Australia

Hi everyone,

Firstly I must apologise because there isn't much advice I can offer on the forum. I've imported the 38ZR in Jan this year and the whole thing is a complete learning experience.

I haven't seen any others in Australia at all to have someone to swap notes with, so thanks to everyone so far that have helped me with tips on this forum. It's almost my sole source of info and help. (the instruction booklet from Donzi was pretty useless)


Here is where some help is really needed. Trim and top speed.

I've measured the level settings for the tabs and drives. For the drives 2.5 on the gauge is spot on level.

When I push it, I need to push the trim out to about 4 to get the motors to rev to 5000 rpm. Any less trim and they really struggle.

With the maximus 34s, I'm getting around 132 kph on a 1/4 of a tank of fuel at 5000 rpm. (82mph)

Early in the year, we snapped a prop shaft. One theory is the prop was surfacing.

When I got the boat, it had 20 hours on it, put on by the dealer playing with it in Chigago.

Am I on the right track here?

Cheers everyone.....,
Aaron

Tom A.

HI!
Congrats on the boat!
It sounds like you are correct on the trim. The boats don't need more than 1.5-2 above even so 4 sounds about right. You should get 5400 rpm out of the motors and you may want to try a 32 pitch prop if you can find one. The boat should run 86-88 mph at top end.
My Bravo's surface as do many on the Zr's you just don't want to over trim them the angle is what puts the strain on them.
Search throught the Donzi section here, there is a lot of info on the 38Zr's.

Australia

Thanks Tom. Being a novice, I'm not sure how to identify if it is surfacing props. Is there anything I should look out for?

I was reluctant to trim past 4 but you think I could give 4.5 a shot to see how it goes?

Do they normally struggle to rev to max RPM if the trim is close to level?

Australia

btw, love the comps. What power setup you running?

Tom A.

You will know if you are over trimmed if the rpm goes up and the speed goes down. You will also get loose and feel like you are not gripping the water.
Try trimming from 3, 4, 4.5, 5, etc. in little increments on a flat day to see where the boat:
A - feels most locked in (ideal running position) at cruising speed
B - drop the throttles and see where the trim point is where you gain the max. rpm and speed.

Once you have those two numbers, you will adjust between them for different conditions and speeds.
Also, make sure your tabs are all the way up when running. You really only need to use them to keep the nose flat on a following sea (going with the waves) and to level the boat.
In following seas I run the tabs so they are just skimming the water to keep the boat from going too nose up.
As for leveling, you may need to drag one tab or the other depending on weather the load is lopsided or you are going into a quartering sea.

Thanks for the complement, I love my Comp too! It runs great! I have a pair of 575's that were bumped up to 700's. I just installed a pair of the IMCO SCX drives this year to hold up to the power and so far they have been great.

Australia

thanks . I'm haning to get back out there and play. Too much fun...

88mph is the aim.

Cheers

Australia

I managed to get up to 85 mph. I was running around 5000 rpm. I had just under a full tank of fuel, around 600 litres on board.

I'm guessing that is pretty good. Thanks for the advice. Cheers

Aaron

Tom A.

When you get to about a 1/4 tank of fuel you should get that last couple mph and rpm out!
Sounds like you got it!

Australia

I tell you what I did find, maybe you may be able to ratify my thoughts.

We broke a drive shaft and lost our prop on the left bank this year. I repaired it all and had a new prop labbed and matched to the right side.

I've set the throttle adjusters to be perfect. It to 3300 odd RPM the throttles are even. But beyond that I need to feed in more throttle for the left bank.

I'm thinking maybe the prop is slightly taller then the right prop.

Have you ever seen anything like that before?