Performance after spring service

redlightning

so pulled the boat in May and had a some service done.  New trim sensors and gauges, new bellows, gimble bearings.  Motors & generator serviced.  Drives serviced. Mechanic replaced spark plugs and commented that it had the wrong plugs.  This season so far we have not had the boat loaded up with more than 4 people.  I have always thought it just wasn't performing as it did befor work.  I notice exhaust fumes, station wagon effect, pretty much every time I take off.  Something just isn't right. Had 6 adults in the boat and it it seemed to take too long to plane out.  Not sure what to expect with my trim gauges since they didn't work when I purchased the boat, but when I trim the drives I get pourposing when trimmed just a hair above the fully down mark on gauge. 
Any thoughts?  

youstolemybeer

Did the boat run ok before the service? If so, talk to the mech that did the work and find out what all was changed. Then have them put it back the way it was.

Dream_Inn

Trimming just a little shouldn't give porpoising, but sometimes it shouldn't take much.  Does the boat perform the same once on plane?  If it performs the same once on plane, then something with trim must've changed.  Maybe the default placement of the drives were changed after they were reinstalled (there is a whole topic on here of which location to have drives with the hydraulic trim). 

As far as station wagon, do you ride with isinglass up?

diggin2day1

The porpoising might be due to incorrectly installed shims on the trim Pistons. I had the same problem with my 270 after I had s new bravo 3 installed.... Struggled to get the nose down enough to get up on plane(couldn't trim down enough). Had the mechanic check the position of the shim... He changed it(quick easy fix) and it made a tremendous difference. 

Dream_Inn

Yes, you hit what I was trying to think of @diggin2day1!  The shims on the trim pistons are exactly what it seems like the issue could be and betting he put them back on incorrectly, not allowing the drive to go all the way in.  It would also mean it doesn't have to trim much once on plane cause they are already out a bit.

Michael T

On my 2013 EC 310 with 350 Mags and B llls  and my 2014 EC 360 with twin 502 Mags Bllls the trim ram shims were set to full negative trim (drives able to tuck-in as far as possible).

Unlike my Rinker bowriders that I usually + trimmed the h*ll out of I rarely added positive trim to either cruiser while underway.

redlightning

Thanks for the feedback.  Yes the boat would plane better before the work was done.  It's exaggerated when fully fueled and with a few people.  I do not run the isinglass.  In fact I have been keeping the walk thru window opened and still getting exhaust smell in drivers seat.

redlightning

This is the part number on the invoice for the NGK spark plugs installed during service.  For some reason I think this is causing a problem.  41-ITR4A15

redlightning

i have the VP Drives.  Is this shim situation something that can be an issue with that drive as well as the MC drives

LaRea

Have you made any drastic changes in load locations?  For example, did you take something heavy from the v-berth and move it to the transom locker?  That could affect running angle, even on a big boat like yours.

If not, I agree it sounds like shims are the culprit.

frenchship

41-ITR4A15 Are the right replacement for the OEM plugs AC-41-993

redlightning

No changes like that.  In fact no real weight changes at all.  I had 50% fuel in the tanks and 6 adults 2 small kids and it struggled to plane out last weekend. I will say i do believe the handling seems different once on plane after the service. kind of loose and i am thinking the description of the drives basically being trimmed up due to the shims is sounding more and more like a reality.  i do have VP drives, this isn't only on the Merc drives is it?

randy56

@redlightning, when I get up on plane and its time to trim up, I go just a bit pass the lowest mark on the gauge. In counting time after pushing trim button count to 2 . If there is a roll in the water from other boats or barges, sometime's pourposing starts, then trim back down or tab down a little. Until it stops, bouncing.

Dream_Inn

How's your boat bottom look.  Any scum?  Maybe does the bottom need cleaning?

Michael T

I have never relied on my trim tabs for "trimming" the boat. I start out fully negative to get on plane then trim up until I start to porpoise then "touch" with a small "tap(s)" it back until it levels. Once underway I tap the trim up or down with the lightest tap possible and watch my mph and rpms for best spot. With my 2013 EC 310's V V that was easier and with my 2014 EC 360's ECO Setting it was a breeze!