The perils of Stabilizers

In 50 years of cruising the PNW, I don't recall ever thinking to myself, "gee, I wish I was listening to a genset running so I could have zero speed stablizers." The thought just never occurred, but I'm a sound sleeper.

Delfin said:

In 50 years of cruising the PNW, I don't recall ever thinking to myself, "gee, I wish I was listening to a genset running so I could have zero speed stablizers." The thought just never occurred, but I'm a sound sleeper.

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Well, if you had the right genset with sound protection, you wouldn't be listening to it.

I'm not saying everyone needs zero speed stabilizers in the PNW. Most don't. But a few find them beneficial. Plus some just choose them over regular stabilizers in case ever needed. If you don't need to turn them on, then don't.

We seldom needed them once we passed Vancouver, but we had our generator running anyway for our refrigeration and freezers and our heat and at least one night I know when anchored near Glacier Bay we were hit by large wakes. Now wouldn't have really bothered us but did smooth things. Had we not already had the generator on, would we have turn the stabilizers on? I doubt it. But as it was they were on.

BandB said:

Well, if you had the right genset with sound protection, you wouldn't be listening to it.

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For many Delfin would be considered the ultimate trawler for near shore and blue water traveling. Zero speed stabs and a nil dba genset would hardly make it better. An owner that knows where to anchor is a plus.

This thread is about stabilization. Wonder if any one here has used a magnus effect device?
If you spec’d or later put in stabilization why didn’t you choose a magnus effect device?

Seems ideal
Works at FD speeds and at rest.
Safe in all weather conditions.
Rotate in very close to the hull. So in skinny waters or docking just rotate them in and negligible risk of damage to them or the hull. But you can deploy in much shallower waters than fish without concern.
No spin up

Don’t understand why they’re not seen more. Please explain.

Hippocampus said:

This thread is about stabilization. Wonder if any one here has used a magnus effect device?
If you spec’d or later put in stabilization why didn’t you choose a magnus effect device?

Seems ideal
Works at FD speeds and at rest.
Safe in all weather conditions.
Rotate in very close to the hull. So in skinny waters or docking just rotate them in and negligible risk of damage to them or the hull. But you can deploy in much shallower waters than fish without concern.
No spin up

Don’t understand why they’re not seen more. Please explain.

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I've been watching Rotorswing for a couple years as they develop their system. Seemed like their products were going to be more geared to 'regular boaters' than the mega moolah yacht crowd.

Don't know if they have dealers in North America yet.

Rotorswing | Yacht stability control - Rotorswing

From the Rotorswing contact page:

RotorSwing Holland would love to hear from you. We are in the process of adding importers and distributors and can assist you with finding installation locations near you.

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Sounds like they might be thinking about ramping up, but they sure are moving cautiously!

Hippocampus said:

This thread is about stabilization. Wonder if any one here has used a magnus effect device?
If you spec’d or later put in stabilization why didn’t you choose a magnus effect device?

Seems ideal
Works at FD speeds and at rest.
Safe in all weather conditions.
Rotate in very close to the hull. So in skinny waters or docking just rotate them in and negligible risk of damage to them or the hull. But you can deploy in much shallower waters than fish without concern.
No spin up

Don’t understand why they’re not seen more. Please explain.

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Quantum has been using since 2004. Their market however is 80' and up but they're highly respected in the superyacht world.

https://quantumstabilizers.com/products/maglift-magnus-effect-rotor-ship-stabilizers/

Dynamic in Holland makes the magnus master for boats in the size range commonly discussed here.

Delfin said:

In 50 years of cruising the PNW, I don't recall ever thinking to myself, "gee, I wish I was listening to a genset running so I could have zero speed stablizers." The thought just never occurred, but I'm a sound sleeper.

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I'm with you.... I do wonder wonder though about some small super quiet gennys...such as one of the little honda inverter generators.... IF they would be enough to power a gyro...then something similar to that.....installed and isolated I'd bet it would be really hard to hear.

Hippocampus said:

Dynamic in Holland makes the magnus master for boats in the size range commonly discussed here.

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Their DMS Magnus Master is limited to a maximum speed of 12 knots. From what I can tell all their products are limited to low speed.

BandB said:

Their DMS Magnus Master is limited to a maximum speed of 12 knots. From what I can tell all their products are limited to low speed.

