Gyroscopic Stabilization on trawler

I went to the FL boat show to look at the Nordhavn 41 with my buddy who owns a Regulator 34 center console with Seakeeper gyro stabilization.

He asked the Nordhavn rep "can you get gyro stabilization in these?"

The Nordhavn rep replied, "Trawlers aren't really a good match for gyroscopic stabilization. They are displacement boats. The N41 comes with fin stabilization...."

So, focusing on "trawlers aren't really a good match for gyroscopic stabilization."

Thoughts, comments, opinions?

I hope Hippocampus chimes in here as he was looking very closely at used Nordhavns but ended up with a Nordic Tug 42 with a Seakeeper system. In short, statement that 'trawlers aren't a good match for <Seakeepers>" definitely doesn't sound right. The only functional complaint I have heard about Seakeepers is from installing under-sized systems. Just as with fins, slower you go, the bigger the system needs to be.

If you or your friend are interested, would definitely reach out to Seakeeper. I am sure they could point you to many happy customers.

I'm not a buyer of Seakeepers only because I'm not keen on keeping the generator running. Otherwise, sounds like people seem perfectly happy with them. As an FYI - my fins work fine.

Peter

In my mind, it's not that an FD trawler is a worse application for a Seakeeper, it's that it's a better application for fins. On a slow boat, sizing the fins to work at zero speed will have less of a drag penalty than on a fast boat. And by having a narrower range of cruising speeds, sizing fins is easier in general (compared to fins on a faster boat).

Relative to fins, in my mind, the Seakeeper has 2 big downsides. It's heavy and it takes up a lot of space. That, and it's not instant-on.

I looked at a Nordy 62 with twin Seakeepers and they reported they were horribly ineffective and a waste of over 100k.

Mako said:

I looked at a Nordy 62 with twin Seakeepers and they reported they were horribly ineffective and a waste of over 100k.

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62 or 63? I know of one 63 that was equipped with seakeepers. The second owner added fins, but didn’t remove the gyros.

I don’t know of any 62s with gyros.

twistedtree said:

62 or 63? I know of one 63 that was equipped with seakeepers. The second owner added fins, but didn’t remove the gyros.

I don’t know of any 62s with gyros.

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Do you know why gyros so ineffective on Nordhavn? Their biggest impact is anchor and low speed, definitely not planing speeds. Is it the weight or hull shape? I can see how zero speed would be easy.

BandB said:

Do you know why gyros so ineffective on Nordhavn? Their biggest impact is anchor and low speed, definitely not planing speeds. Is it the weight or hull shape? I can see how zero speed would be easy.

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I’m not sure, but would love to know. I suspect that it’s just too heavy a boat for effective underway stabilization, but that gyros are good for at anchor. Perhaps better than fins with zero speed stabilization.

A friend has installed dual gyros plus fins in a new N68 build, and I’m interested to hear how they work. He’s big into fishing, and I think that’s where gyros shine.

The weight thing is a good point. Compared to typical Seakeeper sizing for a lighter, faster boat, you may need one or more VERY large gyros to get enough stabilizing force because the boat is so heavy.

Guys I know with seakeepers have them primarily for zero speed operation but rely on active fins while underway. Seakeepers allow a boat to drift - fish the trough with minimal roll. People that buy Seakeepers, rather than fins, are often times disappointed in the displacement speed performance. When neither cost nor room is an object, the combination of Seakeepers and fins is the best of both worlds. If you can only have one, fins is probably the better choice at least on displacement speed boats. I think rslifkin's comment about mass is a good part of the explanation -- Nordhavn's are heavy boats and probably require proportionately larger Seakeepers.

MYTraveler said:

Guys I know with seakeepers have them primarily for zero speed operation but rely on active fins while underway. Seakeepers allow a boat to drift - fish the trough with minimal roll. People that buy Seakeepers, rather than fins, are often times disappointed in the displacement speed performance. When neither cost nor room is an object, the combination of Seakeepers and fins is the best of both worlds. If you can only have one, fins is probably the better choice at least on displacement speed boats. I think rslifkin's comment about mass is a good part of the explanation -- Nordhavn's are heavy boats and probably require proportionately larger Seakeepers.

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That could be it as the biggest issues I've seen with Seakeepers on slow boats is undersizing them. Builders do so to save money and they just are way too inadequate.

I have/had zero speed fin stabilization on both most recent boats, and they are great when drifting. That's where I've used them the most. In our case that's watching whales rather than fishing, but it creates the same rolling in the boat.


I think part of the problem using gyros on larger displacement boats is the slower roll period. A gyro has a limited stroke over which is can counter a roll. If the combination of the amount of roll, and the period of the roll is too much, the gyro reaches it's limit and just stops countering and has to wait for the reverse roll to begin before it can do anything. Otherwise it would contribute to the roll rather than counter it. Fins provide a continuous counter-roll force for as long as needed.

