Fuel Burn for 16v92TA?

[ThirdHatt]

I am having trouble locating a fuel burn rate for Detroit 16v92TA 1450hp. I am surprised that I can't find it online. I saw on another site where CaptDis said that at 2000rpm they burn 140gph, but I was wondering more about displacement speeds like 900-1300rpm.

Does anyone here happen to have the factory fuel curve?

THANKS!

[Spellbound]

61 Davis 16V92's @ 1650-1700 rpm fuel burn was 104gph. Should remember the fuel burn at 10kts (but don't) as that is what we used coming back from Bermuda to Stuart 864 nautical miles. Fuel capacity was 1700 and we used almost all of it.

[ThirdHatt]

Good info! Do you happen to remember the rpm required for the 10kts on that trip?

THANKS!

[SKYCHENEY]

Movin' up, Byron?

[Brian Degulis]

With engines that large your going to hit displacment speed at a very low RPM Proubably to low to consider running it like that for long periods of time.

Brian

[Canuck Dennis]

Unless these are DDEC models you will wear them out real quick running anything under turbo cut in rpm, those big injectors are just washing the oil off the liners at low rpms. Was told they should run over 1700 if possible, lower is ok for short times only. One of the drawbacks of big HP gained by turbo's.
D

[ThirdHatt]

Hmmm. Not sure if they're DDEC's or not until I get there later this week but I did not know that it mattered with respect to low rpm cruising tolerances. I had heard to stay away from the DDEC system if possible. I know that they can be detuned to around 1000hp to last but if you have to run them at 1600-1700rpm the fuel burn will still be 100+gal/hr.

I guess I need some discouragement before falling victim to one of the truly unbelievable big boat deals that are showing up on the market these days!

[Spellbound]

Not positive but remember 950-975rpm as the setting for 10kts. These were the 1350hp non DDEC version. FYI -- We rarely, I mean RARELY ever ran the boat over 1700rpm. Most hours were at trolling speed 8-8/12kts, logged 3k+ hrs before rebuild by Palm Beach Power.

Like you, I also had reservations about the 16 92's until (at survey) talking with Joe Stafford of Stafford Diesel who confirmed the lower cruise rpm and keeping heat out of the "Beast" would lend itself to longer engine life. Was satisfied with all aspects except the fuel consumption (104gph) at cruise.

[StratPlan61]

Byron, if you are thinking about the boat I think you are, you might check on the cost of a rebuild for one of those motors. You rascal!

[Brian Degulis]

Not positive but remember 950-975rpm as the setting for 10kts. These were the 1350hp non DDEC version. FYI -- We rarely, I mean RARELY ever ran the boat over 1700rpm. Most hours were at trolling speed 8-8/12kts, logged 3k+ hrs before rebuild by Palm Beach Power.

Like you, I also had reservations about the 16 92's until (at survey) talking with Joe Stafford of Stafford Diesel who confirmed the lower cruise rpm and keeping heat out of the "Beast" would lend itself to longer engine life. Was satisfied with all aspects except the fuel consumption (104gph) at cruise.

If your boat had been powered with say 8V71 naturals you would have easily logged 10,000 hours before rebuilding. Running those big engines that slow takes it's toll. But yes you will still probably get more hours running slow than pushing them hard. I think if you could run them around 1500 -1600 hundered you would see very good life but that's probably not a speed the boats happy with. You could also consider running displacment speed on one engine. With most boats that doesn't make sense but in a boat that's grossly overpowered for displacment speed it might.

Brian

[sandspur1966]

IMHO that one engine logic needs to be qualified. You cant run these big ole girls with one engine either shut down or in neutral for long periods without freewheeling and damaging the gearboxes.

The prop turns them as it drags through the water and without the motor running it has no oil pressure.

I suppose you could live one iddling in forward and engage the other at the speed you wish but I'd seek a more expert opinion than mine regarding possible problems... beyond the awful vibrations that would cause from being horribly out of sync.

I personally would use the boat as it was designed or...if that isn't what you need, look for another design.

[ThirdHatt]

The boat supposedly makes 1kt for every 100rpm, with a 23kt top speed. Hull speed is 13.4kts and she'll do 12kts at 1300rpm fully loaded. Eventually the low rpm may wash the cyinders down but running at 1900 on plane would cost much more in fuel burn and sooner rebuilds over time than displacement cruising I would imagine.

