New (old) 17'... finally in the club!

[JimCt]

Finally got her in yesterday.  Aside from some strong stbd. helm, most everything went well. Should be able to iron out the helm problem with the motor trim tab.

  One thing that struck me was how (relatively) quiet the Merc. is at WOT.  But then again, my frame of reference is with '70's & 80's OMC motors.

  One habit she seems to have is mildly porposing at WOT, 32 - 35 kts.  It is a gentle fwd/aft rocking motion.  Adjusting the motor trim some didn't seem to help.  At full down trim she settled down some but was still there.  Backing down to ~ 22 kts. stopped the porposing.  Slowly edging the speed back up she remained stable until the rocking cycle slowly started to show itself again.  Any suggestions as to how to remedy this?

  All in all, a good day.  Will get some pictures next time out.

[scott_gunn]

Trim tabs or a hydrofoil will help with the porpoising.  I'm not sure if you have those already or not.

Trim tabs are ideal but hydrofoils will help and are super cheap.  I have a Stingray hydrofoil on my 200.  My main goal was to stop porpoising.  It worked and also helped me get on plane faster will less bow rise - and to stay on plane at lower speeds.

[JimCt]

Thanks for the info Scott.  I went over to the Stingray site & read the explanation of its operation.  Sounds like it's just what I need.

My only concern is that my Merc. operation manual has a big warning about excessive down trim because it may make steering unpredictable in turning, possibly causing the boat to spin-out.  Do I just trim the motor up to keep the bow up?  Will this defeat the purpose of the foil?

[scott_gunn]

The foil will make your trim adjustments more effective.  I think the Merc warning is probably about bow-steer - where the V in the front of your boat digs into a wave.  I guess if you were using trim tabs or a hydrofoil to keep your bow down this could be more of a problem.  It's never been a problem for me.

[jp aquasport]

all 17's torque steer to the starboard side. Buy the largest torque tab that will fit , and adjust the TRAILING edge to the side it pulls. This will
eliminate most of the pull. Trim tabs do wonders with porpoising. Don't
worry,you can trim fully down once you adjust the torque tab.

[JimCt]

JP, adjusted the torque tab two notches as recommended & it canceled out the pull to starboard perfectly.  Amazing what a small amount of tab deflection can do!

Scott, will pick up a hydrofoil this week & give it a try.  Looks like a simple installation.

Thanks for the help!

[jp aquasport]

Foil made NO difference for me. Bennett tabs will give you the
most benefit. They recommend you install the pump in a "dry"
location,which does not exist in these boats. The trick is to seal
the motor terminals and seams with RTV,which allows you to
mount virtually anywhere. My first pump motor failed from corrosion
in 6 moths. My RTV'D replacement is still going strong 15 yrs later...