After two trips it’s still early days. First was eastern Connecticut to the top of west passage RI. The entire trip was into the wind and a short period chop of 2-4. Second was top of west passage to mouth of Chesapeake inside except for NJ coast. Only dealt with a significant swell in block island sound and coast of NJ.
Still, from reading and this very limited experience think the following.
Gyros need to be sized by vessel weight not loa or lwl. So by length Nordies are heavy FD boats. The NT is a moderately heavy SD boat. Both roll period and stiffness are quite different. The round bilge, lower form stability Nordie will intrinsically want to roll more than the hard chined, more form stabilized NT. Yes, the Nordie will have a much greater AVS, less down flooding risk and be a safer more capable boat in a seaway but the Nordic roll period will be shorter and will have more initial stiffness.
So the great thing about gyros is they work at any speed or no speed. Bad thing is they only respond to acceleration and have no effect on a fixed list. Also they only work in one axis. They are usually set up to damp roll not pitching. This matters less on a boat operating at or above hull speed.
Fins don’t care how you got leaned over or if it’s sustained. Their “brain” is set up to return you to a even keel. Fins are set up to respond to any rate of perturbation. Your perception (as a human) is gyros are phenomenal for wind waves and chop but for big waves and swell fins maybe better. Gyros don’t care about slow boat speeds. Well designed SD boats tend to be intrinsically more resistance to roll when at or above hull speed. You need more area for fins and slow boats. FD boats operate below or just approaching hull speed the majority of the time.
In summary if I was spec’ ing a BWB it would have fins or Magnus effect device. Fins for FD heavy boats. Magnus or fins for light, narrow higher speed boats. Works at all levels of heel regardless of how you got there. Works well with heavily ballasted boats. Having external appendages is no biggie. But for a coastal SD boat with more dependence upon form stability gyros work just fine.

Might want to review hammerheads thoughtful thread. My only caviate would be if I was doing mixed use would investigate Magnus effect further. The idea of rotating them in when in skinny water or debris filled waters is quite appealing.

Hippocampus said:

Might want to review hammerheads thoughtful thread.

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Link please, Hippo. Best, KL

Gyros

Not sure why someone would suggest a gyro is not suitable for a certain design of boat, I would assume it would improve stability in any design. That being said, I had a Seakeeper in a 40’ trawler design and can thoroughly recommend them.
I completed more than a 1,000 nm journey day after day with the gyro on the whole way. We were in quite rough and sloppy conditions and it worked a treat. Without it on ( and we conducted numerous on/off tests) you could really feel the difference.
At anchor the gyro is incredible and the Admiral always wanted it on even if there was a slight sign of chop. It even impressed my boating mates who were sceptical.
They are an expensive piece of kit but they do the job .. I now have a 60’ trawler with fin stabilisation .. not the same result and in my experience, not as effective, although difficult to compare.
If you want to invest the money to install a gyro I doubt you would be disappointed.

Cheers and happy boating.
Illerom.

That being said, I had a Seakeeper in a 40’ trawler design

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What was the hull shape of that 40-footer, Illerom? I had a sharpie-design 40' trawler, with flat aft sections and a hard chine (so high initial stability and rapid roll accelerations in confused seas). My feeling is that different hulls respond to different stabilisation approaches. The present vessel, 30 tonnes, deep draft and rounder hull respond very well to the paravane stabilisers we have fitted to her, but my sense is that these would not have worked as well on the sharpie.

I’m afraid my technical knowledge of the hull will probably not meet your expectations, however, she was a full displacement hull, with, I would say, an almost flat aft section. From memory.. approx 20 tonnes (??). I acknowledge that different hull designs would be more or less effective but once you flick that switch(keeping in mind the gyro takes 45 mins or so to get up to speed) the difference was incredible.

Illerom, my experience with a Gyro in a 45 ft boat is as you have described. Worth every Penney. Many people on here jump in whenever they can to make negative comments about them, but have never owned one or used one for extensive cruising. One poster on here was making various claims about them over a 1 year period, including that they were “dangerous”. He subsequently bought a boat with a Gyro. Steve D Anatonio is one of the most knowledgeable boat and system people on the planet. He has written about them, likes them, and has worked with owners who have had them installed on numerous boats, including trawlers. I generally stay out of these discussions these days, but only chime in periodically so that people who may be interested in them hear from someone who has actually used one, for 600 hours.

Well, let me put my cards on the table: I have not owned or used a Seakeeper, but the technology appeals tremendously. Yes, you do have to run the generator to use one, but just like our paravanes, there are plenty of occasions where the sea is calm and airs are light, and so would not be needed. My partner does not have much offshore experience, and she really liked the difference when we dropped the fish in on our last trip to Sydney. Some kind of stabilisation is needed on long passages, I believe.

