Danger with water towing your Tug

S

Sine Wave

Well-known member
Joined
Feb 29, 2012
Messages
61
Fluid Motion Model
C-248 C
Vessel Name
Sine Wave
We recently had our R-27 with a Yanmar 180HP water towed for approximately 3 hours. When we arrived at the service company they found a muffler full of water and the engine was hydro-locked with water in the pistons. This had nothing to do with our original problem. If you have to get towed, be sure to close off the rubber hose coming from the prop shaft seal to the muffler. This can be done using a vise grip pliers and wrapping the hose with a rag to prevent cutting the hose. Never have the boat towed without closing off this line. Knowing this could have saved me over $1000.00.
Sine Wave
 
So what actually happened ? Did the water running past the exhaust outlet cause a negative pressure in the exhaust line that sucked the water through the hose from the cutlass bearing and into the muffler ? Very strange indeed !
 
Is it also necessary to close the seacock?
 
This had nothing to do with our original problem.
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What was the original problem that required the tow?
 
SlackwaterJack":24sr4qjl said:
This had nothing to do with our original problem.
Click to expand...

What was the original problem that required the tow?
Click to expand...

Wow this is tragic! So sorry to hear of the hydrolock event. To help the rest of us avoid this in the future a little more information would be helpful.

As Slackwater Jack ask above what was the original problem which necessitated the towing?

How fast was your boat moving while it was being towed?

Was the transmission in gear (that is forward or reverse) while the tow was going on?

Prior or after the tow (or at any time during your disablement), did you attempt to restart the engine by cranking it for greater than 30 seconds on one or more occasions?

Thanks

Dave
 
Yes. This post got my attention. All the specifics that can be recalled would be helpful. Maybe Ranger could comment on what needs to happen when our boats are towed- boat in neutral, raw water open or closed etc. My condolences on your problem and damage from towing.
 
I know most of the story from Sine Wave. Originally his water pump belt broke. Then after he put on a new belt he was getting a knocking noise so he was concerned that there was something wrong with the engine and had it towed. It turned out that the knocking sound was a piece of crab pot line that got caught in the prop and as the prop turned it was hitting the hull.
I was surprised that towing would force enough water up the small hose going to the mixing elbow and then flow back into the engine to cause a hydrolock, but according to Sine Wave that is what the mechanic told him happened. Shutting your thru hull won't help any. The water would have to pass through the impeller and if it is stationary it would be almost impossible for water to pass through.
 
I guess I am still at a loss as to how this could happen. There are only two openings to the cooling system, intake and outflow. If the impeller is not moving, then no water is coming in- yet how could the water flow past the flap at the exhaust to come in through the back door? I can't help but reason that the boat must have been in gear when towing and the engine was turning over from the force of the water over the prop and causing the engine to pump water. Does this make sense? It looks like closing the inflow valve and taping the exhaust flap shut would eliminate this problem. Anyone else concerned about this?
 
No, there is a small line that comes off the stuffing box and goes into the mixing elbow. When things are normal water flows from the mixing elbow through this line down to the stuffing box. When you are shut down if one was to remove the line from the stuffing box, water will start spouting out. It will not go high enough because the top of the hose is above the water line. I can only assume that if everything was shut down and then the boat was being towed somehow the water pressure from that line was strong enough to go into the mixing elbow and then filled the muffler and then backed up into the engine once the muffler was full. A very odd situation indeed.
 
Jeez I wonder if somehow the transmission was engaged and the motor spun some while being towed with no exhaust pressure to blow out the muffler it filled up the motor just like it would if you were to keep cranking over a engine that would not start. Something does not sound just right. I'd be leery of some of the deductions made by some tow operators. I would wonder how fast they were towing. I'm mean being anchored in some place with some strong current your engine could load up with water? 😱
 
Dave,
Your thoughts about the engine being engaged seems more reasonable to surmise than the siphoning of water up the hose and into the muffler and then the engine. Until it is defined and if I am being owed I will take the hose clamping precaution. I Know of a few tugs that have been towed and this is the first I have heard of this situation.
 
The engine itself could not turn over from just the pressure on the prop from the towing. However if the transmission was left in neutral and the towing caused the prop to spin, then perhaps the conditions might be such that water could flow up the tube. My first comment I think has merit; a negative pressure was set up by water flowing over the exhaust outlet thus drawing water up the tube. Think of how a self bailer works on a sailing dinghy.
 
