If you were starting all over, would you buy a Hatt with DD engines again??

[Walter P]

I had some tired 8-71’s in a 46 Bertram years ago. Smoked like crazy starting up. They made full RPM and ran great.

No I have a 46 HP with perfect condition low hour 8-92’s that have zero smoke on startup. They also run great.

I prefer the older mechanically injected engines over today’s electronic controlled ones. Yes it may be hard to find a good DD mechanic but you will over time. Rather do that then have electronic issues and a “mechanic “ that only plugs in and fixes what the computer tells him to fix and overlooks real mechanical issues.

So it’s really just up to you and what path you want to go down. I recommend a DD boat. Take the money you save on purchase due to “outdated engines “ and spend it on a comprehensive maintenance plan. Try to find documented low hour proper rebuilt engines that pass survey using qualified DD mechanic. Another possibility is finding a nice boat with a failed engine. Should be able in today’s market buy low enough to do true full rebuilds on both and start out with “new” engines.

IMHO

I agree with this. I've owned 4 Hatteras' over many years, all with Detroit's and always felt confident
that they would always get me "home". Now if you feel a need for speed, the newer four stroke engines
will probably out perform the DD's. The newer engines will also eat less oats per horse but remember
that all that will cost you many more boat bucks to achieve. If you're happy to cruise at displacement
speeds as most MY owners do, the DD's will outlive you. If you're a hot rod sport fisher and you simply
must have the extra speed and range of new technology engines then spend the money and be happy,


Walt

[rustybucket]

Everything I'm about to say pertains to my knowledge of sportfish boats. The cabin cruisers are probably different.

I've got several buddies with newer higher hp engines and don't think for a minute that they are free of problems/issues.

They all have had their fair share of issues and gremlins. The biggest difference I've noticed is most of their gremlins are electronic or electrical related and often involve calls to the factory or just outright ecu replacement.

Don't get me wrong, new power is great. The biggest advantages I see to newer power are increased HP for the same size/footprint and less weight.

The fuel economy benefits are pretty close to negligible b/c with more hp comes increased fuel consumption. If you cruise the same speed with the new power as you did with the old you will see some economy improvements but the savings are not anywhere close to offset the cost to repower. In most cases with added hp comes a heavier throttle hand and overall increased fuel consumption.

I would venture to say a Detroit is as reliable or more reliable than any of the new engines when it comes to 'get you home' reliability. A slight computer fault can have you dead in the water on a newer engine.

Heard a story in Panama this year that last summer a bad lightning storm struck quite a few boats (6-8 if memory serves). Only 2 boats made it back in under their own power. One was old mechanical diesels made it in under full power. The second, with newer diesels limped in with one engine in fault mode. All the other boats were new technology diesel and were dead in the water with fried ecu's, sensors....etc.

I'm not trying to sway anybody either way, it's your boat, do what you want but I just don't personally see a huge benefit to us to repower unless necessary.

That said, the next time our engines need rebuilding (hopefully many years from now) I will definitely consider repowering with MTU's in the 800-1,000 hp range. Current detroits in our boat are 600hp and I'd love to go faster. But not enough to pull out newly rebuilt engines to do so.

[Fanfare]

In 1992 when Fanfare was 27 years old I began to consider engine and transmission rebuilds following a couple inconvenient failures, mostly in the Allison transmissions. This was always a nuisance, especially in the Bahamas where skilled mechanics and parts are scarce. Then Hurricane Andrew hit Florida. My old engines, 8V-71 naturals, 350 hp, could not be turbocharged (something about fire above or below deck) but I thought maybe I could find some newer storm damaged engines for swapping. So I wrote Jack Hargrave, Hatteras's genius naval architect, to ask his advice. (I also gave him some attaboys for designing such great boats! I treasure his letter in reply.) He recommended selling the old engines and transmissions and putting in new Detroit Diesel 6V-92TAs at 550 hp with Twin Disc transmissions. 8-92s, he said, would not fit in the engine rooms. After looking at many other options and combinations I went with his recommendation, completing installation in 1993. By then Roger Penske had purchased Detroit Diesel and apparently made many modern engineering improvements in these proven engines. Water cooled exhaust manifolds, a single water cooled turbo, much larger heat exchangers with recovery bottles, longer-lived piston rings, remote electric emergency shut down solenoids, Walker AirSeps complete with air filters, etc.

Now, 26 years later, these engines have been nearly perfect. They start immediately, don't smoke more than 3 seconds, and almost never need oil other than their 100-150 hour oil changes. I replaced one starter at age 3, both fuel/transmission coolers two years ago. The original coolers had the zincs mounted on top, easily accessible but just having the last 1/4 inch of zinc contacting the raw sea water when the engines were off. This eventually led to leaks in the internal fins and tubing which I foolishly tried to fix rather than replace. A costly lesson. The new coolers now have the zincs on the bottom side which I expect will last and protect longer.

