Stabilization - Gyro vs Fins

Have no dog in this fight being a newbie to trawlers. What got to me is the concern about behavior in heavy weather for both gyros and fish. Apparently not the same level of concern for magnus and fins.
Is this a theoretical concern? Talked about but little seen. Have either of you gentlemen had untoward events in that setting?

I can't speak to gyros as I haven't run them.

As to long bilge keels, several Willard 40s have had them installed. One recent owner, a retired scientist and quite objective and technical, definitely felt they had a positive effect. His boar also has fish - his goal was to stabilize on shorter runs.

My 1970 Willard 36 had factory installed Vosper Mini Fin stabilizers. They only recently died after 50 years of service. I occasionally catch kelp, but that's pretty rare. The people who worry about having external appendages are people who don't have fins.

Personally, gyro is not for me because of the power requirements. At this point, 12v systems are not practical for larger boats. Some folks don't mind running their generator 100% of the time. I do.

As mentioned above, my Vospers broke. I replaced with Wesmars. Never occurred to me to consider replacing with fish, but I should have. Not sure oneould have gone with fish, but I should have considered.

Good luck

Peter

Hippocampus said:

Made an error in post # 16. Reversed terms inadvertently. Fish are generally less expensive than fins. Both initial cost and operating costs.

Click to expand...

Hmmm. I would think a retrofit for paravane use on a vessel never having been equipped with them - design costs, fabrication of/on new or greatly improved or at least modified mast, fabrication of poles, rigging, bracing, etc. and then finally installation - would give fins a run for the money in an initial outlay of $.

I had gyros installed on two full displacement vessels, and was pleased with their performance. Both were flat bottomed, twin engine, double skeg, shallow draft. The gyro was up to speed in 35 minutes, and I used dock power when available. You start them up when you think you may need them, not after you know it. They take several hours to wind down, so if unnecessary they can be “idled” if/until it is warranted to reingauge. They did not take that much juice, but I didn’t mind as I was running air/heat. Noticeable whine if close to the installation, but not a bother in the forward cabin or in pilot house. Very good at anchor, and when needed at anchor the conditions are such that the gen running is the least of the issues.

Hired naval architects in both cases to design modifications to the framing on the installs, one vessel has steel hull, the other fiberglass. Gyros removed 80+% of motion in quartering and beam seas, nothing in pitching conditions, so course adjustments were normal for a good ride. Both these vessels had very stable hull forms to begin with.

I sold the fiberglass trawler and replaced it with a vessel utilizing fin stabilizers, and although they activate quickly, I miss the gyro, and worry over picking up debris with the fins.

Gave thought to buying a used diesel duck that was unstabilized except by sail plan. Priced out fish and Quick. Although the mast was in place and scantlings of this steel boat more than adequate without any modifications the cost of a properly constructed fish set up was surprising. The stabilizers themselves the least of it. As these vessels commonly come stock with fish naval architectural fees were negligible. My prior statement was based on that exploration. Fish were a fraction of the cost of gyros in that instance. Still, even without that leg up and starting with an unstabilized GRP trawler fish would be significantly less dear than gyros.

Hippocampus said:

Gave thought to buying a used diesel duck that was unstabilized except by sail plan. Priced out fish and Quick. Although the mast was in place and scantlings of this steel boat more than adequate without any modifications the cost of a properly constructed fish set up was surprising. The stabilizers themselves the least of it. As these vessels commonly come stock with fish naval architectural fees were negligible. My prior statement was based on that exploration. Fish were a fraction of the cost of gyros in that instance. Still, even without that leg up and starting with an unstabilized GRP trawler fish would be significantly less dear than gyros.

Click to expand...

For your intended usage - long offshore runs, I would think Fish would be preferred. The two biggest disadvantages of fish are air-draft and they take some time and effort to deploy/retrieve. Neither are a factor offshore or longer coastal runs.

I doubt there are many Nordhavn's ever built without fins. Many were built with both fish and fins.

Peter

Beebe's book 'Voyaging Under Power' discusses paravanes' fish and rigging, as well other means of stabilization.

Yes a good read as is the rest of the book. Will go with fins and add fish if I think necessary. At present from speaking with more knowledgeable people current preference is
ABT
Niaid
Wesmar

In that order. Think only reason for fish is belt and suspenders thinking. Too much of that leaves you broke.

I would be interested in learning more about bilge keels and their ability to support while beaching and taking advantage very low tides allowing for hull cleaning and painting the below water line hull. Think of all the yard fees you will save.

OldDan1943 said:

I would be interested in learning more about bilge keels and their ability to support while beaching and taking advantage very low tides allowing for hull cleaning and painting the below water line hull. Think of all the yard fees you will save.

Click to expand...

Different animal OldDan - Although the terms are used interchangeably, "Bilge Keels" are the twin-keel configuration that is somewhat common in Europe on sailboats. They are fairly shallow draft and do allow the owner to careen his boat.

"Roll Chocks" are a fixed longitudinal fin. It does not extend far enough down to serve as a kick-stand.

