Eruttan,

MAST HEIGHT AND REEFING

  I agree with taller masts and more sail. 

  I get that there are good arguments for carrying less sail, and then perhaps supplementing with a kite.  And one of those arguments is that using a kite takes work and attention, so you're present for the process, with your hands on the controls, and are less likely to ignore changing conditions.

  That said, we get a lot of low-wind days in Maine where there's just a few knots of sea breeze, and there's no substitute for air draft and carrying windward sail area high up.  I'd rather have the option of moving instead of bobbing, and then have the penalties of having to pay attention and having a slightly less efficient rig at 10-15 knots.  Like you mentioned, by the time there's that much wind, we can afford the cost of carrying that reef.


MAST SHAPE

  As for the masts, I personally am sold on round poles with external dyneema (very slippery, stronger than steel, low-stretch, near-impervious to UV light) halyards and hoops instead of mast track.  Though perhaps soft or semi-soft hoops -- I had a Norseboat 17.5 that I loved, but had to keep repairing a section of the mast with an anti-chafe layer because the parrels would rub on it while on the mooring.

  Reasoning:

    - About as simple as it gets
    - Easier to remove the sail than with a Wharram-type sleeve
    - You can repair and/or fashion the hoops yourself, even out of rope if needed
    - No sail track to purchase, install, bend, curse at, or line up if you have a two-part mast
    - The luff will automatically semi-rotate close to where you'd want proper leading edge on the leeward side of the mast
    - The mast could be fixed, without bearings, and you could just have a rotating a rotating boom
    - Which would help with a VHF/AIS antenna and wind sensors
    - And there's never a concern about the wings sailing the boat or capsizing it if a bearing freezes
    - Or getting into an oscillation pattern that breaks something

  Our catamaran has a rotating wing mast that I really do enjoy adjusting so it has just the right AOA.  I've had a lot of fun with that. 

  But now I'm not interested in more of that fun.  I'm looking for the simplest boat to sail, not only because simplicity reduces cost and the chance of equipment failures, but also because it helps if someone else needs to control the boat.  And also lets me be truly lazy, if that's my goal for the day.

  A wing mast really isn't that much extra work, and it sure does add some extra power when rotated properly (and often gets kind of close on its own with just some minor settings on the rotation limiter for reaching and beating).  I couldn't really argue against one for those who have used one in the past and knows what they want.

  For me, though, the peace of mind of just having some bare round poles up in a big blow is worth it.

  (yes, a properly-oriented airfoil has noticeably less drag, but that said, if it stops rotating, then it's a lot more drag -- I'll err on a worse average but better worst-case).

        - Mike



        - Mike

 

| Flat bottoms are much easier to build and repair. After fairing, fitting and installing floor bulkheads is the most soul destroying boat building job.

Honestly, the composite tech is one of the most attractive part of design, to me. I'll say it every time, avoiding epoxy exposure is a BFD.

| 2 (or three) piece sleeved masts for trailering are no problem, and not much harder to build than one piece (the joining sleeve is a cut off piece of one section slit and glued into the adjacent one. The important part of the build is that everything is straight, which is as easy/difficult for short bits as long.
| My telescoping round mast was probably more work than it was worth (I don't go under bridges or have to tow my boat, which changes the pros and cons), but telescoping wings have some potential.

If Mike had to pull the trigger TODAY, what would you recommend, telescoping round, or sleeved? Or maybe you could hit on the pros and cons of each?
I guess it matters if it is trailered every weekend a summer, once a month, or once a year.
Probably, you will say telescoping wing mast. ;)
You got almost enough time to have it all figured out before he builds it, right?

How does this experimental system plan to handle the dual wing mast, in a marina, dancing during a storm, scenario? Which will be the thing everyone thinks of immediately?

| A couple of weeks ago a client was here and we played with attaching sails to masts with hoops, which make telescoping rigs more viable. The results were promising, he will use them on his 18m/60' mono. More exciting is the work Steinar (he is visiting, the ideas are flowing thick and fast) and I have been doing on a telescoping wing mast (60% of the chord) for his boat. Ordered the sail yesterday for a short length of 1/4 scale model. If it works, it has low sheet loads, little or no twist (ie no vertical sheet loads) and no boom.
| Results and pics next week, maybe.

Sounds like a junk rig! Cheap sails for everyone! Tell Steinar we say hi! Looking forward to the sail updates.

| Reefed sails rarely set as well as unreefed (the sail luff is cut for different mast bend characteristics ) and the drag of the top mast is slow. As Mike says, a bigger issue on a stayed mast than an unstayed one.

Right, but, if the breeze is stiff enough to reef, does it matter you are sailing reefed or the top mast is slow? You are in a 'too fast' condition anyway?

Or are you saying don't reef and rely on the other features like mast give and dumping sail?

Or is this a 'most sailors are stayed mast sailors' so they have a host of reasonable reasons to avoid sailing reefed, so have an allergic reaction to sailing reefed, while it is no big deal at all in a HP?

| A 30' cat will weigh near enough the same as a 40' proa for the same accommodation. The 18m/60' of cat hulls are shorter than the 20m/70' of proa hulls, but the proa hulls are lower and narrower. Therefore the sail area can be the same, although the proa will have much more righting moment.

Does not 'much more righting moment' literally mean one can run a larger sail? So why wouldn't the proa run a bigger sail?

Is there a problem with larger sails that makes one want to run smaller sails? Am I missing something fundamental? Is it sail cost?

Given you hold the righting moment to sail area(?) ratio the same (to give them relatively similar reserve safety) between a cat and a HP, how much bigger is the sail on the HP?

Why should the HP not have that large sail size?

I imagine you can do the same thing with the tri comparison.

I think with an understanding of that sail ratio helps us put the wetted area discussion in a different context.

Follow up. Assuming a 30' bridge deck cat, do you still hold that a 40' HP can match its accommodations/interior space?

| The proa accommodation will be more usable. The proa will be quicker to build (easier hull shapes, only 2 appendages, no unnecessary curves, one simple mould usable for both hulls/decks), faster, safer and more comfortable as it is longer and both sails can be seen without having to turn around. It will also cost more in a marina, but it will have a tender big enough that you can anchor off, motor in and avoid paying altogether.

So, also cheaper to cruise.

| New Ex 40 drawings are finished, will be on the web page when Steinar stops doodling telescoping wings. ;-). First one is being built in Barcelona.
|
| We have also designed the latest "best ever" rudder mount after 2 weeks of discussion, sketches and finger drawings on the beach. Simpler, lighter and easily mounted on the inside or the outside of the hull. First part of the laminate for an El test version is curing as I type. It works for bidirectional or one way rudder sections (NACA0012).

What are the odds that 'best ever' is 'old hat' before its mounted? ;)
Keep pushing the envelope.

| We spent today working on rudder build methods. I drew every one I had tried or heard of in the sand (about 30m of sketches) and we picked them apart. Came up with something simple and quick.
|
| Had a sail on Kitetik (15m Solitarry, weighs about 500 kgs/1,100 lbs, plus 3 crew) yesterday. 25 sqm/260 sq' (20 sq m projected, which is less than a Tornado cat) leading edge inflatable kite, dirty bottom, 10-15 knots of breeze, 30C air temp, a beautiful day. Top speed 8 knots, pretty poor up wind. For the first time, all the systems worked, so we can now move on to boat improvements and bigger kites, starting with a converted 28 sq m (28 sq m projected) paraglider. .

Neat. Do you see cruisers using sails one day? Is the pointing a boat issue, or a sail issue?

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Posted by: "." <eruttan@yahoo.com>