Interesting engine temp observation

[k9medic]

The other day I took my boat on a long trip for a total of 55 hours. For a majority of the trip I ran at 1400 rpms (CAT 3116's) and both engine temps were right at 180 degrees.

For part of the trip, I ran on plane at 2400 rpms and the engine temps ran just shy of 200 degrees. I ran at this rpm setting for a total of 5 hours. About 4 hours into the trip at this setting the engines settled down to about 185 degrees.

I found this odd since both engines did this and the water temperature never really changed.

What gives?

 

[david leonard]

55 hours?? maybe the water is denser off the coast of portugal.

 

[k9medic]

Trip total was just shy of 500nm over 4 days.

 

[david leonard]

wow. either you lost a bet, or hate to fly! seriously, though, where did you travel to? have you taken long trips like this, before? longest i've been on a boat (85 feet), was to cocos island--about 33 hours each way (with an 8 day stay at the island). and that seemed like forever!

 

[my3sons]

The other day I took my boat on a long trip for a total of 55 hours. For a majority of the trip I ran at 1400 rpms (CAT 3116's) and both engine temps were right at 180 degrees.

For part of the trip, I ran on plane at 2400 rpms and the engine temps ran just shy of 200 degrees. I ran at this rpm setting for a total of 5 hours. About 4 hours into the trip at this setting the engines settled down to about 185 degrees.

I found this odd since both engines did this and the water temperature never really changed.

What gives?

Don’t know your situation, but here’s a guess. Strictly a guess.
You’re on the edge of being overpropped and/or raw water side could use some service. You were leaving on a trip so you were loaded down with provisions, your bottom wasn’t the cleanest it’s been and your tankage was full. Maybe some added drag from sea conditions. 4 hours go by.
Sea state improved or changed, bottom got scuffed clean, fuel load was lessened and your motors felt the relief.
I see load relief on my boost and egt gauges all the time, but my coolant temperatures never vary more than a couple of degrees, not really even noticeable on the dash gauges. Somethings up, and it’s not normal if you are noticing it for the first time.
Good luck

 

[FootballFan]

Sounds like an epic voyage!!!

Were you towing your other boat the whole way? (not asking because of temp changes, just curious how the towing rig is working for you ).

My boat is pretty constant on temps, based on throttle. Have never seen that wide of swings. This is based on running to the Chesapeake and back with variable water temps. Warm water June (Okeechobee) to upper Chesapeake in late October. Never a 55 hour run - but consistent over 7-8 hours.

After startup, warmed up temp is around 153-155. If I am cruising at 1200 RPM, will go up to 159 - maybe 160.

For me high end cruise on plane is around 1860-1875 RPM. Settles me in at around 30GPH per engine and gives me 21-22 knots with a clean bottom. (WOT is 2300). Temps will fluctuate around 164-166. The 2-3 degrees up and down is noticeable based on load. High end is wind, swells & waves on my bow. Or if I am inside or an inlet - running against the current.

When running on plane, as load changes its not so much the temp changes - but the fuel burn.

Interesting to compare to our previous boat, 47DB with QSC600's.

On the 47DB we would run around 2600-2700 RPM. I believe WOT was somewhere in the 3100 RPM range.

Burned 30 GPH per engine
Temps would run around 180
17-18 Knots

With current boat, moving an extra 40,000 lbs through the water, burning the same fuel, but traveling 4 Knots faster.

Want to hear more about the 55 hours.

What was your crew? How many people rotating - or did you just drink a lot of red bull and coffee?

I generally know where you started and where you were going. Would you do a single run again? What did you do after you cleared customs, go to sleep?

A 55 hour run is epic - have never done anything like that. Love hearing about it.

@carterchapman how long was your run this past fall when you cut across the gulf?

 

[carterchapman]

51 hours - departed Mobile at dawn and arrived at Boca Grande inlet at dawn - didn't want to risk crab pots at night!. All fuel stops in Panama City/Apalachicola/Carrabelle were out due to Michael. So we had to go 8.7 kts for 440 NMs. We get 1.5 MPG at 800RPM/8.7 KTs. So we only used 50% of our fuel. We planned on 4 ON/4 OFF, but at midnight the first night we hit the unforecast 5-6' beam rollers and took 30° rolls. We ended up napping on the bridge ON/OFF as needed for the next 34 hours - not fun! Susan was a real trooper - I was proud of the Admiral.

My temps run 183° Port/189° Stbd regardless of load/RPM. Really impressed with MANs.

 

[FootballFan]

Torque Matters!

 

[BOB TYSON]

51 hours - departed Mobile at dawn and arrived at Boca Grande inlet at dawn - didn't want to risk crab pots at night!. All fuel stops in Panama City/Apalachicola/Carrabelle were out due to Michael. So we had to go 8.7 kts for 440 NMs. We get 1.5 MPG at 800RPM/8.7 KTs. So we only used 50% of our fuel. We planned on 4 ON/4 OFF, but at midnight the first night we hit the unforecast 5-6' beam rollers and took 30° rolls. We ended up napping on the bridge ON/OFF as needed for the next 34 hours - not fun! Susan was a real trooper - I was proud of the Admiral.

My temps run 183° Port/189° Stbd regardless of load/RPM. Really impressed with MANs.

Astounding! Count this "Newbie" as impressed!

 

[carterchapman]

Susan actually asked me if we want to do it going back up in May!!

 

[BOB TYSON]

Outstanding! I understand there is a talk about naming this route the "Chapman Passage".

 

[carterchapman]

2 0f our last 4 trips have been rough - unforecast conditions...I'm getting gun shy!!!

 

[k9medic]

Jut getting back to the computer...

This is the third time I have done this trip. We moved the big boat over to the Bahamas until the end of July and we will fly back and forth to enjoy it and the water there.

The 55 hours was broken up over 4 days and we did not travel more than 16 hours in a day. Just me and my buddy for the trip.

We pulled a 19' boat behind us the whole way except for when we crossed the stream. My buddy ran the little boat until we got on the banks in the Bahamas and then we linked back up. He was a trooper - 5 hours following me in the back boat running at 16kts. The tow bridle that I made up last year to pull my 16' boat over worked great once again.

I will tell you, we started out of Stuart at 0500 in sea fog and pitch black darkness and ended the trip at 2030 having run for another 2 hours in absolute darkness in the sea of Abaco. It was AMAZING at night out there!

Here is my boat nestled into the marina for the summer. The 19' boat in the photo with the white motor is the one we pulled over. We call it "Lamont" since we bought the boat in a junkyard.