Abt Zero speed?

I ve had Advantage Marine Service in FTL work on the ABT trac stabs on the 84 lazzara I run. I also bought a rebuilt set from them for my own 53 Hatt

(954) 695-2884

Can't help you with FL installers, but someone who knows about them will soon be able to point you in the right direction.

Ref. ABT-Trac, I only tried their hydraulic ones, during a non-stop winter transfer of 3 days and a half on an Outer Reef 70', and they did perform very well, also in some "interesting" beam seas.
In another occasion, I also followed their commissioning, with the technician simulating an actuator fault on one side at a time, and if it weren't for the display showing that the other fin automatically started to work harder, it would have been impossible to notice the difference.
Very effective indeed, also at zero speed.

I wasn't aware that they are now building also electric stabs, though.
Maybe it isn't widely known in the US, but electric fins were pioneered by an Italian company called CMC Marine.
They build some really impressive stuff, also retrofitted to the 75 footer from which I'm now writing BTW, with amazing results.
And available up to huge sizes - they were in fact fitted also in this recently presented 55m vessel, among many others even larger yachts.

If ABT products are equally good, and I don't see why they shouldn't, I would go for electric over hydraulic any time - and even more so for a retrofit.
They are easier to install, less power hungry, less equipment-demanding (no hydraulic pumps, no electric motor to drive one of them for zero speed, no high pressure tank akin to a bomb for zero speed usage, no hoses with high pressure and temperature running around), so eventually they are also bound to be more durable and reliable, if properly built.

Anyway, regardless of whether actuators are hydraulic or electric, sizing and positioning are crucial to a good installation.
Don't have them installed from someone at his first rodeo!

PS: Ops, Pascal posted his comment while I was writing mine.
I told you that someone would have soon given a suggestion on the installer!

Goes to prove what I said about CMC electric fin stabs not being as known as they deserve in the US.
They were retrofitted in the Canados from where I'm writing more than 7 years ago, and they neither gave one single problem since then, nor demanded any maintenance.
Btw, it was an already proven technology already back in those days.
So far, they were used for new builds from Baglietto, Admiral, Benetti, Rossinavi, Overmarine, Sanlorenzo, CdM, Codecasa, CRN, MCY, Moonen, Sunseeker, and I'm sure I'm forgetting others.
As I recall, they were also retrofitted to some large Westports.
So, not exactly a new kid on the block - neither as a company nor as a technology.
In fact, by the time CMC was already supplying fin stabilizers to superyacht builders, at Sleipner/Sidepower they were still building only thrusters...

Now, I can't say anything specific about electric fins from ABT.
In fact, I wasn't even aware that they introduced them in their range - which at a guess must have something to see with some CMC patents that eventually expired.
But to anyone who cares more about the Company/brand, rather than the actual product, I'd suggest to go for electric fins from ABT regardless of how new they are, rather than anything from Sleipner no matter how tried and tested, anytime.

Actually it isn't the same, it's significantly less.
For any given size/effectiveness, electric fins have been tested to demand 30 to 40% less power than hydraulic systems - to the point that you don't even need to keep the genset running while under way, because a decent size inverter and the alternators are enough.
And the lower consumption is a big advantage also at rest, obviously.

Again, I'm not talking of the ABT stuff specifically, but I'd be surprised if ABT shouldn't be capable to build something comparable to CMC - the technology in itself is in fact no rocket science, and mostly based on off-the-shelf components.

Do you mean a lot less with hydraulic?
Well, while under way their current draw is close to nothing - just enough DC to run the control panel, but that's peanuts.
Power for moving the fins is supplied by a PTO hydraulic pump connected to one motor - or both for redundancy, sometimes.
Electric fins instead needs some substantial electrical power for the actuators also while under way, but much less (and with less peak loads) than at anchor, anyway. This is the reason why I said that in a good installation with a decent inverter you don't need to keep the genset running - not for the stabs alone, anyway.

