I/O vs VD settled. Hit a "log."

[JV II]

If you haven't already read all the debates about which is better, inboards or stern drives, do a quick search and find hours of entertainment. There is a lot of discussion about corrosion and maintenance.

Four seasons ago, I got into big boating with a 2007 290DA with twin Bravo III stern drives. Loved them. I upgraded in 2009 to my current 330DA with twin Sea Core BIII's. After 3 seasons, love them. Great mileage, cruising speed, corrosion resistance, maneuverability, and engine room access.

And now this...

I hit a six foot long 4x4 going 27 knots. There was a big bang and the engines reved to redline. I throttled back to neutral the instant of the hit. The engines did not stall. I checked the engine room and there was no water. I lifted the drives fully expecting no props, but they were there and seemingly untouched. I circled around, took the pictures of the log I cleaved in two, tested the throttles and reverse on both engines. Everything was smooth. I moved along at no wake speed then brought it right up on plan and headed back to the dock. There was no vibration. Further inspection found not even a scratch on the props. There has been no loss of any fluids and no water in the bilge.

So, add to the virtues of a BIII drive that it is like a 17,000# sledgehammer that smashes waterlogged 4x4s in half. I am certain that if I hit that with an inboard, I would have lost a prop, shaft, and/or rudder.

 

[Two Peas]

Go buy a lottery ticket pronto. I wouldn't count on the same result the next time...

So what do you do when you move up another 8 feet?

 

[tbirdvet]

The same thing happened to me last season. I put a small dent in one of the prop blades but all else was fine. I thought for sure it would have been a lot worse.

 

[sea salt]

What caused the engines to rev to redline?

 

[fwebster]

I am with sea salt on this one. Be sure your towing coverage is in place.............me thinks you might have spoken too soon.

 

[Lazy Daze]

Sea Salt - they redlined because they popped out of the water from the impact on the drive. That's actually what they are designed to do - luckily they did exactly did.

I know of other people with similar impacts and no damage. I also know of others who sustained damage. The drives might very well be fine - but it would be a good idea to get them checked. Even if for no other reason than to cover yourself in case you find a problem a little ways down the road - this way it's documented with your service department and insurance carrier.

 

[dpvandy01]

What caused the engines to rev to redline?

Pretty sure when he hit the log it caused the drives to rise as he cleared the object. They sort of "ride" over the log. Almost like putting them in the trailer position. When they approach the "over trimmed" position I think they cavitate causing the temporary over rev until they lower back into position. Least, that's how I understand it

 

[dpvandy01]

Lazy,,,,, you type faster than I do. But I'm on my phone,, driving, with a beer and an egg mcmuffin. Kidding

 

[Lazy Daze]

Lazy,,,,, you type faster than I do. But I'm on my phone,, driving, with a beer and an egg mcmuffin. Kidding

But just about the egg mcmuffin, right? :smt001

 

[Carpedmman]

I would definitely have them checked as well! I do like the BIII's when properly maintained they are wonderful-Need repairs-cash in for the big bucks!

 

[ZZ13]

My wife is a engineer's engineer. And a real spreadsheet queen. We are about to buy a cruiser. Its coming down to a detailed trade study she is doing between a 2004 300DA seawater cooled with BIII and a 2005 320DA with Horizons and V-Drive. Factors traded are purchase price, total lifecycle cost and performance. I will have her add "floating log tolerance" as another factor.

 

[tbirdvet]

My Mercruiser BIII manual states that this "break away" feature was designed to preclude any significant damage to the drive and/or engine. I hope they are correct!

 

[300SR]

There is nothing on a boat in salt water that is"corrosion resistance" Sorry

 

[LM230]

I've had v-drives and I/O, so perhaps this might be helpful. I am a lake cruiser, so there is always a possibility of shallow water and the occasional under-water hazard. When you encounter shallow water, sand bar, etc in a v-drive, you're screwed if you go forward, and you potentially wreck the rudders backing your way out. With an I/O, trim and swim, push the boat out of the hazard. This is probably only an issue with inland boating/smaller lakes etc, but I was a nervous wreck in unknown water with a V-drive, even with good depth equipment. JA

 

[JV II]

There is nothing on a boat in salt water that is"corrosion resistance" Sorry

Do you boat in salt water or fresh?
The following make parts of a boat resistant to corrosion in salt water and fresh water:
Anodes
Bonding system
Galvanic isolator
Noble metals
Plating and powder coating
Anodizing
Fresh water cooling
I completed my third season in salt water with no corrosion on the metals due to the above corrosion resistance measures.

 

[JV II]

My wife is a engineer's engineer. And a real spreadsheet queen. We are about to buy a cruiser. Its coming down to a detailed trade study she is doing between a 2004 300DA seawater cooled with BIII and a 2005 320DA with Horizons and V-Drive. Factors traded are purchase price, total lifecycle cost and performance. I will have her add "floating log tolerance" as another factor.

I would advise you to go with something that is fresh water cooled. A 2004 that is sea water cooled in salt water will have a significantly lower life.

 

[ZZ13]

I would advise you to go with something that is fresh water cooled. A 2004 that is sea water cooled in salt water will have a significantly lower life.

I think that is sound advice. Does anyone know if there is any statistical analysis on this anywhere based on actual lifes of comparable engines in the two environments? I'd like to try tofind what "significant" means based on facts. Problem I have with v-drives is the size of the boat needed to get them. We really don't need any more space than a 300 provides. I did some math and for a 50 hour season, it will cost $3750 more in fuel to go the same distance in the V-drive 320 that one could go in the stern drive 300 (based on mpg at each boats optimun cruising speed). There's a lot of maintenance (if done yourself) that can be done for those $3750 a year. That gap increases as fuel prices increase.

The 2004 300 is a fresh water boat its whole life and will stay in fresh water for 3 more years. At that point another decision looms. Might decide I don't like cruisers and their annual costs, and then go to a deck boat.

 

[keokie]

BIII's give you the possibility of surviving an impact of that magnitude without damage.... However, that type of collision is far more likely to cause catastrophic damage that would far exceed the cost of what an inboard may suffer.

I'm a fan of outdrives for certain types of boating (like mine), but I would be extremely hesitant to promote them as more "impact friendly" than inboards.

 

[JV II]

The 2004 300 is a fresh water boat its whole life and will stay in fresh water for 3 more years. At that point another decision looms. Might decide I don't like cruisers and their annual costs, and then go to a deck boat.

You could add on a fresh water cooling system to the 300DA later. Just remember to change your anodes to aluminum when you switch to salt water.

 

[johngus]

can't there be damage to the u joints for the drive after the high RPM while fully tilted?I would have the boat hauled,call your insurance and at the least have the drives pulled and engine alignment checked.I would also check the engine mounts at the stringers to ensure no damage.that was a hard impact and even though no seems no damage now,it may present its ugly face in the future.documant the incident now to protect yourself later..