Saturday, August 14, 2010

Decisions, decisions verse 1- Propeller

As we work to figure out the logistics of getting the purchase finalized, and transporting Legacy (still named the Sally Marie II) up to Tacoma, there are all kinds of other decisions that I'm faced with.

The Catalina 400 comes with an 18"x 2" fixed prop. When the boat was hauled for the survey, that big prop looks like a sea anchor hanging back there. I started to consider a feathering or folding prop. With a little research, two options presented themselves, Max-Prop and Autoprop.

There are some real advantages to these propellers. Under forward power, the blades rotate to give forward thrust, under no power the blades feather or fold to present less drag, and when in reverse, they rotate to provide reverse thrust. The advantages are much less drag when sailing and much better reverse performance than a fixed prop. Other owners of Catalina 400s report an increase in sailing speed of at least 1 knot using these propeller and much less prop-walk in reverse. This would make backing into a slip much easier. The cost is significant. I was quoted $3,150 from Max-Prop and found an Autoprop for sale for $3999! The other disadvantage is that there is increased maintenance required as the mechanisms need to be greased regularly. While the manufacturers may claim otherwise, this would be difficult to do in the water, so the boat would need to be hauled at least every two years to have this done.

Max-Prop is made by PYI Inc. , a company based in Lynnewood, WA., essentially a bit over an hour up I-5 from me. These are the same folks who manufacture the PSS Shaft Seal used on many production sailboats. Max-Prop is a feathering propeller. The Max-Prop has flat blades, rather than the curved blades common on propellers. This allows the blades to feather, presenting a small profile to the water. Because of the flat blades, there is a small reduction in prop efficiency in forward gear.

Max-Prop installation requires that you cut off maybe an inch of the prop shaft. This means that using a prop other than the Max-Prop could be an issue if I ever decided I wasn't happy with it, or needed to replace the prop after an accident or failure.

Autoprop is a little different. It's blades are curved and cupped, giving a little more efficiency than the Max-Prop (or so claims Autoprop). This also results in a bit more drag than Max-Prop under sail. They also are designed so that the pitch angle varies with the speed of the boat and the power from the engine. Frankly, this seems a little like voodoo, but it apparently works. Sailors report significant improvements in under-power performance with the Autoprop.

So what to do? The advantages to Autoprop are increased powered performance, no modification to the prop shaft, and easier installation. The Max-Prop on the other hand has less drag under sail, easier maintenance, is a local company. The Max-Prop likely would be as much as $1500 less in cost as I have a friend who is a dealer. The other issue is that I could easily get a Max-Prop in a few days, plenty of time to install it before Legacy is splashed here in Tacoma. I don't know about the availability of an Autoprop but my guess it would be at least a few weeks which would delay the commissioning of Legacy.

Who knows, I have a little time to think about it but at this point I'll probably go with the local favorite, Max-Prop.

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