Starwind 860

Starwind 860: Range and efficiency

Among the key questions that must be answered in any powerboat's design phase are: How much power does it need, and how far can it go between gas docks?

The Starwind 860 trimaran that I'm currently working on started life as a series of computer simulations to answer these two questions. In today's post, I'll take you through some of these calculations and the logic that led to the final choices.

Starwind 860: Designing for mixed missions

It's a rare boat indeed that is tasked with one and only one mission. The degree of flexibility that's expected, though, varies greatly from boat to boat. My requirements for my next boat fall in the "does everything reasonably well" category, which necessitates a lot of head-scratching and balancing of trade-offs during the design phase.

Starwind 860

Summary: 

Starwind 860

A power trimaran designed to serve a variety of roles. It will be a comfortable day or weekend boat for a family of 4-6, and will be able to take a crew of two on multi-week cruises in coastal areas. The Starwind 860 is also capable of serving as a mother ship for divers and kayakers, or as a cargo-hauling cottage workboat.

 

Length overall: 

9 m

Length waterline: 

8 m

Taxonomy upgrade extras: 

Displacement light-ship: 

1,200 kg

Displacement at design load: 

2,100 kg

Beam overall: 

5 m

Beam waterline: 

1 m

Draught normal: 

1 m

Draught minimum: 

0 m

Bridge clearance normal: 

4 m

Bridge clearance minimum: 

3 m

Length outrigger: 

7 m

Beam outrigger: 

0 m

Wetted surface: 

16 m²

Power typical: 

41 kW

Length/displacement LDR: 

7

Power description: 

Outboard 40-70 hp

Power/displacement: 

20 kW/t

Length/beam: 

9

Length/beam outrigger: 

19

Plans available: 

Not at this time

Build status: 

Under construction.

Design number: 

001

Lake waves, and the origin of a new powerboat

Waves, despite their well-understood mathematical and physical properties, remain a rather subjective point of discussion among cruisers. There's the tendency to exaggerate, of course- we've all heard a story that goes something like "I was beating into a force 6, there were 14-foot waves coming over the bow....". (Force 6, of course, brings an average wave height of closer to 9 feet given unlimited fetch.)

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