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REFIT — Upgrade OLOH's Stabilization System To Increase Performance And Comfort

This page details our selection process for this project.  For a look at the installation process, please click here.

Stabilizers are a common feature and in many cases a necessity on larger boats.  In a nutshell, a stabilizer system works to reduce the roll of a boat caused by wave action and keep it – you guessed it – stable.  The stability of a boat underway is obviously a comfort issue (particularly for those prone to seasickness), but it’s also a safety issue given how items and people can be tossed about.  Rough seas are simply no fun and while stabilizers won’t completely eliminate a boat’s tendency to roll, they can help calm things down a great deal if they are well matched to the vessel.  Stabilizers have been built into boats for decades with fin stabilizers (what we presently have) being the most ubiquitous and having changed little in how they work – until relatively recently.  There are also new systems that have proliferated over recent years, taking advantage of advances in technology.

The short version of how fin stabilizers work is this: fins are mounted beneath the waterline and emerge laterally from each side of the hull.  They’re controlled by a gyroscopic system that measures the boat’s rolling movement which sends that information through electronic controls which automatically change the fins’ angle to exert force to counteract the roll.  Think of what happens when you’re in a kayak and you put the paddle into the water perpendicular to the way the water is flowing.  The down-force causes the boat to begin a rolling motion.  Fins on a boat produce lift that work against the roll movement of the vessel.

Why did we upgrade OLOH’s stabilizers?  After our first year of ownership and a few thousand nautical miles of cruising experience with her we identified her stability in beam (from the side) and following (from behind) seas as something that could be improved upon and increase our enjoyment of the boat.  Our factory-installed WESMAR brand stabilizers did work but not as well as we felt they should have for the way we like to travel.  One of the reasons, per experts and general laws of physics, is that OLOH’s original fins were marginally sized for OLOH’s sixty feet, particularly for the speed at which we prefer to cruise (10 knots).

All of the options we explored would have allowed us to see a benefit from the modern tech that measures the boat’s movement and tells the stabilizers how to react.  OLOH’s factory-installed (2004) system was analog and much more limited in its abilities versus the modern digital technology that the new systems employ.  The new tech greatly enhances how well the system assesses motion and can be fine-tuned and adjusted beyond our original system’s capabilities.

Here are the systems we looked into…

Humphree - Fins

We were primarily aware of the existence of Humphree stabilization after reading about one of their systems in an article about stabilizers in Power and Motoryacht Magazine that pops right up when you do a web search on the subject.  When we visited the company’s site we saw that they have a fin system that was potentially right for OLOH.  When we reached out to the company they were instantly responsive with a note back from the company’s managing director overseas.  The next note we received wasn’t from some marketing person as is typical with online inquiries… it was a personal note from Sean Berrie, the CEO of Humphree’s American division who wanted to be sure we were pointed in the right direction.  Sean connected us with George Lewis who is Humphree’s “man on the ground” as Sean put it, in the southeast.  In the ensuing dialog, we got a tremendous education about their system and George was right there with thorough information and ideas at every turn.  He even reached out to OLOH’s designer for some deep specs in hopes of being able to do theoretical calculations of how their product would improve our boat’s stability.

A couple of highlights particular to our needs:

  • Humphree stabilizers are DC electric powered with NO hydraulics.  This is a big deal.  Even though OLOH’s hydraulic system for the stabilizers was rebuilt just prior to our taking ownership, it is still a major system that has many possible points of failure.  Like any boat system hydraulics need to be maintained but to a greater degree than the Humphree system. The primary maintenance with Humphree fins is replacing the seals every four years (our present fins get new seals every three years).  The engines also need to be running for the hydraulic system to be active.  Electric-only is much simpler.  This is very attractive to us.
  • Full stabilization at all speeds.  Zero-speed stabilization (the system keeps the boat stable whether at anchor or just drifting) has become more commonplace with the advent of gyro-stabilization (see below) and while not the priority for us, a terrific thing to have.

