Sprit rig question

[Frank Pellegrino]

I am wondering if any have experimented with improving the performance of this rig, specifically if you have added a boom and whether it enhanced performance. Has anyone added a small headsail off a bowsprit. I realize this means a stayed mast, but wonder if someone has tried. The boat I wish to build is a 15' beachcruiser (footloose) but I do need some windward performance. The boat would stay in the water, not on a trailer, so a stayed rig wouldn't be a problem for me. Any thoughts ?

[cs]

In my situation to improve the sprit rig perfomance I changed it to a lug rig. Other than that maybe some other can offer better advice.

Chad

[KimApel]

My sprit rigged dory has both a boom and a jib. The mast is unstayed, so the jib luff isn't all that tight, so it's not very effective at improving windward performance; it's just added sail area. The main boom does improve performance, at the cost of carrying around another stick. My advice is that tweaking a sprit rig may produce modest gains, but diminishing returns. If you're looking for windward performance to match a modern rig, you'll have to change to a modern rig -- like a stayed mast, but then it's not really a sprit anymore.

[Milli]

I have to agree with CS, a lug rig does seem to have to "better than expected" upwind performance. The key really seems to be keeping high tension in the luff. If you are considering going to another simple rig I would sure recommend a lug rig; if upwind performance is your goal then maybe a standing lug but I am a big supporter of the balanced lug.

[Tom Jackson]

See Ben Fuller's sprit-rig article in WB No. 165.

[Dave Williams]

Frank,

After several seasons sailing my 22ft sprit rigged boat I added a sprit boom with it's own snotter. Before that downwind performance was poor in light air because the sail would collapse on itself. In strong wind and seas it was downright scary because of rythmic rolling. The addition of the sprit boom helped both of these problems dramatically. It also makes sheeting angle less critical.

Also by adjusting the boom snotter you have a lot of control over sail shape which improves windward ability.

It does introduce a bit more complexity but I think it is well worth it and fun to boot.

As far as the jib I havn't tried it yet but I have thought of useing a double main halyard made out of some low stretch stuff. One part of this halyard would be made off to a cleat on the starboard rail and the other on the port rail, both slightly aft of the mast. This would in effect create a sort of standing rigging for the mast and help control luff tension of the jib.

As some of these other guys have said the lug rig has a lot of merit and the boat I am mainly cruising in now is a fully battened balanced lug (junk rigged) and I am in love with it but that wasn't your question. There are many things you can to do to make your sprit rig more effective and it is a proven and wonderful way to go.

That's what I think.

Dave

[ 01-09-2003, 04:29 PM: Message edited by: Dave Williams ]

[Bill Perkins]

Frank another WB article explained how to rig a topsail on the sprit rig , tho this doesn't seem to have caught on .

[J. Dillon]

Frank,

Lived with the sprit rig for 7 years now and I like it fine. Your not going to get real windward performance but if you tweek it a bit you can improve it . I notice in light air I can tack through 90 degrees but when it pipes up over 10 kts I'll be lucky if I can get 100o. I did add a jib two seasons ago and the improvement was quickly apparent she went quite a bit faster maybe 35% but did not seem to point any higher. I do have to set up this jib "flying" ( no stay) and really tighten up on the halyad hard. I did not add stays instead relying on the main and jib halyard led to the rail on belaying pins and set up hard to support the mast. It worked out fine.

For me the advantage of quickly brailing up the sail to de power the boat is a big plus especially when coming into my berth.

Ben Fuller goes into the rig nicely as Tom Jackson suggested.

Pictured below is my boat the 18'Carrianne.

If you want to see any other images of her E mail me and I'll sen them along
There was an article in WB by W. Garden about topsails but for me it seemed more trouble then it was worth. I usually have plenty of wind.
http://www.imagestation.com/picture/sraid46/pbdc884fa10f4646c0d2d3efc5f2be8d5/fccd7ba0.jpg
. Good luck on your rig selection.

JD

[Frank Pellegrino]

Thanks to all for the helpful suggestions. I'll try to contact the designer about the lug rig and see what he thinks. Again, thanks for the replies.

[Dave Williams]

JD,

I have to say yours is about the finest, nicest setting sprit rig I have seen! Not only this photo but others I have seen. Good on Ya!

Dave

[Rogue Sailor]

From Sailing Magazine, Robert Perry

"This is a sprit-rigged skiff with a boom. I had to check my latest edition of Royce's Sailing Illustrated to identify the correct name for this rig. If you don't have a copy of Royce's, you had better run out and get one. It's a wonderful reference and covers just about anything you can think of concerning sailing boats. The Melonseed is a skiff you can sail or row. The builder increased the sail area by 25 square feet to improve performance. The Melonseed loves a good breeze."

[brian.cunningham]

Heere's a pic of a Melonseed with a boom from http://www.melonseed.com

http://www.melonseed.com/boat8.jpg

Interesting sail shape the boom gives.

more here pics under sail (http://www.melonseed.com/photos/under_sail.htm)

[J. Dillon]

Thanks for the post Brian. :cool: That image and site for the Melonseed is super. She looks like she is really smokin along. :D

JD

[Bill Perkins]

Isn't that a beauty ? No condescending to the f-glass . To me model is more important than material , and that's a superior model . God bless Mr. Crawford for producing them . That's a sprit boom , a distinction I think is worth preserving . Traditionally the Mellonseeds carried a regular boom , like other hunting skiffs with dagger boards. The tensioned sail foot produced by the sprit boom can't pass over the centerline if the board is raised in shallow water . Now the Crawford boats are being fitted with centerboards ( heavier , intrude in the cockpit ? ) to accommodate the sprit boom .