I was lucky enough to buy new Detroit Diesels at about the peak of their development. DD suggested getting the new DDEC (version 1 of now 4) electronic controls which would add 35 more horsepower but I decided to stick with what I knew how to fix, the proven mechanical injection model. This has worked out very well.

If I had to re-engine today I suppose I would have to spend another year checking engines, transmissions, gear ratios, engine mounts, weights and balances, and frequent discussions with my naval architect. There is probably much improvement with modern technology but also greater complexity involved in today's obsession with exhaust emissions giving far higher maintenance costs. In all this time with my "new" engines I have only had the stbd. engine tuned up once. Nothing ever on the port. So I am very happy with the old DD two-stroke engines. Best of all, last I checked DD was still manufacturing the 6V-92TA for the U. S. Coast Guard's 47 ft. Motor Lifeboats (now there's a recommendation). So if one of mine breaks I can still get a new one!

[krush]

Can you give me a couple of reasons for not owning a DD boat?

Does your daily driver automobile have a carburetor? Do you use a rotary dial phone? Are you reading this message I wrote on a CRT tube monitor?

Detroits are old, they leak, they are loud, and they use more fuel. All that can be ignored. But also, they are getting more difficult to get decent parts for (and prices will continue to go up).

Some new engine designs are junk and break a lot. But a few models are super reliable (cummins m11, 8.3, 6.7...cat 3406, c18,c32). Some of the cummins can still be had 100% mechanical. The difference in performance, fuel efficiency, and lower cost is amazing. DD lovers also forget that most of these modern engines will easily do 5,000-10,000hours or more before rebuilds if used properly (and that is on plane, not hullspeed).

[Seapig100]

I bought my 45c 3 years ago the 8 71s and transmissions had 400 hours on them, they start in 40 degree weather without any smoke. We have put 300 hours on her and have been very pleased. She is slow, but I don’t care my plan from the beginning was to run at 8 knots and she burns 6 gallons an hour at that speed. Every 45 Hatteras I have seen with modern 4 strokes has been at least 100k more then what I paid for mine. I agree with everything Krush said but if you plan on running hull speed I don’t see justification for the extra money.

[Eddieclemons]

The responses to my question have been amazing, the experience and knowledge here is unbelievable. I hope to start looking at a few boats this Fall if there still around. I have become much more comfortable in moving forward in purchasing in either engine direction when the right boat for us presents itself.

Thanks,
Eddie

[madhatter1]

Years ago I worked with Renovators Yacht in St Pete locating boats for restoration projects. Whatever it was we found the determining factor was what is "the sum of the parts". Same goes for buying any older boat. What are the minuses and the pluses added together. Nice boat with sad engines. Cosmetically challenged but solid mechanicals. Any condition with a modern repower (done correctly or incorrectly)

Whatever you find just add up the sum of the parts. If interested offer accordingly.

[jim rosenthal]

Very good discussion and I agree with Krush; many of the best 4-stroke diesels are still available in mechanically injected versions. When I bought my Cummins 370s, the new QSB engines were available, but cost a lot more, and I didn't see the point in another 15 hp per side. Now, of course, they are up to 500+ hp, but using that kind of power in a Series 1 36 C is difficult and possibly dangerous. I like what I have. If anything happened to them, which I certainly hope it does not, I'd probably just buy the same thing again.

[Boatsb]

I'd have considered the 6.7 very seriously. It's a phenomenal engine and will outlast the 5.9 based on superior engineering.

Yes it cost more but in the end it's a huge upgrade.

I've not seen issues with any of them except for the EPA garbage forced into them. As a long term investment I believe it's a better return.

I'd consider the 6.7 in my 41c as a great and fit. I'd have to modify the keel to use all the hp but even if it needed a rebuild at 5k hours it's a great deal.

I don't hate my Detroits but to be realistic I'd not book for another boat with them when theres so many better options and opportunities.

[Walter P]

Good post Jim...... I think that to say that one type of engine (or brand) makes the most sense for
all boaters is wrong. As I stated in my earlier post, everything depends on the owners preferred use of
his boat and his need for speed. With all due respect the Cummins engines that you have are an excellent
choice for your boat and the way you choose to use it. Not so with the boater that just wants to amble
along slowly and rarely goes above displacement speeds. As far as economy is concerned, there is no
question that the newer engines are more economical to run, but you need to put a lot of gallons through
them to justify their cost over the older Detroit's. These points have been discussed on this forum many
times in the past and I think we all agree that there are so many governing factors to digest while trying
to decide what's best for your use. I think the most important deciding factor is what will it take to make
me happy with my boat and how much am I willing to pay for that happiness.....

Walt