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

Mast & sail are matched on a sailboard rig & the wishbone boom is not going to whack you on the head. I recall a time when I was board sailing in Brightlingsea Creek on a hot, dead calm, summer's afternoon. I say board sailing, but in fact I was sitting astride the board with my feet dangling in the water & holding the sail rig vertical with one hand on the mast & the other grasping the foot of the 6 sq m sail. I was stuck 200 yards from the shore. I could hear the cheerful voices in the clubhouse & I was desperate for a cold one. Bugger, bugger, bugger.

I pumped that sail for all I was worth. Inch by inch I crawled nearer & just perceptible on the water was a ripple, but agonisingly far; but so near. Then I was in it. I didn't need to stand. I was wafted ashore with the mast held easily upright & I was in the bar before the rig floated to the ground. Try what you've got first. I think you'll be gratified.

All the best,

Perry

 

In a word it sounds TALL. A 15ft mast, that's 230% of the hull length? I would concur that you should do some good calculations and the values you have listed don't add up. You doubled the sail area, shortened and raised the boom and you figure the rig moment only doubled for the same wind? The CE would have to be the same so the rig could not get taller -obviously not true. Your righting estimate is similarly challenged. It looks to me like you are neglecting the weight of the rig and your body, estimating the righting as the weight of the lead as a pure pendulum. 13 lb sounds heavy for the mast. A good hollow wood one could be half that. You talk about righting at 90 and 30 degrees. The important question is how much righting and how much wind can you stand up to at 10 to 12 degrees -that's a proper place to get 'in the groove'. When most keel boats heel 20 degrees they would be better off reefing down. I think the minuet might sail better upright. BTW weather helm comes mostly from heel, not from sailplan fore-aft geometry, and heel also destroys rudder control.

I can understand the attraction of a big sail plan with lots of reef points. That would extend your ability to sail in light wind. But based on your reported speed and angles, your previous rig got you to hull speed -you will not go faster except downwind or down waves. I would add that if your new hull is a proper strip plank it will be a significant improvement over your cardboard.

Your idea to follow the luff curve of the windsurfer sail would be a good idea but it gets screwed up as soon as you reef. Windsurf sails use lots of outhaul on the boom which is mid mast. Your boom down low can not match those forces.

If you are open to suggestions mine would be a little shorter mast (unstayed) and a little longer boom for about the same area. Full batten main sail with the appropriate luff curve. The key is to make an excellent main that can feather away the gusts and never flog. Forget the self tacking blade jib and just do a nice overlapping Genoa from the masthead to a roller furler on the short sprit you have already drawn. The blade you drew would be too small and the self tacking and gap to the mast would make it absolutely worthless. The fractional rig is pointless because you don't have a backstay to tension. The Genoa would be big enough to make a difference -particularly down wind. The overlap would do wonders for the efficiency of the plan and roller furling is THE easiest way to reduce sail. On full size boats helm balance dictates that the main be reefed, but as I have said, your boat with the monster rudder will have no problem as long as the boat is upright and rolling up the genoa and feathering the main will keep you upright to fairly high wind speeds.

 

The old rig did NOT get me to hull speed in light winds. It would only get me to hull speed broad reaching in 12+ knots of wind. The test day was somewhat of a fluke, normally I don't sail in such strong wind.

The hull length is 8 feet, so its only 188% (15/8) of hull length.

The 13 lbs I listed is simply a guess. I heard carbon masts are around 8 lbs so I figured mine was about 12 or 13 to be safe with rigging. It's just a tapered 15' fiberglass windsurfer mast.

If you look, the boom would actually get longer than the old gaff boom, but I could make it even longer I suppose. I don't like the idea of relying so heavily on the rudder to deal with weather helm.

I really don't feel comfortable cutting the mast until I am sure by testing it's too tall. I would rather sail it with the top few feet unused. Perhaps I could match the luff curve to the sail with a single reef in it, so the top 3/4ths of the sail is what would be left, and then if it sails best with a single reef in it, I could go ahead and chop the mast and remove the bottom panel of the sail.