But the scenario where power consumption really matters is in use at anchor.
That's where also hydraulic stabs demand a lot of current, because you must run a pretty substantial hydraulic high pressure pump, normally driven by three-phase motor.
So, in a typical single phase boat (as I guess your 74 footer is), you must keep the genset running, then feed a VFD unit for the conversion into three-phase current, and then use it to feed the electric motor that eventually spins the hydraulic pump that keeps pressurized the whole fins circuit, inclusive of a big tank reservoir for dealing with peak demands.
With electric fins, you get rid of all the above, feed the stabs control unit with AC from the genset, job done.
Really makes hydraulic technology archaic, in comparison.
And mind, I'm saying this as someone who spent 17 years of boating with a wooden trawler equipped with Naiad hydraulic fins, and enjoyed every minute of it.

Now, for a Lazzara 74', I would think that 0.8 sqm fins should be enough, but let's say 1 sqm to stay on the safe side.
It's a size that with CMC system demands a 5kW AC supply (peak, not constant).
Mind, I keep referencing CMC just because I happen to know their systems, and I'd expect ABT electric stuff to be roughly comparable, nothing else.
I'm not one of their salesmen!
So, just one of your 20kW genset is plenty, depending of course on how much power your other onboard equipment demand.
But don't expect the three-phase electric motor that you should keep running at anchor with hydraulic stabs to demand less current.
Its peak absorption could actually demand even more than 5 kW, and as I said on average you can expect electric fins to need 30 to 40% less current than hydraulic stabs, when used at zero speed.
Imho, a total no brainer nowadays, particularly for a refitting, but not only.

4 stabs was a Gyro Gale thing which I don’t believe any other stab manufacturer tried. Any new system will use two fins, you ll just need to glass the forward holes

Actually, 4 fins are not rare at all, but only on very big boats - or better said, ships.
Dilbar, a 500+ feet monster built by Lürssen, is one example that springs to my mind, but there are many others.
I don't think there are a lot of vessels fitted with 4 fins on anything under 200 feet or so, though.
Even the Admiral that I linked in my post #3, with all her 180 feet, only relies on one pair of fins.

But in principle, all builders of very large fin stabilizers, ABT included, offer the possibility to control two pairs of fins.
After all, essentially it's "only" a matter of having a more sophisticated control unit, with algorithms calibrated for coordinating the movements of 4 fins rather than 2.
There are some pros in such choice, the most obvious being a smaller size of each fin and some capacity to smoothen also pitching and not only rolling - though the latter is actually more theoretical than real, because the forces necessary to stabilize pitching are a multiple of those required to stabilize the roll.
The cons are also rather obvious: more parts that can go wrong, to start with. And as we all know, on a boat whatever can go wrong, eventually will.
Besides, there is an additional layer of complexity introduced by the need to manage the four fins consistently, which is yet again something that can go wrong.
Last but not least, additional costs, both for the components and for the installation.

Bottom line, considering that two fins systems are by now tried and tested also in boats much bigger than yours, they are as effective as 4 fins at stabilizing the roll, and their total lack of effectiveness in stabilizing the pitch is irrelevant in practice (because also with four fins the pitch reduction is negligible), you can see why nowadays two fins are by far the most popular choice for anything but super/mega yachts - also as OEM installations.
So, even assuming that ABT can offer a 4 fins system properly sized for your boat (which I think is unlikely), my bet is that they would recommend you a two fins system anyway.

On the other hand, I understand your wish to re-use the existing fins positions, but you should consider two things:
First, in a two fins system the forces that each fin can transfer to the hull are much higher than in your old system - probably not double, but almost.
Therefore, the four areas of the hull where the previous fin actuators were mounted, which were obviously made strong enough for that purpose if that's how the boat was originally built, could possibly be not strong enough anymore to sustain the higher loads of the new two fins system.
Second, in a planing hull the typical best placement for 2 fins stabilizers, longitudinally, is roughly at one third from the stern and two thirds from the bow.
Now, I have no idea about the placement of your old fins, but ruling out the forward position which obviously can't be anywhere near the ideal placement of 2 fins stabs, it would take a lot of luck to find out that the other couple of fins astern were mounted in a place that can work equally well with two fins alone.

Anyway, only a careful inspection made by an experienced technician can tell you what the real possibilities are.
The only thing that an expert can probably confirm you without even looking at the boat, is whether a four fins system could make sense or not, at that size. This is something that I would expect ABT to tell you over the phone in two minutes, if you can reach one of their engineers.
Or if you are interested in another view, I can ring my contact at CMC and ask him, no problem at all.

Yeah, we all know multiple pairs are used on large boats... not the subject of this thread.