in.   mm.  
33 a 838 S shaft – see table
42 a 1067 M shaft – see table
52 a 1321 L shaft – see table
62 a 1575 X shaft – see table
25 1/2 b 650 vane axis knob
18 c 464 VXA1 course clamp
16 d 426 VXA2 worm drive
11 1/2 e 297 ratio knob
6 f 153 emergency tiller
4 1/2 g 117 rudder lock pin
19 h 480 balance weight
3 j 76 rudder front
3 k 76 vane/shaft axis
56 1/2 l 1435 vane height
31 1/2 m 800 rudder immersion
32 n 820 mizzen boom clearance

RUDDER SHAFT LENGTH The HYDROVANE shaft length is chosen according to the height of the stern. The table below shows the required shaft length, S, M, L, X, or longer, assuming that for free vane movement, the stern rail is not more than 24 inches (610 mm) above the deck and does not project aft of the stern. Otherwise, the next longer shaft may be needed.

Shaft Length
Max. Stern Freeboard


34 in (860 mm)


43 in (1090 mm)


53 in (1340 mm)


63 in (1600 mm)

As Required

more than 63 in (1600 mm)

MOUNTING BRACKETS – H (hinge), E (elbow – single strut) and A (double strut)

HH Brackets Conway 36
HE Brackets Biscay 36
EH Brackets UFO 34
HA Brackets 48ft 17 ton cutter
HH Brackets Valiant 40
EH Brackets Coaster 33
AH Brackets Off Center Moody 422
EH Brackets Nicholson 45
HA Brackets Nicholson 43

‘H’ ( HINGED) BRACKET – MUST BE ONE ‘H’ BRACKET – Every installation requires two brackets, one of which must be an ‘H’ bracket. The ‘H’ bracket is located at about the closest point from the shaft to the stern.


HALLBERG RASSY 352 H/H – 2 ‘H’ Brackets

SINGLE STRUT/TUBE ‘E’ (ELBOW) BRACKET – If the reach from the shaft to the transom for the second bracket is less than 20 in. (50 cm.) then the ‘E’ bracket can be used. It has a single strut/tube that will be cut to the appropriate length.


VICTORIA 34 H/E – Upper ‘H’ and Lower ‘E’

DOUBLE STRUT/TUBE ‘A’ BRACKET – For installations where the distance required is at least 16 in. (40 cm.) the two strut/tube ‘A bracket may be used. Although expensive, the ‘A’ solves all strength and positioning issues. The two struts of the ‘A’ bracket are V shaped at an angle of 40 degrees. The arms may be angled up or down, on the same plane or otherwise and the flanges fully rotate to be flush with any surface.


OCEANIC 46 A/H – Upper ‘A’ and Lower ‘H’

CONSIDERATIONS: Single strut ‘E’ bracket versus the double strut ‘A’ bracket We always prefer the ‘A’ – cost and ‘the fit’ are the only negatives. The single strut ‘E’ has two weaknesses:

  1. The tube can work free from its clamps if the ‘tightening sequence’ is not strictly adhered to – it’s a difference of the tube being pinched at the edges or completely gripped by the clamp.
  2. We set a maximum length of 18 inches. The system is designed to handle that much leverage…… but the bigger rudder and for bigger and faster boats we do get nervous.

Next vulnerability is flimsy transoms. The ‘E’ will probably attach in the open area of the transom – unfortunately, not near an edge where there is more fibreglass and structural integrity. If the fibreglass can ‘work’/flex or the bracket ‘works’ then it is only a matter of time before a failure will occur. The Hydrovane must be absolutely rigid. Sounds scary, but …….. The history is that not many have worked loose – all suspect for ‘tightening sequence’ issues – and only once have we seen a casting fail. Finally is the unforeseen – a collision with a floating object or more likely errant vessels in a marina. An ‘A’ bracket is simply far stronger and able to withstand loads or blows from directions other than what it was designed for.

OFF CENTER – A good portion of Hydrovanes are now installed off centre – see separate section on OFF CENTER INSTALLATIONS. Performance is not an issue with the Hydrovane off centre. This quote is from the TRUE STORIES tab: “……Having previously owned a Hallberg Rassy 382 which had your vane system on her I would not consider anything else. My family and I sailed the HR382 across the Atlantic and through the West Indies up to Florida and even though the Hydrovane was off centered it didn’t miss a beat! For your interest in 1972 my wife and I sailed a 28 footer with a transom hung Hasler trim tab system out to New Zealand and some time after that I had a yacht with a local —— pendulum servo system. The Hydrovane in my opinion is the ultimate!”
Owner of a Hallberg Rassy 42 ketch Auckland, New Zealand


Sweden Yacht 45 – 30 in. offset! Note – use of PVC pipe as dummy shaft and use of tape for positioning – struts not on same plane

FLEXIBILITY IN POSITIONING – The only critical position required is to have the shaft vertical. The brackets are merely holders that, when tightened, clamp the shaft in place. There is considerable flexibility in determining the location of the brackets which is most helpful when dealing with surprise obstructions on the inside of the transom. Within certain maximum and minimum requirements the location of the brackets on the shaft may be moved up or down. See PARTS tab for detailed pictures of the brackets.

See INSTRUCTIONS and TIPS tabs for complete installation and other instructions.

