sail rig for 12' semi-dory

[scepticus]

I want to build the 12' Chaisson semi-dory from the lines in Gardner's Dory book. That shouldn't be a problem.

However, I'd like to add a centerboard and sail rig, but don't know what type and size of rig to plan for. It has been suggested that I use the rig for Shellback Dinghy.

Thoughts? comments? Suggestions?

[Kermit]

Looking for one more-or-less off the shelf? You can likely find any number of sails for small craft. One thing fershur, I'd make it a spritsail. Read Pete Culler on spritsails in SKIFFS AND SCHOONERS.

[Keith Wilson]

How about the Universal Bolger Rig? It's a 59 sq ft triangular sail with sprit boom, very docile, with low sheet forces and non-critical sheeting angles. Downwind behaviour is exemplary. You can make the mast from 16' lumberyard wood, and standard Bohndell sails are avaliable for Dynamite Payson for about $175. See "Build the New Instant Boats" for details. The rig is used on many Bolger designs: Teal Gypsy, Nymph, Cartopper, etc. The only real disadvantage is that the spars won't fit inside the boat

Here is Dynamite Payson's web site. (http://www.instantboats.com/)

[Kermit]

Yup. I re-read Culler last night. He's still right.

[Steve Paskey]

There's no question that the best way to go is to borrow a rig from a proven design with a comparable size, weight, and ability to carry sail.

Given that the 12-foot semi-dory is longer and more burdensome than the Shellback dinghy, she could stand (and probably needs) more sail.

The closest comparisons I can think of would be Joel White's Pooduck skiff (similar to the shellback but larger), which sports a 65 sq. ft. lug rig (I'd skip the optional jib), and John Welsford's Golden Bay Dinghy, a 12-foot sailing skiff with a 72 sq. ft. lug rig. (Dimensions for the sail and spars are shown in Welsford's book.)

I'm with Kermit on the sprit sail. As it happens, Culler's Skiffs and Schooners has the necessary dimensions for a couple of sprit rigs of about 65-67 sq. ft., with 12 foot spars.

[cs]

I'm going to say balanced lug. I like it a lot better than a loose footed sprit sail.

Chad

[scepticus]

Thanks for everything so far. I had an uneasy feeling about the size of the shellback sail so I'm encouraged by the suggestion for something a little larger.

Ok, time for a bunch of my ignorance to leak out...

I think I know what a lug sail is, but what's different about a "balanced lug"?

Similarly, I think I know what a sprit sail is, but what's a "loose footed sprit"?

Obviously I have more research to do and Culler's book is now on my list.

Anybody got any guesses as to what Chaisson might have chosen for this boat? Since, it's his hull design, it might be nice to equip it as he might have.

[Keith Wilson]

"Loose-footed" is sometimes confusing, since it can refer to two diffeent things:
- A sail with no boom at all, or
- A sail with a boom, but where the sail is attached to the boom only at the clew and tack, hence loose footed.

A loose-footed spritsail has no boom. The upper corners of the sail are supported by the sprit and the mast. The clew is located only by the sheet. I personally don't like this kind of sail, for the following reasons:

- Sheet forces are very high for the sail area. This is because the sheet must hold the clew in toward the center of the boat, hold it down, and keep it from moving in toward the mast.

- Sail shape depends greatly on the point where the sheet is attached to the boat. The best sheeting point varies with the point of sail.

- It's difficult to control sail shape downwind. Since there's nothing to hold the clew out, the sail tends to balloon. This can cause very unpleasant rythmic rolling in some boats.

IMHO, just about any loose-footed spritsail would be greatly improved by the addition of a sprit boom, which fixes all of the above problems, and still allows you to put all of the spars inside the boat. Look at theMelonseed Skiff (http://www.melonseed.com/melonseed_skiff.htm) web site to see this type of rig.

[scepticus]

Originally posted by Kermit:
Looking for one more-or-less off the shelf? You can likely find any number of sails for small craft. One thing fershur, I'd make it a spritsail. Read Pete Culler on spritsails in SKIFFS AND SCHOONERS.Any more info on this book? If anybody has it the ISBN number would be ideal. I'm having trouble locating it.

[A. Mason]

My father's 12-foot Swampscott sailing dory design [Ms. Peach] has a spritsail rig of 51 sq.ft.

Hope this helps, Anita

[Milli]

A balanced lugsail would likely work great for your boat. Go to lugsails on this link (http://marina.fortunecity.com/breakwater/274/michalak/alphabetical.htm) and you will get lots of information on building them from polytarp. I made the one from the article using the methods described and it was easy. The sail performs great and is very easy to manage. Should be the right size for your goat as well.

Just make sure you size your board and rudder properly and position the the board to balance the CE of the sail. If you hunt around the above website you will find some links that discuss this.

[dadadata]

"
Should be the right size for your goat as well.
"

I find my goat needs about 30 extra square feet to head upwind reliably.

