Sunday, March 8, 2009

More Mast Rake

It seemed to me on the last trial that the boat wanted more weather helm when on the wind. (There really wasn't any at all.) I spoke with Matt about this and he suggested more mast rake via moving the step. I planned for this adjustment and have not permanently fixed the step yet. It is secured temporarily by a single bolt. I moved the step 75mm forward, which seems like alot but I didn't want an ambivalent result. Here is a photo at anchor. Compare with the prior post. Sailing in 15 plus knots, all points, over and under powered. With this rake the boat rounds up on her own when overpowered, but it does it in well-behaved way, then will bear off again once the gust passes. All a good thing, in my view but will see what Matt has to say. I may try a mid-point and see if I like that better. The boat tracks well on most points, especially on a beat and in a consistent breeze. With this ballast (~270 lbs of water in 5 gallon cube shaped jugs), she is remarkably stiff once heeled as long as one sits on bottom. In moderate (underpowered) conditions, a helm seat (eyes above cabin combing) works great.


boldav said...
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boldav said...

ENIGMA'S mast is heavily raked back I think to increase the overall length of the cabin space and to balance the boat so that it rounds up in the wind. It looks to me that the increased rake in FANTASMA'S mast now should do the same.

By the way, I was generally pleased with using sand as ballast aboard ENIGMA in Cedar Key last year since it is 60%-92% denser than water. Unpacked dry sand is 1600 kg/m3, unpacked wet sand 1922kg/m3, salt water 1000kg/m3. However, now I've moved on to less environmentally friendly lead (11,350 kg/m3) to save more space and really get the ballast down low.

By the way, FANTASMA looks great!

Anders said...

Hi, I guess you follow Sven Yrvinds project up in Sweden. He has just made a 126 kilos bronze keel for his boat.

Now, for the Enigma, you guys use lead, sand or water as ballast. Is it critical to be able to move the weight around or should you have more weight in certain places, like near the chines or near the mast foot? Could you for instance mount steel plates on the inside bottom of the boat? I guess it would provide more ruggedness and even distribution of weight.

I can't quite get my head around the boat's ability to withstand the forces of the wind with its flat bottom. It would be helpfull if you could write a few words on the theory of ballasting this boat...