Pulley ratios.

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trebor
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Re: Pulley ratios.

Post by trebor » Fri Jan 23, 2015 10:16 pm

Hi Jim, I have googled sailing bridle images, their are dozens, I assume the bridle you mean would be similar to a Horse?
I would be concerned with rope dropping over centre board every time mainsheet went slack.
Hi jpa, The boat in question is a Minisprint mk 2, their is no where on floor for a ratchet block, plus I want a centre main not aft main or centre/aft main, you probably know the minisprint but here is a link to mine.
http://s1149.photobucket.com/user/aquab ... sort=3&o=3
Robert
Minisprint 4230
Tinker Traveller 160
Mirror 61147 Anastasia
http://www.aquabatdinghy.co.uk

JimC
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Re: Pulley ratios.

Post by JimC » Fri Jan 23, 2015 10:53 pm

trebor wrote:Hi Jim, I have googled sailing bridle images, their are dozens, I assume the bridle you mean would be similar to a Horse?
I would be concerned with rope dropping over centre board every time mainsheet went slack.
Surprisingly hard to find a decent image.

Image



This is with off the boom sheeting, which I'd always use anyway. Block and becket fixed to the meeting point of the strops, mainsheet goes up to a single block on the boom, down to the bridle again, and up to a ratchet and then to hand. Its 4:1 really. On the minisail you could probably lose a purchase.

I'm not sure why you'd be worried about rope dropping on the board area to be quite honest. The mainsheet rarely goes that slack, and the bridle means it usually drops well to leeward of the centreline.

You can probably rig up a trial with bits you have in stock to see how you get on.
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Last edited by JimC on Fri Jan 23, 2015 11:05 pm, edited 1 time in total.

Rupert
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Re: Pulley ratios.

Post by Rupert » Fri Jan 23, 2015 10:55 pm

With the stupidly long Minisail boom, getting one stiff enough, but not crazy heavy, so you can do centre sheeting, is going to be a problem. This is the reason they tend to be done Laser style, Laser style but without the last block (off boom) or aft main. Otherwise, you have very little control over the leech, as the boom simply bends. For a 10 foot long boom, the only way I could see it working without so much weight it feels horrible to sail would be to have a fairly large diameter carbon boom, which will cost more than the boat.

If you are doing things Laser style, then you only need a single rachet block in the boat. This has to be clear of the centreboard, of course, but maybe a bracket off the back of the seat moulding would work for it. You'll grow to hate a hoop as you crash into it when falling off the wing/seats.
Rupert

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trebor
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Re: Pulley ratios.

Post by trebor » Sat Jan 24, 2015 10:48 am

Theirs nothing simple.
I have a lot to think about.
Strop or hoop, I have tried off the boom sheeting, did not like it.
Centre/aft always dropping over something.
Aft main not enough experience to comment (probably simplest though).
Centre main, like this.
I am currently running Aquabat with centre main, that was the photo for ratio question, the boom on Aquabat is longer than Minisail by about 6", (the boom is 60mm the mast is 55mm), I set it up like this to trial centre main for the Minisprint.
Robert
Minisprint 4230
Tinker Traveller 160
Mirror 61147 Anastasia
http://www.aquabatdinghy.co.uk

Rupert
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Re: Pulley ratios.

Post by Rupert » Sat Jan 24, 2015 9:06 pm

I guess if you use less kicker and mainsheet tension than I do (I tend to push boats very hard to get the last bit of speed out of them) then you'll put less pressure on the boom, so whether aft or centre main will make less difference, as the leech won't be as closed anyway.
Rupert

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trebor
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Re: Pulley ratios.

Post by trebor » Sat Jan 24, 2015 10:18 pm

Hi Rupert, I have bit the bullet and brought a two hander, an Enterprise, Aft rigged, should get some practice now.
The Aquabat does not seem to mind centre main, (so far), I do not thrash it though, so the issues raised would probably not show up, what would happen if someone thrashed round a race course though is another matter.
I may try Aft rigging on Minisprint if I can get on with it.
Robert
Minisprint 4230
Tinker Traveller 160
Mirror 61147 Anastasia
http://www.aquabatdinghy.co.uk

Rupert
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Re: Pulley ratios.

Post by Rupert » Sun Jan 25, 2015 5:46 pm

Don't forget, front foot across first when tacking, so you face aft! Congrats, great boats.
Rupert

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trebor
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Re: Pulley ratios.

Post by trebor » Sun Jan 25, 2015 7:38 pm

The neumonic I was taught on RYA level 2 was TCP, trap change push, so add to that FFF, front foot first = TCPFFF, here comes a steep learning curve :D
Robert
Minisprint 4230
Tinker Traveller 160
Mirror 61147 Anastasia
http://www.aquabatdinghy.co.uk

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