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Old 03-31-2021, 09:28 PM   #1
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Stabilization - Gyro vs Fins

Looking at adding a stabilization system to my 35' Taiwanese Trawler. I've got proposals for fins and a gyro. Both very close to the same price. The gyro would likely be a bit more "invasive" because it involves temporarily moving the engine forward, and it's one 540 lb unit with about 90% of the components all within the main unit.

The fin system sort of has the components more distributed around the engine room, and of course requires drilling holes in the hull.

A pal of mine had fins installed on his deep water motor sailor, he says he'd now go for the gyro.

I'd be interested in hearing opinions...

Thanks in advance.
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Old 03-31-2021, 09:37 PM   #2
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From my point of view it would be a question of do you want stabilization at anchor or not. The down side of gyros is running the genset. That is a question you have to answer for yourself.
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Old 03-31-2021, 09:48 PM   #3
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From my point of view it would be a question of do you want stabilization at anchor or not. The down side of gyros is running the genset. That is a question you have to answer for yourself.
The gyro is a 12 volt system. I should have mentioned that stabilization at anchor is not something I need.
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Old 04-01-2021, 09:39 AM   #4
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When the gyro requires service, will the engine need to be moved again? I would check that very carefully. Installation of both I expect will be a challenge in a 35' boat.


I'd suggest that you independently review the installation guidelines for both products to see how much of a compromise is required for each installation. Are both products able to be sized optimally? Will their physical installation location be within recommended ranges, or will they be located in sub-optimal locations. Can appropriate hull reinforcement be done in both cases? Who is engineering the hull reinforcement? Access to desired locations can be seriously compromised by other equipment, tanks, cabinetry, bulkheads, etc.



Setting installation and service issues aside, I think gyros are probably better at at-rest stabilization vs at-rest fin stabilization. But underway I think fins are decidedly superior.
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Old 04-01-2021, 09:43 AM   #5
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The gyro is a 12 volt system. I should have mentioned that stabilization at anchor is not something I need.

You will need to check the power consumption of the gyro 12V against your alternator capacity, other loads while underway, and your battery bank re-charger needs. I would be surprised, or at least suspicious if a significant alternator upgrade isn't required. Most alternators are not continuous duty, yet the new gyro load will be continuous. If your total loads are more than perhaps 75% of the alternator capacity, I would definitely include an upgrade in the project.
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Old 04-01-2021, 11:26 AM   #6
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Have you considered "flopper Stoppers". Kind of expensive to get installed correctly and they can be a pain to haul around, under bridges, etc. but No power consumption.

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Old 04-01-2021, 11:29 AM   #7
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Have you considered "flopper Stoppers". Kind of expensive to get installed correctly and they can be a pain to haul around, under bridges, etc. but No power consumption.

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Do those work at all hanging off a midship cleat or are they useless unless on poles? The website mentions trying off a cleat and it may suffice.

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Old 04-01-2021, 11:36 AM   #8
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Do those work at all hanging off a midship cleat or are they useless unless on poles? The website mentions trying off a cleat and it may suffice.

-tozz

For at anchor stabilization, flopper stoppers (cones, plates, etc.) hung from the midship cleats will work, but extending them out further on poles will make them more effective.



If you're talking about paravanes for use underway, they have to be out on poles, at least for any setup I know of.
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Old 04-01-2021, 12:07 PM   #9
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There was an article a couple of years ago about fins that run the length of your boat on either side in Pacific Yachting. I think these fins must be different to what you are referring to as everything including install was $5000 for the guy. He is located in the Coombs area (Goats on a Roof location) but the install took place in Nanaimo, so he "has fins, will travel." (If you get that reference, you're dating yourself).

So the fin on either side would start at the front of your boat and taper outwards to about a foot or more by the time they reached your transom. Apparently this install is popular with the commercial fisherman. The owner of the boat found the fins to be effective at reducing side to side roll but not pitching. Also they weren't effective in a following sea.

If your boat looks like a picture of a CT 35 I just checked out, the boat is a copy of a Grand Banks design. If they stayed true to the GB design, your hull is slightly rounded and with the fly bridge moving the center of gravity of your boat up, what your boat does in rougher weather with wind - rolly polly - its just the nature of the beast. The fins will slow down the roll somewhat.

