Sail servo

[David Aitken 1Participant @davidaitken1]

Hi looking for help I have a kyosho seawind 2nd hand it’s been lying about for a while the sail arm servo has stopped working it’s a hitec hs715bb sail arm and I want to replace it with something the same but not to expensive I have looked on ebay but don’t know what one I looked at one with 20kg torque and 180 degrees but the I have is only 90 degrees turn help please

[David Aitken 1Participant @davidaitken1]

Help

[Gareth JonesParticipant @garethjones79649]

HI David,

I think the best fit would be a Hitec HS765HB sail arm servo. It is almost the same size or perhaps very slightly shorter in length and has the near enough the same torque as the HS715BB and the same arm length. The principal difference is the travel is greater at 140 degrees rather than 90. Your options to reduce the travel would be to adjust it within your transmitter, if it has that capability, or use a device such as a Servomorph, available from Component Shop. The Servomorph allows you to adjust the range and speed of a servo. You would need to find space inside the hull, but they are not very big.

Gareth

[Malcolm FraryParticipant @malcolmfrary95515]

Greater travel for the same stick movement is rarely a problem, depending on the original string layout. On most boats designed with 90 degrees in mind, the line runs through the arm end and doubles back to a bulkhead, increasing travel but reducing torque. A longer arm or one with more travel just needs connecting direct to the arm. This assumes that there is room inside the boat for the greater travel. Alternatively, shorten the arm.

Or my favoured solution, use one of the small drum winch servos. Same size as a standard servo, lots of pull, usually costs less than a sail arm servo, easier to mount.

Either way, first thing is to determine the actual travel needed, then start looking for solutions.

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