I have had Seakeeper 6’s in two trawlers and both were installed well after the original build. The first boat was 47 OAL, twin engine, flat bottom, hard chine, 16’ beam, at 25 tons displacement. Did nothing for pitch but that was easily accommodated by adjusting course to take more on the beam. On the beam the system remove 80% of roll from an already very stable platform. Second is a 42’ twin engine with similar underwater characteristics, beamy with hard chimes, 40 tons displacement in all steel. Similar results. I sold the first boat and replaced it with a vessel with fin stabilization but I still prefer the gyros.

Kit, yes the generator run turns off some people and I can understand why depending on how and where they cruise. We are just coastal cruising and I am often making water [AC system] anyway because we are away from the dock a lot and go through a lot of water for domestic use, showers, and rinsing our water gear off. Running the Gen is not not an issue for us. I generally avoid running it at anchor for environmental reasons, but will run it at a rolly anchorage and they improve the comfort and safety for everyone.

Just to close this out from me ... running the genny to operate the gyro was no issue ... our generator was reasonably quiet and the gyro emitted a low hum .. once you got over the initial noise (and guests asking "does it make a noise when it runs?") and people started talking (and drinking) you wouldn't know it was on. In comparison to the boats that rarely, or never, move from their moorings or berths we are big users and it was on a lot over the 12 months we owned the boat.

Cheers and happy boating.

Think the elephant in the room is Magnus effect stabilization. Very happy with the Seakeeper mind you. However have already had the experience of going through repetitive clunks on the hull as we passed through the C&D. They opened up the drainage ponds up the bay and all that junk collected in canal. At a moonless 10pm all you could do was just plough ahead. Exhausted from 24h for several days running and fragmented sleep did slid across the mud within yards of our assigned berth in Deltaville. With no protuberances both situations were a non issue. Yes think for our use pattern on a SD boat gyro is a great choice. With fins think it would be worth at least 10 points in your systolic. Didn’t run the channels not wanting to worry about shipping so fish would have been impossible. No risk from the seas but the short steep chop was unpleasant. In this use pattern gyros shine.
So think fins don’t like running aground or being hit. Think if not but when in many cruising grounds. Think fish aren’t a good idea in skinny water or where there’s a lot of weed. Last few years there’s a lot of saragasso. To the point it’s hard to fish.
So Magnus effect stabilization has appeal. Several vendors offer devices that pivot so easy to retract when in skinny or debris laden waters . So not vulnerable. Most effective at trawler speeds. No hydraulics and easy to maintain. Yes, for a full time passage maker fins may remain the best choice and the Humpries seem most impressive. But for a boat doing both coastal and passage if I was spec’ing a boat would give serious thought to Magnus.

My biggest advice on stabilizers is to select systems that the builders have had great success with.

We see some here who have had success on smaller trawlers and Fletcher's experience with Helmsman is very positive. It appears Helmsman have figured out how to appropriately size them for their boats.

Meanwhile, if Nordhavn says "no", then I wouldn't attempt with them. It took them years to get fin stabilizers working without problems on their boats. I don't know their issues with gyro, whether it's the weight of the boat, installation, or undersizing the gyro. However, I know enough I wouldn't be the one to try to figure it out.

I'm a huge fan of vector fins from Sleipner but only used them on medium sized planing hulls, although I know they've been used on non-planing hulls. I know Sunseeker and Princess have great results with them and a Sunseeker 65' with them is far better than the same boat with gyro, largely because the gyro doesn't help much at speed. And, yes, I've been on one with both gyros and another identical with Sidepower vector.

Even if your boat isn't a new build, talk to the builder before doing a retro-fit. Also, the biggest mistake I've seen with gyros is undersizing. Then the user says they're horrible, but all that's really wrong is the builder or the buyer tried to save money and bought too small a unit. Always better to go the next size up.

Even reputable builders have been known to err in figuring this out. I'll give you Hatteras as an example. They've put gyros in their MY's. Mistake as the owners are very disappointed since they aren't effective at speed, so need either zero speed or both fins and gyros. Fins and gyros are very popular in larger yachts. However, Hatteras is putting them in a lot of SF. You say, but SF's run fast? That's what I said before asking further. Turns out that when fisherpersons really want them is when anchored and when running at trolling speed. Trolling is when you see floods of seasickness. SF owners don't care much about lack of stabilization at high speed as the boats perform at high speed without. So, why not zero speed or vector for SF's? SF'ers swear fins are not as effective, but worse, that fins interfere with fishing. It's taken a while to reach this preference.