I did my first Canadian fleet school training on a retired 152 feet wood hulled mine sweeper. I would cheerfully shoot the Navy architect who designed this boat. This sucker rolled if you blew on it, same problem, rounded bottom with high citadel.

My first boat...lol:

https://www.google.com/search?q=bay+...J2tYPxkpcc4WsM

This boat had wood planking laid over an aluminum ribs. The wood and rounded design was so that it would ride higher in the water assisting avoidance of mines in the water. It did ride higher.... lol.

Your boat should be fine for the Inside Passage area, maybe the west coast of Vancouver Island ocean swells might provide some...... fun.

So if you are interested in the fins here is my suggestion.

Call Independent Chandlery 250 - 248-2293 and ask for the name and contact info of the guy who does the fins. This guy is not part of their business but has his office in the same location about 40 yards from the store. They will give you a phone number and maybe an email address, its the email address you want, this guy doesn't answer his phone, too busy working on projects. But he does answer emails, maybe not for 4 or 5 days. There are no slings at French Creek Marina so he might want to work on your boat in Nanaimo.
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Old 04-01-2021, 03:40 PM   #10
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We installed a Quick gyro on Fintry (see image left) two years ago. It makes a big difference in conditions over about 20 knots on the beam. Reduces roll 80-90%.



Fintry displaces over 300,000 pounds, so the gyro is a cube a meter on a side, weighs 3200 pounds, and needs 7kW running. For a 35 footer, the Quick would be around two feet on a side and weigh maybe 500-600 pounds. We used Quick because the Seakeeper would have been much larger. Installation was not too bad, but of course Fintry's engine room is 20' square and there was space on the engine bed from replacing the main. We're completely satisfied -- delighted, in fact.



The unit goes 2,000 hours between maintenance - mostly grease -- which can be done in place. Note, by the way, that a gyro can be put anywhere -- it does not need to be on or near center in either direction, but of course you must pay attention to weight and stability issues.



In waters with any kind of trap buoys -- lobsters, crabs -- I wouldn't want fins. I also wouldn't want them in ice. Even in buoy free water, I would worry about anything outside the hull - what happens if something hits you there?


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Old 04-01-2021, 04:28 PM   #11
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Call Independent Chandlery 250 - 248-2293 and ask for the name and contact info of the guy who does the fins. This guy is not part of their business but has his office in the same location about 40 yards from the store. They will give you a phone number and maybe an email address, its the email address you want, this guy doesn't answer his phone, too busy working on projects. But he does answer emails, maybe not for 4 or 5 days. There are no slings at French Creek Marina so he might want to work on your boat in Nanaimo.
That would be Roy Brown. He used to have Independent Shipwrights and his wife Cynthia ran the store. But my info is dated so they may have changed ownership. But Roy is the bilge keel guy.
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Old 04-01-2021, 05:25 PM   #12
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Was looking at a non stabilized boat for purchase. Then also asked around my contact group.
Take a ways
Gyros need run up. Need significant power. If sea state exceeds ability of precession worthless for s stabilization and may make things worse.
Fins are outside so groundings, debris and entanglement may injury them. Designed and surface area optimized to work in a limited range of speed. Require service that requires a haul. Will help in all seastates and not make things worse even when forces exceed their capabilities. Create drag so decrease range.
Fish have no electrical demands but as per Canadian govt may increase risk of capsize if one fails or goes airborne. Requires sufficient water depth so not safe to deploy in skinny water. Creates drag so decreases range. Deployment and retrieval can be problematic.

So if in a full displacement hull and expect to see weather on occasion fins may make best sense.
If only in deep water doing long transits and concerned about electrical demands fish may make sense.
If boat is relatively light or you can afford multiple systems and in SD hulls with a large range of speeds gyros make sense.
Boat we were looking at was hard chine steel with very heavy L/D ratio. Although just 41 loa both Quick and Seakeeper suggested a system for a 60’er. Cost was much higher than fish or fins. Fins are less expensive than fish but if done right not all that much. The big savings is no electrical requirements and minimal service expenses. For our program would have done fish and flopperstoppers if we bought that boat.
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Old 04-01-2021, 05:45 PM   #13
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As an alternative 'outside the box', have you looked into bilge keels or other fixed fins? Many commercial fish boats have these. No power required. Their effectiveness, however, would not be as great as gyro, active fins or paravanes.
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Old 04-02-2021, 01:03 AM   #14
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Hi Guys,

Lots of great replies, thank you for taking the time.

