Minifish with Mistral 6.0 windsurf sail

MtlNdo

MtlNdo

Member
I recently bought a Mistral 6.0 windsurd sail. It is in excellent shape. With it I also got a 15 foot fibreglass mast.
I have embarked on a project of converting this windsurf sail into an alternate High Aspect style sail for my minifish.

For less that $14 I have purchased an 8 foot Polished Aluminum 1inch diameter rod at the local hardware store. It has thick walls and is very stiff.
This will become my boom
I am having a wood turner make a 40 inch hard wood mast extension with the top fitting into the windsurf mast while the bottom will fit into our standard 2 1/4 mast hole openings. I have purchased a laser 2 Gooseneck which I will fix to the hardwood mast extension. It pivots both horizontally and vertically.

I have picked up a couple of harken blocks.
I will need to install a few more Grommets into the bottom of this sail.

This sail is about the size on a laser radial sale yet my mini only weighs 80 pounds compared to a laser's 130.

Should I not see a significant speed increase?

Any other issue that you think I should aware of.
Have any of you tried such a project before.

I will also track any speed advantages with my GPS and report.
I will post pictures once this project is complete.

Thank you
 
Everything Old is New Again
 

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I am almost certain that you fill find that the boom ends up too high so that when you sheet in, the load is primarily in the downward direction. In order to sheet in tight, you will be pulling down so hard on the boom end that you will either break the mast or break the mast step, or distort the sail so much it will look (and feel) like crap. I have experience with this idea from using windsurfing sails on lockley skimmer iceboats. What we ended up doing is welding some two foot tubes onto the end of the runner "plank" and sheeting from the ends of top ends of the tube. This substantially changed the sheeting angle. A 1:1 sheet with a ratchet block worked fine. The skimmers FLY with a windsurf rig.

Not sure how you can do this on a minifish....its too skinny. Think about windsurfing....you pull the sail in, not down. Leech tension is not controlled by sheet (arm) tension as in a typical sailboat.

Good luck and post pics.
 
First, I agree with what Tim says. I think there may be another problem too, but the solution might help fix both problems.

I believe the center of effort (CE) of the windsurfing sail is going to be further forward than the standard Minifish sail. This would lead to lee helm (you would have to push the tiller away from you to go straight.) To fix this, you would want to have the windsurfer sail tipped back to move the CE back. To do this, the lower mast you are making to stick in the deck could be bent, just like on a Laser 4.7, which has a bent mast to move the CE back. Now that the mast is bent, the clew won't be so high up. Perhaps you could build a 3 legged pyramid on the back deck with the top of the pyramid at the same height as the clew.

Also, not sure why you need grommets installed in the windsurf sail. Just have the boom be loose-footed, attached only at the gooseneck and the clew.

Looking fwd to pictures and reports! BB
 
Re:Minifish/Mistral 64 sq.ft windsurf sail set new speed

After measuring my speed on 5 different days (including yesterday) on the standard minifish sail, the max speed I was able to reach was only 5.7 miles per hour as measured my Garmin nuvi 250. Our lake is small (½ mile long) and set high in the mountains and so wind conditions are not constant on the lake.
Well yesterday after only 20 minutes in the water with my new Mistral rig (64.5 square feet) I hit 7.5miles per hour. It was a fast fun ride. It was a more performance than I was used to from minifish. Please see my pics below.

Some notes to our loyal sunfish forum veterans who wrote me back.
I want to thank you Dan, Tim and Beldar for giving me things to consider.

Your advice has been very helpful in this project of mine.
I have only been sailing for a year now and love both my sunfish and my minifish, yet I had never modified the sail rigs before.
I had no clew that a minifish II even existed.
Same with the concept of CE. I found that my 15 foot tapered fibreglass mast bent quite a bit and so that allowed the sail to move back enough to motor me forward at fun speeds.
I had to cut the mast extension down to 29 inches as 40 was just too high.
Beldar said “have the boom be loose-footed” and I listened…I had no clew that this would work. Thank you again.

Also by painting the aluminium boom and the wood mast extension gloss black to match the mast , this rig looks really good.

Thank you again all.
mtlndo
 

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Neat!

PS: You might go faster if you sit a bit more towards the front. From the pictures it looks like the stern is dragging.
 
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