Bad day ...

Upon returning home last weekend after a night anchoring out, I pushed our boat to semi-plane to blow out the turbo/exhaust system as I usually do as I normally run slow while underway at around 1400rpm.

While running for about a minute at just over 3000rpm (we have a Mainship 34 Trawler with 370hp Yanmar) my wife and I could smell burning while sitting in the flybridge. My initial thought was the smell must be external to the boat as we had a breeze in our face from running the boat over 10kts. Within a couple of seconds the alarms went off. I instantly throttled back to idle and ran below. The engine room was filling with water and a raw water hose had come off and was spewing water in.

Ran back to the console, steeled boat out of the ICW channel while cutting the engine and dropping the anchor (I think this all happened at the same time).

Ran back down to engine room, closed thru-hulls and assessed the situation.
Had about 8" of water, and the hose that had come off was the raw water to the oil cooler exchanger, which also feeds the dripless prop shaft. The hose clamp was missing. The bilge pumps had been doing their job. The water never got to the high-water pump.

I refastened the hose with a new hose clamp and restarted the engine. I observed for a few minutes in the bilge and things seemed "ok". We were within a mile of home so I idled the boat back.

After pumping out the bilge (beyond what the bilge pumps get) I found the broken hose clamp; it had snapped in half at a point where there was some noticeable corrosion on the stainless steel.

This boat is new to me (only had it a few months) and I hadn't done the do-diligence of checking all the hoses & clamps. When we bought the boat, we motored it home from the mid-Florida East coast to the mid-Florida West coast, taking it around the bottom of the state. We were lucky on that trip because I didn't have spare clamps on board, or even tie straps.

In addition, the hose that had come off only had a single clamp on the end that failed even though the other end was double clamped.

I don't need to ramble about the lessons learned here, as they are obvious.

I checked my tranny oil and it is up, clear and not smelly. Any ideas out there as to what I would have been smelling when the alarms went off? I don't see or smell and issues now. Surely something that got hot enough to smell on the flybridge while underway at speed must have caused some damage somewhere. Any ideas where I should look? At slow speeds (I haven't gone beyond idle since) there doesn't appear to be anything wrong. All temps, etc., are within normal ranges.

Any input appreciated. Thanks!

You could have been smelling the exhaust as you would have been getting "air exhaust" without being mixed with water.

Check the exhaust hoses for heat damage. That is most likely what you smelled.
The first indication of raw water failure is often louder exhaust

Running at a high RPM and no cooling to the PSS, could have created the smell?

Thanks for sharing so others may learn.

What does your Yanmar operators manual say about running at low rpm for extended periods of time?

Greetings,
Mr. dd. "...what I would have been smelling when the alarms went off?" that was a notice from the odor fairy letting you know something was amiss. Pay attention to those type of hints...

Wow, that was a close one!!

I doubt if you were just smelling diesel exhaust. It has a characteristic smell which we all know about, not a burning smell. It probably was something that was overheated and drove off burning paint, oil, coolant or something similar. Surprising it got up to the flybridge in a head wind though.

Did you lose any coolant? If not then you probably didn't overheat the engine itself but may have overheated the tranny oil, engine lube oil, exhaust components or intake air. I think the big risk was running hard with no raw water cooling the after cooler. That would have kicked up EGTs significantly due to the hotter intake air and could melt valves and pistons if it kept going long enough.

I am not sure there is any proactive diagnosis that you can do other than watching coolant levels and oil levels. Any loss of coolant in the future may be due to a head gasket failure, but like I said if you didn't lose any coolant during the event you probably caught it in time.

Also check the blowby tube that terminates right above the air filter element. Is it puffing under load. That is an indication that the pistons scuffed.

David

Between the smell and the alarm was no more than 2 seconds. Instantly reacted at that point. I would have also reacted to the smell, but it would have taken by brain another second to process :-(

Bad day or good day?

Was it a bad day because of the problem?

Or was it a good day as you quickly became aware, apparently shut down before any serious damage, bilge pumps worked, water quickly removed and able to safely get home.

I have a similar philosophy about auto accidents. If you're in one and no one is seriously injured then that was a good day, a lucky day.

Seems to me you reacted and handled this very well. Logic prevailed rather than panic.

bayview said:

Check the exhaust hoses for heat damage. That is most likely what you smelled.
The first indication of raw water failure is often louder exhaust

Click to expand...

Agree...if a turbo engine and running up in the higher end of the rpm range.....I will bet burnt rubber (powerful smell outside even) in the exhaust, even brunt fiberglass tube if one is near the exhaust elbow.

I have had this occur dozens of times on gas and diesel boats.

If you can squeeze the exhaust hose and it crinkles...probably the smell...it may not need immediate replacement depending on the damage...but replace as soon as you can.

If you can squeeze it...pop it off and look inside, often the burn goes 6" to several feet depending on the power at the time.

I spin things up at the end of a run as well. I make it a habit of only doing it from the lower station where I have full instrumentation and am close to the action should anything not feel or smell right..

You mentioned that the hose that popped out was feeding your dripless seal. Any possibility that the smell was coming from there? I guess a dripless with no water at high speed may become hot.

By the way, must your story remind me something.
Looking at your ER with 8" of water in it, what a feeling isn't it?

L

I would make sure you wash everything down with Salt Away...just as a precaution...just watch any electrical lines. Sounds scary but I do a check everytime before we go out...and replace any clamps that just dont look like they are gonna last.

I too have a 34T Mainship (2005). I am in the process of replacing all Engine room hoses and new Sandvik/ABA Clamps(AC pump, Generator & Engine raw water supply as well as exhaust hoses) The 5" x 3' exhaust hose took the better part of a day to remove and replace. I noticed that it was deteriorating after bringing it home from Daytona Beach, FL to Wilmington, NC (500 miles) after purchase. All of the hoses are date stamped 2004 from when the boat was manufactured. I guess this is called taking care of "Deferred Maintenance"
Good luck with your boat and please, check all other hoses.

Todd

i am also replacing all of the stainless steel hose clamps. I am going with AWAB non-perferated clamps.