I had (briefly) considered the flopper stoppers, but they appear to add more hassle to an outing, and based on a pals experience, they weren't that effective. He took them off and installed hydraulic fins. His offshore boating experience is pretty extensive, and he did try the flopper stoppers on a trip or 2 before deciding on the change. Funny though, after many years with the hydraulic fins, he's not a real fan of those either. Apparently, you need to be able to install the fins at a particular angle to maximize the effectiveness, as well as optimally positioned fore and aft.

I hadn't thought about fixed fins, but I'm not sure how effective they'd be, given that they don't actually work against the rolling action.

The gyro is less fussy about location, so that's a plus. Another advantage is no holes in the hull and no protrusions.

Apparently, the gyro can start stabilizing at about 36 minutes into the spool up phase, which takes 50 minutes. The power consumption is 80 amps for spool up and 33-62 amps operating, depending on sea state.

It seems as though the 2 options sort of cancel each other out with advantages and disadvantages.

Thanks again for all of the replies!

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Old 04-02-2021, 05:56 AM   #15
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You can’t just drop in a gyro . There is constant torque on the hull from all directions. You need a proper bed to be glassed in to the hull. Your existing stringers may not be made for the lifting force .
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Old 04-02-2021, 06:21 AM   #16
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Thought flopperstoppers are a totally different thing than fish (stabilizers). Flopperstoppers are squares grates with plates attached on top hinged to open upon descent. Fish are triangles with weighed tips and a line (commonly chain for initial length) dragged off the end of a pole.
Thought true flopperstoppers are quite effective at anchor and never used underway. Cones are also used as flopperstoppers but less effective.
Thought the latest generation of fins are no longer are simple NASA foils but rather complex shapes to both decrease drag underway and make them effective at anchor.
If I was doing new construction would give serious thought to magnus effect devices that can rotate back to be parallel to the hull. None of the downsides of of fish or gyros with the downsides of fins mitigated in large measure. Also available without hydraulics in the size vessel under discussion.
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Old 04-02-2021, 07:29 AM   #17
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Hi Guys,

Apparently, the gyro can start stabilizing at about 36 minutes into the spool up phase, which takes 50 minutes. The power consumption is 80 amps for spool up and 33-62 amps operating, depending on sea state.
Colin

Fintry's Quick gyro (see above) is at full speed in a little under half an hour and starts stabilizing immediately, albeit at a minimal level.


The spool up time is realy a non-issue. If you think it's going to be gnarly when you get out of the harbor, you can start it before you get underway. If conditions are not that bad, you can turn it off. If while underway conditions are deteriorating, it's like taking a reef -- do it early.


All three methods share the disadvantage that they cut range. Fins and fish by increased drag and the gyro by increased fuel use for whatever is generating the power. Fintry's gyro uses 7kW, which is about 3/4 US gallon per hour, about 10% of our no-gyro consumption at 8 knots.



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Old 04-02-2021, 07:42 AM   #18
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All three methods share the disadvantage that they cut range. Fins and fish by increased drag and the gyro by increased fuel use for whatever is generating the power. Fintry's gyro uses 7kW, which is about 3/4 US gallon per hour, about 10% of our no-gyro consumption at 8 knots.

In this sense, drag while in use vs not varies. All add weight, gyros likely being the heaviest option. However, they likely add the least amount of fuel use underway. Fins vs paravanes for in-use drag will vary, with fins likely having less drag. However, unlike the other options, fins add drag even when they're not in use.



On a slow boat, all of the options are viable. On a faster boat, a gyro or fins will be best, as paravanes would only be usable when going slow and need to be stowed before speeding up.
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Old 04-02-2021, 08:04 AM   #19
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Made an error in post # 16. Reversed terms inadvertently. Fish are generally less expensive than fins. Both initial cost and operating costs.
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Old 04-02-2021, 08:08 AM   #20
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Circumnavigator why did you pick Quick? Your fine vessel looks to be heavy displacement steel. Did you put in multiple units? What was total expense including installation? Did you look at other options? Why did you not pursue those?
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