Seakeeper? Other things?

Think there’s little question stabilization is worth the money and effort. About that there’s a general consensus. The discussion is which type.

Fish are quite limiting for many people. Require significant depth for deployment and significant effort as well. Need to go to storage position (except possibly in some anchorages) when not in use. Not an issue for voyaging boats but a real issue for those utilizing a boat intermittently in a coastal setting. Canadian warning that they may decrease ultimate stability if one fails maybe overwrought but not without supporting data.
Fins increase wetted surface, turbulence in use so parasitic drag. Hence increase fuel burn. Should be tuned in surface area for expected speed through the water. That maybe ideal for FD hulls running with very limited different speeds but not for SD hulls with wide variation in speeds of operation. Damage with groundings or strikes maybe overwrought but does occur.
Gyros need genset running on virtually all boats. In all but extreme weather said to be the most effective mode of stabilization. Takes time to spin up or down. From limited experience found this to be a non issue as weather forecasting is adequate to know well in advance if needed. But downside of ~3/4 g/h of fuel burn exists. Comparing to lost speed or fuel burn of fins is case specific but one would think gyros are more energy hungry. Gyros in vacuums said to be more effective, spin faster, less energy intensive per rpm than non vacuum but at expense of breaking and reestablishing vacuum if internal service required.
Magnus said to be as effective as gyros. Retract so less issues in skinny or debris laden waters. Less energy intensive. However do create drag (same as fins) more pronounced at higher speeds. Minimal drag if not deployed.

Not an expert but think above is a decent summary. Nothing is perfect or suitable in all settings. In choosing for a new build as per O.P. would think decision should be driven upon what he intends to do and where.

An interesting advertising article comparing "vector fins" (a new term for me - apparently curved fins) vs gyros.

https://www.yachtingmagazine.com/boat-stabilization-fins-vs-gyros/

Many of the fin-benefits are unique to "vector" vs straight fins such as traditional Naiads.

Also from Imtra, a discussion on their vector fins compared to straight fins. Apparently, they create lift which is their magic.

https://www.imtra.com/learning-cent...s-vs-straight-fin-stabilizers—which-is-better

Obviously a slightly biased piece, but much has the ring of truth.

Peter

After reading all the opinions being posted, I will be focusing most of my research time on the Mantus system, it just seems to tick the boxes for me, especially in Australia with the large NM we log in the Pacific trips and East Coast of Australia, planning large voyage to PNG and Indonesia and I can’t see much sea-keeper service available in the area so best to keep it simple and Mantus kinda of does that for me tbh.

Mobcat said:

After reading all the opinions being posted, I will be focusing most of my research time on the Mantus system, it just seems to tick the boxes for me, especially in Australia with the large NM we log in the Pacific trips and East Coast of Australia, planning large voyage to PNG and Indonesia and I can’t see much sea-keeper service available in the area so best to keep it simple and Mantus kinda of does that for me tbh.

Click to expand...

Not familiar with Mantus. Do you have a link? A quick Google search didn't turn up anything applicable.

Peter

Mobcat said:

... I will be focusing most of my research time on the Mantus system... planning large voyage to PNG and Indonesia and I can’t see much sea-keeper service available in the area so best to keep it simple

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Seems like an excellent conclusion. I was really surprised to read about the amount of maintenance required by gyros. And if that (factory tech) maintenance is required every 500-1000 hours like stated, then that would be a non-starter. Personally I'm a big fan of flume tanks, based on the few I've known, but they're a bit too non-conformist for most.

Owning a SeaKeeper and having had a detailed educational with a certified tech can say service is replacing one easily accessible zinc once a year. I will do this myself. Big service done by certified tech is at the thousand hour marks. Factory service timing is variable. From talking with tech usually around once a decade.
My read is less not more service than with fins.

Hippocampus said:

Owning a SeaKeeper and having had a detailed educational with a certified tech can say service is replacing one easily accessible zinc once a year. I will do this myself. Big service done by certified tech is at the thousand hour marks. Factory service timing is variable. From talking with tech usually around once a decade.
My read is less not more service than with fins.

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I hear what you say, in part at least. But 1000 hr service is going to be far more often than once a decade for anyone who unties their boat from the dock on a regular basis. Do you have a good estimate of what the cost of that 1000 hour service will cost?

With my Naiads its seal every 3 years and a bit more for every second one to fully pump through grease etc. Even then a 1-2 boat buck cost is all it is.

