you mentioned a lot of play in the drives when moved by hand. i have same issue. my steering arms SEEM to be tight, but there is a lot of play in the end of the steering cable. have someone move drives and then the steering wheel while checking transom from inside and you will find where the play (loosness) is. fix that first. that stock merc power steering is marginal at best. make sure it is at it's best. 780hp is a lot of motor for a 26. get rid of the nosecones. they slow the boat down. and hanging out in front of steering axis they put real stress on that shaky steering of yours. (ours).

I think that some of that play will go away once you start the motors. Obviously you need to be SUPER carefull with checking play with the motor running!!! My boat has a lot of play with the power off were the tiller arm and cable and power stearing actuator all bolt on with the motors off. Once I start it up that for the most part goes away.

[QUOTE=Diego9040;3637955]not that it relates directly with your problem but it's likely your tachs or speedo are wrong.
3700rpms at 60mph with your props = .01 slip. even if you have 1.36 gears that's only .10 slip with the drives tucked in. this needs to be fixed to prop the boat properly. good luck & be safe!

I am still trying to find the right guy to assess all this issues, but since i received all of your advises, I ve been using the boat trimming the drives out carefully and it seems to be very stable at around 60 mph,but i am NOT going any faster till i have an expert doing it with me.But it feels good to play with the drives and boat goes way smoother on the water,i guess less drag.

Derek , the bad part is that only the left drive has a nosecone,not the right one,no doubt that has to be even.Will take care of this soon...
Still i am more and more convinced that it was bow .

How did you get rid of that play, mine is not that bad,other fast boats at the marina have way more than mine.

[QUOTE=vette131;3642467]I am pretty sure the speed/rpm numbers are correct,will double check sunday,and post them,are these numbers not posible?excuse my ignorance,but as i said earlier, i am new to speed boats.

i haven't corrected it yet. i had the boat 5 years ago. it had the turn-right-when-pulling-off-power problem then. i just got it back in january. i will try to get a look at it soon. i have a replacement motor to go in mebbe this weekend. i hope other is ok. 1 nosecone? get rid of it!

I have seen in some websites selling the add-on power steering systems that claim they would take away that side to side play , i beleive i saw it in keithheickert.com .

http://www.keitheickert.com/c-868-imco-marine.aspx

there is an extra "h" on the website above , correct one is Keitheickert.com

I might be blind, but I did not notice it was only one drive running a nosecone in the pic. GET IT OFF bofore you even consider running your boat again. As some would say "There's ya problem" I define it as being absolutely down right dangerous. Just curious, but didn't the seller point this out?

The only way to get rid of the play is to upgrade your steering as mentioned before. The stock Merc steering has nothing to do on a twin 454 26' boat, period.