Follow tried and proven and don't try to reinvent the wheel. Our most recent boat purchase came with Humphree Interceptors and Humphree stabilizers. I had no experience with either on any other boat other than those I was on from this builder. However, the builder had extensive experience with them.

One cannot simply answer yes or no as to whether Gyros are good or yes or no even as to using them on trawlers. Threads like this are excellent because they point to specific gyros on specific boats and they also mention builders not recommending them. Also, keep in mind that a builder's recommendation today may change in the future as they experiment and gain experience.

I'm going to suggest one other thing. This is unscrupulous if you lie or mislead in doing it. However, we've done it openly and honestly. Let's say there's a boat out there you know comes a couple of different ways but the builder doesn't have any you can try and none are in charter. (If you can rent or charter a great option). However, they are for sale used. How much are you willing to pay for a sea trial of both versions? it should be costly but it may really pay off in the long run. If you do this, make sure the owner approved and the majority of what you pay goes to the owner (and sizable to his captain).

I don’t have an opinion on Magnus effect stabilization since I don’t know any boats that have or had it. A little bit of market acceptance would make me look harder at it. Even if it actually is a better system for the future, its not likely to be found on an existing trawler so it really is only a choice for someone doing a new build or an after-market addition.

The concern about vulnerability of fins is overblown. Most debris in the water is either floating on the surface or sinks to the bottom, and misses the fins in either case. The fins are also built to take some substantial impacts without damage. Boats with fins (including ours) run up and down the inside passage in BC every day and unavoidably take regular hits from debris in the water without damage. We have pushed through ice and logs for more than a few miles and our fins are still happy as can be.

Not sure about other boats, but ours will sit on a flat bottom without the fins touching. While I don’t recommend it, some moderate contact with the bottom wouldn’t necessarily damage the fins either.

Gyros and fins have their strengths. Gyros are better suited to planing and SD hulls that are relatively light, and fins are better suited to heavy, slow boats that generally operate in the same speed range. We can imagine exceptions, but the general rules are valid.

FWIW, I would say Hippo’s new boat is in the range of size, weight and speed where either fins or gyro can be a good choice.

I looked at gyros and it seems like a good solution and keeps everything in the boat but in looking at where i could put it in my boat it came at a significant loss of space. I know of a fellow np45 that is prepped for a sea keeper but his layout is different then mine and i believe his is on the port side which may present some counter ballasting issues. I ended up with fins mostly because they had no impact on my space in the hull.

Hi Rod,

I think you may be referring to me re: the Seakeeper. I had the mounts installed on the starboard side at the factory. The idea is to move the house batteries (now starboard) to port if we decide to install the gyro.

If we ever get to that stage weight and ballasting will be revisited.

Following you project with interest.

Rob

I think one takeaway is that there are a LOT of considerations, and one should be cautious about simple takeaways. How's that for a self-contradicting statement?


Seriously though, BandB points out that much of the take-up in SD boats is actually about fishing. The boats just happen to be predominately SD for other reasons.


On-board space can be the driving factor in choosing between fins or gyros, regardless of which you might otherwise prefer.


The balance of your desire for underway roll reduction vs at anchor or slow speed roll reduction will influence your decision.


And where you operate and/or the design of your boat's electrical system can make the need to run a generator a deal breaker, or completely moot in the decision.


Past successes or failures on other boats could be a result of poor sizing, and not because the boat can't benefit from that form of stabilization.

Folks break into 3 groups as regards motion sickness. From Navy and NASA research everyone can get seasick just tolerances vary. Some are more sensitive to fast frequency perturbations. Others slow. Others both. Think deep V sitting in chop while bottom fishing or multihull underway v a ship or heavy FD cruising boat in a swell. Have had crew who had no troubles corkscrewing in a serious seaway but lose their cookies planing in the ding in chop. Knowing yourself and usual crew (S.O.) should enter into your thinking about choice of boat and stabilization. I’m a newbie at this so chime in with knowledge and experience but the physics would suggest gyros might do better with chop and wind waves and fins with swell. One would think latency to response and effect would be less with a gyros as well as better effect with fast acceleration perturbations. Fins with slower (even if bigger) perturbations. If this is true then the history of folks putting fins on open ocean voyaging boat and gyros on boats operating on the shelf makes sense.

Broadly speaking, the Nordhavn rep is right. Gyros are most effective on light, planing vessels. You can use them on heavier, displacement vessels but the heavier the vessel the more gyro you need to make it work. The last stat I saw from SK indicated that about 75% of their production went to sport fish and other planing vessels. There's a reason fewer full displacement vessels are fit with gyros.

Gyros are both space and power hungry, the 41 simply doesn't have the room for one, not without giving up valuable storage space, and it would need a larger genset to run the gyro and other onboard AC gear.

In short, gyros are effective, I've used them on planing vessels and they work well, however, the N41 not the right vessel for a gyro.