Attached is a picture of Veronica, a Willard 40. The owner reported enthusiastic results. In his opinion, they did not so much serve as a stabilizer, but more to dampen the roll and prevent oscillations from build-up. Several W40 owners have had them installed, most recently Lilliana who was laid-up in San Carlos (Sea of Cortez). Cost was around $5k. Owners have been satisfied with the result, though part of it is due to the low cost.

Peter

Colin4 said:

The company I’m considering has done a lot of Seakeeper installations and their main guy has been in the engine room to check it out, and the subject never came up. I will be bringing a up.

Click to expand...

Have they done installs on a vessel similar to yours? If so, maybe a look at one and a discussion with owner as to how it is performing.

Colin4 said:

The company I’m considering has done a lot of Seakeeper installations and their main guy has been in the engine room to check it out, and the subject never came up. I will be bringing a up.

Click to expand...

Colin,

Our Seakeeper (SK) was installed at the yard in Asia, and SK sent a technical person there to oversee and advise. There are very specific guidelines as to the structural reinforcement for the box, for both new installs and retrofits.

Surprised to hear your local person didn't bring this up, but if you had not signed on the dotted line and just looking for rough ideas and pricing, I would assume they would eventually get in to the nitty gritty if they are following the corporate SK process.

The local dealer in our area who represents SK is very good. He is ex Aus Navy (Engine) and a 25 year master electrician. Very detailed guy who spends a lot of time making sure things get done right. He does new installs on a routine basis and can't keep up with demand. They are installing these in high end go fasts like Rivieras, Sport Fishers, Slower speed cruising boats like many of ours, and a variety of others down to a Ranger Tug that is parked 100 ft away from me. The few guys that work for him have been to SK training school and have tech sheets to follow for anything from routine servicing to major repairs.

BTW, power demands are not bad. If I remember correctly, mine takes about 10 to 12 A to spool up, then settles in at about 8 A, but don't quote me on that. The specs in SK are the go to.

There are a-lot of good options out there for stabilization, and the best fit is different for everyone depending on how we use our boats, distances run, and whether we use the Gen a lot anyway for things like making water when offshore, so running the Gen to power the SK is inconsequential.

Have a newbie dumb question.
Fins work better if you’re making adequate speed through the water. They are typically sized to be effective at your average cruising speed. In a seaway, particularly if going into the waves it’s often desirable to slow down. Maintain adequate rpm and speed as you confront and rise in the first half of the wave. Then decrease rpm once you pass the apogee and maybe even surfing.
So is the effectiveness, in actual use, of active fins decreased when in a significant seaway?

Hippocampus said:

Have a newbie dumb question.
Fins work better if you’re making adequate speed through the water. They are typically sized to be effective at your average cruising speed. In a seaway, particularly if going into the waves it’s often desirable to slow down. Maintain adequate rpm and speed as you confront and rise in the first half of the wave. Then decrease rpm once you pass the apogee and maybe even surfing.
So is the effectiveness, in actual use, of active fins decreased when in a significant seaway?

Click to expand...

I'd say it depends on 2 things: how conservative is the fin sizing? And how much does the hull shape lead to you changing speed through water as you encounter waves?

Hippocampus said:

Have a newbie dumb question.
Fins work better if you’re making adequate speed through the water. They are typically sized to be effective at your average cruising speed. In a seaway, particularly if going into the waves it’s often desirable to slow down. Maintain adequate rpm and speed as you confront and rise in the first half of the wave. Then decrease rpm once you pass the apogee and maybe even surfing.
So is the effectiveness, in actual use, of active fins decreased when in a significant seaway?

Click to expand...

The fins adjust amplitude and reaction to sea state. Even my 50 year old Vospers had a lo-med-hi switch to adjust for sea state. Modern ones are much better. Similar to how an autopilot is adjusted to sea state.

Peter

My fins are speed controlled by the computer. Works so well, it almost seems as if the fins can see waves coming and react to meet the wave rather than waiting for the wave to hit. I don't know about your assertion that you slow down to meet waves....I generally set the throttle and go. Fins make driving the boat so much easier.

Gordon

My limited experiences were mostly on an Henrique sport fish going out to the canyons. When going into 6-9’ with short period we’d slow down. Have seen more going to weather on my sailboat on passage. One of the reasons I’ve reefed is to avoid being frequently swept by green water and decrease pounding. Not racing. We’re all about comfort. Assumed others do the same.

Hippocampus said:

My limited experiences were mostly on an Henrique sport fish going out to the canyons. When going into 6-9’ with short period we’d slow down. Have seen more going to weather on my sailboat on passage. One of the reasons I’ve reefed is to avoid being frequently swept by green water and decrease pounding. Not racing. We’re all about comfort. Assumed others do the same.

Click to expand...

Every boat will hit a point where you have to adjust speed. But how much you have to, whether you need to start adjusting over very wave and when you hit that threshold will depend on the boat. Some go to weather nicely, others prefer following seas. Same way some sailboats pitch like crazy going to weather while others pitch less but play submarine through every wave.