Heck, our boats were designed for planing and many of us run at displacement speeds all the time, even though that was not what they were designed for.

[Brian Degulis]

13.4 kts hull speed? How long is the boat ?

Brian

[stormchaser]

The boat supposedly makes 1kt for every 100rpm, with a 23kt top speed. Hull speed is 13.4kts

You have a boat with an even 100ft waterline? Because that's what it would take to get a hull speed of 13.4 knots. To figure hull speed, it.s 1.34x the square root of the LWL.

[ThirdHatt]

That is correct, the boat is 104' LOA and a 100' waterline length. I looked at it yesterday but I am wary because it is a bigger project than even I expected (of course). I am looking at another 104' of the same make tomorrow with 12v92's that supposedly only needs paint. I doubt that is true, but we'll see.

They are all but giving boats away down here at the Ft. Lauderdale boat show. Attendance is way down and real buyers have a serious advantage. Many sellers are in a bind and must get out.

[Brian Degulis]

Ok that's a little diffrent for some reason I was thinking this was one of the 65' Cs with those big engines. With that size boat I would think you coiuld run displacment speed without being horribly under loaded. If your thinking your always going to run displacment speed consider larger props to load them up more.

Brian

[ThirdHatt]

Brian, That's just what I was thinking. I have no need to plane a boat like that nor do I want to supply the fuel to feed the beasts at those revs. At displacement speeds the fuel burn is still higher than I would like to see, but is manageable. She holds about 9200 gallons so all I'd have to do is bite the bullet and fill up while fuel is (relatively) cheap and it should last me a few seasons at displacement speeds!

The 12v92 boat that I am going to see tomorrow would be more fuel efficient but they are DDEC's and I do not know if that is good or bad. What do you think of the DDEC controls on a 1990's vintage 12v92?

[Brian Degulis]

I don't know anything about the electronic DDs. I know Garyd has them on his boat and likes them. In todays engines Cat, Cummins, Deer the electronics are excellent and they eliminate all the concerns about running big engines slow.

Brian

[ThirdHatt]

Fair enough. The DDEC boat I saw this morning was more than twice the boat that the 16v92 boat is overall. A complete paint job, update the electronics and service the mechanicals and back in business.

For me, I think one of the biggest issues with these boats is the aluminum hulls. I'm just not sure if I want to deal with blisters, and this coming from a Hatteras owner!

[Brian Degulis]

I would be very comfortable with a quality aluminum boat in fact more comfortable than a quality glass boat. I like steel and aluminum (and I sware it has nothing to do with the fact that I build them ha ha) Seriously I like metal because it doesn't fool your not depending on chemistry in construction. If a metal boat has a problem it jumps out and bites you glass boats are a lot more sneaky about it. The blistering your talking about has 2 causes stainless or other metals that are not properly isolated and im proper painting procedures. The most common problem on recreational boats is the heavy use of fairing compounds over a poor intial prime coat. The good thing is both are obvious and unless the boats just been painted you should see it.

Brian

[saltshaker]

I would find out what it will cost to paint her before you pull the trigger. Years ago, I looked at Striker that needed paint. Quotes to paint it were almost double that of a glass boat. This boat needed a lot of sanding and fairing due to the condition of the paint, but the numbers were outrageous.

FYI I've always heard the number used by most to major 16v92's was 100K per set. When that was all there was for the big sportfish, most owners would budget that in every 3-4 years or 1200-1500hrs.

[ThirdHatt]

I would be very comfortable with a quality aluminum boat in fact more comfortable than a quality glass boat. I like steel and aluminum (and I sware it has nothing to do with the fact that I build them ha ha) Seriously I like metal because it doesn't fool your not depending on chemistry in construction. If a metal boat has a problem it jumps out and bites you glass boats are a lot more sneaky about it. The blistering your talking about has 2 causes stainless or other metals that are not properly isolated and im proper painting procedures. The most common problem on recreational boats is the heavy use of fairing compounds over a poor intial prime coat. The good thing is both are obvious and unless the boats just been painted you should see it.

Brian

I am glad to hear that, but I am concerned about the added mainenance of dealing with blisters. The two Browards I am looking at both have blisters at the cap rails and at any right angle. I understand that these will all be properly repaired during the paint job but they come back. Apparently there is no way to stop them from coming back. The paint job price is right at $100k whether I do it here in FL or bring it back to LA.

