Preferred engines in 41 or 43 TC/DC

[Propeller Head]

I have been watching and learning from this board for a few months now as I have an interest in owning a Hatteras. We currently own a 34' express cruiser but would like to move to a 41 or 43 TC/DC without the flybridge at some point. I see them with 6V53N, 8V53N, and 6-71N's primarily. I realize this question may be a matter of opinion but I would like to know which engine would be the best choice as far as maintenance, durability, economy (NMPG), and noise in a 41 or 43 TC/DC.

Thanks....

 

[Boatsb]

I have a 41 Convertable with 8v53 detroits. Its a bit slow and heavy but they are original 1966 engines and they still run great. I cant see the 6v53 being able to get on plane without being at the pins so I would say its between the 8v53 and the 671n's. There are more 671's out there but the 8v53 was very common fo a while.

 

[egaito]

Not sure if this will help unless you run across a boat that's been refit, but my 41C is powered by Cummins C series engines installed as part of her refit in '94.

The engines seem to be a great match for the boat. She cruises at about 22 kts, burning about 24 gph, and tops out around 26 to 28 depending on fuel and water onboard.. They fit nicely in the engine room, and as best I can tell, no major rework was done beyond bigger shafting.

I checked with a retired Hatt guy before I purchased her, who told me the hull was plenty strong for the increased HP.

 

[Freebird]

I have a '65 41DC with gas engines (7.4 MerCruisers 1993). When I first came across this boat, I assumed it would be diesel. When I found out it was gas, I thought it would be a dog. When I saw it coming down the river, I was amazed.

It cruises an honest 20mph on GPS and gets .78mpg with a full load of fuel and water. I've had it for sale for a few months, and no one who has looked at it has balked at the asking price. Everyone who was serious had to sell their boat first, and two lookers came to the same conclusion: it was too big. My response was why are you looking at 41 foot boats?

I have only encountered one other boat in this class on the river, and it was a 43 with 671's. In speaking with the owner, it became obvious my boat would run circles around his and get better fuel economy to boot. I would never have thought it, but the facts speak for themselves.

Check it out in the FSBO section on this site. I'm seriously thinking of turning it over to a broker now that I'm ping-ponging back and forth from TN to FL, so I'm ready to deal if you're serious.

 

[jim rosenthal]

I would agree that the 8v53s or the 6-71s are the diesels to have, unless the boat has been repowered. Parts for 53s are said to be a little less expensive. I would not be scared of a gas engine boat either but the market values them at less. Once again, a thorough engine survey, regardless of what's in there, is essential. Just my opinion, I know not everyone agrees on this.

 

[SeaEric]

I have never seen an older 41 with the 671's. They seem to have 6v53's and 8v53's. The earliest 43's likewise mostly had 8v53's. It seems like 671's became more prevalent in those boats in 1973 and later. The 41 performs best with the 8v53's and the 43 performs best with the 671's. The later 43's with the 671ti's were the best runners, as you would expect.

 

[Jaxfishgyd]

I have 6-71N's in my 1973 43'. Both totally rebuilt in 2000 just as I was buying the boat. It topped out at 18 kts (2450 rpm), cruised at 15 kts during seatrials.
AFTER the Admiral moved all the stuff onboard, it now tops out at 15.5 kts but I still only normally run her at 9 kts as that is her hull speed where we burn just under 7gph including the 9 kt genset.
I have enought trouble getting insurance on her with diesels, can only imagine how much it would jump up if I had gas engines... Plus with diesel running about 70 cents a gal cheaper than gas in the marinas around here....
Plus in Randys case, Tenn doesn't want him and Florida will not accept him which is why he's really ping pongs back and forth....

 

[Jaxfishgyd]

Oops,
One of the biggest factors in diesel engines comes when it's time to dock, Gas engines need throttle use whereas diesels in most cases, you never touch the thottles...... Helps in the "pucker power" level being lower..

 

[egaito]

Oops,
One of the biggest factors in diesel engines comes when it's time to dock, Gas engines need throttle use whereas diesels in most cases, you never touch the thottles...... Helps in the "pucker power" level being lower..

And where it hurts is when everyone is yelling "NO WAKE" as you come into a marina, with one in neutral, the other throwing out white water behind the boat!

Wouldn't trade them for anything.....

 

[Capt K]

Before my 50my, I had a 1967 41tc with 653's. The boat had no bridge. It was a great running boat at about 12knots. I knew some other 41's with the 853's but most of them had the flybridge so were a little heavier, but the 853's did push them a little faster.

My old 41 is owned by someone on this forum and it's still very much out there. The beauty of these naturals is that you can run them 200 or so off the pins all day long and they never even break a sweat!!

The 41tc without a bridge was probably one of the best sea boats I have ever run. Very heavy and very low center of gravity.

K

 

[Trojan]

I have a 1973 43DC with 6/71N. I run wot at 2650 RPM. I plane at 13 MPH and can cruise from 14 to 20 MPH. I choose a 11 MPH cruise. I Kick back play some tunes or watch TV on the bridge. I take 6 people with me when I go. I run my generator most of the time and the kids watch TV or xbox in the salon. Motor noise is not an issue. But they do make noise. It's a good noise you know your not paddling. I love my 6-71 Detroits. I use no oil between changes and have no oil leaks. I have around 600 hours on each motor. I run My boat 135 hours a year and live on it 6 months a year.