A few other benefits (from their literature):

  • 360° rotation – combats anchor walk: The 360° rotation allows Humphree to rotate the fins 180° and gently pull the anchor when anchored at the bow. This minimizes the so-called anchor walk and will keep the bow against the wind to a noticeable extent reducing waves coming from the side. 
  • Compact size & low weight: Sturdy and compact with unbeatably low weight. A depth of only 310mm from outside hull.
  • Optimized hydrodynamic profile: Fin designed for low drag
  • Coordinated Turn: The Humphree Coordinated turn function makes it possible to turn in a very comfortable way and without cavitation from the fins.  No more leaning during turns, or the fin stabilizer keeping your boat from turning.   The Humphree system follows your boat’s rudder during turns and helps keep the boat level and stable.
  • Fin replaceable under water thanks to the flange mount design without a heavy shaft inside.  So no need for an inconvenient haul out at the nearest marina.   Fins are designed to be lower profile and located far enough outboard to not increase the boat’s draft in most cases.

It is likely that the Humphree fins would work where our fins currently are located and the servos which actuate the fins would likely fit where our current fins’ actuators are   There would be fiberglass work involved retrofitting the new fins through the hull.  We’d also need to add a 24-volt battery bank and charger to power the system.  While every job is different we were told to anticipate approximately ten days with two guys for the installation.

We were thoroughly impressed with Humphree and enthusiastically encourage anyone looking into stabilization to check them out.

Seakeeper - Gyro

Perhaps the biggest advancement in stabilization for recreational boats in recent years is the proliferation of computer-controlled gyroscope stabilization.  Seakeeper has the biggest market share and their equipment is commonplace on many new builds as well as a popular retrofit item on older boats with Seakeepers now available for vessels as small as twenty-seven feet.

It’s pretty incredible technology.  The short version of how it works is this (from their literature): Inside a vacuum encapsulation, a flywheel spins at speeds of up to 9,700 rpm. When the boat rolls, the gyro tilts fore and aft, producing a powerful gyroscopic torque to port and starboard that counteracts the boat roll.

Why it’s an attractive option…

  • It can be installed virtually anywhere on board which allows for great flexibility.
  • No outside appendages.  One of the disadvantages of fins is the natural “drag” or resistance they create which compromises a boat’s efficiency.  It’s also one more thing to snag a line or get whacked by an underwater object.
  • Electrically powered and completely self-contained.

Some considerations…

  • Weight.  While we would lose some weight by the removal of equipment related to our current system, the Seakeeper spec’d for our boat comes in at 2,195 pounds.
  • Size.  Its envelope is approximately 3.5′ x 3.5′ and just shy of 3′ tall.  While there’s flexibility as to where it can be installed we’d have to find a big enough spot for it somewhere.
  • Spool up time.  It takes around 45 minutes from the time it’s powered up until the gyro spools up to effective stabilization speeds.  People who own them have learned to work with that but it is something to be aware of if you’re accustomed to quick departures that can quickly have you in rough water.
  • Power requirements.  While OLOH’s generator is always running when we’re underway, it is absolutely necessary for the operation of the Seakeeper.  This means if we want to take advantage of zero-speed stabilization we can’t shut down the generator at anchor (which we hope to do more when we have an inverter to handle our refrigeration) and if the generator shuts down underway for some reason we lose our stabilization.
  • Cost.  Of the options we explored, it is the most expensive.  The unit that would be appropriate for OLOH lists for $99,400 not including installation.

We have not been directly in touch with Seakeeper but their website is terrific (check it out for simulations, explanations, and videos) and we have been familiar with their gear for many years.  You always hear pros and cons about any product but one person we know with a factory installed Seakeeper on his three-year-old 65 footer swears by it.

WESMAR - Upgrade Fin Size And Technology


It didn’t take much research to learn that the simplest way to go about this project would be to work with what we had.  The fins that were installed by the factory when OLOH was built were likely chosen for the boat’s optimal 18-knot cruise speed and less fin surface area is needed to provide stability at those higher speeds. Again, our preferred cruise speed is 10 knots.  OLOH’s fins were 4.5 square feet minus the fiberglass that needed to be removed to miss hitting part of the hull as they swing.  With the common thought being that we would see improvement in stability with larger fins we looked into what WESMAR could do for us.  Between their larger fins working well with our existing gear and the new technology available with their modern control system this is an extremely viable and cost-effective option.  We could have replaced our original fins with larger ones to see if the improvement was substantial enough before doing anything further -or-  upgrade both the size of the fins and the electronics that control them for maximum impact.

