OFF CENTER INSTALLATIONS

We have been providing off centre installations for 40 years!

Sweden Yacht 45 - at ARC Finish - note big offset of his Hydrovane

We talked to the owner of this Sweden Yacht 45 at the London boat show in January 2008. He reported absolutely no problem with his big offset on his Atlantic loop last year.

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• Yes, a big problem for servo pendulum systems but generally not an issue for auxiliary rudder systems ... and best handled by a Hydrovane.
• We used to recommend a 12 inch (30 cm.) maximum - but no longer  - having received excellent reports from far greater offsets
• Regardless - an amidships installation is always preferred - best protected by the keel and any aberrations in the water flow are unlikely

Outbound 46

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UNSOLICITED EMAIL RECEIVED JUNE 2007

WAUQUIEZ 40 PS - BIG OFFSET OF 30in. / 75cm.

"Tell your colleagues."

From: available on request
Sent: June-29-07 3:03 PM
To: will@hydrovane.com
Subject: Qwyver Wauquiez 40 PS

Hi Will,

Our hydrovane, mounted way off centre, has just completed its first 500 mile passage. Everything from F7 on the nose and rough seas (North Biscay) to a gentle F4 from behind.

The Hydrovane performed brilliantly, and we are delighted with it. Tell your colleagues.

Best regards,

John Andrews & Freda Haylett

Wauquiez 40 PS - offset of 30in. / 75cm.

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For more testimonials regarding off center installations see the TRUE STORIES tab

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POTENTIALLY DISASTROUS FOR SERVO PENDULUM SYSTEMS - BUT NOT AN ISSUE FOR HYDROVANE'S AUXILIARY RUDDER SYSTEM

We often hear such a concern probably because this issue is so critical for the servo pendulum type systems. If their blade/paddle lifts out of the water the boat could instantaneously 'spin out'...... imagine that in a storm! Conversely, an auxiliary rudder system, like HYDROVANE, has neither the likelihood of its rudder popping out of the water and even if it did not much would happen because:

• Even if it did lift out of the water, which would last for only a few seconds, the boat should hold course as the main rudder is locked 'on course' - preventing any 'spin out'.
• The rudder does not swing from side to side like the servo systems. Theirs might even lift out of the water when amidships.
• The rudder is longer, reaching much deeper in the water
• Anyway, the only likelihood of the rudder coming out of the water is when heading upwind - but that is the easiest point of sail for steering - most boats almost self steer themselves when 'on the wind' - needing little help from their Hydrovane.  

About half of all the Hydrovane installations in recent years are off center.

Hans Christian Christina 43

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EXCEPTIONS

OFF CENTER INSTALLATIONS & DIRTY WATER - The correct term for our slang expression of 'dirty water' is 'hull form stability'. A boat is always pushing its equivalent displacement weight of water out of the way. At the aft end of the boat that mass of water fills back in - hence the direction of flow around the Hydrovane rudder is .... well an unknown - but is likely not all in the true fore and aft direction. Our large number of performance reports tell us that in almost every case any adverse flow is not enough to upset the performance of the Hydrovane rudder. But in a few instances we have seen enough distortion in flow to require moving the Hydrovane to amidships.

We can only wonder if all those boats with offsets would get even better performance with the Hydrovane amidships - where the water flow is most likely in a balanced or true fore and aft direction.

TEST WATER FLOW AT TRANSOM - When under way put a paddle in the water at the transom to identify the water flow direction. (This test is perhaps too crude as the water flow changes with depth.) If the flow is strongly distorted an offset installation might be unwise.

OFF CENTER INSTALLATIONS