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Rooster 8.1 rig on Laser

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Pierre View Drop Down
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Post Options Post Options   Quote Pierre Quote  Post ReplyReply Direct Link To This Post Topic: Rooster 8.1 rig on Laser
    Posted: 28 Feb 07 at 11:57am

Good grief, until something happens untoward, then second guessing outcomes would appear somewhat pointless. 

There is no empiracle data to work from, or even any material data available, so who knows what will happen? Probably not very much.  Just top mast sections breaking as per usual.

Looks like a good idea to me, and far more likely to get the nod on the expenditure front from the family banker.

 

 

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Post Options Post Options   Quote Norbert Quote  Post ReplyReply Direct Link To This Post Posted: 28 Feb 07 at 10:52am
Originally posted by Adam MR 1137

The age of the boat will also come into play, due to the mast step losing some stiffness over the years and probably becoming more brittle aswell so the gust impacts may affect it more on an older hull.


But this will be of consequence regardless of which rig you use, standard rig or 8.1

Maybe Rooster could build a carbon/kevlar cassette to fit inside the mast step. Steve?
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Post Options Post Options   Quote Adam MR 1137 Quote  Post ReplyReply Direct Link To This Post Posted: 28 Feb 07 at 10:46am
No, beacuse when a gust hits a sailor who is fully hiked the boat heels therefore reducing the load on the rig! There would be momentary instant where the load would be greater before the boat has started heeling, however most materials can take much greater loads in short temporary stints than they could if the loading were permanent. The age of the boat will also come into play, due to the mast step losing some stiffness over the years and probably becoming more brittle aswell so the gust impacts may affect it more on an older hull.
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Post Options Post Options   Quote foaminatthedeck Quote  Post ReplyReply Direct Link To This Post Posted: 28 Feb 07 at 10:12am

[/QUOTE]

Once the helm is fully hiked the boat is at max load regardless of rig size ...

[/QUOTE]

no the max rig loads will be when the helm is fully hiked and there is a gust

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Post Options Post Options   Quote Guest Quote  Post ReplyReply Direct Link To This Post Posted: 28 Feb 07 at 8:38am

Originally posted by Jimbob

In my view Medway Maniac is oversimplifying the forces on the boat.
If a 16 st sailor were sailing an 8:1 rig upwind in steady wind 'A' fully blocked and fully hiked then he would be bound to put more stress on the boat and the mast foot than if he were sailing in a lesser wind 'B' since he would not be fully hiked in the latter. A normal 13 st sailor in wind 'A' would already have released his blocks and be luffing to reduce side forces.

Once the helm is fully hiked the boat is at max load regardless of rig size ...

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Post Options Post Options   Quote radixon Quote  Post ReplyReply Direct Link To This Post Posted: 28 Feb 07 at 7:50am
Can't wait to see it at the Dinghy Show.
Just out of interest Steve, have Laser Centre taken any interest or raised any concerns with you about this, or have they not seen it yet?
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Post Options Post Options   Quote Steve Cockerill Quote  Post ReplyReply Direct Link To This Post Posted: 28 Feb 07 at 7:16am

I think you Guy's are all talking lots of sense.  One more thought though, once a boat is planeing (never really sure how to spell that) the loads are reduced.  I always think of boat going through the transition from non planeing to planeing generating the most loads on the rig. 

We are considering providing a carbon top mast for the boat.  We have one for show at the Dinghy Show - its over half the weight of the aluminium version, and perhaps more responsive. 

Happy sailing - whatever you sail!

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Medway Maniac View Drop Down
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Post Options Post Options   Quote Medway Maniac Quote  Post ReplyReply Direct Link To This Post Posted: 28 Feb 07 at 12:59am

Originally posted by Jimbob

In my view Medway Maniac is oversimplifying the forces on the boat.
If a 16 st sailor were sailing an 8:1 rig upwind in steady wind 'A' fully blocked and fully hiked then he would be bound to put more stress on the boat and the mast foot than if he were sailing in a lesser wind 'B' since he would not be fully hiked in the latter. A normal 13 st sailor in wind 'A' would already have released his blocks and be luffing to reduce side forces.

That fits in with what I was saying. I suggest you re-read both my latest posts on this topic.


In the real world there are also gusts up to twice avge wind speed and there is inertia (of both the boat/rig system and sailor's mind). When the gust strikes there would be an immediate large increase in forces on the sail (and stressing moment at the mast foot) before the system and the sailor's brain started reacting to the increased forces by heeling, releasing main, and heading up. That is why masts get broken.

Surely those loads are a function of the inertia in the boat, which is largely down to the mass of the hiked sailor - a boat+sailor of zero mass would have zero inertia loading, whatever rig you put on it. Nonetheless, the heavier sailor will on average load the boat more heavily, which accords with what I've already said.

Whatever, you appear to be agreeing with my conclusion that the boat is potentially going to be more highly stressed by the bigger rig. For my money it's the off-wind loads that are likely to break the boat and mast.

 



Edited by Medway Maniac
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Jimbob View Drop Down
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Post Options Post Options   Quote Jimbob Quote  Post ReplyReply Direct Link To This Post Posted: 27 Feb 07 at 11:50pm
In my view Medway Maniac is oversimplifying the forces on the boat.
If a 16 st sailor were sailing an 8:1 rig upwind in steady wind 'A' fully blocked and fully hiked then he would be bound to put more stress on the boat and the mast foot than if he were sailing in a lesser wind 'B' since he would not be fully hiked in the latter. A normal 13 st sailor in wind 'A' would already have released his blocks and be luffing to reduce side forces.

In the real world there are also gusts up to twice avge wind speed and there is inertia (of both the boat/rig system and sailor's mind). When the gust strikes there would be an immediate large increase in forces on the sail (and stressing moment at the mast foot) before the system and the sailor's brain started reacting to the increased forces by heeling, releasing main, and heading up. That is why masts get broken.

Jimbob
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Post Options Post Options   Quote Adam.s Quote  Post ReplyReply Direct Link To This Post Posted: 27 Feb 07 at 7:05pm

Originally posted by Villan

You still have to catch the clew though!!

Good point whilst having it hit you round the head!

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