Owner notes · Repower planning
Thinking about a new engine for my Katama.
My 1975 Katama has a Yamaha 85 two-stroke. I mainly cruise, and I’m considering a four-stroke. I’d like to keep the engine weight the same or lower.
What I want from the change
I’m not in a hurry to replace the engine. My use is mostly cruising, and avoiding extra engine weight matters to me.
The boat is a 1975 Katama, commonly described as a 17-footer. Before comparing new engines, there are details to pin down: the current Yamaha’s exact model and weight, the boat’s capacity information, the condition of the transom and what the existing rigging can support.
Start with a clear brief
For this kind of project, give each installer the same information: the boat’s identity and capacity documentation, the engine’s model plate, how the boat is used, and the preference not to add engine weight. Ask for the exact proposed variant and a weight comparison on the same basis.
Leave the old engine’s weight blank until it’s verified. “Yamaha 85” alone may hide differences in year or shaft length. Check what each published weight includes, then account for rigging, batteries and any fuel-system changes separately.
The installer still needs to assess the actual boat. A weight target alone can’t settle whether an installation is suitable.
Three questions for the installer
- What work does the boat need? Include the transom, mounting, rating, steering and fuel system in the assessment.
- What can stay? List the controls, gauges, harnesses and steering that can be reused. Using the same engine brand doesn’t establish compatibility.
- How will the finished job be checked? Agree on propeller selection, setup, a sea trial, warranty handoff and responsibility for follow-up adjustments.
Compare the whole job
An engine-only price leaves plenty unanswered. Controls, labor and setup can change the total considerably. A higher quote may include work that another installer has left as an allowance.
The repower buying guide lists the items to compare and links to manufacturer resources. Mark each item “included,” “extra,” or “not yet determined.” Final engine selection should follow an assessment by a qualified installer who has seen the boat.
Based on Mark’s reported setup and priorities, July–September 2026. No engine brand has sponsored this article. Editorial standards.