Monday, June 9, 2014

New prop

Indigo Propeller
According to the specifications, the Atomic 4 should have a cruising RPM of 1900 and a wide open RPM of 2400. Apparently most people have too large a propeller and too low of an RPM. My problem was the opposite.

My cruising RPM was 3200 at 5 knots and if I wanted to get to 5.5kn I would be pushing 3500 RPM. While this RPM is still within the tolerances for the engine, it created a lot of unnecessary noise and vibration.

My old prop was a two blade 12x6 and it was undersized. I'm sure this helped a bit in my club racing since it had lower drag, and it was tolerable for cruising under power but it was an issue fighting heavy currents large waves. A sketchy trip through Letete Passage last year (yes, at the wrong tide...) confirmed my need for more available speed.

Indigo PropellerAfter a recommendation from Bill on Lady Hamilton I picked up a prop from Indigo Electronics. Indigo was very easy to deal with and were quick sending out the prop. The prop is a three blade 10x7.4 and seems to be of high quality.

After finally launching this weekend I was happy to test out the prop and see the results. My cruising RPM is now at 2600, at 5kn. This is still a little higher than desired, but much better.

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