vibration

same boat, 85 silverton 34', twin 270 crusaders. got a vibration just before we go up on plane. runs smooth to about 1800-2100 then vibration sets in till plane than runs smooth. shafts straight, props good,cutless bearings good, no growth, engines aligned. any thoughts. several people told me it is just in the nature of some boats to do this just before plane. that sounded hokey to me. its not a violent vibration but its definately noticeable.

Are the rudders shaking at that point? THat sometimes happens with lots of power, but when the speed is still a bit slow. Do the rudders have free play, and what is the toe in?

You need to identify the source of the vibration. Just start or a recurring issue just now being addressed? last time it was hauled?

Most hulls load their engines the most right before achieving plane and the "vibrations" usually peak at the same time. It's when any vibrations 'increase (above normal)' that i start looking.

Another item to check is the motor mounts, especially if they are original. They do have a finite lifetime and i'm sure most die from calendar age (vs running time). Being Crusader specific, they aren't cheap. I was amazed at how much mine had worn in their 15 years of service. their replacement made a noticeable improvement.

no shimmy in the rudders or play,toed about 1/4". just got a call they have a cancellation for the lift friday so I guess it will wait till next spring. that will give me a chance to recheck the props,shafts etc etc. thanks, hold the thought till next year. rick

well, just answered my own question. the diver lied to me. there was an incredible amount of crustation on the props. guess i'll buy my own suit and start checking them myself next year. whats the thought on what to use on the running gear to prevent barnicle growth?

running gear, old school: bare metal, metal etch, primer, hard epoxy, two coats; New school: pay a yard guy to put on propspeed.

Ditto DD's post - we use the 'old school' approach for everything but the props.

Shame about the diver; may sure you spread the word on how wonderful he did your inspection.

Never trust a diver!

Jeff