Some highlights…

  • 7.5 square foot fins, which were being recommended to us, have the same shaft size as our original 4.5 sq ft fins (the shaft that the fin is attached to goes through the hull of the boat and is connected to the actuator inside the boat which moves the fin).  We liked this as it’s never a bad thing to avoid making holes in your boat bigger.  Also a big savings in time and cost.
  • The entire job was expected to only take a few days which also helps to keep costs down.  It was expected that the fins could likely be replaced in a day while the boat is already out of the water for scheduled maintenance.  The new electronics can also usually be done in a day and the boat can be in the water when that takes place.
  • The new gyro is a 3-axis system versus the boat’s original 2-axis system.  Simply explained, the new gyro gathers a greater amount of information to read the boat’s movement much more precisely than the old setup giving more feedback to the electronic brain that tells the fins how to react.  We were told this would improve the ride, especially in a following or quartering sea (which is where OLOH needs the most help).
  • The new digital controller allows for a great deal more fine-tuning to better adapt the fins’ movement to our boat’s characteristics and has many setting options (versus our original system’s ability to only adjust sensitivity and trim).  The new system can also be easily interfaced with OLOH’s electronics network to receive even more information (speed and position) to further enhance stability.  A note for anyone with nearly any brand of fin stabilization looking to improve overall performance… WESMAR’s new, state-of-the-art electronic gyro and controller is a relatively easy, low-impact upgrade that is definitely worth looking into.

OLOH’s former, very basic, analog stabilizer controls.

WESMAR’s new DSP5000. A LOT more control.



As far as larger fins further affecting performance because of increased drag, we were told by the experts that this would be negligible.

WESMAR was wonderful to deal with and tremendously helpful from our first contact with them, connecting us with their distributor in Fort Lauderdale who reached out immediately to discuss our situation and make recommendations.  We were then connected with Jim Monroe at Yacht Equipment and Parts in Fort Lauderdale whose team is WESMAR factory-trained and very well versed in their stabilizers having installed and serviced them for nearly twenty-five years.  That’s the kind of experience you want on a job like this.   Jim is a stand-up guy who was a pleasure to work with, extremely knowledgeable and most generous with his time, getting on board OLOH to assess our former setup and answering any questions we’ve had.  While Jim has since retired, we would encourage anyone looking to work with WESMAR to contact them directly.  In Florida, WESMAR’s Bob Leatherman is the guy you want to reach.  He was terrific.

After a great deal of research and deliberation we were confident that, on balance, this was the right decision for us.

For a look at the installation process for our upgrade, please click here.