At the show there are several late 80's vintage Browards for $2.2-2.6M with paint jobs that are 5-8 yrs old and they ALL have blisters along the cap rail! They are telling me that it is regular maintenance to deal with blisters every year. That is not easy to do with Awlgrip because you will always "see" the repairs but they all use Awlgrip. There is a good deal on a big Burger I found out about yesterday and may go look at it today, but again I am intimidated by this extra maintenance of the aluminum hull.

I went on a 1987 Hatteras factory 77CPMY with the engine room access from a big door in the cockpit which is nice because you don't have to haul oil and parts through the boat. No V-drives, just short shafts so VERY smooth running. 12v71ti's and a good owner/captain combo. I felt comfortable and "at home" in the engine room and crawling around the boat. Unfortunately, it has the light white-washed wood that was so popular in the late 80's and early 90's. I was hoping my next boat would have a 20-21' beam and all the Hatt's are 18'2".

[Brian Degulis]

I'm not understanding why you have blisters along the cap rail? Is there a stainless hand rail bolted to it? If that's what's causing the blisters there are a few diffrent ways to correct that forever. I've seen lots of aluminum boats like this where the cause of the problem is obvious but it's never corrected makes no sense to me. Plain and simple an aluminum boat doesn't have to blister but of course the causes have to be addressed.

I built an aluminum hard top and radar mast for my Hat. I used stainless fasterners but I insolated with fiberglass washers and sleeves. Now 2 years down the road there is no blistering and there never will be. Around the same time I made an aluminum bracket to hold my davit hook. I went to install it and relized I had no sleeves or washers but I put it on anyway. In 4 months I had blisters.

Brian

[ThirdHatt]

Brian, I am not sure exactly why but 5 out of 7 Browards that I looked at have blisters at the top of the hull where it meets the caprail. Two were the ones I looked at buying that were not in the show needing paint/blister jobs, but the other 5 were all several times more money and on display for sale in the show. They all had bubbles under the paint at the top of the hull. THe Captains said that it was indeed time to repair them, but they eventually come back. Not sure what the deal is but I am not a welder and just don't know anything about metal boats.

[Brian Degulis]

I think what you would probably find is that those boats are being re painted like glass boats. They probably grind down to clean metal and then build up from there never addressing what's causing the blistering. It would have to be blasted down to bear metal then an anti corrosive must be applied to the correct mill thickness then the fairing and cosmetic steps can follow. I bet it's the skimping on the anti corrosive that's the root of the problem. The fairing compounds and sand able primers are porous so without an anti corrosive if the finish coat is breached then water can migrate down to the metal causing the corrosion that pushes everything off.

Brian

[ThirdHatt]

Okay, I finally got a 16V-92TA engine performace curve faxed to me from Detroit Diesel. There is a "fuel consumption" curve that shows @ 1200rpm fuel consumption is nearly 50 gal/hr per engine (seems very high) up to nearly 80 gal/hr @ 2300rpm, which is probably about right.

Just under that curve, there is a "fuel-propeller load" curve that shows only about 18 gal/hr @ 1200rpm (sounds good to me) and goes up to nearly 80 gal/hr @ 2300rpm where it meets the "fuel consumption" curve.

My question is this: Does this engine in gear turning a prop running 1200rpm burn ~18gal/hr or ~50 gal/hr?

[Paul45c]

Byron, I'd really think twice about anything Broward -- have you heard the old saying "don't be a coward, buy a Broward."?? Here in the land of the big motoryachts, a lot of people knock them. They're definitely the price boats of the bigger boys. Folklore reputation aside, I also have two friends who have had direct experience captaining them, and they had nothing good to say. One was fairly recently bringing a 95' down from somewhere in the mid-south and he hated the trip...it's really on the big side for many parts of the ICW to feel comfortable in, and yet it had a rough time handling even 5-7' seas with any kind of grace. The boat actually shuddered in those seas, he told me. My boat broker has been on many sea trials for them, and he seconds their poor seakeeping abilities. He was even on one where the hull had parted from one of the stringers.

FWIW, I'd seriously consider the Hatt MYs you cite, blond wood or no. I've just done a lot of veneer work in my 55c. I replaced the old rotted out slider window frames with fixed frameless/seamless. Well and good, but someone had glued mirror to the inside of all the panelling over the "chair rail" height. They glued it so well that it ruined the panelling when I was able to get the mirrors off. A good marine carpenter has bonded 1/4" thick new afromosia panels to the old and it looks stunning. It wasn't that bad a job.