BILL

 

[Propeller Head]

Thanks to everyone who replied. I really appreciate the information....

 

[lisaann]

i have a 1968 41c with 671n's boat cruises a honest 18knts at 2100 full throttle is 2520 24 knts.8v53s are o.k. bot getting hard to find parts, if you have achoice 671 are the way to go.there was a company in florida that was installing 671n's in these boats for a while, mine were installed in 1990. 853 were the factory diesel option i know of one that has 653s though i believe they were not original

 

[Trojan]

Odd? 6-71 J&T DD are rated at 2650 RPM. I see other listings at other RPMs.


BILL

 

[Will]

Not all J&T 6-71s are rated at 2650 RPM. It depends on the engine configuration. Regardless of rated RPMs and horsepower, the service life of 71 series engines rapidly deteriorates at RPMs in excess of 1800. That is why some run well in excess of 10,000 hours between overhauls and others barely make 2,000 hours.

Will

 

[Jaxfishgyd]

I normally run my 6-71Ns at 1100 rpm with a daily "run up to cruise of 2000-2100" for 5-20 mins depending on if I've cruised for the day or just a couple of hours.
Boat just "feels" good at 9 kts............. and my wallet prefers it too

 

[Propeller Head]

Not all J&T 6-71s are rated at 2650 RPM. It depends on the engine configuration. Regardless of rated RPMs and horsepower, the service life of 71 series engines rapidly deteriorates at RPMs in excess of 1800. That is why some run well in excess of 10,000 hours between overhauls and others barely make 2,000 hours.

Will

Maybe I do not understand your point Will. A previous post indicated you could run these naturals 200 RPM off the pins which I assume means max RPM without hurting them. You suggest that running them > 1800 RPM (68% of max RPM) will significantly shorten the life expectancy. I had always understood that diesels perfer to be ran at 80% +- (check manufacturers recommendation) of max RPM for long life. Can someone clarify this with respect to 653's, 853's, and 671's? Thanks....

 

[Boatsb]

Some conversions were running higher RPMs to get higher HP. The problem is that they wear faster at 2700 WOT than the ones desiged to run 2200 WOT. The block is the same but the builder pushed the design further. Think of an engine as a tank of water. Full when new. Put a 2" hose on it and it drains in 30 minutes. Put a 3" hose on it and it drains in 15 minutes. You still only have the same size tank. Do you need to drain faster or can you go slower and have it last?

 

[Will]

To get back to the point of which engines to install for a re-power.

I have an all but emotional attachment to 6-71s. They have been essentially unchanged since they were first produced around 1939. A friend once said that if you get the parts of a 6-71 close enough to each other, the engine will run. This is the third boat I've had with them and it was a requirement when searching for another boat two years ago.

That said, if I were to re-power, I'd look at one one the new industrial quality diesels like Cat., Cummins or DD-MTU. They are more fuel efficient, cleaner and parts will probably be available beyond the availability of those for the old DD two cycles. I'd never consider gas for a heavy 40'+ boat unless speed was the only consideration. Gas engines could never come close to matching the long service life of an industrial quality diesel. And with gas of course, comes an increased safety hazard.

So, that's my two cents worth. I feel better now.

Will

 

[Paul45c]

Maybe I do not understand your point Will. A previous post indicated you could run these naturals 200 RPM off the pins which I assume means max RPM without hurting them. You suggest that running them > 1800 RPM (68% of max RPM) will significantly shorten the life expectancy. I had always understood that diesels perfer to be ran at 80% +- (check manufacturers recommendation) of max RPM for long life. Can someone clarify this with respect to 653's, 853's, and 671's? Thanks....

Sigh...this gets debated so much. I don't think there's more fertile ground for more strenuous debates than this one issue.

I'm no mechanic, but I talk to every Detroit one I can find. The consensus I've developed is that for a motor that limits out in the 2300s somewhere, you certainly won't hurt it running it for extended cruise periods between 2000 and 2100. I've been VERY careful to stress that all I care about is longevity, not what the motor CAN do. And the mechanics will repeat that these old Detroits can sustain 2000-2100 indefinitely without shortening life, and for the most part, you're doing them a favor if you can hack the fuel bills. Everything about the motor's design, they tell me, is to develop the full power it's rated for; that's obviously not to say that you keep it at WOT, but a lot of these guys laugh at the shade tree mechanics who claim they don't lube well or whatever when you get to where you can hear the turbos.

For turbo motors, you have to get it up over 1800 at least periodically to keep the turbos turning at a high enough rpm to keep them in top form. Lolling around is not good for a turbo. As in everything, clean oil is the key.

I had a little Volvo that was a 3900 rpm motor. I cornered a Volvo rep at the Lauderdale boat show a number of years back when I still had that boat/motor and asked him his recommendation for a cruise RPM if I only cared about what was best for the motor. He said 3700 rpm. I said, "ok, I know it is supposed to be capable of that, but what's an honest rpm when you're really looking for max longevity between rebuilds?" "3700." In fact, he professed surprise that I didn't have a plaque on my gauge console that said "recommended cruise rpm 200 off redline." He claimed all Volvo-powered boats were supposed to have that on the panel. He looked me right in the eye and said that motor would get crudded up inside if it wasn't run up to those rpms for a significant amount of its cruise time, it's designed to run at that rpm, and that's that. I went away shaking my head, thinking, 3700?!! All I can tell you is what he told me. So, your 200 off the pins principle is accepted in many circles, it would appear.