I wont ask what an internal bearing replacement what cost given removal of the heavy item from the boat and return to factory, but do you know at what hours that would typically occur?

I know you like the SK, fine. But until you give some numbers I cant accept your closing sentence (in red in quote) at face value.

Not so bad

Insequent said:

[/COLOR]
I hear what you say, in part at least. But 1000 hr service is going to be far more often than once a decade for anyone who unties their boat from the dock on a regular basis. Do you have a good estimate of what the cost of that 1000 hour service will cost?

With my Naiads its seal every 3 years and a bit more for every second one to fully pump through grease etc. Even then a 1-2 boat buck cost is all it is.

I wont ask what an internal bearing replacement what cost given removal of the heavy item from the boat and return to factory, but do you know at what hours that would typically occur?

I know you like the SK, fine. But until you give some numbers I cant accept your closing sentence (in red in quote) at face value.

Click to expand...

Yeah alls good Hippo that’s what Onan said about my 2 x 12kva generators I would only need one lol �� …. I am so happy to of installed two, one for redundancy as the amount of time spent on controller issues on them has been insane and with out having 2 of them we would of been very inconvenienced and have to of cut short many a long journey especially in the Pacific Ocean , I am honestly getting to the stage of anything I can’t service myself via email or phone call I don’t want on board, it just becomes more of a hassle than the benefit imho.

In SF Bay, I hauled for paint every 2-3 years and replaced seals every second haul at a cost of around $1500. I also replaced an oil cooler a few years ago that was a few hundred bucks plus the cost of oil. 25-yrs of ownership, probably around $7k in service in todays dollars. Maybe a bit more but not much. Penalty for deferred maintenance is a weep or leak but you can keep going for quite a while. I also had to replace a bushing that was knocking. There is a removal tool that aids removal of the fin but it's pretty straightforward and fairly easy to fabricate.

Best I can tell is fins require more frequent service compared to Seakeepers but lower tech so it can be done by any decent mechanic. The penalty for deferring maintenance is manageable with fins, more risky with gyro. A bearing failure on a high RPM massive weight will render the system inoperable (or risk catastrophic failure).

I think it fair to say the longterm maintenance of Seakeeper and Fins is roughly equivalent. The routines and intervals are different but over a 10 yr period it is likely close enough that it wouldn't skew a decision for one or the other.

Peter

Mobcat said:

I am honestly getting to the stage of anything I can’t service myself via email or phone call I don’t want on board, it just becomes more of a hassle than the benefit imho.

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I'm kinda at that point too. If I can't get enough documentation on how to service the thing (and access to any computer tools needed for diagnostics), I'll go buy a different one that doesn't require as much access to factory techs.

rslifkin said:

I'm kinda at that point too. If I can't get enough documentation on how to service the thing (and access to any computer tools needed for diagnostics), I'll go buy a different one that doesn't require as much access to factory techs.

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Getting much harder to do. Many modern Tier 3 engines are difficult for a DIY owner to service. Other equipment aboard are similar such as watermaker and many nav systems. Refrigeration and HVAC are mostly discard and replace instead of repair Over the last 10 years there has been a a trend towards electronic interfaces to control all creature comforts. God help you if there is an IP Address conflict down the road.

It's a balance. I've skewed hard towards the DIY mindset because I'm not a great mechanic and I plan to cruise in out of the way places. You give up a lot of cool stuff by doing that.

Peter

mvweebles said:

Getting much harder to do. Many modern Tier 3 engines are difficult for a DIY owner to service. Other equipment aboard are similar such as watermaker and many nav systems. Refrigeration and HVAC are mostly discard and replace instead of repair Over the last 10 years there has been a a trend towards electronic interfaces to control all creature comforts. God help you if there is an IP Address conflict down the road.

It's a balance. I've skewed hard towards the DIY mindset because I'm not a great mechanic and I plan to cruise in out of the way places. You give up a lot of cool stuff by doing that.

Peter

Click to expand...

I agree that it's not always possible. But I'm used to dealing with electronics for service in cars, etc. So I'm not afraid of maintaining an electronic engine, I just want to be able to get my hands on the tools and documentation so I can do more of the stuff before having to call for help. Instead of "uh oh, it's got an error code, better call the dealer to come out and scan it"

Tier 3 engines are fine to service and repair there not that complicated, it’s the company’s manufacturing them is the problem , if you are going to build marine engines or any marine components you need for all proprietary service and maintenance information to go on board with the product, I’m so sick of having to beg for information in regard to repair it just seems so wrong, these products are so expensive and relatively easy to maintain and repair if the knowledge is shared like it was in past times ie pre 1990.

