Waveless Stab stabilizers

I am. In fact, The boat from where I'm posting right now was retrofitted with them.
Generally speaking, they work as well as anything hydraulic if not better.
And for retrofitting, going electric rather than hydraulic really is a no brainer.
If you are interested in anything more specific, just ask.

I wouldn't touch anything from Gyro Gale. Not familiar with CMC, however would highly recommend sidepower curved stabilizer fins, ran a boat extensively with them and they were incredible both at anchor and cruise speed.

Recommending sidepower fins is well and good generally speaking, because it's a good product.
But to someone who is looking for a retrofit, and also said he has "nothing hydraulic on the boat at all"?
Seriously?!?

No need to worry about the "new model" claim.
CMC was the very first among builders of fin stabs to develop a fully electrical system, more than 10 years ago, and by now they have a very large installed base, up to megayacht size.
The latest versions just incorporate some refinements of what is by now a thouroughly tried and tested technology.

The need for hull strengthening is a more relevant subject instead.
Which depends on the specific boat and the position where fins are going to be installed.
I'm not familiar with your boat, so I can't comment on that.
But you'd better check that with your yard anyway, both for identifying the best position (which is important!) and for how much reinforce is necessary.
Anyway, generally speaking, on GRP hulls not originally designed for fins, the short answer to your question is yes.
Typically, with additional mat layers around the area where the fins are going to be installed, possibly extended up to the nearest stringers.
Such reinforcements do NOT depend on the stabilizers brand you are going to install, though.
All fin stabs can transfer strong lateral forces on the hull, wherever they are attached to - that's the nature of the beast.

I understand how electric is easier to install but adding an hydraulic pump and running some hoses is no big deal

when I took out the 1970 vintage Vospers from my boat during the repower and installed the new Tracs I had the hull reinforced as the new ones are much larger. We added about 3/4” glass to the hull covering the whole section between the outer stringer and the hull side, going up a few inches on both. Probably not needed on an old hatt hull but made me feel better and pretty easy to do.

Running hoses might actually be more or less complicated depending on each boat, presence or not of w/tight compartments, etc.
But I agree that it's not a big deal, normally.

I guess what you have in mind are under way-only hydraulic fins, though.
In fact, while zero speed capability doesn't make any difference with electric systems (aside from the fin size and shape), it IS indeed a big deal with hydraulics.
A hydraulic pump on one engine is not sufficient anymore, and you need either another PTO-driven pump on the genset, or (more frequently) a separate pump driven by an electric motor, which being 3-phase, also needs a VFD unit for the electrical conversion.
Besides, with under way-only hydraulic fins there's no need for a compensation tank, but for zero speed operation you must also install a relatively large, high pressure tank somewhere in a possibly already busy e/room.
If I should put the two alternatives on a complexity scale from 1 to 10, I'd give electric a 5, and hydraulics a 9.
On top of that - and this is somewhat related to the complexity and number of components - when it comes to reliability, it's actually the other way round. I.e., higher with electric than hydraulics.
All of this without even mentioning other (arguably minor) advantages of electric systems, like the possibility of running them at least for short periods on batteries alone, and the possibility of operating them oriented backwards, to restrict the boat from slowly "swimming" forward when at anchor with very little wind - which in a busy anchorage can potentially interfere with other anchored boats.

Bottom line, nowadays you would struggle to find any valid reasons for not going electric in general.
But when retrofitting, as I said in my first post above, it really is a no brainer, imho.

Sidepower has an entire line of 100% electric fins. Hydraulic can be retrofitted fairly easily as well (that's what all fins were almost, up until 5 years ago), Just install the electric hydraulic power pack with the tank and everything built in, a seawater pump, VFD, some plumbing and run the hoses. Although electric would be easier, the bulk of the retrofitted systems oon yachts has been and is hydraulic. The electric power pack and vfd aren't that big. He mentioned Wesmar which to my knowledge only produces hydraulic. I tried to pull up Side-powers site, but the Siepner site is down right now.

An electric hydraulic pump and An extra VFD is no big deal. We already have 4 VFDs anyway. 2 for the chillers and 2 for the ER blowers

Pascal, you mean on the big Lazzara you are in command of, I suppose?
I've yet to come across any 56 footer with one VFD unit, let alone four!

Do they? Since you mentioned curved fins - those which IIRC they call "vector" - I assumed fully hydraulic because they are the only ones I'm aware of.
If they also made them with electric actuators and control unit, that's new to me.
Would go a long way in confirming what I was saying ref. hydraulic systems being by now outdated, anyway.
Though of course their installed base is still larger - by this token, would you repower a boat today with mechanical engines because there are still more of them around compared to electronic ones?

You keep moving the goal post. I would go with whatever system worked the best for my application. If I was sending a boat to a remote place, yeah I'd highly consider mechanical engines. Just like I'd go with whatever FINS worked the best for my application. I've used a few sets of the hydraulic side power fins and they work amazingly. But your logic does not work, because you're highly against PODS and in a twin engine installation they are far ahead of shafts as far as performance/fuel efficiency, maneuverability etc. I've used the vector fins on a few boats and they're the best stabilizers I've used. I have not used KMC electric fins.....but have over the years used most all of them including both seakeeper and quick gyro's. I've used electric ARG fins and wasn't really that impressed with them.

Doh! Are you sure I'm the one who's moving the goalpost?!?
The engines were just meant as an analogy, and now you throw in also pods, out of the blue.
You said "Sidepower has an entire line of 100% electric fins", and now that you've only used their hydraulic stuff.
Make up your mind, Captain.

Hydraulic would be a fine retrofit in most boats and not that big of a deal to install. Sidepower now does make electric fins, I just haven't had the opportunity to use them, so if that's an easier retrofit could go electric. Same fins so should work the same or better.

By using the mechanical engine versus electronic, you're talking about technology moving forward......well so are pods when you think about it, but you are strongly against them and moving forward in your own areas.

Since you insist, I'm against them because I think they are a real move fwd only for two categories of people:
Those who build and sell them, and the boatbuilders who can save costs by adopting them.
Oh, add possibly also boaters unable to maneuver a boat, and unwilling to learn.
But since I don't belong to any of these categories, I'd rather stick to stuff that doesn't break every other week.
That's just my opinion anyway. And then again, am I the one who is moving the goalpost?

We're getting way off topic. But new hydraulic stabilizers (modern technology) work really well if the installation and sizing is correct. Electric has it's merits too and those work really well as well given the same parameters. And yes, an easier installation in some cases. The sidepower curved fins I have used in a couple of boats were all hydraulic, the power pack and VFD aren't that big and hose runs generally aren't that long in those installations. They actually are the most effective stabilizers I've used. That being said Electric also has it's issues. The boat with the ARG electric stabilizers, when the stabilizers are on, it screws with the autopilot compass which is mounted over 10' away and the autopilot compass swings 30-40 degrees when they're on.

As for VFD's I've run several yachts with chillers in the 55'-65' range that had 2 VFDs, one for each chiller. Not much bigger than a battery charger mounted on the wall.

While the pods need a little more maintenance and probably have a higher failure rate (not obscenely higher), they're a good 30-40% more fuel efficient, a lot less vibration, no visible smoke, and smaller engines for the same speed and more range......also allowing more room for interior space.....so they have many merits over props and shafts IN a twin engine installation. But that's way off topic.

Easier to run wires than hydraulic hoses, no hydraulic pumps (engine driven or electric), electric motors have full torque all of the time. But yes, hydraulic is proven and works well and is reliable.