This year Plume was hauled out at Svendsen’s Bay Marine in Richmond, California. While the primary task was some fresh coats of bottom paint, we also took the opportunity to tackle maintenance and upgrades: replacing the engine intake seacock (Plume’s last original seacock and hence a potential failure point), fitting a new prop, and servicing our Monitor windvane.

We have been using a 2-blade CDI plastic 14x10 prop until now. We were extremely satisfied with its performance and never had any issue with it. In addition, its price point does not prevent you to carry a spare (which we did). However, when production was discontinued, we switched to a more traditional option: a 2-blade Michigan bronze 13x12.

We measured boat performance before and after the prop change by recording GPS speeds over ground at different RPMs, running reciprocal courses in the channel in front of the boatyard to discount for current (see table below). The new prop performed slightly better at low rpm, but the difference was not significant. Regarding other factors like hull cleanliness, and not counting the load on the engine (consumption), it is not possible to draw a clear conclusion (beside our new prop is more shiny;-).

back to the water

To the water with new bottom paint, seacock, and prop

2-blade Michigan bronze 13x12

2-blade Michigan bronze 13x12

windvane back after servicing

Mounting the Monitor windvane back after servicing


RPM Old Up Old Down Old Avg New Up New Down New Avg % Change
1600 3.55 3.15 3.35 3.85 3.10 3.48 +3.7%
2000 4.60 4.20 4.40 4.70 4.15 4.43 +0.6%
2400 5.18 5.04 5.11 5.40 4.85 5.13 +0.3%
2800 5.65 5.55 5.60 5.85 5.45 5.65 +0.9%

Old CDI and new Michigan props SOG for different RPMs