Stabilizers

[MYTraveler]

Originally Posted by Gordon J

We have about 2000 miles on our boat, and I am currently in the Bahamas. I have not yet encountered any sea state where the stabilizers did not help. But I also have to say that I doubt I would be in seas where I would have to question their effectiveness.

I should have mentioned, 7,500+ nm in this boat. Same conclusion.

[Gordon J]

Originally Posted by Lepke

Large gyro stabilizers work in most conditions. They are internal and the spinning mass counteracts roll with gyroscopic torque. It's not necessary to be moving for the gyro to stop the roll. No thru the hull outside fins, etc. Work on boats 10 tons and up. Maybe smaller.
https://seakeeper.com/
Sea Gyro for Ships and Boats

For a stabilizer like this? I have fin stabilizers and the internal components take little room in the engine room. I would be hard-pressed on our 46 foot boat to find space for a Gyro.

[twistedtree]

Originally Posted by caltexflanc

I was just referring to motions acting on the boat while underway. Sorry for the confusion.

I don't recall the bit about following seas in the Naiad manual. I operated in some wicked following seas and never had such an issue. Maybe not wicked enough?

One thing I do, as reinforced by two excellent techs is that they should never be turned off when underway. At the very least, centered.

The slower the boat the bigger the fins have to be. So there's a big variant right there affecting the OP question.

My experience is all with ABT, so other may vary...

Everything made since about 2009 is self-centering and self locking. And self tuning. I turn them on when I start the boat and turn them off when I shut the boat down. Otherwise they are always on, and for all intends and purposes, always help reduce roll.

As others have pointed out, if you are going really slow their effectiveness will be diminished, but for any normal forward cruising speed they are always beneficial.

[twistedtree]

Originally Posted by NewbieFromNJ

Somewhat familiar with the pros and cons of conventional vs the gyro stabilizers. Appears a severe following sea may be a pro got gyros and a con for the conventional. Not sure how the paravanes would fit in here.

I don't think this is correct, at least not the fin stabilizer part. We have about 25,000 miles on two different boats with ABT stabilizers and have never experienced anything by positive results in all seas, following included.

[SoWhat]

Originally Posted by chriscritchett

Was waiting for this to show up. Coming on strong in most markets, even for ~30’ boats now. Not cheap, but no active stabilizers are. Have seen a lot of skeptics be really impressed by gyros.

$27K not including installation. I think I'll hang some buckets over the side

[caltexflanc]

I suppose you could include sway, often referred to as "crabbing" in this context, but I guess I never thought of it as something that upsets one's equilibrium.

The gyros are pretty cool, especially at slow/no speed. They first gained popularity on sportfish boats for that reason (who are not about to add paravanes for a number of reasons). The ones I am familiar with all require a generator to be running, where as fins
run off a hydraulic pump from one of the engines.

[Gordon J]

Originally Posted by twistedtree

My experience is all with ABT, so other may vary...

Everything made since about 2009 is self-centering and self locking. And self tuning. I turn them on when I start the boat and turn them off when I shut the boat down. Otherwise they are always on, and for all intends and purposes, always help reduce roll.

As others have pointed out, if you are going really slow their effectiveness will be diminished, but for any normal forward cruising speed they are always beneficial.

I too have abt Trac and follow same procedure. I turn the stabilizers On and off with the boat.

[Fletcher500]

I am not debating which system is better, because a lot of people have fins and love them. There are positive and negatives for any system. We are having a Seakeeper installed in a 45 ft. Trawler new build, and I have not heard anything from the builder or yard regarding lack of room. They are putting in a hatch above it to allow install and improve access. A lot of these Gyros are going in on new builds these days, including retrofits on existing boats.

[stubones99]

I went aboard the SeaKeeper Gyro test boat at the Stuart Boat Show a couple of weeks ago and was impressed. It was at the dock, and with 4 guys trying to rock the boat, once they enabled the gyro, it stopped rocking within 1.50 cycles.

The guys said most of the power goes to keep the gyro spinning, not hydraulics... I would have thought differently.

On the other hand, Tony Fleming had a gyro installed early on in Venture and removed it due to bearing noise, according to his book, Riding the Tide. I would have to assume that they have improved the technology since then, and he does not name the vendor of the ones he installed and later removed, replacing with fin stabilizers.

One of the installers said some cruisers with fin stabilizers are adding SeaKeepers to provide stabilization while at anchor.

[NewbieFromNJ]

Here’s a good read fin vs gyro:
http://www.jimmyrogersyachtbroker.co...-need-to-know/

[Donsan]

Originally Posted by Fletcher500

I am not debating which system is better, because a lot of people have fins and love them. There are positive and negatives for any system. We are having a Seakeeper installed in a 45 ft. Trawler new build, and I have not heard anything from the builder or yard regarding lack of room. They are putting in a hatch above it to allow install and improve access. A lot of these Gyros are going in on new builds these days, including retrofits on existing boats.

How heavy is your SeaKeeper? The dude in the Panbo article says his was 1200 lbs and it was installed in the lazarette. In reading through his Loop blog, it gives the feeling it added several inches to his draft. He ended up moving several things toward the bow to compensate for additional weight on the stern. Isn't it best to install the SeaKeeper in the middle of the boat?