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This is a 'trawler' forum

MurrayM said:

This is a 'trawler' forum

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And as we well know nearly half the people here own boats that wouldn't be classified as trawlers. Many have boats that can reach more than 12 knots.

Granted, but for the other half the question remains. Compared to gyros the cost is in the same ballpark. Why isn’t there more market penetration for magnus effect devices? Seems to a significant degree the downsides of fins and gyros are avoided.

Hippocampus said:

Granted, but for the other half the question remains. Compared to gyros the cost is in the same ballpark. Why isn’t there more market penetration for magnus effect devices? Seems to a significant degree the downsides of fins and gyros are avoided.

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The downsides of fins and gyros are few if installed, maintained and operated properly. Our fins have done great!

Hippocampus said:

Granted, but for the other half the question remains. Compared to gyros the cost is in the same ballpark. Why isn’t there more market penetration for magnus effect devices? Seems to a significant degree the downsides of fins and gyros are avoided.

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Magnus seems to be primarily a European development with very little marketing or support in the US.

Similarly, we're huge fans of Sleipner/Side Power Vector Fins. Yet, have seen very few of them. We had them on a Sunseeker Manhattan 65 and were thrilled with them both at speed and at anchor and slow speed. Not as unique as Magnus but still a great option and I have tested vs. Gyro on an identical boat. Also had a captain friend who is a gyro fan and he had a customer with them on a Sunseeker and totally swears by them now, was a quick convert. I think most people are like I am, very slow to try something different than what they're use to. It's a big investment in something you're not as familiar with.

OK Maybe I shouldn't read these threads Just a quick question. The boat we're surveying this week a Hatteras 42 LRC mark II has Naiad stabilizers that the owner proudly proclaimed that the boat specs out for 4.5 fins but this boat had a 6' system installed. Should I be worried about the extra stressors on the hull, and how much extra pucker factor do these fins (if extra sized) add to normal operations. I'm flying down for survey so will get a look at them next week with haulout .

Wildbill said:

OK Maybe I shouldn't read these threads Just a quick question. The boat we're surveying this week a Hatteras 42 LRC mark II has Naiad stabilizers that the owner proudly proclaimed that the boat specs out for 4.5 fins but this boat had a 6' system installed. Should I be worried about the extra stressors on the hull, and how much extra pucker factor do these fins (if extra sized) add to normal operations. I'm flying down for survey so will get a look at them next week with haulout .

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4.5 sf is small for a displacement boat. I would almost guarantee virtually all Hatt 42LRCs with stabilizers had 6sf fins.

Hatt has been installing stabilizers since at least the 1970s. They know what they're doing. I wouldn't worry a moment about structural integrity.

There is a decent Hatt owners group elsewhere on the net. If curious, you may want to ping them too.

Peter

Love to hear the different thoughts... If any NEW information on the details (worst thing a boat owner can imagine) I get flashbacks for my basement would flood when it rains!

One of the reasons we choose our NT42 was it had a SeaKeeper 5 in it. It sits between the stringers in the middle lazerette and is bonded/resting on those stringers. Those stringers go forward to serve as engines beds. We have no exposed appendages being a single screw boat.
Currently going down the ICW. Decide in the morning whether to run it after our morning coffee and last look at weather. Does need ~45m to fully wind up and 15-20 m of leaving the pump on until it winds down enough bearing cooling is no longer needed. So it’s a a bit of a pain as only need it occasionally for rivers or bays/inlets. Still it truly works so worth it.
If I was doing new build my first choice would be Magnus Master. Immediate on and off. Retracts to parallel to the hull so much less risk with a grounding.
This thread is about a sinking and my heart goes out to the owners. But for many of us the more statistically relevant occurrence is grounding in mud or sand. Would think fins would make it harder to rotate the boat or given they are installed at a slant to power through or back off a grounding.
Much to say for fins on a heavy FD hull doing blue water. Independent of sinking much to say for Magnus effect or gyros for lighter boats in mixed coastal blue water or just coastal service.
Then again with metal having the ability to deform and stretch before puncture perhaps the combination of cored, solid grp or cf with fins maybe particularly troublesome for coastal boats.

Wow: I had forgotten about that post from 2016! I didn’t clarify in the original post that it was a cored hull KK, and it was assumed that insufficient core removal at installation was contributory. Despite that incident, I subsequently purchased my current DeFever with Naiads, but in a solid FRP hull. Love ‘em. Safe travels to all.

