I wonder if that little bit of wind was just enough to tilt the boat forward so that the prop was sucking air momentarily as the bow tipped down over the top. Could that cause the prop to feather? Power boat racers have a person assigned to the throttle in swells. I don't have a feathering prop, just speculating out loud.
Steve Thomas C&C27 MKIII Port Stanley, ON - Geared Gori prop ----- Original Message ----- From: Andrew Means via CnC-List To: cnc-list@cnc-list.com Cc: Andrew Means Sent: Thursday, June 16, 2016 12:25 Subject: Stus-List intermitent vibration/shudder in ocean swells Hey all - My friends and I are currently in Tofino, BC on day 6 of a much needed vacation. So far our Yanmar GM30F and 3-bladed max-prop have been performing brilliantly, sipping diesel and pushing the boat through the less-windy sections of Strait of Juan De Fuca and up and over some large ocean swells on our way up to Tofino. Yesterday on the way up from Ucluelet I felt a shudder/vibration as the boat crested a swell. It was short but pronounced. The motor didn’t change RPM at all or seem under load. About 10 minutes later it happened again, also over a swell. This time we had to lower the RPM of the engine and let it idle - when we brought it back up it was smooth again. This happened maybe 6 times over the course of the passage, always starting as we were at the top of a swell. We’d been going through swells at the same angle under power the day before with no trouble, the only difference this time was that the little wind there was was behind us. The only thing I can think of is that one of the blades of the max prop is feathering as we go over these swells. I have no idea how one would fix that - or if there’s any way to do so without hauling the boat out (hoping to avoid that mid-trip…) Any ideas? -- Andrew Means S.V. Safari - 1977 C&C 34 Mk I Seattle, WA ------------------------------------------------------------------------------ _______________________________________________ This list is supported by the generous donations of our members. If you like what we do, please help us pay for our costs by donating. All Contributions are greatly appreciated!
_______________________________________________ This list is supported by the generous donations of our members. If you like what we do, please help us pay for our costs by donating. All Contributions are greatly appreciated!
