Hatteras retrofit cost and ideas

You can find people to work on the old 2 stroke DD's all over the world. The US military spread them all over the place and many are in service in far away places as generators, truck engines, heavy equipment, etc. Parts can still be had for them, although there might be a little lead time for some things. The old 2 strokes are more efficient at slow speeds (<1000rpms) than even modern 4 strokes, but are a little less efficient above that. I like the 71 series, and although a bit crude......oil leaks, can smoke on startup, can load up after a lot of slow speed running, they're easy to fix and run and maintain. The 92' series I'm not as big a fan of as they don't generally enjoy nearly the same service life as the 71's. It's FAR cheaper to rebuild them than replace. The thing with D.D's is you never really can have a clean engine room, clean bilges....if you stay after it you can keep everything relatively clean, but not clean clean.

However replacing has good options too if willing to spend 3x the money. More HP to weight ratio, cleaner running, electronic controls, warranty, quieter, faster boat, more fuel efficient at cruise etc.

Everyone stayed with 32 volts until that era, Bertram even later and others. It's 25% more efficient than 24 volts. If an item uses 15 amps at 24 volts it will use 12.5amps at 32. Battery chargers weren't that large back then, most items were a bit more in-efficient, etc. etc. It's quite a bit to change to 24 volts. Depending on wire size you might have to re-wire the entire boat to switch to 24 volts, usually not on a Hatteras. Rewiring a motor yacht that size is a major undertaking both in cost and work involved. You can get around that by also converting to more efficient systems that use less electricity (toilets, pumps, LED lightbulbs etc. etc.) Engine starters, alternators have to be converted to 24 volts. Every DC system, F.W. pump, blowers, bilge pumps, toilet pumps, battery charger, battery bank re-configured, light bulbs, and on and on, it can get quite lengthy and expensive. If it's a working 32 volt system then keep it, as other people have said you can find the parts and just carry lots of spares on board and replace as needed. Some things will get around having to swap, like some LED light bulbs are rated 12-36 volts so as long as they're the right footprint convert to LED's.

A Near 80 year old design (older?) and other than DDEC, there is no efficiency or improvements left.
They are wonderful when they are running but when the time comes for rebuild, you must consider re-powering.
Half the weight and a cleaner motor may not pay for itself, but life is easier.
Lucky for Pascal, he's already ripping up the boat, a heavy DIYr and a budget he can live with.
I am so looking forward to results with the new engines.

Till I win the Lotto, My 71s will be fine.

The higher the voltage, the thinner (lighter) the wire required.
You will smoke wires dropping from 32Vdc to 12Vdc and consuming the same wattage at the ends of those small wires.

Yeah sorry I swiped "post" by mistake then the edit didn't post

So... Well.. First Detroits are WW2 two cycle tech Done and outdated. I am not necessarily a big fan of electronic engines, at least mechanical four cycle is more efficient and clean.

Second. Like it or not, the number of buyers who will or even consider a Detroit is getting bigger. Just like some people will not look at a 32b boat. Combine both, plus an outdated galley down wifey says no layout and you be cut off half the buyers.

Third. Rebuilding original DDs In frame is pretty much like going to a casino or playing the stock market. No guaranties. Sure you may find a reputable guy or shop but it doesn't take much to screw it up. And it's a lot harder to document to a buyer. I mean when you see a boat a advertised with rebuild engines how do you know I'd you are offered a spray can special or a real overhaul ?

So I looked around and came to the conclusion that the best option was not to rebuild the ole DDs, not to go for new yanmars or deeres but factory recon cummins. They are pretty much mostly new engines for the cost of a no warranty DD rebuild

In my case it s a no brainer

I was quoted $30k for 315hp cummins with new ZF with two year warranty... Or $38k for the 450s also with new ZF gears

A good, no warranty 8v71 Natural rebuild is about $20k plus rebuilding the Alison ...

All understood and correct.
Interested to know if your going to Smart craft controls and what hp.
,rc

i converted my 1972 58 hatteras yachtfish to 12 volt about 8 years ago and have not had one problem with the wiring being undersized.
it was a no brainer for me....when repowered the po used 12 volt john deeres, a 12 volt generator and 2 of the heads were replaced with 12 volt. all i had left was bilge pumps lights windlass, and blowers

I do not have a good answer to this. I would not volunteer this info to your insurance or purchasing surveyor also.

I remember the wiring on the 1979 58' YF I ran for many years to be pretty large gauge for the loads they were carrying. I would think converting to 24 volts would be fine, but 12 volts would start making the wiring size simply too small gauge for many items. It's possible the heads use a lot less amperage than the galley maids, but who knows. The wiring on a set of 24 volt vacuuflush pumps on a boat I was just working on is 14 gauge, I replaced both heads with Raritan Marine Elegance which use 10-12 amps I think.

i didn't change any of the wires,didn't change any panels, only some of the breakers, and didn't change any of the fixtures, just the bulbs in them.

my insurance company know about the change and didn't have a problem with it. it was noted in my purchase survey that the system was being upgraded to 12 volt. upgraded is the word the surveyor used. as for a purchasing surveyor, i'm not worried about that, i have no intentions to sell her, she is the perfect boat for us.

If the fuse/breaker size is correct for the wire gauge, then, in theory, the fuse /breaker will pop before you cook a wire.
Still, be sure your insurance is up to date and the fire extinguishers are current !

The issue on older boats is not just wire size but the age and quality of the wiring. Back in 1970 is was very good but now it s completely outdated

I don't know when builders started using tinned wire and thinner strand but in the early 70s they did not. I have also found dozens of electrical taped butt connectors, most clearly original to the boat. All that means higher resistance which becomes critical when you switch to a lower voltage.

In my case since I am moving so many things, opening so many walls, tearing down so much stuff, replacing the wiring is a no brainer. Using Ancor marine tinned wire, 10 ga for the DC with the correct yellow color for Dc negative, and 12ga for the AC wiring. Straight runs without connection and heat shrink connectors at each end.

I have never heard of a DC Negative being yellow. Whose rules cover that one?

It s an ABYC recommendation

https://www.defender.com/pdf/abyc-wire-color-chart.pdf

Black or yellow is acceptable but yellow is becoming more and more common. Avoids confusion with the black wires used in for AC wiring