Through hull penetrations with leverage arms should be installed along same engineering path as spade type rudders insuring the hull skin is fortified to handle impact, bending and twisting loads without damaging hull skin. Grounding, docking accidents, etc. should result in the fin arms or shafts to bend or break before exceeding hull skin tensile strength.

Since I’m no engineer please don’t try to drag me into deep water on this but as I recall a proper installation must factor the water forces applied to the blade shape and size the the stock or shaft size and material selected with considerations for the mathematical bending arm and moment. With this info the correct diameter and alloy is selected for the water loads on the blade. I’ve never seen a stabilizer installed through the hull skin without lots of labor inside building a strong foundation for flanged port. There may be some old Hatteras or Halmatic hulls with enough skin strength but that’s just a guess.

On GRP hulls of solid construction it requires laminating a doubler block inside of sufficient area to safely spread any stabilizer loads well out into the hull fabric. If a stringer is nearby it’s smart to tie this block into a major longitudinal stiffener like this. This can be done with laminated knees or fabricated SS saddle or angle brackets. Depending on location and interferences and no stringers then laminating a couple of ‘hat-section’ stiffeners is prudent and as before tied to the doubler block.

Sandwich or cored hulls can get quite involved as all core must be removed and the hull skin rebuilt as a solid laminate or core panel of sufficient engineering strength. Once the compressible core is removed and skin reconstructed the doubler pad and supports are constructed as done on a solid glass skin.

Wood planked, cold molded, or plywood hulls will also require a large doubler pad and depending on frame spacing and size may have to be laminated in several frame bays until sufficient area is achieved to fully support the stabilizer. Once the doubler pad is constructed it should tie to or integrated to the hull frames by using longitudinal riders or existing stringers atop in order to spread the loads further into the hull structure.

Steel and aluminum hulls are treated the same way as a solid glass hull skin but instead of doubler pads it’s possible to weld in transverse sister frames and longitudinal intercostals or stringers using a strong plate to land all bolts on.

No matter how the hull is constructed the stabilizer company should provide lots of engineering specs on a proper installation. The ones I’ve read years ago were nebulous to say the least but then there are way too many variables to offer concise details for every boat. Personally if I had such an installation in my future I’d make a call to the manufacturer and ask for a tech rep on site with suggestions. Well documented of course.

I always shake my head when I hear that stabilizers are installed in just a few days as I cannot imagine even constructing a proper foundations in less than a week with cure cycles etc. locating the stabilizers can entail lots of head scratching in order to locate for optimal performance. The problem is interferences inside some of which can be very costly. On many yachts gaining work access for foundation work can almost be impossible if interior joinerwork must be removed or worse tankage. Obviously this kind collateral work and expense can be prohibitive but don’t let your budget or the yard talk you out of a sound strong installation. I’ve been involved in two costly stabilizer accidents one underway hitting a dredging boom another where the hull slipped in the TraveLift slings. One went to subrogation against the yard the other deemed a fortuitous operators negligence and paid. Neither could get a nickel out of Vosper and another company I forgot. Bottom line they were not installed to spec.

When I worked at Merrill Stevens in Miami years ago it took the yard a full month to install Vospers on ‘ Chanticleer ‘ 115’ steel DeFoe for Ralph Evinrude and Francis Langford. And three weeks on the 84’ wood ‘ Gov. Bradford ‘. On the Bradford we had to empty two fuel wing tanks and shift the empty tanks inboard to gain access. Dirty, hot cramped job and as a young grunt they filled my plate with this work for like two weeks. Even had to paint surfaces never again seen

Rick

garbler said:

On GRP hulls of solid construction it requires laminating a doubler block inside of sufficient area to safely spread any stabilizer loads well out into the hull fabric. If a stringer is nearby it’s smart to tie this block into a major longitudinal stiffener like this. This can be done with laminated knees or fabricated SS saddle or angle brackets. Depending on location and interferences and no stringers then laminating a couple of ‘hat-section’ stiffeners is prudent and as before tied to the doubler block.

...

I always shake my head when I hear that stabilizers are installed in just a few days as I cannot imagine even constructing a proper foundations in less than a week with cure cycles etc. locating the stabilizers can entail lots of head scratching in order to locate for optimal performance. The problem is interferences inside some of which can be very costly. On many yachts gaining work access for foundation work can almost be impossible if interior joinerwork must be removed or worse tankage.

