Monohull · 5 documented fitments
Propeller upgrade for the CNB 78 — what fits, what changes.
Drawn from 5 documented CNB 78 fitments: the common setup is a Varifold 4-blade behind the Volvo Penta D4-175. 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 5 real installations — not a size chart, a service record.
| Engine | Power / max RPM | Drive | Typical ratio | Documented propeller | Rotation | Records |
|---|---|---|---|---|---|---|
| Volvo Penta D4-175 | 175 hp / 2800 | Shaft | 2.78:1 | Varifold 4-blade | Left-hand | 5 |
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 CNB 78
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 CNB 78
- Tip clearance rules the maximum diameter — roughly 10–15% of prop diameter to the hull. The Builder asks; we verify before supply.
CNB 78 propeller questions
What size propeller does a CNB 78 take?
Documented CNB 78 installations most commonly run a Varifold 4-blade, matched to the Volvo Penta D4-175 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 CNB 78 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 CNB 78 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 CNB 78
The Builder pre-fills from these 5 documented fitments — confirm your engine and gearbox, and an engineer replies within one business day.