New/old engine "efficiency" ??

[MikeP]

Once again I have to question the thought that dumping the DDs and installing "modern" engines provides any fuel efficiency benefit...

I just read a test of a new Searay 51 footer with a 15'4" beam - basically it's just a hair smaller and about 10,000 lbs lighter than a 53MY. The fuel burn at the same speeds a 8v71TI 53MY can obtain are HIGHER for the Searay per the test than that of the 53/DDs. As is typically the case now, the new Searay can achieve considerably higher top speed and if you want to run at 20+ knots, it can do it whereas a 53 cannot. But I find it really interesting that all the hype re how much more efficient modern engines are doesn't seem to actually work out that way on the water...

 

[rsmith]

I agree we spend a lot of time at 8-950 rpm trolling and get 1nm/gal. I don't even see the big advantage to the LRC's except they carry massive quantities of fuel for long passages. I've seen plenty of these modern engined now that they have some time on them have all kinds of electronic problems. ECM'sECU's EC whatever ever craps out and your out of luck. I've seen several truck applications where the wiring harness breaks down from the constant vibration and causes intermittent problems.

 

[Boatsb]

I agree we spend a lot of time at 8-950 rpm trolling and get 1nm/gal. I don't even see the big advantage to the LRC's except they carry massive quantities of fuel for long passages. I've seen plenty of these modern engined now that they have some time on them have all kinds of electronic problems. ECM'sECU's EC whatever ever craps out and your out of luck. I've seen several truck applications where the wiring harness breaks down from the constant vibration and causes intermittent problems.

But the new engines are better for the environment.

They burn a lot less fuel. Especially when being towed.

 

[carolinacoast]

A mechanic told me once that all of the technology was applied to emissions at the expense of efficiency. Reliability takes a hit with the added electronics, but much easier faster to diagnose, often remotely.

 

[Boatsb]

Just changed the oil in my dodge 6.7 cummins. It's black as a detroit. The soot injection system (egr) is doing what it's designed to do. It will shorten the life of the engine. Reduce its efficiency and Raise it's cost.

If it were in a boat without us requirements I would get an increase of about 15 -20% efficiency.

 

[Ross Macdonald]

Just purchased another boat last December with 3406E Cats after having put about 1300 hrs. on the old 12-71s in our 1979 60 EB. We just finished a trip of about 880nm with the Cats and I can tell you the fuel economy wasn't any better at 9.5 kts with the Cats. We averaged about 14-16 GPH for the trip and the only advantage over the DDs was no oil consumption and a little cleaner. Outside of that I agree with R Smith that if any of this electronic stuff craps out you are screwed. Fortunately this boat has a manual backup but I sure miss the simplicity of the 12-71s. Ross

 

[rsmith]

A mechanic told me once that all of the technology was applied to emissions at the expense of efficiency. Reliability takes a hit with the added electronics, but much easier faster to diagnose, often remotely.

Not! The answer to throwing codes today is always "flash the computer" it never works but it makes the customer feel like their doing something. The other phrase to remember is "known good part" seems half this electronic crap is bad right out of the box. I had a several times replaced parts that didn't fix the problem only after making me crazy found out the new part was NFG right out of the box

 

[rwappleton]

The US military has been trying to replace the B-52,C-130,KC-135 and the CH-47 for well over thirty years. Everything they come up with is "more efficient" but at the end of the day the replacement just will not do the job.

A well maintained Detroit that is not trying to produce more than 1 HP per cubic inch will last for ever!

IMHO you can not save enough on fuel or maintenance to pay for a refit unless you have a serious issue and I will bet now it's one of those more than 1 per jewels.

Ya'll really think as good as these boats are built that Mr. Slane didn't think of that too?

 

[Vincentc]

We went for a ride Saturday on a Tira Sovran 4300. It is a very nice boat. Laid out well, comfortable, and quiet. Volvo IPS 370 hp, counter rotating props.

The test reports I read for the 28000 lb hull said about 30 kts top speed and 20 plus cruise with .7 nmpg plus.

I observed from the electronic read out on the boat approx. 1.5 nmpg at 8 kt cruise.

Lilly Marie's DD 671 ti's are are rated 390 hp. She will top out at about 17 kts, and cruise her 34000 lb hull at 8.3 kts getting about the same 1.5 nmpg efficiency as the Volvos.

Mid 20th century Detroit engineering vs 21st century euro tech, as far as efficiency at hull speed, it looks like a draw.