tag:blogger.com,1999:blog-3209493946963010404.post6305207644305164854..comments2024-02-25T10:43:07.698+13:00Comments on STREAM OF CONSCIOUSNESS: ______________ LENGTHENING A ZEPHYRS CENTERBOARD _____________ Alden Smithhttp://www.blogger.com/profile/06601028197387499096noreply@blogger.comBlogger6125tag:blogger.com,1999:blog-3209493946963010404.post-19628625815545618692017-02-24T21:13:09.987+13:002017-02-24T21:13:09.987+13:00Max, you are quite right. It is a dagger board not...Max, you are quite right. It is a dagger board not a centerboard. Pivoting boards are not all that common in NZ - the OK Dinghy and Finn being the exception - so the terms seem to have become interchangeable over the years.<br /><br />Personally I like the pivoting board as it is a hell of a lot more forgiving - dagger boards have a rather abrupt way of indicating you have hit the bottom.Alden Smithhttps://www.blogger.com/profile/06601028197387499096noreply@blogger.comtag:blogger.com,1999:blog-3209493946963010404.post-19588243165160064902017-02-24T21:01:17.972+13:002017-02-24T21:01:17.972+13:00Presumably it's a daggerboard, over here a cen...Presumably it's a daggerboard, over here a centreboard is a pivoting board v's a daggerboard which slides up and down vertically (like a laser, optimist etc).<br /><br />Whatever it's called looks like you did a good job.<br /><br />MaxBursledon Bloggerhttps://www.blogger.com/profile/14020592383830135476noreply@blogger.comtag:blogger.com,1999:blog-3209493946963010404.post-37117463860420644052017-02-22T22:35:10.281+13:002017-02-22T22:35:10.281+13:00Yes, the maximum allowed length - which is 1370mm,...Yes, the maximum allowed length - which is 1370mm, which makes for quite a long centerboard.<br /><br />As the centerboard is made of wood it has positive flotation which means it can have a tendency to float upwards a little when sailing. To stop that happening I have a length of elastic 'bungy cord' which I loop over the top centerboard to stop it floating up. When sailing downwind I quickly take the loop off so that I can raise the centerboard vertically and reduce drag.Alden Smithhttps://www.blogger.com/profile/06601028197387499096noreply@blogger.comtag:blogger.com,1999:blog-3209493946963010404.post-17584479420870106222017-02-22T20:29:30.953+13:002017-02-22T20:29:30.953+13:00All right! Therefore you want to have the maximum ...All right! Therefore you want to have the maximum allowed length of centreboard.<br />Did not know that you could use different positions. Thought that the centreboard would pop out when not fully downward.<br />Interesting. As a racer you not only have to trim the sails but also the centreboard.<br />Benhttps://www.blogger.com/profile/16337494349546448043noreply@blogger.comtag:blogger.com,1999:blog-3209493946963010404.post-66131623458122134802017-02-22T17:41:22.314+13:002017-02-22T17:41:22.314+13:00Ben, you are quite correct that with underwater ar...Ben, you are quite correct that with underwater areas where racing is concerned there will always be a balance to be found between 'lift' and 'drag'(friction). <br /><br />This 'lift' and 'drag' compromise is more of a factor for the designer in a yacht with a fixed keel because the amount of keel area cannot be altered. <br /><br />In a centerboard sailing dinghy the centerboard can be kept down when sailing to windward (into the wind) to make use of the full area of the centerboard and providing maximum lift - but - when sailing downwind the centerboard can be pulled up to reduce drag. This is what I do when racing 'Slipstream' :<br /><br />- Centerboard fully down when sailing to windward. <br /><br />- Halfway up when running downwind with the mains'l 90 degrees to the wind direction.<br /><br />- Partially up when sailing on a beam reach.<br /><br />Judgement that comes with experience is used when deciding how much to pull the centerboard up when sailing off the wind especially in fresh conditions because the amount of 'grip' in the water that the centerboard gives provides direction for steering and balance to keep the boat upright.<br /><br /><br />Alden Smithhttps://www.blogger.com/profile/06601028197387499096noreply@blogger.comtag:blogger.com,1999:blog-3209493946963010404.post-56348595525828283622017-02-22T01:26:34.737+13:002017-02-22T01:26:34.737+13:00Hi Alden,
I can’t help thinking this is too coinci...Hi Alden,<br />I can’t help thinking this is too coincidental. Aren’t you overlooking something? May be the design of a centreboard is optimized for different situations. I know that a longer centreboard of the same width creates more “lift”, so that you can sail closer to the wind. However it creates also more drag, that slows you down. You win perhaps at close hauled but loose at beam reach? Personally I would have liked to test at least two centreboards of different length and measure the performance. The outcome could be that you take different centreboards for different race conditions and routes. Although not a sailor, I like experiments :-), as you know.<br />Benhttps://www.blogger.com/profile/16337494349546448043noreply@blogger.com