First of all, there is no shut off valve on my R27. The hose must be clamped off. I think and it was confirmed by the mechanic that negative pressure on the exhaust outlet caused by the towing caused water to enter the muffler from the prop shaft seal. This continued until the muffler filled and then the water migrated to the cylinders causing Hydro-lock. My original problem was losing a belt on my water pump. I changed that but after leaving port a short distance there was a large vibration which I thought might be a Head gasket problem due to the engine overheat. The problem turned out to be a clump of old crab trap rope caught in the prop.
A short tow would probably not be a problem but if it is long like mine was, clamp off the hose.

I may have more after reading the replies.
Sine Wave
 
More answers:
Water cannot enter the engine through the seacock when the engine is not running as far as I know. The tow was approximately 3 hours at 7 to 8 mph. The transmission was in neutral. I did not attempt to start the engine while being towed. The engine would run prior to my being towed but would not turn over when we got to our destination. There was water in the cylinders when we arrived at our destination. Hydro Lock
Water did not enter through the exhaust hose as someone thought. The negative pressure probably caused the syphoning of the prop shaft seal water to the muffler until it filled then the water migrated to the cylinders through the exhaust valves.
Hope this explains the problem. Let me know if you have more questions.
Sine Wave
 
Thanks for sharing this. I get it about clamping the line. What I can't understand if the tow person knows of this problem occurring why did they not recommend clamping the line before starting the tow? Seems like Ranger Tugs ought to have a tech bulletin about towing procedures no?
 
Scuffy":3px430mu said:
Thanks for sharing this. I get it about clamping the line. What I can't understand if the tow person knows of this problem occurring why did they not recommend clamping the line before starting the tow? Seems like Ranger Tugs ought to have a tech bulletin about towing procedures no?
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Boats break down, boats get towed, and it's always been that way. As a general rule the person doing the towing has no responsibility to the vessel being towed other than a safe completion of the task at hand. The owner of the vessel being towed should have enough knowledge of his vessel to prevent damage not directly related to the tow itself.
I see no negligence on the part of the towing vessel or it's operator in this case.
I think it's unrealistic to expect every person operating a towboat to be familiar with every system onboard every vessel he tows. If the owner/operator of the vessel being towed isn't familiar with the procedures required to keep his boat from being damaged he needs to examine his level of personal involvment and skill.
I've spent many years towing things of almost every size and description. My main focus was always a safe tow. I'm sorry the OP's engine was damaged but he should look no further than himself for the cause.
I do agree that Ranger Tugs should come up with some kind of procedure and notify the owners to keep the same thing from happening again.
 
After reading Sine Wave's original post, I thought the problem was sufficiently strange that I copied the post (with a correction indicating that one end of the hose goes to the mixing elbow, not the muffler) to a towing service to which I subscribe. This towing service is highly experienced. Below is their response.

"This is a new one to us. We have seen engines fill with water, but typically due to a high speed stall, never at a 6 – 7 kn tow. We have water currents with the tide equal and greater to 7 kn at some of our docks and have never seen this issue with the Yanmar engine. We tend to agree here that it must have been a perfect storm of events to cause the water inflow and the reoccurrence will be very rare to never. A ball valve in the line would be a great safety measure for 100% security."

I am sure within the many Tugnut followers, some others have had to submit to the indignity of calling for a tow. None, so far, have posted that they to, have experienced engine water lock. Also there are some Ranger skippers who do trolling for fish using an OB "kicker". This is pretty much the equivalent of being towed, yet no reports of main engine water lock from these individuals. My thoughts are that the real cause of the engine water lock is yet to be identified.
 
Has anyone contacted the maker of the shaft seal? I would be interested in their response. Given the thousands upon thousands ( if not millions) of such devices installed on boats around the world, if they had any reports of similar problems, one would think the inclusion of a check valve would be common or at least a warning note in the manual and/or installation info would be noted.
Contacting a few experienced marine surveyors for their comments would also be a good idea.
 
Because we still don't know what the reason for the tow was.
I would guess that the raw water pump impeller and wear plate were worn or had vanes missing. This I would think could be the cause or at least another potential cause of this happening. The speed of the tow over 3 hours may be enough to force water thru an unobstructed (failed water pump) system and into the exhaust.
Don
 
This is not something I would have thought of had it been me being towed- would you have thought of it? Amazing all the stuff that come up on this website.
 
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