Day Sailer Genoa Jib

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Day Sailer Genoa Jib

Postby diesel » Wed Sep 02, 2020 11:31 am

Have read several posts by owners who have flown a genoa on their Day Sailer 3's from the late 1990's . Anyone using one now ? dimensions? will the boat sail up wind on genoa alone?
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Re: Day Sailer Genoa Jib

Postby tomodda » Wed Sep 02, 2020 1:34 pm

Jenny ALONE? Can you imagine the lee helm you'd suffer? Methinks you'd better raise your main as well.

Anyway, I'm assuming that by Genoa you mean a sail that is hanked to the forestay and is bigger than 100% of the fore triangle, say 110% or so. I've see on this forum and other internet sites where folks are flying asymmetrical spinnakers, but those fly free of the forestay. And foreward of the forestay, usually on a short sprit to keep it clear. So, for a true Jenny, you have a large triangle, with some overlap of the main. You'd have to get it custom made, so really can't tell you re: dimensions... but, roughly speaking, in standard IJP dimensions - I (the luff) continues to be 16 feet, J (the foot) will be 10% or so more than the distance from the forestay to the mast, and P (the leach) is - do the trig.

Hopefully, this answers your questions, but I have a question for you - why? What are you trying to do with a Genoa? It's not necessarily the best solution, I've not seen many true Jenny's for a fractional rig and certainly not on a small boat. Asyms probably make more sense, I've been kicking that around in my own mind for low wind (which I get a lot of)!


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Re: Day Sailer Genoa Jib

Postby GreenLake » Wed Sep 02, 2020 1:37 pm

Welcome to the forum!

Many people who don't race their DaySailers have experimented with flying other types of headsails than the standard DaySailer jib. That's not limited to the DaySailer III, and the experiences of people with other types of DaySailer in terms of this particular topic should fully applicable to your boat.

One popular sail that's been discussed here more recently is the Doyle UPS which is a sail that appears to be something in between an asymmetric spinnaker and a code zero. Dimensions are individual. Some people fly it like a genoa, on the forestay, some people have rigged a small bowsprit where they mount it on a furler ahead of the standard jib. While it appears to be usable as an upwind sail in some conditions (not sure I remember offhand how high you could point with it), my understanding is that it would be used with the main. Not by itself.

You might check on suggested dimensions used by those who fly this from the standard head stay; you should be able to find that in one of the discussions of the Doyle UPS.

I would be skeptical that you could balance your boat upwind under a genoa alone. The centerboard is, what, about two feet behind the mast. In order to balance the boat, the "center of effort" for your sail plan would have to be somewhere above that point. For a single sail, a rough approximation of the center of effort would be the midpoint of the sail, or the point where the lines from the middle of each side to the opposite corner meet. You can see that even with a rather generous 155% overlap your center of effort will stay forward of the mast, meaning that your sail will want to drive the bow down unless paired with a main that drives the bow up.

Since the 1990's we've reorganized the forum and now have section that's dedicated to the discussion of sails and sail plans. I've moved your topic there where it may have a better chance to be noticed. However, not all threads stick to a single topic and some people might have discussed issues like this under Rigging or Improvements. So use the search function to look for the Doyle UPS, for example.
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Re: Day Sailer Genoa Jib

Postby AndrewB » Wed Sep 23, 2020 2:51 pm

diesel wrote:Have read several posts by owners who have flown a genoa on their Day Sailer 3's from the late 1990's . Anyone using one now ? dimensions? will the boat sail up wind on genoa alone?

I posted in another string related to Asymmetrical Spinnakers but will provide the dimensions here for you just in case. The sail I bought was listed as a Drifter sail and was sold used on Masthead Sailing Gear. It's basically a lightweight Genoa. If the standard J measurement for a DS is 6' then I'm calculating this as a 150% sail. The boat will sail upwind with this setup, but as the others have mentioned you'd probably want the mainsail up. Haven't tried sailing it without the main

Luff 14'9", Leech 15'1", Foot 8'10", LP 8'7" (1.5-oz Nylon and has a luff rope w/snaps)

With the way the sail is built it would be easy to sail in place of a jib if you are using a forestay setup without a furler--simply snap it to the forestay and off you go. My boat has a furler, so I had to find another way to rig up the Drifter.
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