[ThirdHatt]

[QUOTE=Paul45c;111046]Byron, I'd really think twice about anything Broward -- have you heard the old saying "don't be a coward, buy a Broward."?? Here in the land of the big motoryachts, a lot of people knock them. They're definitely the price boats of the bigger boys. Folklore reputation aside, I also have two friends who have had direct experience captaining them, and they had nothing good to say. One was fairly recently bringing a 95' down from somewhere in the mid-south and he hated the trip...it's really on the big side for many parts of the ICW to feel comfortable in, and yet it had a rough time handling even 5-7' seas with any kind of grace. The boat actually shuddered in those seas, he told me. My boat broker has been on many sea trials for them, and he seconds their poor seakeeping abilities. He was even on one where the hull had parted from one of the stringers.
QUOTE]

WOW! Paul, I can't thank you enough for the advice and real-world experience. I actually had not heard these things you mention before. From what I can gather Browards and Burgers are like Ford and Chevy with respect to build quality, everyone has their personal preference but they are actually fairly similar in overall quality. I know a very experienced surveyor that was personal friends with Frank Denison and he explained to me that Browards and Burgers were in fact quite similar but Broward used three different thicknesses of aluminum in their construction where Burger used two. He said that old man Burger always charged more because he wanted to, but it did not mean that Burger's were any better than a comparable Broward. He also told me that these boats are coastal cruisers and in that capacity they perform well. Those who try to make ocean passages do not belong in these boats.

I would love to stay in a Hatteras but an 18' beam is simply not enough when you're talking 70-85' in length. Also, Hatteras tapers the hulls down so much in the rear that even an 18' beam means a only a 14' wide cockpit. I may just have to wait until some of the semi-custom boats built in the last 10 years come down. Many have a 21-23' beam on a hull from 72-85' in length, now THAT is a stable platform!

Paul, I'd love to chat with you more about the Browards, etc but I can't find your number. I'll send you a PM.

[doc g]

Bryan , you read the actual fuel use from the propellor load curve so, 18 gals/hr at 1200 rpm is what it should be as long as the boat is propped to turn out 2300 @WOT.............................................. ......Pat

[Brian Degulis]

Yes there are 2 curves one shows what HP the engine is capable of producing at any given RPM that's the engine curve. It will have a coresponding fuel consumtion curve showing what the engine will consume if it's fully loaded at any particular RPM.

The other line is the prop curve it to will have a coresponding fuel consumtion curve. The prop curve shows the fuel comsumtion and HP produced based on the load a fixed pitch prop will require. That's the one your interested in that shows the consumtion you can expect with the OEM configuration at any particular RPM.

If you look at the 2 curves it's easy to see why fuel consumtion is so much lower in the lower RPM range. Your only using a fraction of the HP available as you increase RPM you use a higher and higher percentage of available HP up to WOT @ 100%

Brian

[ThirdHatt]

Pat and Brian, thank you both for confirming my suspicions. I mis-read the graph before. It is actually 13gph at 1200rpm, not 18. 13gph per engine to run at displacement speed is very reasonable considering the size/hp of those engines. Hmmm.

[Brian Degulis]

Check the HP on the prop curve @ 1200 RPM the fuel consumption rate would indicate around 210 HP being produced per engine. If that's about right it sounds like a lot for displacment speed. I know it's a big boat but it's probably not all that heavy and 420HP sounds high. I'm guessing you could do better than 26GPH at displacment speed.

One of the nice things about a long boat is that it doesn't take a whole lot of HP to run at displacement and because of the lengh the displacment speed is high. So you GPM OR MPG can be better than a smaller boat.

Brian

[ThirdHatt]

Brian, the "power-propeller load" curve shows something between 175 and 190hp at 1200rpm. I cannot read it more accurately than that due to the thickness of the line. I tried to scan and import it earlier when I got it so that I could post it here, but no luck.

I am intrigued that I could run these motors like I run my 8V71ti's, 1200rpm all day then just spin them up for a short time to clean them out. I hate the idea of twice as many holes to deal with when rebuild time comes around though.

BTW, the weight is listed around 155k lbs, but if it carries 9k gals of fuel and 1k gals of water, that is a HUGE swing in displacement depending on load. Fill 'er up while fuel is cheap and cruise for several years @ 1200rpm?