As for the genoa, I could very easily drop the self-tacking jib, and just go with a genny. That would help with sail area forward. I just didn't like having to change the sail trim every 60 seconds... It didn't help I didn't have a fairlead on the jibsheets so every time I uncleated them, they would fall away from the cam cleat and I would have to reach down and find them... somewhere under my knee...

And for a fractional rig, Why is it useless? I suppose the reduced load from setting the head lower would be offset by the increased low speed power from having more sail up high...

 

Sorry for my mistakes. I thought the boat was 2M (based on the thread title) and your sail report sounded and looked like a greater success. Wind speed tends to be much greater the higher you get from the water and the separation of the three small sails on your old rig lost quite a bit of pressure. I think your new sail plan has more than enough size for a reasonable amount of wind.

Were you planning on full battens on the main? A large sail can work on a small boat as long as it is low drag. You just ease the sheet.

Making a good main that reefs fast and well is not easy. Making a good main that feathers fast is easy. I stand by my assertion that as long as your boat is upright and moving forward that rudder will have no problem with weather forces. BTW your inclined boom would need a solid 'kicker' over the boom because the angles are bad for a vang underneath.

The reason I said that the fractional jib was useless is that the reason sloops use them is so that they can bend the mast to shape the sails by pulling the backstay tighter. You have no backstay so you can not do this. It sounds like you are planning a sleeved main sail so the fractional forestay would get in the way of the sleeve. It is better to just put the stay at the mast head. The headsail does not have to go to the top -some separation avoids backwinding the main. BTW with no back stays your forestay will sag for lack of tension. This makes it hard to make a good heavy upwind sail. For light winds and downwind it's no big deal.

I see your point about not cutting the mast. Wind force drops as the square of the speed, so no mater how big your sail is it will be right for some wind speed. The lower the drag, the higher the wind speed before reefing. We can calculate quite a bit, but ultimately you sailing is the goal. Make a fast cheap tyvek sail and try it out. BTW it is not uncommon for small boats to have multiple sails they pick from for different wind speeds. You could have a mast extension below deck.

 

I am planning on full battens with a luff pocket. You have an excellent point about the sleeve and having a masthead rig.
Why do cats have fractional rigs? They have no backstay. I don't think I'll need a vang because I have a traveling mainsheet attachment, but I might change that.
I suppose I could try the Tyvek. I've got plenty for that purpose. I'll give it a shot.

 

A masthead rig is not absolutely necessary with a sleeved main. If the sleeved main uses a zippered luff and has a mast step that allows the stick to stay standing w/o any wires, the sail can be hoisted and then the wires attached.

The shrouds were about 3.5' from the top of the main on this boat:

 

In my case this is an unstayed mast, so the only issue here is that I want to attach a jib, and I also want to be able to reef the mainsail while underway without disturbing the jib.

 

Lots of fractional rig boats have no backstay, apart of course from dinghies. A well designed fractional rig can depower automatically - basically when a gust hits, the extra force on the leach and topmast force the mast to bend, which then depowers the sail. When bendy fractional rigs hit the offshore scene in the '70s some of the top sailors (like Tony Bouzaid of multi world title winner "Waverider", IIRC) said that the ideal was to have a rig that could "breathe" automatically and therefore it was normally wrong to use the backstay.

Some boats rarely use the backstay but carry one just to induce extra bend when required. Others use the backstay to induce bend all the time, partly because they use a stiffer mast that won't react like a dinghy-style rig.

In modern carbon yacht rigs with short-overlap high-aspect foretriangles the backstay is a pretty critical control because the stiff masts and short topmasts reduce the rig's ability to bend automatically.

Cat rigs are a different beast again; they use less automatic bend because they can control sail shape with high downhaul loads and by varying mast rotation, and they normally need stiff masts because they have so much stability. But that sort of rig only really works well with stable boats that use very flat sails.

