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Old Dec 04, 2010, 07:01 AM
delaneyp is offline
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1915 Schooner Mariette
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Sydney, NSW, Australia
Joined Feb 2008
243 Posts
Ray, don't undersell yourself - anyone who can build a ship as detailed and beautiful as Surprise (and get it to actually sail) is an engineer in my books !

Dan, the RMG Smartwinch is quite a beast - it will pull 18A at a stall torque of about 30 Kg-cm - but, it will only do this for a short time before automatically shutting down to prevent thermal damage. Moving the stick back resets the winch & off you go again !

You are quite right in pointing out that "knock-downs" result in the max current draw - my initial intent with the model was to just look at an overall average current draw for a typical sailing session, & 3A to 5A "average" looks realistic in 20kph winds.

Your comments about blown fuses & servos got me thinking about worst case knock-downs - the model predicts an 80deg heel angle at a wind speed of over 100kph, & this results in a total current draw of about 7A-8A for the worst-case mainsail winch. As this is under 50% of the max stall current, I am reasonably comfortable that we won't have a winch melt-down (specially considering the self-protection features of the winch).

Well, that's my theory - but at least its a starting point ! Reality may well prove to be a little different !

Kind Regards,

Peter D.
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