Why would I need more than one Seakeeper?

If you’ve read our article Seakeeper Sizing and Performance, you’ll know that there’s more to determining which Seakeeper is right for your boat than just the boat’s length. There are a lot of factors that go into determining that one 45-foot vessel should have a Seakeeper 5 while another should opt for the Seakeeper 6. As boats get larger and larger, there are more options for stabilization, but let’s backtrack a little and figure out the difference between a Seakeeper 5 and a Seakeeper 6.


We name each Seakeeper unit based on its stabilizing power, which is measured in angular momentum (Newton meter seconds, or N-m-s). Read more about that in our article Time’s Up: Angular Momentum > Torque.

  • Seakeeper 1 – 1,000 N-m-s
  • Seakeeper 2 – 2,000 N-m-s
  • Seakeeper 3 – 3,000 N-m-s
  • Seakeeper 4 – 4,000 N-m-s
  • Seakeeper 4.5 – 4,500 N-m-s
  • Seakeeper 5 – 5,000 N-m-s
  • Seakeeper 6 – 6,000 N-m-s
  • Seakeeper 9 – 9,000 N-m-s
  • Seakeeper 18 – 18,000 N-m-s
  • Seakeeper 26 – 26,000 N-m-s
  • Seakeeper 35 – 35,000 N-m-s
  • Seakeeper 40 – 40,000 N-m-s

So, with this, you can see that the Seakeeper 6 is twice as powerful as the Seakeeper 3; the Seakeeper 9 is three times more powerful than the Seakeeper 3, and so on.


Seakeepers work great alone, but they can also work together. Think about a group project in school. You could take on the full workload by yourself, or you can split it up between more members, giving each person some of the work. Seakeepers work the same way, because they can be combined for greater power. You just have to add up the units’ angular momentum.

For example, two Seakeeper 3 units will have the exact same stabilizing power as one Seakeeper 6 (3+3=6). You don’t have to add them to match another existing unit, though. You could simply add a Seakeeper 2 (2,000 N-m-s) to a boat with an existing Seakeeper 18 (18,000 N-m-s) to get 20,000 N-m-s of force (the Seakeeper 20 doesn’t exist).

Right: A 56 Viking with two Seakeeper 6 units.
Refit done by Tri Sea Stabilizers.


There are a few reasons a Dealer might suggest more than one Seakeeper:

Left: This 165’ Mangusta had 7x Seakeeper 16 units and 2x Seakeeper 9 units. Each unit comes with its own 5-inch display so that the owner has operational and diagnostic information for each unit separately.

Refit done by Tri Sea Stabilizers.


Most people don’t opt for multiple units unless they need to, but you don’t have to worry about making the decision. Our certified Dealer network will help guide you to the stabilization options best for your boat and how you use it. You can always reach out to us directly, or find the Seakeeper Dealer nearest you for an installation quote!

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