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Budman
09-03-2003, 02:21 PM
I have a 2001 Donzi 16 Classic 305 EFI, and wondered how far do you normally trim the motor up at full speed. I need more prop since it came with a 19" Vengence, and may go to a 22" Turbo. I was running around 55 mph at 4500 rpms and had plenty of throttle and power left. The trim was about half way up. Most of my experience is with outboards where I would trim it all the way until it just about turns squirrely.

MOP
09-03-2003, 04:19 PM
From my experience very little if any trim is needed the 16 rides bow high, sometimes I give it a slight tap or two. At slower speeds in bad chop I do put a fair amount of trim coupled with a fair amount of tab working one against the other it keeps the bow cutting the chop and if it does come off one it comes down a little softer try it, it helps quite a bit.

Barry Phillips
09-03-2003, 06:21 PM
I had an 18 with a 250 HP 350, a Bravo 1 drive and a 23" Vengeance. The Vengeance would ventilate by the mid trim point. Just below the mid point on the trim gauge seemed optimum. Although the boat felt bow high at lower settings it wasn't, in pictures I have, it looked almost flat on the water. I now have a 22 and it seems to need even less trim. On the newer boats there is a trim alarm that sounds off at just above the half trim point on the gauge.

SO-SLO

1996Z15
09-03-2003, 08:25 PM
Okay so on older Donzi's how do you tell when to stop adding trim to the boat? I usually stop at the 1/4 point; I'm afraid to go any further for fear that I mess something up. Is it safe to go closer to the half way point? How do I tell when I've gone too far?

Rootsy
09-03-2003, 08:26 PM
i find that by trimming and watching a gps and feeling in your arse through the seat you can find optimal trim... it is not the same at all rpm's and it changes with different props. my SS setup is way more sensative to trim than teh GEN II was on the 16.

you should feel a slight change of vibration and noise from the drive when you overtrim and it loses it's optimal angle of attack and slip begins to increase and speed decrease.

basically... i found that i would have to trim til i couldn't hold onto her anymore (maybe just above 1/4 out from full in) and either get out of it or tuck the nose in for control... i do not think i ever totally tapped her full potential in the GEN II form...

used to like to porpoise midrange also with the vengence...

boldts
09-03-2003, 11:03 PM
If I'm totally wrong about this, just say so! It wouldn't be the first time :D On my 22 Classic, I do not pay attention to anything but the tach. (I'm assuming by half way up, your talking about the trim gauge?) My Bravo1 also has a trim stop that only lets it go so far before you have to use the trailer trim button. Anyway, back to how far is to far. Watch the tach and trim out until you see the tach RPMs increase, but in you butt, you can feel the boat isn't going as fast as it was. There will be a point where the RPMs take off, but the boat doesn't go faster. Simply hit the trim button back down with a quick touch. You will see the RPMs come back down and definitely feel the boat go faster.

That is how I've always done it. Heck, half the time that gauge isn't accurate anyway. Now if your running down in front of the beach or working as a patrol boat at a offshore race and lots of people are watching? Trim her out until you have a nice rooster tail flying out the back. Looks fantastic and of course brings many comments from those who don't know your actually going slower wink

MOP
09-03-2003, 11:58 PM
I like a lot of the guys have run both the 16 and the 18. The 18's I ran required a lot more trim which did wonders for speed. My 16 and a few others I have run needed little or no trim at WOT, they need tabs to kill the porpoising at mid range and in chop.

Budman
09-04-2003, 07:33 AM
Thanks for all the input. It seemed like the mid point on the trim indicator seemed to work best overall at high speeds. I was watching the RPM's, trim indicator, speedometer, oil pressure, and also had to remember to watch the lake to see where I was headed. Ha ha ha....