SD20
Yanmar's long-running small saildrive with a dog clutch and a 2.64:1 reduction, fitted behind the 1GM10C, the 2GM20C/3GM30C and later the 2YM15, 3YM20 and 3YM30.
The SD20 is a saildrive leg with a constant-mesh bevel gear set and a mechanical dog clutch, giving a single 2.64:1 reduction ahead and astern and a dry weight of 30 kg for the standard leg (long-reach leg also offered). Yanmar's parts catalogue groups it with the SD30 and SD31 and records part changes going back to 1984, and the earlier installation manual lists it for the 1GM10C, 2GM20C and 3GM30C. When the GM range gave way to the YM engines, the SD20 carried on: Yanmar's 2004 SD20/SD50 operation manual lists it for the 1GM10C, 2YM15, 3YM20 and 3YM30, and Yanmar's 2013 drive-systems page still offered it alongside the SD50.
Oil for the SD20 is gear oil except behind the 1GM10C, which shares engine-type 10W30 oil. It was superseded in 2015 by the SD25, which keeps the SD20's outline and dimensions so existing installations can be repowered.
Sources
- 1. SD-Series Sail-Drive Operation Manual, models SD20, SD50/SD50-4T (copyright 2004) — Yanmar
- 2. Yanmar SD20/SD31 Installation and Operation Manual, specifications page — ManualsLib
- 3. Parts Catalog SD20, 30, 31 (0CF10-M40201EN, last update Jan. 2009) — Yanmar
- 4. Drive systems (saildrives, ZT370, pod drives, gears datasheet list), 2013 capture — Yanmar Marine
- 5. Yanmar releases new 30hp engine and SD25 saildrive (7 July 2015) — boatsales.com.au
- 6. Operation Manual 2GM20(F)M(C), 3GM30(F)M(C) EPA certified engines — Yanmar
Specifications compiled from manufacturer sources.