Went on the internet looking for a SeaKeeper service manual. No joy. Told by wrench this is intentional by the company. They want no one but certified technicians opening the thing. But also told I could replace the zinc myself now that I know where it is. So far we’ve done ~1800nm and have yet to go back/forth Newport to Bahamas. We’re not dock queens. Still expect a $5k plus bill every 1000h. Currently under 500h. So you have more DIY with fins than gyros and tech hourly costs keep climbing but all in all think (don’t know) service costs will be a wash. Every 200h will replace zinc. As a new owner don’t know if that’s the right interval. Little information I could get suggests it is. I’ll pull it every 100h or 3m until I know. It’s five bucks, some plumbers tape and 1/2h of my time. Zinc we just pulled needed replacement.
Look at their website. SeaKeeper seems to be the dominant gyro vendor. They have service centers just about everywhere as they are popular. Don’t think that’s a limitation. I’m on a single screw common rail trawler run coastal. I’m no longer crossing oceans. Some people think they’re Shackleton. I think I’m a slub out having fun. Got other stuff to worry about.

Hippocampus said:

But also told I could replace the zinc myself now that I know where it is. I’ll pull it every 100h or 3m until I know. It’s five bucks, some plumbers tape and 1/2h of my time. Zinc we just pulled needed replacement.

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For the record, hydraulic fins always have some sort of sea-water cooler....and a zinc somewhere.

I agree Hippocampus. After the dust settles on the two systems (fins/gyros), it's essentially a wash on maintenance. I totally understand there may not be a Seakeeper service center everywhere, but in thinking about it, not like the thing self-descructs at 1001 hours. It's something you can plan a year (or more) in advance - just as people do about haul/paint.

Glad you're putting so many miles on your new boat. Impressive. As someone who's watched you throughout your purchase journey, great to see it come together. Thanks for being so generous with sharing your experiences!

Peter

Magnus vs Fins

I've been reading more about Magnus effect and zero speed stabilizers, particularly on the Rotorswing Holland website. Some comments / questions:

• First, I love the idea of going with electric stabilization versus hydraulic. Hydraulics are just one more system to bother with, unless your vessel is already equipped. But for a new construction, I don't want to mix too many systems. Electric systems, their dependability and safety, have increased since the days of the Pardeys who wouldn't allow even an electric flashlight onboard (exagg.).
• The vendor does not post power requirements, but I wonder what the difference would be between a Magnus and a fin. I assume that the Magnus would require less power, and this would be important for the "zero speed" function, since running it all evening off a battery bank would be important.
• What is the voltage requirement for electric systems, DC or AC?
• Although I personally lean more towards the Magnus, I don't like the fact that they stick out 2-3 feet outside the envelope of the hull, and outside the beam. Fins generally fit within the beam/draft boundary. At least this is what their website shows.
• Does anyone have indicative pricing to compare Magnus vs fins?

I'm late in getting to this but have two comments that may be worth considering:
1. You indicate you may head south to the Caribbean. If you will be traversing Gulf of Mexico you will encounter more crab pots than you will be able to count. If you head north to Maine it is even worse. We had fins in Seattle, don't have them here in FL.
2. Having a 43E myself there is more than ample room for a gyro.
Jim

I've gotten quotes on the Magnus from two companies, not cheap but in the same league with fins. The power requirement was in the 2KW range worst case (each, if you have two), run by an inverter @ 240V (they are all from Europe). While they stick outside the hull envelope, they are retractable. While there are crab pots in the Gulf and up the Eastern Seaboard, Maine lobster pot density is in a whole 'nother universe by comparison. I think a big advantage to Magnus is you could retract them and they would not snag pots (or would let go of a snagged one), while fins are just going to snag and hang on till you go overboard with a knife. Magnus can also be run at an angle, less effective but more likely to shed debris.

Five months ago I was about 15 NMs off Pt. Dume heading down swell at 8 plus Kns. Had an impact with an object in the water that felt like the boat was hit by a large truck. It was a significant blow. The impact occurred at the bow, and then again on the port side below the water line. If I had fins, I think there was a very good chance they would have been seriously damaged.

I posted this on another string but thought I’d post here too. I got to demo the DMS MagnusMaster at Trawlerfest in Anacortes. We were out on a 65 ton steel trawler with two stabilizers. It was a flat day so the DMS owner, Patrick, was using the stabilizers to rock the boat.