As a general rule the more stable the boat the stiffer the mast can be and the more "locked in" the bend can be. I'd imagine a Minuet type would want a very flexy mast.

 

Cats tend to have fractional rigs because they have direct stays with no spreaders so they attach lower to keep the angle reasonable which keeps the compression load on the main beam down. The jib must attach at the same point, the 'hounds'. As CT explained it's not a 'never' but most fractional rigs on keel boats are for mast bending with backstays. This includes the mini AC and 2.4. Your rig will be unusual in having a jib on an unstayed mast. This is not done much because forestay tension will be weak. Your traveler will help but it is limited to the width of your narrow boat. It would be nice to have a 'kicker' vang to control twist when the sheet is loose.

CT brings up the idea of gust response on a flexible mast. I have been told repeatedly that this is hard to get right and I have never heard of one that reefs well.

 

A square top main will automatically depower depending on vang tension regardless of mast bend. An unstayed square top rig will get the CE lower and be a more effective planform than a triangular sail.
In my experience, a square top rig will have its effective center of effort further forward than will a triangular sail of the same sail area/CE height.*
*corrected

 

That's good to know, and may help get the center of effort forward and help with the weather helm, especially when it heels over. I'm hoping I can reduce the size and weight of the rudder to reduce wetted surface area at some point. It sounds like I might ought to consider making sure there is some sort of a vang on. I noticed already, just with the rigid mast, that I had a hard time getting enough halyard and 'forehaul' tension on the head and tack of the jib to get the luff perfectly straight in strong wind, and it was also stretching the luff of the jib quite a bit, ruining the shape, so I got it to set better relaxed slightly. This was on the rock-solid steel mast with the gaff rig, not the bendy-flexible fiberglass mast.

It would seem like mast flex would add additional weather helm, especially when sailing hard on the wind, as the mast would flex off to leeward. This is what I'm talking about: The solid black line is a reference line, not the mast or anything like that.

 

Squaring the top of your main will be a waist if you don't have enough vang force to keep it from twisting off too much. As I said before, your angled boom favors a solid above the boom vang of 'kicker'. You could try both with the windsurfer sail and boom to see if you like it.

The forestay tension is a tougher problem. I don't think you will ever get good tension without a back stay of some sort. You could do a makeshift running backstay by pulling the topping lift (just a line from the masthead) to the upwind corner of the transom -or even the halyard. This adds a bit of goofing around and it can get in the way. The jib can be cut for a saggy stay but this may just be too much. My thought is that you should only need the jib for light wind or downwind. Under those conditions the sag should be manageable.

You are right that mast bend contributes to weather helm but heel will be your limiting factor. I noticed on your sail plan the mast is on top of the keel. I am not sure how that would work -offset the the keel? Since you are rebuilding the hull anyway you could put the daggerboard box behind the mast and make it vertical. This would be more convenient since you could use a halyard to lift the keel and take it out of the hole in the roof.

Before you get too concerned about balance and cutting down the size of your rudder you need to get the sail plan and righting straight. When you know the boat will stay upright you can think about reducing whetted surface.

 

I'm only redoing the belly skin, and it's almost done now. The daggerboard is slightly to the right, and the mast is slightly to the left. I don't want to move the daggerboard aft any more; I scoot as far forward as I can with one leg on either side, and if I move it aft, I can't sit as far forward.

 

Ahh, very important to position the body right when it weighs more than the boat. Almost done with the the hull? That was fast!

Looking forward to news of the next sail.

 

Yep! It looks like March 7 will be warm enough to take it out. I doubt I'll have the new rig on by then. I also need to get the bowsprit worked out and make some sort of dolly to make handling easier.

For those of you considering making one, the staggered daggerboard and mast work perfectly fine and have no problems I can find. If you want them inline, I would recommend just moving the mast farther forward so it is in front of the daggerboard. Definitely don't move the daggerboard back.