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Old 02-27-2017, 11:36 AM
OllyP123 OllyP123 is offline
 
Join Date: Feb 2017
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Location: london
Optimist with Topsail and spinnaker - Extra sail area

Hi

The optimist is the only dinghy we can take on our yacht however I have slightly grown out of it. I would like to put on a spinnaker, which has been done before. Also I would like to increase the sail area. To do I think that the best method would be to make a topsail with just over 1 meter square sail area. I thought I would attach a pole to the top of the mast and fill in the gap between the sprit and the pole but also go up a little bit higher.

I think I would have to rake the mast back massively or it would be extremely unbalanced so I will have the top sail tie of the normal sail attached around the pole or I won't fit under the boom.

Firstly will there be any issues in how the sail is balanced even when it is raked fully back? Also how would I work out the camber ratio and draft position for the topsail. Would I just make it like a normal sail except it is just a different shape or would I have to factor in other things. Also what would be an appropriate topsail size for a 60-80kg sailer?

Thanks in advance

Olly
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  #2  
Old 03-01-2017, 06:58 PM
messabout messabout is offline
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Join Date: Jan 2006
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Location: Lakeland Fl USA
If you add a topsail, do you not need to increase the height of the mast? If you are going to make the mast longer, why not just have a sprit sail with a longer luff? That way the center of effort will not move much if any.

There is a practical limit to how fast you can make an Opti go. If you add power beyond that which the little boat can use..... you have not gained much, if anything, aside from the satisfaction of having exceeded the bounds of practicality.

As you say, you have outgrown the boat. If that is to be taken to mean an increase in the skippers weight, then there are some arguments that you can make about power to weight ratio which also has its limitations in a boat like the Opti.
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  #3  
Old 03-01-2017, 07:12 PM
Munter Munter is offline
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Join Date: Jul 2007
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Location: Australia
The Opti already has a tendency to push the nose in. Adding sail up high will accentuate that when sailing downwind. The effect on other points of sail will depend a lot on how the extra rag is set, eg the tightness of the leech, the amount of twist etc.
Also - be careful you don't overload the mast gate and mast foot - without stays to take the load these two areas will be carrying more load than usual.
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