In the first video I am propped with elbows on the counter behind the helm to stabilize the phone and was standing on a rug. Within a few seconds of turning on the stabilizers the boat heeled so much that the rug slipped out from underneath me (that's what induced the alarmed look on Patrick's face). This video is a little over a minute and the rocking occurs at the end. Pardon my colorful language. There's a second video of using a single stabilizer to rock the boat.

There's a third video that I won't post where I was sitting in a folding chair on the deck in front of the helm with elbows propped on the chair arm rests. Because I was focussed on recording and not balancing I got tossed out of the chair. Between the rug slipping and the chair dumping I’m pretty sure most folks thought I was drunk.

Two stabilizers:
https://youtu.be/PjLrRoUbs8o

One stabilizer:
https://youtu.be/VhUudTeqNyc

And to Fletcher500’s scenario above, the rotor will shear pins and swivel sternward if struck with sufficient force. Access to the shear pins is easy and I should be able to replace them on the water if needed (I think).

I'll be getting a single rotor on my 20 ton Helmsman 43 when it arrives in a couple months. Should be more than sufficient for those unpleasant runs to California.

NSM, those Magnus videos are impressive. I was wondering how they would fair in an impact so the shear pins and auto aft swivel make sense.

Bumping a slightly older thread, any boaters out there who installed a DMS MagnusMaster who have had a bit of time with the system? I'd be most interested to hear your thoughts about it. How's it worked for you? I'm told the maintenance is minimal. Has this been the case?

We have one installed but haven't had much weather to test it. I concur that the maintenance will be minimal. There aren't many moving parts and the unit is pretty compact inside the boat.

We've used the DMS in demo mode to rock the boat in calm conditions. It can induce a robust amount of roll (haven't measured yet). We've also run next to a few ship wakes to see how it works. After running with and without the stabilizer the wife approved of the installation.

Looking forward to testing in real life.

Have you considered an electric option that doesn't need a warm-up time?

Jklotz said:

Bumping a slightly older thread, any boaters out there who installed a DMS MagnusMaster who have had a bit of time with the system? I'd be most interested to hear your thoughts about it. How's it worked for you? I'm told the maintenance is minimal. Has this been the case?

Click to expand...

Before I decided to go with electric fins I spoke with DMS at length. Patrick is a real genuine guy, won't tell you BS stories, the rotor system really works well. It is incredibly sturdy and does not require any maintenance (or minimal). Electricity usage is minimal, so can easily run it off the batteries.
I visited DMS on Boot in Dusseldorf in January and although in the end I did not decide for them we had a great talk and still very welcome. I can highly recommend them as a company, they are true professionals.

Why did I decide not to take their system ?

At the time only the rotor system existed and you need about 3 to 4 kts through the water to have it work. In the Med we don't have a real current, so on anchor or a low speeds it would not do anything for us.
We definitely wanted to have a system that would work underway, on anchor and in port, so I had to go for a different system. And that system works absolutely perfect, with also minimal usage of electricity.

Mambo42 said:

We definitely wanted to have a system that would work underway, on anchor and in port, so I had to go for a different system. And that system works absolutely perfect, with also minimal usage of electricity.

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Which system was that, if you don't mind me asking?

Jklotz said:

Which system was that, if you don't mind me asking?

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We have the CMC waveless Stab 25. They are electric fins, we have the 220 V version and they work like a charm. Always on stby, so will react instantly if they detect a disturbance. Uses very little electricity.

This is what the unit looks like in the ER. On the outside they are just like normal fins, but the fins are bolted to the motor. If they hit something they will break off without damaging the motor. Just bolt on a new fin and you are on your way again (has not happened to us )

Wow that looks so much superior to traditional hydraulic stabs

rslifkin said:

On the paravanes topic, I've wondered whether it's possible to build a paravane setup that when retracted folds the arms aft against the hull sides rather than straight up in the air. Arm length would be limited (shorter arms might also make vertical storage a non-issue), so they wouldn't be as effective for a given size of fish, but it might make paravanes practical in a wider range of situations.

If it could be done without pushing air draft above 14'6" I wouldn't mind paravanes on my boat. Provided the launch / retrieve can be made easy enough, I'd be happy to use them for a few hour run down Lake Ontario. In confined waters where they'd need to remain stowed, stabilization would typically only be for boat wakes and such, so doing without stabilization would be fine.

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Definitely Yes. Paravane booms folded aft have been done many times. See previous threads. I think the only reason to not do so is the extension fore and aft might be a problem.