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

Not quite, LOA includes bowsprits
LWL doesn't

 

RC,
Nice job! You sure are going to a lot of trouble to make the boat look like a miniature cruising keel boat. I am wondering if you have fully considered the performance cost of making one thing look like another. Your sail plan is classic performance cruiser, but on an unstayed rig I can't imagine the high aspect jib having a useful shape up wind with no forestay tension. The fractional rig has no purpose since there is no backstay to bend the mast. The main sail also looks much closer to the triangle of a common backstay rig than your first boat -why give up the square top?

My suggestion is that you take a look at the sail plans of Freedom 21, 25, and 29 yachts. They are all unstayed rigs with a huge main with lots of roach and spinnakers on a loose pole across the foot. If you map out the sails for wind speed and angle I think you will find this is a fantastic rig. A lone main is best upwind and the pole allows the spinnaker to be pulled back overlapping (for light upwind like a big Genoa) or forward and past the center like a long articulating bowsprit downwind or reaching -but there's no bowsprit lengthening the hull. The semi-catboat hull shape would be attractive at your scale as it allows more weight aft that can move off center for righting.

https://www.youtube.com/watch?v=Mx7bMnQgRoY

I know this is pretty far off of what you are drawing but I think it makes sense with what worked on your first boat. If you stay with your current plan I would at least keep the square top main and leave room for running back stays in the future -I think you will want them.

Your project has inspired me to mess around with a super small sailboat but with completely different goals. I am just trying to add sailing capability to a kayak without interfering with paddling. Since the sail does not need to work in wind under 7mph I can keep the rig small. It's just a cheap WaterQuest10 with a roller Genoa (will try other sails). So far the findings are
-roller furl works but is less useful than hoped partially furled
-low aspect foils are more desirable on low speed boats
-definitely need lee board, peddle steering, and a boom for sheeting past the edge of the narrow boat.

I am wondering how our hulls compare -what is your beam? Mine is about 30 inches, 250lb rated capacity or about 300lb displacement max but I will be about 220lbs total with the 40lb boat.

 

Thanks! The biggest problem is I'm trying to keep the rig as far forward as possible, and carry as much sail up front as possible. I ditched most of the squaretop since I had a hard time with the shape up top-too flat. I could give it another go though. I've had a hard time getting a good mainsail shape with the sails I've made, and had a lot more power from the headsails, so I'm extremely reluctant to give up on headsails, because they are so easy to get reasonably good results from. You bring up a good point about the lack of luff tension on the headsail. On my first pocket yacht, the 11 foot steel mast is so stiff that I can get plenty of luff tension to get it really flat. The new one will use a fiberglass mast so it will be a lot more flexible, and may have a lot more sag. I can account for some of that in the cut of the sails, but I may need to move the head of the jib lower on the mast to get more tension on a stiffer part. (It's a tapered mast)

PS: I really like that video you sent. That's a sweet setup. I'm afraid I would screw up the mainsail shape too much for it to work well though.

 

Are you calculating the sail centre effort using 100% of the foresail? I have read some reports that that area that is overlapped shouldn't be counted. though I'm no expert so maybe some who are could enlighten us on that one. Also many Norfolk broads boats have a small foresail, going to a foresail that had no overlap would allow you to have a self tacking arrangement making sailing much easier single handed.

 

I'm eyeballing it based on the entire sail. I could calculate it more exactly, that would probably be a good idea. I'm still mostly focusing on the hull design right now. The exact position of the keel, rudder, and the rig design will be next. I'd like the self-tacking feature, but I don't want it's limitations. On the first version, I can't use one because the keel lifts into the foretriangle, and I really really like being able to switch out headsails and reef the main while underway, seated in the cockpit. I also really like the extra sail area. In 3-5 mph of wind I'm at about 3/4ths of the speed of a fleet of lasers. Once the wind picks up I have to reef down and I am about even with an Opti in speed.

 

When doing the area calculations for the jib or any wire or "flown" sail, you measure the "fore triangle", not the actual sail. The fore triangle is the height of the hoist, times 1/2 of the perpendicular to its base (at the tack).

 

How about trying a roller reefing head sail?

 

Furling is definitely on the list! I think I might do like the VO65s do, and have a furling setup I can hoist, maybe a thin piece of flexible tubing running up the luff to twist the sail.

 

The Yeoman (20Ft Bermudan open sailing boat) I sail in the winter, has a carbon fibre tube running over the wire in it's luff bolted to the top of the roller reefing drum . It has made reefing and furling a lot easier, as the owner used the original sail, we get a little distortion at the top of the jib / genoa. However when he eventually gets a new sail made, it will be made for the job and not have the problem.
This was done professionally, fitting and remaking to sail to fit over the tube cost £500, But I think your skills will do that a lot cheaper.!!

 

LOA traditionally/generally does not include spars such as bowsprits but modern usage seems to be heading that way.

 

Regarding "keeping the rig as far forward as possible" I think that you should have a model for the skipper -2/3 of the displacement and a huge factor in operation.

https://grabcad.com/library/manikin

Next I think you need to abandon the 'rules' of full sized displacement boats and go with a rough free body diagram with a check of proportions on boats from RC pond models to AC12s up to "real" keel boats of 6 to 10M. Due to differences in the relative reynolds numbers (air and water) the smaller the boat the larger the water foils relative to sail area. The lower water speed also makes stall more likely (favoring lower aspect ratio) and rudder balance irrelevant. Personally I would not balance the rudder and might even sweep it back to get more 'feel' and ability to avoid stall. Trying to achieve balance with a target 'lead' is a fool's errand by my logic. Just make the keel the best you can, put it where you want, then make the rudder big enough to provide the control you need. Balance actually has no direct performance benefit -it just enables foil area minimization. On an 8ft boat I think foil stall will be a better guide to surface area minimization.

About square top mains -the optimum is an elliptical loading so square tops tend to be flat anyway, deflecting for 'gust control'. It is actually hard to design right and about impossible to make it work reefed. It takes a balance of batten and mast tip deflection. Your mast sounds like it is from a windsurfer -which would make it easier but I understand just skipping the square top.

I am glad you like the freedom spin video. Of course that was a sales video -I found another that has a much more skeptical perspective, random conditions, and a single handed amateur.

https://www.youtube.com/watch?v=pc1-AsMX8uQ&list=PLMXw4o38auN2Yipg2M1Si-cLWRw_Powtt

I think three sails is one too many on an 8ft boat. I like asym spins, but I like poles for control and pulling the tack to windward more. You could actually do both by pulling the pole foreward to tack the asym. or you could just outside gybe the pole. The part that interests me most is the ability to 'reef' by varying the overlap of full sails.

For furling I like to let the sail material decide -stiff materials prefer to be rolled, limp materials prefer to be bagged.

 

I've never come across that,

LOD length on Deck,
LWL length Water line,
LOA length over ALL, (including FIXED bowsprits and bumkins)

is what I've known for the last 40 years.

 

From the class rules:
"Maximum LWL shall not exceed 8 feet.

Maximum LOA shall not exceed 8 feet. (From Transom to front of hull, not including rudder or bowsprit, even if permanently attached, or boom)"

 

RC, I must have missed something: what class rules?
--
Also, to everyone- in my opinion, it would be better to resize a picture that is too large to allow
posts to be read in the normal way on a whole page......(see page 20)

 

I wrote up a set of 'class rules' for the pocket yachts I'm building to keep them small and somewhat similar, so they don't end up like the 2.4 meter keelboats or optis.

Have a read and please give feedback.