Bravo 3X

[John G]

I know this has been talked about many times before but I've searched RIBnet & can't find the answers I'm looking for so am putting this one out there again;

I know these drives keep failing but...

Is it only with the Yanmar 315hp engine?

Does the 3X version suffer the same problems?

Exactly where/how do the drives fail?

What are the differences between 3 & 3X?

Does the 3X use a shower - if not will this help?

Thanks guys - hope you can respond to this 'old' question!

[Alan]

Drive failures primarily but not exclusively with the 315hp Yanmar and both the 3 and 3x leg. Personally I believe that weight of boat is a factor, e.g. heavier RIBs see a greater chance of failure than lighter ones but that may in fact be bollocks as I am basing it on boats I know that have experienced failures vs boats I know haven't. No more scientific than that.

Can't tell you exactly how they fail but the sound like a bag of spanners when they do and go bang very quickly and that being half way between Stornoway and the Kyle of Lochalsh is an inconvenient spot for it to happen unless you have international rescue in the shape of Hot Lemon to hand!

Similarly unsure of exact technical differences between 3 and 3x except that the 3x is 'strengthened'. A drive shower is not a standard fitment on either but is rather an aftermarket device. I suspect the Mercruiser would never sell one as OEM as that would rather be admitting there is a problem! A shower will help but not guarantee to prevent failure.

[John G]

Thanks for the reply Alan

Does no one else have any experience / comments on these drives?

I have heard of some scandinavian companies mating them to 370hp & even 440hp Yanmars - surely that's asking for trouble!!??

[Dieselroy]

Hi Alan
We have driven our 9,5m Tornado with a 320 hp Mercruiser diesel
with bravo 1 xr for nearly 350 hours this season, we have changed drive
oil every 100 hours, and it still performs nice.
What ive heard is that when the boat is out of the water, and you
dont go off the throttle when it goes into the water again is whats killing these drives.

Makes sense to me as our boat doesnt have much airtime since its long and heavy.

Roy

[Alan]

Originally Posted by Dieselroy

Hi Alan
We have driven our 9,5m Tornado with a 320 hp Mercruiser diesel
with bravo 1 xr for nearly 350 hours this season, we have changed drive
oil every 100 hours, and it still performs nice.
What ive heard is that when the boat is out of the water, and you
dont go off the throttle when it goes into the water again is whats killing these drives.

Makes sense to me as our boat doesnt have much airtime since its long and heavy.

Roy

Key point in your post is Bravo 1 drive rather than B3. The Bravo 1 more robust it seems than the Bravo 3(x). Bravo 1 is single prop vs counter rotating Bravo 3x.

John - Try Pm'ing Brian, poster hereabouts. He has a 9.5m Scorpion and has switched from B3(x) to Bravo 1 after eating two B3 drives in short order. (one of which was the incident in Scotland I described earlier.)

[Dieselroy]

Hi again
What kind of boat do you have?
why cant you use Bravo 1?

Roy

[Brian]

John G.
Hi.
I have had 3 B3s 2 B1s and a B2.

In reverse order:
The B2 failed after 20 hours
The two B1 failed after 29 hours each.
2 of the 3 b3s failed after 150 hours each.
After fitting the third B3 I sufered a lack of confidence in the drive and changed to a B1.

Now it can be told!
The problem (apart from the first B3, that failed because someone left out a needle valve in the first 100 units manufactured-and it failed in a specific way) was that in hindsight the engine was not aligned correctly at time of supply OR sufered a rear mounting failure. Once this was discovered, by a very clever engineer called Jake, here in Alderney, the problem went away.
Now the last thing I want to do is to point a finger. The engine was removed and refitted by at least two sets of engineers over the years-so I am not blaming anyone but myself!

I now have a new B3 (Serial Number begins with a W not an M) which has an integated cooling system in the form of a vaned top to the gearbox and am a very happy bunny.

My advice is to fit a new B3 as your boat is lighter than mine and a B3 gets rid of directional bias and gives a much higher top speed.
As far as I know an X model is diesel and a non-X is petrol-but what do I know?

If you need to know more-give me a bell on 01481 823187

[Paul Glatzel]

John

I am by no means an engine/drive expert but i've run a B3 coupled to a Yanmar 315Hp for 3 years & 700 or so hours - training, charter, pleasure etc. Ours is a 2000/1 model with a shower as standard

The most serious problem we had was snapping a drive shaft in a F7. Our review of this led us to believe that the rib took off (8.5m diesel & very heavy) and as it re-entered the water the torque emanting from a unbelievably powerful engine (if you have experienced the turbo kicking in at 2k revs you'll understand) meant that the prop was prevented from rotating as fast as it wanted to shearing the top of the shaft (I have the offending item in my office as a souvenier). To prevent further issues we instigated a set of rules 1) driving at the limit increases the chances of stress related gear failure - so was banned 2) no full lock turns with full power on or coming on - imagine the stresses being put in the UJ 3) good regular servicing

Since doing so we had no issues bar usual wear & tear. In short i believe if you have this particular combination then you do have a set up that if not managed is at greater risk of failure than some others - however manage it well and its an awesome combination and no less reliable than other setups.

Digressing ..... I do have a personal view that some of the RIBs nowadays are so capable in heavy weather that they are driven at speeds & in ways that mean gear failure is almost inevitable (over time) if they are really pushed. As skipper there is a need to ensure you don't break your kit by being sensitive to the way you are using it.

Feel free to call with questions but please bear in mind i'm not very technical!

Paul