[ 01-11-2003, 01:03 AM: Message edited by: Bill Perkins ]

[Dennis Marshall]

JD, I notice that your spritsail does not have a very high peak. Stambaugh, in "Good Skiffs," refers to Culler's experience and says that higher peaked spritsails give better windward performance than those with moderate peaks because they don't have a tendency to twist off to windward as easily. This insight was repeated when he was discussing Jordan Boats "Footloose" design. I have a high peaked sprit on my Dobler 16, but I haven't sailed her enough yet to comment on the windward performance. I can't wait until spring!

Also, my spritsail has a boom, but I was thinking of changing to a spritboom. My question is how does one figure the placement of the boom on the mast? Does it matter? Also, does the foot of the sail need to be cut differently for a sprit boom than for a regular boom?

Dennis

[J. Dillon]

Never considered a sprit boom. Something else to varnish. :( I don't like the idea of getting my old cronny crew heads banged when I come about. :eek: I can live with the rolling when before the wind, it isn't too bad. ;) Can you brail up the sail effectively with a sprit boom ?? :confused: Wait don't tell me I won't try one any way. :rolleyes:

Thanks Dave for the compliment.

JD

[Todd Bradshaw]

High-peaked spritsails will often point a bit higher than those with lower peaks, though I don't think you'll find it to be a drastic difference. One of the advantages of the spritsail is that it uses relatively short spars to project a fairly high amount of sail area. Higher-peaked models usually need longer sprits, which at a certain point may be more cumbersome than beneficial in the overall scheme of things. The boat's never going to point like a 12-Meter anyway and nothing you can do will really change that much.

The clew end of the sprit-boom should be no higher than the heel end and is usually lower, but the actual best angle is found by experimentation. It affects foot, luff and to some extent leech tensions, so you want to find an angle that is capable of tensioning everything reasonably well, especially in conditions where you are using high snotter tension to flatten the sail for light or heavy air conditions. If everything is hunky-dory, you can then ease the snotter tension a bit in medium wind conditions or when sailing off the wind for creating more draft in the sail.

The foot of a sprit-boomed sail is cut differently from that on a regular boomed sail (which itself may be cut differently for a loose-footed boomed version and a laced-to the boom version). The sprit-boom tensions the foot in a straight line between the clew ring and the tack ring and it's sail is best cut dead straight along that edge and reinforced to take the extra tension that the sail's self-vanging nature puts on it.

A loose-footed, non-sprit-boomed sail is usually cut with a bit of round on the edge and broadseamed to give the foot a bit of a cupped shape. When you convert it to a sprit-boom, it's edge usually stretches out and often a crease will form across the foot and along what would be a straight line from clew ring to tack ring. The foot round below the crease just kind of sits there in a distorted bundle. If you do convert the boom to a sprit-boom, you may want to have somebody chop off the foot round and reinforce the edge, but try it first and see if it presents a problem.

The thing that is probably of more concern is the luff. Sprit-booms are subject to the "bow and arrow principle" - The mast is the bow, the sprit-boom is the arrow and the leech and foot edges of the sail form the bowstring. Snotter tension is like pulling back on the arrow. It pulls on the bowstring and bends the mast.

This can quickly "use up" the one to two inches of luff curve built into the sail, rendering it dead flat, even if the conditions don't call for a flat sail. Further tensioning will probably start distorting the sailshape (humps, creases, loose leech, etc.) and hindering it's ability to function as designed. Sprit-boomed sails are pretty easy to make, but the cardinal sin is failing to build-in enough allowance for mast bend (in addition to any allowance for luff curve-generated draft) and ending up with a sail that is nearly always too flat or distorted just by the basic geometry of the rig.

That's probably more than you wanted to know on the subject and people convert sails to sprit-booms all the time, often without a problem - but as the Wicked Witch said to the flying monkey "These things must be done delicately..."

[Mike Field]

Aileen Louisa (15') carries a flying jib. Not a lot of extra canvas, but it seems to make a disproportionately big difference to speed. I wouldn't consider doing without it.

One halyard is led down each side to a belaying pin at the outer trailing edge of the mast thwart to act to some extent as shrouds. Tension in the jib luff can be got quite high because the bowsprit is supported from below by a wire bobstay (invisible in this photo, I'm afraid. The bobstay is the only real bit of standing rigging.)

http://www.iws.net/wier/FieldBOAT5.jpg

The mainsail was originally loose-footed, but I got rid of ithe boom to improve, inter alia, cranial comfort. Along with Jack, I haven't found much of a problem in rolling when running. But the sail certainly collapses inwards and balloons forwards quite a bit. I suppose I could fix it by poling out with the boathook or an oar, but I never bother.
________

That's a nice photo of Carrianne, Jack. I don't remember seeing that one before.
.

[dadadata]

If I'm not mistaken the "Delaware Ducker" rig -- a ducker being something akin to a beamy canoe -- uoften used a boom with jaw on a spritsail.

Todd Sez:

Sprit-booms are subject to the "bow and arrow principle"

Interestingly enough, it would seem that a jib set flying might tend to bow the mast in the opposite direction. Food for thought anyway. I never considered the possible cancelling effect of the two "bowstrings".