2001 Horizon 76 - Sea Trial

The gyro is leaking or a fin is loose on it's shaft.
New controls will not fix this.

It should not need trim tab in calm conditions except to get up on plane faster. It sounds like stab issue to me. I would ask what did the fin indicator show but I think you mentioned the display had some issues.

stabilizers are important to comfort. Worth checking with Naiad if the control system could be upgraded. If too costly then repair the existing system

I really struggle to understand what in those seatrial results is bringing you to these conclusions.
Capt J obiously doesn't know how those stabs work, and what he said about them being unable to correct an inherent list is plain wrong.
Besides, let's assume he's right instead: why on earth they should be less effective at higher rpm/speed, when exactly the opposite is true for ANY fin stabilizer system?

Now, I don't know what sort of malfunctioning is affecting that Naiad equipment, but pretty sure there is something wrong.
Capt Ralph might well be right on the money envisaging either a leaking gyro or a loose fin.
I would add to that also the possibility of fin actuator(s) leaking, when at higher speed the fins rotation encounter a higher resistance from the water flow, but this is all just guesswork.
Bringing onboard someone with grey hairs and experience on that equipment is what you really need.

Regardless, I wouldn't spend one cent for the Multisea II controller, because that is NOT a more modern system.
It's just an electronic interface that allows a bit more tuning to a system which remains old and entirely electro-hydraulic.
Which doesn't mean bad - far from it. In fact, it actually doesn't need any tuning at all, when it works as it should.

Something I haven’t seen discussed is How do the stabs perform in normal operations, both at hull speed and at cruise ? Do they keep the boat from
Rolling? Any abnormal behavior?

even in calm conditions they could be tested using another boat wake.

or did the seller’s captain left them off except during these tests which would be a sign they are not working correctly. Personally, the stabs are always active as soon as we leave the dock.

I don’t see how a loose fin would be able to deflect and cause a list at higher speed since the shaft is positioned in the forward section of the fin. The pressure on the section aft of the shaft is much higher than on the pressure on the smaller forward area, forcing the fin to be centered in the flow.

Unlike when in reverse when the prop wash could force the fin hard over if hydraulic pressure was lost.

Two divers pushing against a locked fin, can not generate the force of water flowing in or against it.
Moving forward will center the fin, when the shaft is told to twist, it will, the fin may follow or not, when the shaft twists back, the fin may follow or not.
Remember, it's still a tight fit, no key, then can slip and designed to do so (usually under even greater forces).
At speed, the fin is pushed back into position by the passing water.

But I am backing off of that idea and leaning here;

But I just remembered a problem from my past, a leaking cylinder piston seal.

The Cheoy Lee 58 owner tells us: All system would start up fine. Driving a straight line required attention and sometimes the boat just felt funny.
If checking things out, the first thing to do was slow down, check everything.
Stabilizer was cycled, AP was cycled, Props were cleared, bilges checked, then give it the gas and all seemed well and sometimes for many more hours.
The owner stated it was the AP and preferred then on to drive by hand.

The needles were in the wheelhouse, none on the fly-bridge.
The owner and family were always on the bridge and nobody cared a bit of the lower small bench seat below.
The seat was usually covered in provisions and junk anyway.

Later on a test ride, our associate was at the wheel house watching over the full inventory of pressure and temp gauges for everything, including the needles.
He reported never before had observed the position display needles moving differently and in strange segments of the gauge range.
He went to the engine room and noted the servos were not centered on a smooth day and hardly moved when the boat did roll.
From this was more confused.

After that we "T"ed in pressure gauges and found bad cylinders.

New cylinders and adapter kits (obsolete rod ends) installed and all was well after.

I am not a Naiad heavy (just fortunate to have worked on a few successfully); I'm convinced this boat has a problem.
Another more senior member has said the same thing.
Still another senior member says all o k.
Jury still out on the rest.

But it's your money.
Your going to be the entertainer with a sky lounge full of people standing sideways on a smooth day.
Have it fixed by an old grey haired, real tech.
A hose guy just knows the hoses are not leaking.
Throwing a fancy operator panel and reservoir top end at it ($30k+) may still not fix it.


Captain Ralph Crapps
Marine Solutions & Associates Inc.

That seems to be more than service or routine repair. Why did they have to replace the stiffener, hull block and do some glass work? These are tell tale signs of having taken a hit.

Agreed.

Doesn't explain the list issue. Unless fins were not installed correctly.

Is the list issue new or been happening before this?

I have good faith in THE Cable yard but everybody has a bad day.

However, This could be where the cylinder piston seals got blown or other fluid parts stressed. Not just a backing block.

Did anybody give the props a pencil test when it was up?

So after $36k worth of repairs, a surveyor still found delamination around the port stab And recommended removing the whole thing again???

at this point you need assume major stab work is needed and get $25/35k adjustment on the price.

btw, is that a cored bottom or solid glass?

when I removed the old Vospers from my 53 and installed a larger new ABT Trac system, I had my fiberglass guy reinforce the entire area between the outer stringer and hull side (actually up 6” against the hull side) with over 1/2” of glass. And that was on top of a heavyly build 1970 Hatteras hull!