Engine overheating in narrow channel surrounded by boats

[Jared1048]

Hopefully your weekend sailing wasnt like mine...

While out in a narrow channel with dozens of boats out enjoying the sun had an emergency over heat alarm sound. Being only 15 minutes out was pretty shocked to hear that buzzer go off. I immediately killed the engine and went down below to start checking stuff.
I remembered there being a lot of those weeds growing up in the marina so went to the raw water intake screen and found it completely full (this was cleaned about a month ago!). After cleaning this out opened all the windows to provide better ventilation and hopefully cool down the motor quicker. We start the motor again and continue on our trip but are now freaked since we have to pass through 2 bridges.

We get through the two bridges and for the second time now have the buzzer go off. We kill motor again quickly and pull out genoa to continue to maintain boat maneuverability. Boats are passing us from boat sides looking at us like “that guy” being an a$$ trying to sail through this congested area. We pull out our main to help keep momentum with there being practically zero wind. While trying to squeak through this channel now notice a Police boat. Now maybe some of you would of welcomed this I don’t have too many positive stories that involve the Police so am now really stressed out (though I have all the required stuff if stopped). I am thinking he is definitely going to stop me for trying to sail through this area with this many boats. I know I can still use my motor if the situation becomes an emergency though.

Now in open water start taking the impeller assembly off the boat. Looking into it from hose adapter now start checking each blade to see if any are broken. Nope, all good and place it back on motor but with really tight tension hoping it was just a loose belt. Start motoring and AGAIN have it go off. This is really getting old now…

While removing and checking hoses for obstructions manage to crack the air evacuator thingy on the water cooling line that attaches to the exhaust mixing elbow (not known yet).

We have had the manual out and have been looking over everything double checking stuff. Maybe there is too much backpressure on exhaust hose we think. Maybe it’s got too much carbon built up? After about 40 minutes throw the swim latter down and I stick my hand in the exhaust. About every 10 seconds I feel a big gush of water but it feels questionable. But now there steam coming from the engine bay! On closer look the water is shooting slightly shooting out of hair line crack in the water hose going into the exhaust elbow. A piece of a trash bag wrapped tightly around it reduces it to a small drips (a temp solution until we can get back to port).

After sleeping on it think that I should double check under the boat to see if something is caught on intake. Luckily I’m a certified diver so have all the gear I need. Get to marina and take off the hose attached to the seacock and the flow is dribbling out of the end. I don’t know how much water should be coming out so don’t know if this is a problem. I try to blow into it but it doesn’t budge even the slightest. Now I grab a coat hanger and start pushing it through the hole. Now more water is coming out! A few more jabs and the water starts gushing out maybe 6-9 inches above the seacock! Success!

I’ll definitely be more aware of what’s in the water from now on and leave some dive gear on board to ensure we can properly check what’s under the water line.

 

[Steve Dion]

Jared:

As I remember, the thru hull on the H'31 is rather small. You may be able to take a small screw driver and clean out anything that is in the intake from above. I had some small gravel that was stuck in mine at one time.

It appears that you have probably cleared the fitting.

 

[Clark]

Been there; done that. Our lake is bad about growing weeds in the summer. I've had to go thru that 2-3 times the last 4 years. What I found was that a hefty water toy air pump nozzle will just fit into the raw water intake line. Jam it in there and give the piston a few hard shoves and it cleared the intake right up.

 

[Jared1048]

Jared:

As I remember, the thru hull on the H'31 is rather small. You may be able to take a small screw driver and clean out anything that is in the intake from above. I had some small gravel that was stuck in mine at one time.

It appears that you have probably cleared the fitting.

Coat hanger was perfect for the job. It was pretty small though.

 

[Jared1048]

Been there; done that. Our lake is bad about growing weeds in the summer. I've had to go thru that 2-3 times the last 4 years. What I found was that a hefty water toy air pump nozzle will just fit into the raw water intake line. Jam it in there and give the piston a few hard shoves and it cleared the intake right up.

Thats a good idea. I actually have one to get all of the water out of bildge that the pump cant get. Hopefully there wont be a next time though

 

[Don12364]

Firstly one can HEAR if there is no raw water flow from the exhaust note long before the engine overheats and the alarm sounds or any damage is done.
Then I suggest searching this board to read how others use a dinghy pump to clear the seacock and through hull.
Also, if your strainer is on or below water line, it is an easy check just to open the seacock momentarily after cleaning the raw water screen and before reassembly to tell whether the through hull is clogged and so is worth doing every time the screen becomes cleaned.

 

[Benny17441]

A blast of compressed air will usually clear a blocked intake. In the case of a restricted intake where you still have some water flow and safety is at stake you may continue to run the engine at slower RPM without the likelyhood of damage. There is a small safety cushion between the temperature at which the buzzer will sound and the temperature at which damage will occur. This is where having a temperature gauge in addition to the idiot light may come in handy. The gauge will give you an indication if the increase in temperature is stabilizing or if it is just contininuing to increse. Overheating is the leading cause of engine oil breakdown so after any incident we will change the oil. We did motor once with a restricted intake for about 15-20 minutes just by monitoring the temperature gauge. We were entering an unfamiliar channel marked by ranges and loosing daylight fast so we gave it a try and after the first few minutes we realized we would be able to motor around 1500 RPM for whatever time it was necessary as the temperature had stabilized. The sound of the buzzer was a little anoying so we snuffed it with a towel.

