Synchronizing twin Bravo one stern drives
#1
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I just got my Formula 292, it has twin 377 mags and Bravo Ones, I noticed that the indicators are not even and also when running , as I trim up one side starts shooting a rooster before the other, I think they are off a little bit and I was wondering if anyone else has dealt with this or knows how to adjust them. It also blows out the props just as its planning, I'm wondering if this might be part of the problem.
Thanks!
Thanks!
#2
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From: Carmel, IN
Sounds like you have two issues here. The first is the drives trimming up at the same rate. To correct this you will need to adjust the trim indicators located on the outdrives. There are videos on Youtube on how to do this and its not hard at all.
The second issue is getting the boat on plane. These boats are heavy and you need to coax them up on plane. What I do with mine is start with the drives all the way down and then start advancing the throttles to get the boat moving and bring the motors up to about 3200 RPM and let the boat come on plane before you start trimming out. If you are getting a rooster tail, you are way over trimmed. The stepped hulls like a little positive trim and thats it.
I run labbed 28P Bravo props and typically have 1/2 tank fuel and 2 people on board. If I have more people, I use the tabs to help get on plane.
Dave
The second issue is getting the boat on plane. These boats are heavy and you need to coax them up on plane. What I do with mine is start with the drives all the way down and then start advancing the throttles to get the boat moving and bring the motors up to about 3200 RPM and let the boat come on plane before you start trimming out. If you are getting a rooster tail, you are way over trimmed. The stepped hulls like a little positive trim and thats it.
I run labbed 28P Bravo props and typically have 1/2 tank fuel and 2 people on board. If I have more people, I use the tabs to help get on plane.
Dave
#3
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To set up the drive indicators there are several ideas on HOW to do it correctly.
I have trimmed down as far as possible and adjusted the indicators to the 0 setting.
Then adjust/trim the drives so they are at the same angle as the bottom of the boat.
Bubble level centered on bottom of the boat. The bubble level centered on the cavitation plate.
Make note of that reading on the trim indicators. They should be close.
If the indicators are different, adjust the short one out to match.
I have trimmed down as far as possible and adjusted the indicators to the 0 setting.
Then adjust/trim the drives so they are at the same angle as the bottom of the boat.
Bubble level centered on bottom of the boat. The bubble level centered on the cavitation plate.
Make note of that reading on the trim indicators. They should be close.
If the indicators are different, adjust the short one out to match.
#4
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Joined: Oct 2002
Posts: 263
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When cruising, now you know when you trim both drives to the same number, the drives are close to the same angle in relationship to the bottom of the boat.
Trim the left drive to when the rooster starts to show, stop, trim the right drive till it just starts to show. The indicators should read close to the same.
Now your drives are matched for trim.
Lower the drives where the rooster is gone and trim indication is matched.
Push the throttles up till both engines are at 3000 RPMs.
Listen to the engines. They should be steady in the noise they make.
If you get a wow-wow-wow droning sound, the engines are not matched.
Trim the left drive to when the rooster starts to show, stop, trim the right drive till it just starts to show. The indicators should read close to the same.
Now your drives are matched for trim.
Lower the drives where the rooster is gone and trim indication is matched.
Push the throttles up till both engines are at 3000 RPMs.
Listen to the engines. They should be steady in the noise they make.
If you get a wow-wow-wow droning sound, the engines are not matched.
#5
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If you have the pulsing sound of Wow-wow-wow then one engine is running faster than the other.
For simplicity, only move the right throttle, and push it forward VERRY SLOWLY. If the droning sound speeds up, you are going the wrong way. If it slows down, then continue to advance the throttle till the wow-wow comes together and actually stops.
When the droning stops, the engines are matched in speed to where they are harmonically balanced. Make note of the tachometers and see how far off the tachometers are.
None are exact. But I have seen many that are really close.
If you have ever flown on an airplane when the sync system is broken, you know exactly what that droning sound is.
For simplicity, only move the right throttle, and push it forward VERRY SLOWLY. If the droning sound speeds up, you are going the wrong way. If it slows down, then continue to advance the throttle till the wow-wow comes together and actually stops.
When the droning stops, the engines are matched in speed to where they are harmonically balanced. Make note of the tachometers and see how far off the tachometers are.
None are exact. But I have seen many that are really close.
If you have ever flown on an airplane when the sync system is broken, you know exactly what that droning sound is.



