The use of upper spreaders and shrouds allows for the carrying of light weather extras without using runners. An in boom roller furling set up is a suggested option for the main but the plans show slab reefing lines leading to the cabin top winches. The headsail is roller reefing.

The first Sienna 20 is a charter catamaran that operates out of Auckland New Zealand. Please check out her website at www.catamarancharters.co.nz

Study Plans available for only: US$30.00

Working Plans available for only: US$5,500.00