Seriously, you can find the Canoe Sailing Resources 2003 page from my Cheap Pages (see link) - and there are lots of sail plans for canoes around 50-100 sq ft; the rig can be adapted.

Chesapeake Light Craft's Jimmy Skiff sail is another possibility. Almost identical in dimensions to the Universal Bolger Item. A few inches variation is all.

[sailingmedic]

Originally posted by Keith Wilson:
"Loose-footed" is sometimes confusing, since it can refer to two diffeent things:
- A sail with no boom at all, or
- A sail with a boom, but where the sail is attached to the boom only at the clew and tack, hence loose footed.

A loose-footed spritsail has no boom. The upper corners of the sail are supported by the sprit and the mast. The clew is located only by the sheet. I personally don't like this kind of sail, for the following reasons:

- Sheet forces are very high for the sail area. This is because the sheet must hold the clew in toward the center of the boat, hold it down, and keep it from moving in toward the mast.

- Sail shape depends greatly on the point where the sheet is attached to the boat. The best sheeting point varies with the point of sail.

- It's difficult to control sail shape downwind. Since there's nothing to hold the clew out, the sail tends to balloon. This can cause very unpleasant rythmic rolling in some boats.

IMHO, just about any loose-footed spritsail would be greatly improved by the addition of a sprit boom, which fixes all of the above problems, and still allows you to put all of the spars inside the boat. Look at theMelonseed Skiff (http://www.melonseed.com/melonseed_skiff.htm) web site to see this type of rig.

[sailingmedic]

You are so very right about spritsails needing booms to have any control at all. I was happy to read your comments as it validates what I have learned through experience. The thing is that I was seeing with my own eyes tremendous improvement on all points of sail and confirmed with GPS when I used a sprit type boom on my spritsails. The difference was night and day. The sails were poorly controlled and poorly trimmed most of the time due to the sheet angle problems you described. The thing is I would see so many old designs without a boom I kept asking myself am I doing something wrong because it must have worked for the old timers. Well the answer is no I was doing nothing wrong it is simply a earlier step in the evolution of sailing and those same old timers shaved with a straight razor. We have come a long way so step up to the triple edge razor and a sprit boom. By the way my boat is a 21-foot crotch island pinky.

[almeyer]

think I know what a lug sail is, but what's different about a "balanced lug"?
On a standing lug, the tack is attached to the mast. If the rig has a boom, which I recommend, the boom has either boom jaws or some type of gooseneck. The luff intersects the mast at the tack, but then runs forward of the mast to the throat.
http://www.imagestation.com/picture/sraid181/pd8ac7b32ef777a18450882e4355121ee/f2e8c2ea.jpg

A balanced lug is similar but the boom is attached to the mast aft of the tack. The entire luff is forward of the mast.
http://www.imagestation.com/picture/sraid175/p1b54a85c2ea3e03a5d7b318c79b7e74d/f3802396.jpg

My wordsmithing ability is less than fantastic, hopefully the pictures will explain it better.
Al

[Thorne]

I'm faced with the same decision -- what sail to rig on my 13'6" Chamberlain dory skiff?

I bought a cheap Sabot rig ($75 for mast, boom and sail) for windy days, and will experiment with that before designing / making / purchasing a larger more trad-look sail for the heavier 13' mahogany mast I also picked up.

As Milli suggests above, here is Jim Michalak's page on lugsails, where he discusses the three types: dipping, balanced and standing.

He covers the various elements of sailing ability for each design, but obviously prefers the balanced rig. He does say that the tack has to be set VERY tightly on the balanced lug to avoid twist when sailing downwind.

http://marina.fortunecity.com/breakwater/274/2000/0615/

http://marina.fortunecity.com/breakwater/274/2000/0615/lugreef2.gif

If you are thinking of going for the leg o' mutton sail, consider picking up a suitably-sized jib on Craigslist or eBay and converting it to a sprit-boom sail. Haven't tried it myself but on one of (I think) Jim M's pages he suggests it as an alternative to buying a new Bolger or other maker's sail.

[ 11-20-2005, 11:35 AM: Message edited by: Thorne ]

[Rick Clark]

almeyer Said in his post:

(On a standing lug, the tack is attached to the mast. If the rig has a boom, which I recommend, the boom has either boom jaws or some type of gooseneck. The luff intersects the mast at the tack, but then runs forward of the mast to the throat.) smile.gif

From Rick>> In a reply to useing a gooseneck, I have made a belt out of 2" wide nylon strap 44" long lined with parts of and old wool blanket you double it back as one end hooked to the boom and punch hole in it with a soldering iron. It lets you have all the adjustment you need , It works, and is less marring on the mast. You just have to tye it to the mast, I use 1/4 rope. ;)

[ 11-22-2005, 08:35 PM: Message edited by: Rick Clark ]