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Increasing mast rake in stronger winds

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Barty View Drop Down
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Post Options Post Options   Quote Barty Quote  Post ReplyReply Direct Link To This Post Posted: 04 Jan 05 at 3:07pm

After extensive testing we have found that mast rake on the Playmobil Catamaran makes little difference in performance.

Can anyone confirm this?

[see 'Playmobil Review' topic under For the Magazine]

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Andi View Drop Down
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Post Options Post Options   Quote Andi Quote  Post ReplyReply Direct Link To This Post Posted: 17 Nov 04 at 4:04pm

I like the sound of this but our shroud terminals have only a round hole the same diameter as the pin.  I will have to see if we can get some shrouds made up with the same terminal as yours - our system works securely for on the water rig changes but it is a fiddle in choppy water trying to line up the pin with the hole.

- Andi 

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redback View Drop Down
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Post Options Post Options   Quote redback Quote  Post ReplyReply Direct Link To This Post Posted: 17 Nov 04 at 12:09am
Hi Andi.  You'll find you can get two pins through the eye of the shrouds, one above the other.  Hence if you slaken the rig and pull the bottom one out the mast will rake further forward, and there's no danger of losing the rig over the side.  It can be done whilst afloat.
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Post Options Post Options   Quote Andi Quote  Post ReplyReply Direct Link To This Post Posted: 16 Nov 04 at 5:55pm

I like the sound of but don't understand the two pins idea.  We use two pins but the upper one is there only as a retainer to trap the wider part of shroud terminal in place - I wouldn't like to rely on a fully tensioned shroud staying in place - the pin might bend a bit.  What type of chain plate and shroud terminal do you have?

I have started raking the rig again in the mental winds we have been having through Sept/Oct.  I do this ONLY to achieve an open upper jib leach as the RS200 jib tracks are basically in the wrong place and don't go far enough aft.

With a single sail like a Phantom dumping forestay tension sounds like an excellent idea as a means of increasing rake ( no jib luff to worry about )  Reduced mast support at spreader height should allow windward bend and the upper mast to fall off ( even more than the ( you lucky sods) carbon stick would normally do. 

   - Andi

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Post Options Post Options   Quote redback Quote  Post ReplyReply Direct Link To This Post Posted: 16 Nov 04 at 12:35am
Yes it is difficult but here's a cunning plan.  In strong winds put 2 pins through the end of the shrouds and this gives the extra a rake.  If the wind dies off whilst afloat you can then ease the rig tension, pull out the bottom pins and retension. And hey presto the rake is reduced and no danger of losing the rig over the side.  We don't worry too much about too much rake ruining our off wind performance since we bang up our 18m gennaker.
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Post Options Post Options   Quote PhantomHelm Quote  Post ReplyReply Direct Link To This Post Posted: 14 Nov 04 at 5:07pm
Yes, you can do that but it's a hell of a lot more difficult to do on the water!  What I usually try to do it drop the mast back on an adjustable forestay when beating, and then retension the rig when reaching for maximum power.  Difficult to do this by adjusting the position of chain plates/stay adjusters.
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Post Options Post Options   Quote redback Quote  Post ReplyReply Direct Link To This Post Posted: 13 Nov 04 at 11:01pm

Originally posted by PhantomHelm

I thought the idea was that dropping the mast back reduces rig tension, allowing the mast to bend off sidewards in gusts and hence depowering?

I've tried that and it works a bit, but in my class we move the pins for the shrouds and retension to get the same rig tension and that works even better.

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Post Options Post Options   Quote PhantomHelm Quote  Post ReplyReply Direct Link To This Post Posted: 07 Nov 04 at 5:58pm
I thought the idea was that dropping the mast back reduces rig tension, allowing the mast to bend off sidewards in gusts and hence depowering?
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Post Options Post Options   Quote Andi Quote  Post ReplyReply Direct Link To This Post Posted: 18 Sep 04 at 8:31am

IWe had a Topper Spice twin trapeze for a while and yes; mainsheet tension and no kicker and we had way too much power in 10mph wind.

I can see that on boats with stiffer masts and kicker not mounted on the mast ( ours practically is ) (and probably with a less neutral spreader setting than we use) the increase of mast rake does cause various secondary changes:  lower shrouds slacken, spreaders induce more pre-bend, jib leads effectively move up and aft.  Kicker not on the mast like in an Ent is good because you get more jib luff wire tension when you use kicker ( especially if you have stiff mast which doesn't counteract all the extra luff tension by bending so much that it slackens the shrouds and hence the jib luff.

   - Andi

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Post Options Post Options   Quote redback Quote  Post ReplyReply Direct Link To This Post Posted: 17 Sep 04 at 6:27pm

On my boat (L4000) I have lower shrouds and therefore rake is a quick way of adjusting them.  When I rake the mast back it opens the jib leech and eases the lowers.  It barely affects mast bend aloft.  We have discussed the benefits of opening the jib leech but easing the lowers is doubly beneficial.  1. eased lowers allow more mast bend and this flattens the mainsail and makes the slot wider.  2. eased lowers makes the rig more flexible, it has a more springy feel and this help absorb the gusts which are more violent in windy weather.  Indeed I find the boat goes better even in gusty light winds with eased lowers (which I ease by moving the pins).  It doesn't point as well though and it is less powerfull, but it accelerates much better.

Talking of flexible rigs.  You can get the same mainsail leech tension in two ways. 1. kicker, 2. mainsheet.  Using kicker gives a more accelerative rig more able to respond automatically to gust, less powerfull ultimately but makes life a lot easier for the crew since they don't have to move around so fast.  With the kicker slack and main used for leech tension the helm has to play the main a lot since the boat is less forgiving and the crew is in and out like a yo-yo, however the boat will feel more powerfull in the gusts.  Combine this with mast rake and changing the tension of the lowers and you have a fair few variables to get wrong.

On my boat it is possible to have an upright mast, tight lowers and leech tension by mainsheet and in any sort of gust the boat produces massive heeling force (even in a F2), the crew goes out on the wire, the centerboard stalls and the whole lot starts going sideway.  Those with a more forgiving rig simply sail away from you. 

I remember crewing a RS800 on several occasions when we were already moving with speed and the helm pulled the main in too far.  The boat slowed so quickly it felt like you'd sailed over a mooring warp, it then went into irons and we went swimming.

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