This Post Has 26 Comments

  1. Again a great post with valuable Iinformation. I learned a lot. Looking forward to the final decision and follow up posts! P&L
  2. Hi guys Love my Seakeeper. Would never ever by a boat without one. Even when we had to shut an engine down and our speed was at a minimum it saved us out there. Also, at dock, with 30 knots blowing us into the dock - we clicked it on - lowest RPM setting - and didn’t rock at all. AWESOME!!!
  3. Dear AJ, Tim and Jasper: Great information and research. Good luck with your choice of new stabilization options. We have Naiad and they work OK. Getting quality service has been very difficult in the past and have had to personally replace various parts ourselves with instructions from dealer over the phone. We returned from Italy yesterday. Stayed in Il San Pietro, Positano. Wonderful time and magnificent smaller hotel. Good to be home though and now planning to head south with YOREL within the next two weeks. Best wishes, Jill and John
  4. In my 48 ft ocean Alexander ( with previously no stabilization ) In 2015 I had installed the Weimar 7.5 sq. Ft. Fin (for slow or fast speed) with the 3- axis gyro system (4800 previous model). There was a short learning curve for me with finer adjustments at different speeds and sea conditions for my boat, but customer support was very helpful. Much improved ride and I am very happy with the Weimar system. Although there are other good systems available, with your current set up I think you made a very good choice.
  5. Randal - thanks so much for your comment and feedback. It's great to hear from someone who has real-world experience with what we're doing. And yes - given our current setup this really seemed to be the best all-around option for us. See you out there!
  6. Hi thanks for you input, the package arrived yesterday, work starts in the morning,, here in the Philippines. we will sea trial after installation and do a real test end of the month when we do a 95 mile trip in open ocean. Our Wesmars have served well for 15 years, 8000 hours and half way around the world, but looking forward to even an even better ride. Again, thank you for your input, Capt Brian Calvert MY Furthur
  7. I currently have a 2002 Wesmar system on my boat with 4.5 sf fins. They're installed on my Hampton Yachts 550 Pilothouse. I was not aware that a fin size upgrade was even possible until coming across your site. Did the larger fins bolt directly into your existing system or did it require retrofitting? Did existing hydraulics have enough power to drive 7.5 sf fins? Anxious to hear your reply.
    1. Hi Michael - Beautiful boat. For our situation, the fin upgrade was essentially plug and play in that the shaft size for our original 4.5 square foot fins was the same as the 7.5 square foot fins and no changes to the mechanical systems were necessary. I’m guessing that is universally true. The new fins had to be trimmed a bit to clear the chines on our hull. In case you missed it, we completely detailed the installation process at If you're located anywhere near Florida I would encourage you to reach out to Jim at Yacht Equipment and Parts who did an excellent job facilitating our install - (954) 463-7222. Be sure to tell them OLOH sent you. Please keep us posted on your project and good luck!
  8. Nice article! I am considering upgrading our current wesmar stabilizers (from your pic it looks like we have a similar setup as your old one). However, zero speed stabilizers are a top priority as we spend a lot of time at anchor. Does your new system offer this? Or do you know if it is an option through wesmar?
    1. HI Kate - glad you found us. There is a zero speed setting on our system which we have yet to try. Because our PTO (Power Take Off) comes from our engines, it would be impractical for us to use at anchor as one of our engines need to be running for the stabilizers to function. But there's something there for a system configured differently. I would suggest you reach out to WESMAR to see what they have to say. Let us know how you make out.
  9. Thank you for posting this upgrade. I have the exact same system you had in my 58ft trawler. I also wish to upgrade my system. As cost is always a factor can you tell me how the price compares on sticking with Wesmar vs the Humphree system? I like the idea of going all electric. Please email me if you prefer.
  10. We are looking at a Hampton 550 with small Wesmars, would you email me the cost of your upgrade? Thank you in advance, great website!!
  11. Hi guys, Found your website and youtube channel when I was searching for stabilizer information. We have a Defever 49 and are searching for the right stabilizers for quite a while. I spoke with many suppliers and all of them have their great sales pitch, but it is good to hear it from the end users themselves. Like you I have been debating between all electric or the old fashioned hydraulics. The gyro system of sea keeper unfortunately won't work for us, it takes up too much space and way too much electricity. I know you are running at 10 kts, but have you tried your stabilizers at a lower speed, say 7 kts ? 6 - 7 kts is about our cruise speed with a hull speed of around 8 - 9 kts. Am curious to find out how efficient they are. Back in 2018 you had not tried them on anchor, has that changed already ? Perhaps you have encountered a situation where you had to use them on anchor, so switching on an engine ? If so how efficient was that ? I read the highlights for the choice of Wesmar, but was there anything else in Humphree that made you decide for Wesmar ? If you don't want to share that in the open I can understand, perhaps you could send it via e-mail. Thanks in advance and safe travels. It is nice to have found your channel. 95 % of the Youtube channels are sailing vessels, the amount of motor vessels is limited unfortunately. So you are a welcome addition.
  12. Could you also email me the cost and how it works when at anchor. We Are getting a 56 foot symbol and are thinking of upgrading. Thank you
  13. Looking at a boat that has old wesmar stab. Also interested on the cost to upgrade. Last boat had ABT-TRAC stabs and loved them. How often do seals need replaced in the wesmar system?

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