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I think it depends a lot on the boat. Some get lucky and doing a strong enough install isn't all that big a deal, others require a lot more time moving stuff and a lot more structure to be created. I'd still expect close to a week even on the easy installs though unless the structure was pretty much ready to go ahead of time.

On my boat, I think I'd be in the lucky camp. I'd have to move some generator exhaust components and trim a corner of the generator mounting board for the stbd side (nothing in the way on the port side in the same spot). But otherwise, there's not much in the way of where fins would want to go (based on where I see them on other boats) and the backing plates would be butted up to both a longitudinal and a transverse stringer, making it easier to build a strong enough area to spread the load. The picture below shows the area where I'd expect to put fins if I added them (in the gap between the generator muffler and the transverse stringer).

On other boats, as you mentioned, you have to remove tanks or other major stuff for access and you may be a lot further from heavy duty structure making the reinforcements much more significant.

rslifkin said:

I think it depends a lot on the boat. Some get lucky and doing a strong enough install isn't all that big a deal, others require a lot more time moving stuff and a lot more structure to be created. I'd still expect close to a week even on the easy installs though unless the structure was pretty much ready to go ahead of time.

On my boat, I think I'd be in the lucky camp. I'd have to move some generator exhaust components and trim a corner of the generator mounting board for the stbd side (nothing in the way on the port side in the same spot). But otherwise, there's not much in the way of where fins would want to go (based on where I see them on other boats) and the backing plates would be butted up to both a longitudinal and a transverse stringer, making it easier to build a strong enough area to spread the load. The picture below shows the area where I'd expect to put fins if I added them (in the gap between the generator muffler and the transverse stringer).

On other boats, as you mentioned, you have to remove tanks or other major stuff for access and you may be a lot further from heavy duty structure making the reinforcements much more significant.

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Yes you have a great looking installation location. Just a doubler and laminate some knees or angle brackets to the big stringer and those floors or the transverse hat sections. If it were me I’d make some glass knees and laminate so you won’t drill holes and encourage water ingress.

Rick

garbler said:

Yes you have a great looking installation location. Just a doubler and laminate some knees or angle brackets to the big stringer and those floors or the transverse hat sections. If it were me I’d make some glass knees and laminate so you won’t drill holes and encourage water ingress.

Rick

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Exactly my thoughts. If only stabilizers were cheaper hardware-wise, I'd be making that a winter project one of these years. Even better, the hull is solid glass and the stringers are just hollow glass boxes, so there's no core material to worry about getting wet anywhere in the area.

rslifkin said:

I think it depends a lot on the boat. Some get lucky and doing a strong enough install isn't all that big a deal, others require a lot more time moving stuff and a lot more structure to be created. I'd still expect close to a week even on the easy installs though unless the structure was pretty much ready to go ahead of time.

On my boat, I think I'd be in the lucky camp. I'd have to move some generator exhaust components and trim a corner of the generator mounting board for the stbd side (nothing in the way on the port side in the same spot). But otherwise, there's not much in the way of where fins would want to go (based on where I see them on other boats) and the backing plates would be butted up to both a longitudinal and a transverse stringer, making it easier to build a strong enough area to spread the load. The picture below shows the area where I'd expect to put fins if I added them (in the gap between the generator muffler and the transverse stringer).

On other boats, as you mentioned, you have to remove tanks or other major stuff for access and you may be a lot further from heavy duty structure making the reinforcements much more significant.

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Your Chris has clear bilge position for fins! So... ya thinken bout puten em in??

Art said:

Your Chris has clear bilge position for fins! So... ya thinken bout puten em in??

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If it makes it into the budget at some point, I'd love to. Realistically, there's a lot of stuff I'd spend money on before fins though. Even if I managed to DIY the whole install I can't see doing it for less than $60k in just equipment cost from the research I've done. And some would call that crazy, considering that's pretty much the entire value of the boat, if not more.

rslifkin said:

If it makes it into the budget at some point, I'd love to. Realistically, there's a lot of stuff I'd spend money on before fins though. Even if I managed to DIY the whole install I can't see doing it for less than $60k in just equipment cost from the research I've done. And some would call that crazy, considering that's pretty much the entire value of the boat, if not more.

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$$$ Ouch! $$$