TIMBER PADS – A timber pad is a piece of non-ferrous material ( often teak wood or a synthetic like Micararta is used) that is fitted between the HYDROVANE bracket flanges and the transom. The timber pad is fashioned or shaped to pick up any contour differences between the flat flange face and the transom. For metal hulls it is always wise to insert a timber pad even when the two surfaces are flat or flush with each other. The purpose is to eliminate any potential for electrolysis – which can occur even between apparently like metals – eg – the HYDROVANE aluminum flange and an aluminum hull. The HYDROVANE castings are all made of a very high quality magnesium alloy – probably different metal than an aluminum hull.




  Vane too close to arch

 Ooops …..! All installed, put on the vane, push it over, rotate it for a full 360 degrees to see if it hits something ………… Not Good!

Vane Hitting Arch 2

Fortunately, these two pictures show that the vanes are able to incline by most of their capability – still do their job although hitting some structure. Worst of all if the vane hits an overhead structure like an arch or bimini and is unable to incline – cannot function properly. Then major changes are required. Contact Will or John…. and send them some pictures. If, like the above pictures, the vane hits a side or overhead structure that is nearly  28.5 in./725 mm away for the Stubby Vane or 37 in./940 mm for the Standard Vane – that is not so bad ……. Well, not good either but tolerable. In this case the vane will reach/hit the side support on only certain points of sail. As the  vane will be well deflected before it hits, then that is OK – not a problem for performance – only a nuisance. It is not a problem because the vane can deflect through most of its motion causing the rudder to turn and get the boat back on course. Which means the Hydrovane can still do its job. So often the vane is almost quivering as it deflects from side to side by the smallest amount. In many conditions the vane rarely fully deflects. To deal with the ‘hitting’ of the vane against the arch support:

  • Improve sail trim so that such dramatic course corrections are not necessary
  • Change the inclination of the vane – change its axis – so it clears the support
  • Change course by a bit
  • Put a piece of foam on the section that it hits to soften the blow, reduce chafe of the vane cover, deadens the annoying hit sound


Too often at the wrong stage of installation, like the example above, it is discovered that certain of the boats aerial equipment on the aft end conflict with the normal operation of the Hydrovane. The Hydrovane vane needs a lot of airspace – can be as tall as 10 feet/3000 mm. to 12 feet/4,000 mm. above the water and more importantly it has a lateral reach of over 4 feet./1,200 mm. in all directions at that height – yes, a full 360 degrees! If your boat has:

  • Bimini that reaches aft
  • Arch supporting solar panels or communication gear
  • Radar post/mast
  • Wind Generator
  • Antennas
  • Any other aerial obstacles but not davits (normally are low enough)
Then we need pictures taken at 90 degrees to the transom and from dead aft – pictures showing from the water to the top of those obstacles –  in order to properly configure an installation.


VANE COMPARISON – Standard, Stubby, Extendable

Our three Vanes: Standard, Extendable (contracted), and, Stubby

Our three Vanes: Standard, Extendable ‘XT’ (contracted), and, Stubby

Our three Vanes: Standard, Extendable 'XT' (extended), and, Stubby

Our three Vanes: Standard, Extendable ‘XT’ (extended), and, Stubby

Vane comparison: 

Vane Length (in) Length (cm)
Standard 54.25 138
Stubby 43 109
Extendable ‘XT’ – contracted 41.25 105
Extendable ‘XT’ – fully extended 51.75 131


  • H bracket creates a distance from shaft to transom of between 1.5 in. ( 3.8 cm) to 4.5 in. (11 cm.)
  • The minimum distance required for an E bracket is 8in. (20 cm.)
  • The minimum distance required for an A bracket is 16in. (40 cm.)
  • The maximum exposed shaft between the top bracket and the drive unit is 18 in. (46 cm.)
  • Space, distance between the bottom bracket and the bottom bearing: between 2 in. and 10 in. (5 cm. and 25 cm.)
  • The minimum separation between the two rudders should be 8in. (20 cm.)
  • Weight – In water weight varies from:
    • Lightest – 66 lbs. ( 30 kg.) – ‘S’ shaft and two ‘H’ brackets
    • Heaviest – 113 lbs. ( 51 kg.) – ‘X’ shaft with the ‘A’ and ‘H’ brackets
    • Average – 83 lbs. ( 37 kgs.) – ‘L’ shaft with an ‘E’ and ‘H’ brackets


In most cases we need only the A, B, C and D measurements see schematic below If there are any interfering obstacles then we need those relevant measurements:

  • Rudder – E – only if the rudder is near the transom – within 4 in. (10 cm.)
  • Pushpit Rail – F, H, G – only if the pushpit rail might be in the way – but it is good to have those measurements anyways
  • Mizzen or Arch or Bimini – I, K, J – for mizzen boom – use this same format if there is an arch or any overhead structure
  • Posts for Radar or Wind Generators – For wind generators and radar masts – measure the lateral and forward distance from the mid point of the transom cap rail to the radar/generator mast or post
  • Scoops or Steps of Swim Platforms – We want to draw the side profile at that point where the Hydrovane will be fitted – From the tip of the transom measure both the vertical height and the lateral distance forward for each step.


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Shafts, axles and fastenings Generally 316 (EN58J) stainless steel except the main shaft which is Ferrinox 255 (Super Duplex), solid stainless
Castings LM25 anodized aluminum alloy and silicon bronze
Bearings Glass Filled PET, PFTE and Acetal (Delrin). Nylon ball race on rudder shaft.
Rudder Solid N6 nylon casting. Tapered NACA profile
Wind Vane Reinforced nylon cloth (ripstop) on anodized alloy tube frame
Course control 4in. (100mm) oilon worm gear