Minuet Yachts: a 2m fun boat-can the design be improved?

Progress, Nov. 8 2014

Hey guys! All the glassing work is done, and the bottom paint is finished. I ordered 68 lbs of lead from Ebay yesterday, and will start working on the daggerboard/keel soon. Here is current progress. I'll be putting a single Hobie 16 rudder on the back.




I also got myself a 15 foot fiberglass windsurfer mast, and worked out my sail inventory. 7 sails total. Maximum 2 at a time. What do you guys think about the sail center of effort vs center of lateral resistance balance? The sail area looks a bit too forward to me.

Mainsail, working jib, and 2A spinnaker.

 

The main and jib look like they're just about right-definitely not too far forward. Keep having fun and good luck!

 

Phew, good. Glad it looks that way. I was a bit worried about it.

 

Can I ask why you went for the very high aspect main? They are great in their place but tend to work better on low-drag hulls like performance cats.

 

Sure!
3 reasons:

1. The boat is extremely slow because of low hull speed (4.5 mph), so I am trying to compensate for it by sailing closer to the wind, and as I understand it, high aspect ratio sails do that better.

2. I have a tall mast. (15 feet.) I have a short mast too, (7 feet) and a gaff rig for it, but that will not sail too well upwind, and I dont like the limited sail area from such a short mast. I sail a lot in very light winds (0-5 mph)

3. It looks cool.

The sail itself is not set in stone, I just have the mast for now, I haven't sewn the sail yet.
Would you recommend another rig?

Here are three production minuets with the production rig for comparison.

 

Here is a homebuilt wooden strip mini 12 (2.4m actually) build site that I stumbled on today. Perhaps it might be of interest to other people as well. Designed using Deftship. Very detailed build info.
I started a search after I saw the Illusion Regatta info on the Sailing Anarchy front page.
https://sites.google.com/site/gbr99diary/tips/home

I had no idea the information that is available such as the thread about the stitch and glue 2.4MR on this site in the design section. Also a lot of info about scratch building a 2.4MR on the 2.4MR class site. Hard or maybe not possible to find free lines or plans though.

 

Beautiful 2.4 meter-thanks!

 

That is one impressive 2.4 meter! I like it!

Doug, What do you think about this? Would you recommend another rig, especially since I'll have to sew the sails myself?

 

Almost everything about design is a compromise-if you lowered the main aspect ratio the CE would move aft and the boat would probably have too much weather helm. The disadvantage of such a high aspect main is that it is not as effective as a lower aspect sail off the wind but you have a spinnaker so that's not a worry, in my opinion. And it does look cool and will work fine. Now, this assumes that you've done the numbers and that you have plenty of righting moment. It also looks to me like you've included a reefing system in the design and that's good. I wouldn't change a thing at this point.
PS- that high aspect main would work well with a rotating section like on a Hobie Cat(not the actual section but the concept)-if you use a non-rotating straight section the flow on the sail will be badly messed up. I'd bring those reef points down one panel or have two sets.
Good Luck-and have fun!

 

You mean a rotating wing mast, like a Hobie has? I have a round windsurfer mast, and because It has no track, I'll have to attach the luff either with a sleeve and a zipper, or, more likely, hoops or loose lashing around the mast. I plan to attach a small block to a loop off the front of the mainsail to hold the head of the fractional headsails. I would need another loop at the top for my large drifter sails that are not fractional, and when I reef, the new head of the mainsail is at the perfect level to serve as the head of the fractional headsails. The only modification to the mast then would be a tiny block at the top for the main halyard, and the headsails are attached to the luff of the main.

Do you have any better ideas? I don't really like this system, but I think it could work just fine.

 

2.4m Plans and other info:
http://www.24mr.se/projects.html

 

--------------------------------
I'd tend toward using a bigger than normal sock luff(sleeve) but I'd get a sailmakers advice first. In the aeroSKIFF picture below the main has a sock luff with a zipper that allows reefing.It is set on a round non-rotating mast. With a high aspect ratio main, the way you handle the intersection with the mast is critical so don't hesitate to get a sailmakers advice.

 

Sorry for the late response.

As Doug has mentioned, high aspect rigs tend to not perform too well going downwind at wide angles of apparent wind, and in slow boats you often spend a fair bit of time going dead downwind.

Are you sure that you will be able to point high with this boat? Slow boats often don't point particularly high because the factors that make them slow (comparatively high drag, etc) also often force them to point low. There are obvious exceptions, such as the 2.4s that have popped up in this thread, but the fact that they point extremely well (they can beat a Vanguard 15/Laser type of boat upwind in the light stuff) with a very conventional rig which sort of underlines the fact that it's not the aspect ratio of the rig that is the limiting issue.

This could be related to the fact that (AIUI) the L/D ratio of the rig is not what counts - it's the L/D ratio of the rig and hull together. If you have a high drag hull (which the Minuet must be) you need a high lift rig, even if it gets it at the expense of high drag. We see this when people do things like swap rigs between high performance and low performance windsurfers, or when skiffs try A Class cat rigs - the high aspect/low drag rigs cannot push the draggier hulls around very well. You also notice this when a Laser and an International Canoe race in light winds - the supposedly inefficient low-aspect Laser rig is actually more effective downwind than the tall Canoe rig.

The balance of a tall rig in a boat that heels can also be problematic - effectively the driving force is being generated further to leeward away from the boat when it is heeled, which causes extra weather helm than if it was a lower rig. I don't know how to quantify this as I'm not a NA, but it's something you can really feel in many dinghies, and in windsurfers where you can separate the balance effects of the rig position from the balance effects of hull heel. Effectively, a tall high-aspect rig may not improve helm balance when compared to a lower rig where the C of E is further aft but also further inboard when heeled.

Personally I also prefer "soft" sails at low apparent wind speeds as they are much easier to read. This isn't conservatism as where I come from, full battens have been accepted in racing classes for many decades. One class I sail has switched to fully-battened mylar jibs and it's accepted that in drifters they are slower than the old and slightly smaller dacron jibs.

Finally, a high aspect big-roach rig tends to work better with flat sails (otherwise the leach hooks) and a more efficient mast; if you don't get flow over the first (say) foot of the sail behind the mast it's no big problem if you have a 7' long foot but it's a major problem if you have a 1' long foot! Obviously pocket luffs are an option but they are extremely hard to "read" in light winds, and can tend to make it difficult to change shape.

All of the above is just what I've gained from personal experience and listening to and reading those who know better. I'm just throwing out a few thoughts; it would actually be interesting to see how the very tall rig works.

 

So basically you're just criticizing the aspect ratio of the main only? What would you recommend for it? Lengthen the width of the whole sail? Switch to a different type, like a gaff rig? Just chop the mast shorter? I hate to do that though... Irreversible, and I need more sail area in light winds at high elevation.


Doug, do you think attaching the halyard block for the foresails straight to the zippered luff of the main is acceptable? Can you think of a better way to get a fractional sail on there?

 

No, not a good idea at all. On my rig I attached the shrouds about three feet below the top of the mast and left a hole on each side of the sock for the shrouds to get at the mast. When I stepped the mast it went into a receptacle in the deck to hold it up while it was rigged . My zipper was in the center of the sock-you could move it to one side just leave enough of a cutout for the sock to rotate. But again get a sailmakers advice on this if you can.
As long as you've done your numbers I'd go with your high aspect rig. Good Luck!