Sumara of Weymouth

Adventures of a small yacht

Where is Sumara?

Rudders, Tillers and Self-Steering Gear – Part Two

7th February 2023

Trim Tab Self-Steering

This is the beautifully built Vertue “Tui of Opua” with its trim tab self steering gear

Last week I had intended to just post a short piece about the repair I have just made to my rudder hangings. Then I got a bit carried away and went on (and on) about rudders in general. That spurred Bruce Morley to drop me a line about his rudder which incorporates trim tab self-steering. Bruce built Tui of Opua himself and launched her in 1994. Bruce and his wife Thelma have lived onboard ever since. The yacht is described by Vertueyachts.com as “one of the finest Vertues in the world” – quite an accolade!

Their trim tab self steering was based on information from “The Blue Book” by Peter Woolass.

When I was researching self-steering before my Atlantic Crossing I did contemplate using a trim-tab system on Sumara but I never plucked up the courage to slice through my rudder. I ended up going for a Windpilot system, but more of that later (Part Three!)

The big advantage of the trim-tab system is that it avoids needing a mass of stainless tubes to support the weight of the servo pendulum type of self-steering. The tab is really a servo-tab enabling the relatively light force of the wind against the vane to deflect the trailing edge of the rudder and steer the boat.

Below are some drawings and photos which show off the mechanism which Bruce successfully built for their yacht.

Side elevation of the trim tab self-steering from
Peter Woolass’ blue book “Vertue”
And here is the side elevation in real life on Tui of Opua
From “The Blue Book” “Vertue” by Peter Woolass
Beautifully executed mechanism on Tui of Opua
It looks tough and purposeful
That’s not going anywhere – if you know what I mean!

Thank you Bruce for sending through those photos. I am sure they will inspire some Vertue owners to utilise the same system.

Next up will be servo pendulum self-steering gear.

Update 1st May 2024

Trailer Marine made a trim tab system called Hydra Auto Steer Trim Tab. They are no longer made, but a search of Ebay may come up trumps.

Alasdair

, , , ,

4 responses to “Rudders, Tillers and Self-Steering Gear – Part Two”

  1. Rudders, Tillers and Self-Steering Gear – Part Three – Sumara of Weymouth

    […] the most elegant solution for Sumara would have been the trim-tab as detailed by Peter Woolass and used by Tui of Opua, but I really didn’t what to take a saw to my rudder and probably didn’t feel confident […]

    Reply
  2. David Hadaway avatar
    David Hadaway

    Very interesting implementation.

    I’m currently building a trim tab based emergency rudder which also acts as self steering from a horizontal axis wind vane to fit on my Dehler 36 CWS

    Inspiration came from a book by Bill Belcher ISBN 0 7153 8176 8. No longer in print, bought the Book S/H.

    He’d made various designs along with documented test results and very good technical explanations of pro’s and cons.

    Using a trim tab act as a self correcting servo makes so much sense as it removes any requirement for thirsty electronic drives on a main rudder.

    Leo Goolden on Tally Ho has also added a trim tab similar to your installation and is driving it with a small Helmsman linear drive for autopilot use. Very practical and simple to install.

    email me if you require further information or photo’s, project is about 2/3 of the way through with the rudder and trim tab almost complete and a stern mounted frame also in progress.

    This can doubles as dingy stowage when rudder dismounted.

    Reply
    1. Alasdair avatar
      Alasdair

      Well thanks for the input. I am sure anyone embarking on installing a trim tab system will find it helpful especially if they can find that book. Please do send through a photo of your system when you complete everything and I will add it to the post. Regards, Alasdair

      Reply
      1. David Hadaway avatar
        David Hadaway

        Many thanks for your prompt response. I liked the simplicity of your course setting arrangement which is the one bit I have not finalised yet. Wishing you fair winds. David Hadaway – Noon Hi

        Reply

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.