Yanmar 6 Cyl/Brav III I/O and shower cooler

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bondstreet

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I am looking at a boat that has a Yanmar 6LPA-STZP 6 Cylinder/Bravo III I/O equipped with an outdrive shower cooler. My research indicates that they are common in high performance applications, but this is on a fishing boat with 315 HP. Is it because the diesel exhaust is hotter than on a gas engine? Is the combination of the YANMAR and the Bravo III a bad thing?

Thanks for the insight.
 
A couple diesels i looked up recommended BII because it was the heaviest duty and was capable of running a 23"(?) diameter prop.

check 'marine diesel'

Exhaust should be fine with water cooling.

I actually have a Yanmar to bravo conversion for sale. Mainly consisting of a bell housing with flywheel adapter and coupler with exzhaust adapter that goes to the thru hub exhaust. If you're interested, I can take pix so you can check out the conversion.

PS,
This conversion should go on a boat with the BII already installed but neeeds an engine. Would require beefing up the stringers.

The other conversion is probably just as complicated. Moving the diesel aft and beefing up the transom and sealing up the prop shaft components
 
Yanmar ultimately went to their own drives. Wonder why?
 
Charlie doesn't the need for special cooling indicate too much load?
 
It may be a B II outdrive. I am looking at pictures online. The boat is 34' long with a 12' beam. It just may be that that's alot of boat to push through the water. I am a little leary of "things that don't come with the orignal package but solve problems." I haven't spoken with the owner yet, only the broker, so I don't know the story behind the outdrive shower cooler installation. I think, but am not certain, that diesel exhaust gas temps are higher than gas engines becasue the combustion is caused by pressure and not spark. I was thinking that if exhaust gas temp was higher, then it may be helpful to cool the top of the outdrive. There isn't more than about 3 qts of oil in an outdrive, so to extend the life of the outdrive, the cooler was added.
 
That's interesting Steve!

As far as a drive cooler, I have one on my BII. It's the drive itself that creates the heat. Specifically, the gears and whatever load put on them, but the gears themselves generate the heat. If you've ever had the chance to put your hand on the exhaust water It will be barely luke warm.

A 34' boat is a bit much for a single engine/drive but, it gets on plane, the drag would be greatly reduced. Then, this boat may may run at displacement speeds.
 
i would contact mercury tech support with the engine model # and spec and ask them if the specific stern drive in question is rated for the engine. mercury makes a bravo III that is rated for a diesel engine. find out if this drive is within the mfg's hp and torque specs. if the drive shower is an un needed extra that made the current owner happy great. if the drive is not a good match, its a good catch before you buy.
 
I contacted Merc tech support this afternoon. They are going to look into the issue for me. I don't know the deadrise, but it isn't a deep-V hull and is typical for the Chesapeake Bay. The boat wieghs 18,000 lbs, is 34' long, and 12' wide. Draft is 42". I am thinking that the hull configuration and weight may be too much for the outdrive. The boat is about a 4-hour drive away and I won't get to look at it for a week or two. Merc told me that if I can provide the outdrive serial #, they can provide its history. I will let you know what they come back with.If I can't figure it out ahead of time, I will be sure to ask about it during the survey and check it out during the sea trial. I just hate to get to the spending money point to find out that is a show stopper for me.
 
Just remembered a friend had a 454/330 HP with an older TR/TRS drive in a 25' faralon. He kept spinning the coupler. Things like that happen if you slam it with a heavy boat. Bring it up to speed slowly to reduce the load and it should be good. The 454 is said to have torque comparable to diesels.

Looked at a couple threads from Offshore Only and one guy mentioned using a single BII on larger fishing boats(40'+) up in alaska.
 
That is a lot of boat for io. The history of diesels with out drives wasn't good iirc. I would keep looking
 
quote:
Originally posted by jtybt15

Just remembered a friend had a 454/330 HP with an older TR/TRS drive in a 25' faralon. He kept spinning the coupler. Things like that happen if you slam it with a heavy boat. Bring it up to speed slowly to reduce the load and it should be good. The 454 is said to have torque comparable to diesels.

Looked at a couple threads from Offshore Only and one guy mentioned using a single BII on larger fishing boats(40'+) up in alaska.

Click to expand...


I had the same set up in a 27' Sea Ray with a 10' beam. That set up was rugged & bullet proof.
Al
 
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