 

[Allan12210]

Jared,

The same problems plagued me in the past. Some of the modifications I have made to make the problem easier to address in a hurry have been 1) relocate the strainer closer to the front of the engine compartment so I can get to the hoses fast, 2) when overheating, pull the hose going into the strainer and if no water is coming in, give two honks with the air horn and listen for the bubbles under the boat otherwise pull the lid on the strainer, 3) installed an electric analog water temperature gauge to see if it is a false alarm or see the temperature creeping up above normal in advance for some sort of preemptive action, and 4) I found a 10 gpm flow meter that reads 2.0 at idle and 7.0 at 3000 rpm which is also a good monitor of what is going on. That is installed after the strainer. Until all of that, my advice too would be to learn what the exhaust sounds like normally and see how much water flows out. Don't forget to keep the mixing elbow clean too.

We just got back from a week's cruise in Monterey and I had two blockages. People thanked me for vacuuming the ocean for them. The first in Moss Landing where a big hunk of grass clogged up the hose right at the strainer. My first clue was the exhaust didn't sound right and there was no water splashing out. A quick check of the flow meter showed 0.0, When I pulled off the hose crud was basically sticking out and I pulled it out. Still hit it with the horn and off we went. The second time was four days later motoring up from Santa Cruz to Half Moon Bay and I kept watching the temp gauge creep up from the normal 185 degrees to just below 210 where I believe the alarm goes off. Flow was around 5.0 gpm. I didn't want to go below in the seaway as I am prone to sea sickness when my head is down in the engine. I kept backing off on the rpm and the temp stayed down enough to get to the harbor. The strainer had kelp leaves in it that blinded the screen. After that was cleaned we made it back to San Francisco and everything was normal. Having been a process engineer makes me do these things, but it is helpful to monitor and try and catch an issue before being stuck between a rock and a hard place.

Good luck,

Allan

 

[Jared1048]

Jared,

The same problems plagued me in the past. Some of the modifications I have made to make the problem easier to address in a hurry have been 1) relocate the strainer closer to the front of the engine compartment so I can get to the hoses fast, 2) when overheating, pull the hose going into the strainer and if no water is coming in, give two honks with the air horn and listen for the bubbles under the boat otherwise pull the lid on the strainer, 3) installed an electric analog water temperature gauge to see if it is a false alarm or see the temperature creeping up above normal in advance for some sort of preemptive action, and 4) I found a 10 gpm flow meter that reads 2.0 at idle and 7.0 at 3000 rpm which is also a good monitor of what is going on. That is installed after the strainer. Until all of that, my advice too would be to learn what the exhaust sounds like normally and see how much water flows out. Don't forget to keep the mixing elbow clean too.

We just got back from a week's cruise in Monterey and I had two blockages. People thanked me for vacuuming the ocean for them. The first in Moss Landing where a big hunk of grass clogged up the hose right at the strainer. My first clue was the exhaust didn't sound right and there was no water splashing out. A quick check of the flow meter showed 0.0, When I pulled off the hose crud was basically sticking out and I pulled it out. Still hit it with the horn and off we went. The second time was four days later motoring up from Santa Cruz to Half Moon Bay and I kept watching the temp gauge creep up from the normal 185 degrees to just below 210 where I believe the alarm goes off. Flow was around 5.0 gpm. I didn't want to go below in the seaway as I am prone to sea sickness when my head is down in the engine. I kept backing off on the rpm and the temp stayed down enough to get to the harbor. The strainer had kelp leaves in it that blinded the screen. After that was cleaned we made it back to San Francisco and everything was normal. Having been a process engineer makes me do these things, but it is helpful to monitor and try and catch an issue before being stuck between a rock and a hard place.

Good luck,

Allan

Wow, sounds like you have it dialed in! After this scare I was definetly wanting a better process to know whats going on with the engine temp. I'm still worried about my alternater also. It hasnet given me any troubles but I would like to have a volt meter gauge to keep me in tune with what my alternater is doing and if I'm pulling too much with stereo or other misc things. I've had one in almost all my cars and it has saved me several times.

I replace my mixing elbow only 3 months ago so its good. I did get my hand into the exgaust to get a feel for what it feels like before and after. Listening to just the sound isnt precise enough. We have lots of waves and its muffled pretty bad. Maybe in time

 

[Numlock]

Yup, happens to us frequently in eastern Lake Ontario/1000 Islands. Lots of weeds late in the summer. I use a chopstick to clear the intake. Just poke it down the hole and then the water gushes up. Shut off the intake, put everything back together. Dip out the water, etc. And off we go. I haven't had the alarm go off, but when the water stops coming out the exhaust, I know it's time to clear the weeds.

Cheers,

Numlock

 

[Deleted member 78819]

It's that time of the year in Minnesota as well. I think our problem starts when backing out of the slip. I'm pretty sure we're chopping up weeds as we do so. Checking the strainer and clearing the through hull is a weekly routine in the fall.