Monohull · 10 documented fitments
Propeller upgrade for the Jeanneau SO 42i — what fits, what changes.
Drawn from 10 documented Jeanneau SO 42i fitments: the common setup is an Autoprop H5 behind the Yanmar 4JH4E. Typical result: 300–400 fewer RPM at cruise and up to 20% fuel saved over fixed pitch.
The fitment card
Documented engine variants & what they wear
Aggregated from 10 real installations — not a size chart, a service record.
| Engine | Power / max RPM | Drive | Typical ratio | Documented propeller | Rotation | Records |
|---|---|---|---|---|---|---|
| Yanmar 4JH4E | 54 hp / 3000 | Shaft | 2.36:1 | Autoprop H5 | Right-hand | 10 |
Indicative only — gearboxes and apertures vary between years and repowers, which is why every supplied propeller is verified against your boat first. Data current as of 2026.
Your numbers
What the change feels like on a Jeanneau SO 42i
Indicative curves for this size of boat — drag the cruise line. The independent-test pattern: the same six knots on several hundred fewer RPM, with the fuel flow following.
Worth knowing
Considerations for the Jeanneau SO 42i
- Tip clearance rules the maximum diameter — roughly 10–15% of prop diameter to the hull. The Builder asks; we verify before supply.
Jeanneau SO 42i propeller questions
What size propeller does a Jeanneau SO 42i take?
Documented Jeanneau SO 42i installations most commonly run an Autoprop H5, matched to the Yanmar 4JH4E on a shaft drive. Exact size depends on your engine, gearbox ratio and aperture — every recommendation is verified by an engineer before supply.
How much fuel would a Jeanneau SO 42i save with an Autoprop?
Typical savings over a fixed-pitch propeller are up to 20% at cruise (documented band 15–30%, honestly less if you already run a folding or feathering prop). Put your engine hours and diesel price into the fuel calculator for your own numbers — then the Builder for a verified recommendation.
My Jeanneau SO 42i has a different engine than shown — does the data still help?
Yes. Repowers are common and the database usually holds several engine variants per model. The Builder starts from your actual engine and gearbox; the model records confirm diameters and clearances that are known to work on this hull.
Get the verified recommendation for your Jeanneau SO 42i
The Builder pre-fills from these 10 documented fitments — confirm your engine and gearbox, and an engineer replies within one business day.