Re: Super Maramu Main Mast Furling foil Sheered


ngtnewington Newington
 

In my opinion you may be able to drop the whole thing down about 10 cm or whatever the depth of the gear, if necessary you could shorten the top lashing between the sail and the top bearing. But to strengthen the foil I would try and source an internal bushing that slides snugly up the foil. This would spread the load. There is quite a lot of torque onto that foil when furling the sail all concentrated at the bottom. To simply use the foil alone may not last very long.
What material should the bushing be? If it is perfectly round then the obvious choice is aluminium, machined to fit, but it could be some kind of composite material or even in a pinch, for an at sea fix  a piece of hardwood until a machine shop is found. 

Nick

Amelia AML 54-019

Kilada Greece

On 27 Jan 2020, at 08:24, Danny and Yvonne SIMMS <simms@...> wrote:

Hi Graham,

I would say you are fine to drill a new hole and drop the foil. As to cause I will lay odds that the  bearings in rhe swivel at the top are full of salt making it hard to turn and that extra load directly contributed to that failure.

Regards

Danny

SM 299

Ocean Pearl

On 27 January 2020 at 15:28 "Graham Boyd via Groups.Io" <crwggb@...> wrote: 

SM Main mast furler foil sheered at base just above the gear box (see pictures).

This metal fatigue event rather spoilt our Chinese NY cruise yesterday. The actual sheer occurred when furling the sail head to wind in 15 kts of wind. 

Has anyone else suffered this failure? If so what was the fix?

I understand from this site that the top of the foil in the mast is unsupported. This makes me wonder if there is sufficient "extra" length of foil in the mast to just drill new holes in the foil above the sheer line and drop it back into the gear box. Would the swivel then "fall off the top" of the foil when the sail is hoisted? Failing that extending the foil at the top to support the swivel with the sail up could be the answer.

Any thoughts/experiences welcome!

Graham
SM140 Sula
Hong Kong

jj

Join main@AmelYachtOwners.groups.io to automatically receive all group messages.