[Delfin]

Originally Posted by NewbieFromNJ

Here’s a good read fin vs gyro:
Gyro Stabilizers and Fin Stabilizers, What you Need to Know

Good summary. The only disagreement I would have is the statement that active fins result in a reduction in speed due to drag. No doubt true on boats moving at fast speeds, but for trawlers, IMO, there is no speed penalty in a typical seaway since a stabilized boat feels less drag overall than one rocking and rolling.

[Fletcher500]

Originally Posted by Donsan

How heavy is your SeaKeeper? The dude in the Panbo article says his was 1200 lbs and it was installed in the lazarette. In reading through his Loop blog, it gives the feeling it added several inches to his draft. He ended up moving several things toward the bow to compensate for additional weight on the stern. Isn't it best to install the SeaKeeper in the middle of the boat?

I have avoided commenting much about this because I have never had a boat with stabilizers. Everything I know is from reading and talking to others.

Long story short:

Seakeeper did a computer generated analysis of our boat, weight, etc. It will be the first Helmsman to get a Gyro. They came back and said the SK 9 model would result in the most roll reduction. As noted, the 9 is $ and heavy.

They also provided data for expected roll dampening for the 5 and 6 models within our boat. The 5 and 6 models are much less money, smaller, and lighter. I felt the 5 or 6 would provide the best solution with all factors considered. The 6 is essentially a 5 in regards to size, but with more advanced components so it provides about 20% more torque.

The 5 was available to ship from SK right away, and it was heading to a container with other gear the builder was sending over to the yard. I therefore went with the 5 model.

[Fletcher500]

Regarding location, yes, the Lazarette location probably resulted in that. A lot of Express Cruisers are now getting these. The engines on EC's are already located aft because the designers are squeezing every inch of space/volume to get more cabin space below. Combine that with Pods is resulting in a lot of weight aft. They are still managing to get these in boats in 40 - 50 ft. range. In these type of boats instances, it would be cramped.

[menzies]

Unless things have changed since I looked at them, one "issue" with the gyros is that you have to have a pure sine generator AND keep it running while requiring the stabilization.

[GGroves]

Last summer we installed a Seakeeper 6 in our DeFever 45 RPH. I am not entering into a debate between fin vs. gyro, just that the gyro worked for us. We didn’t want any protrusions from the hull and it was not that much more than a fin system.

The gyro works at any speed, 0 to 12 kts. If you can go faster than 12 kts, than your planing hull shape obviates the need for a gyro at high speeds. Ours weighed in at 800 lbs and we did have to re-balance the boat. But then again, it had an inherent list that I needed to correct anyway! It does take 45 minutes to “spin up”, but we start at the dock before we depart, so it is running we we need it. With the engines running under way, the generator noise is negligiable and at stop, what little generator noise we have covers the gyro. Actually, you can’t tell it’s running with everything off when plugged in to shore power.

It is designed to handle roll actions. So, like the fins, it will subdue beam waves and also help with the squirrelies with following seas. Again like the fins, it does nothing for the pitching action you get when pounding into a sea, except helping to keep the boat flat if you take one on an angle.

Stabilizers are not necessary, but neither is airconditioning. They just make the cruising far more comfortable and thus enjoyable and after all, isn’t that what it’s all about - enjoyment.

Gary

[twistedtree]

Yours is by far the most relevant example/experience for this group since your boat is typical of TF trawlers. So many seakeepers have been in stalled in sport fishing boats and fast cruisers which is not a good example for a slow trawler.

[GGroves]

We were fortunate that we had room in the engine room and did not have to do any modifications to the compartment. The gyro is mounted off-center and the installers did reinforce the stringers for the gyro mount - one inch thick aluminum plate glued to the stringer and then glassed over. The gyro can be mounted anywhere aft of the fore/aft center of moment.
Gary

[JDCAVE]

Originally Posted by Delfin

Good summary. The only disagreement I would have is the statement that active fins result in a reduction in speed due to drag. No doubt true on boats moving at fast speeds, but for trawlers, IMO, there is no speed penalty in a typical seaway since a stabilized boat feels less drag overall than one rocking and rolling.

The evidence for KK42’s suggests actively stabilized vessels loose about 0.5-1.0 kts at cruise rpm, as compared with unstabilized vessels. We loose about 0.5 kts from cruise when our paravanes are in the water.

Jim

[Delfin]

Originally Posted by JDCAVE

The evidence for KK42’s suggests actively stabilized vessels loose about 0.5-1.0 kts at cruise rpm, as compared with unstabilized vessels. We loose about 0.5 kts from cruise when our paravanes are in the water.

Jim

I know that is what they say Jim, but it doesn't make much sense to me. For example, paravanes operate by directly creating drag - it is the whole principle of their operation. If paravanes create .5 knots cruise reduction with chains or cables attached in a KK42, plus a forward slopping dolphin being dragged through the water, then how does an active hydrodynamic fin create the same or more drag? Further, the most slipperly presentation of a hull in not when it is swaying from side to side, as it is more prone to do when rolling, nor when it is presenting greater wetted surface when heeled, but rather when it is upright.

With active fins, at least on Delfin with her hull shape, turning on the fins has zero impact on speed, or at least none that I can detect with GPS, so whatever drag there is comes from inefficiencies in the fin hydrodynamics, which don't intuitively seem like would be much.