Robbe Smaragd

[Joe BeckettParticipant @joebeckett71895]

Which sail winch and steering servo?

[Joe BeckettParticipant @joebeckett71895]

Hello All,

I've been lucky enough to get probably the last un-made kit of the 1996 Robbe Smaragd sail boat with all the fittings kits. It's a BIG boat, 55"! The plans call for a Robbe 8336 sail winch (not included), which is no longer made/available. Can anyone suggest a suitable alternative? Same problem re the steering servo (also not included), the rudder is HUGE! and the plan suggests a servo of 'suitable type' but gives no further info?

Any advice welcome.

Thanks

Joe

[geconParticipant @gecon]

Hi Joe, Do you know the spec of the Robbe 8336 sailwinch? If so it should not be a problem to find the 'right' alterntive.

I have just 'googled' the 'Robbe 8336 sailwinch' and a post named BILLINGS BOATS ROBBE 8336 is there with the spec of the original.

Newer Servos probably are smaller than the 8336 and may have the same -or more- power. Read the recent Comtessa yacht posts for servos from Howes models. These are much cheaper than the Graupner and KRICK units I used last year. KRICK has taken over a number of projects from Robbe.   

You will need a winch with 6 turns of the drum I think. This should give about 40-45cm of sheet length. 

George

Edited By gecon on 08/12/2021 17:56:09

[Malcolm FraryParticipant @malcolmfrary95515]

A Hitec HS785HB will probably be a drop-in replacement. A Kingmax 6 turn winch is smaller and will generate the pull required, but being smaller is running much nearer its limits. The Hitec carries a larger diameter drum, so its 3 and a bit turns is fairly equivalent to the Kingmax's 6.

A bit of searching for a Futaba 8336 (I think its the same animal) turned up this spec –

Specification:

Dimensions: 59.4 x 29.0 x 52.2 mm

Mass/weight: 110.00 pond/g

Operating voltage: 4.8 – 6.0 Volts

Nominal voltage: 4.80 Volts

Nominal voltage: 6.00 Volts

Torque: 80.00 Ncm Torque: 100.00 Ncm

more Specifications:

Operating voltage:´4.8 – 6 Volts (from receiver battery)

Current drain approx. Idle 9.5 mA – No load 230 mA – Nominal load 1.4 A

Drum Ø:´38 mm (winding Ø

Winding travel: approx. 12 cm/revolution

Revolutions: approx. 2 – 5 (4 revs. with Futaba systems)

Torque: 100 Ncm corresponding to:´approx. 11 kg with 17.5 mm drum approx. 5.3 kg with 38 mm drum approx. 3.3 kg with 60 mm drum

Suitable for sail areas up to about 0.65 m 2 with the 38 mm drum.

Edited By Malcolm Frary on 11/12/2021 10:39:56

[geconParticipant @gecon]

I'm certainly not a winch expert. The only experience I have is from the Fisher 34 project when I had to find out if the whole idea was even feasable. My Comtessa kit yacht is fitted with the recommended closed drum winch from Krick which can almost certainly be 'ousted' by cheaper products from the UK.

I have noticed though, that the winch torque/power given for performance at 6v is usually the max voltage recommended. The prefered voltage is 4.8v-6v given that a fully charged Rx batt will produce more than 4.8v for a while. A fully charged 6v battery could damage the servo electrics. Some servos however can accept 6v +.

The winch servos in my Fisher have open drums and are mounted 'sideways' to reduce the risk of the lines dropping out the groove.

Servos with closed drums give more mounting-freedom and security in this respect -without having to use a guide tube etc.

George

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