lugsail with sprit boom

[mizzenman]

Hi I'm thinkin' of the main sail for my 18' skif.

the sprit-boom would be easely removed to provide a lose footed sail in hard weather, and the sprit would be high enough not to bang heads.The benefits would be a better standing sail, especialy down wind. So why havent I seen this being done before?

The hull is not even turned over yet so anny nesesary mods to the design would be easely acomplished.

[Cedric Rhyn]

Go and have a look at John Welsfords designs, he has been using
Sprit boomed lugsails for years, www.jwboatdesigns.co.nz (http://www.jwboatdesigns.co.nz)

Cedric Rhyn

Hi I'm thinkin' of the main sail for my 18' skif.

the sprit would be easely removed to provide a lose footed sail in hard weather, and the sprit would be high enough not to bang heads.The benefits would be a better standing sail, especialy down wind. So why havent I seen this being done before?

The hull is not even turned over yet so anny nesesary mods to the design would be easely acomplished.

[Thorne]

They are commonly done -- I think that our resident sail expert Todd Bradshaw wrote up an excellent recent post on the pro's and con's of booms on lugsails. As I recall, there were advantages and disadvantages.

Unless the sail has to be cut differently for the boom (and I don't believe it does but I'm guessing here), why not try it without a boom first, then build one if desired.

I've just gone from a simple sprit-boom setup on my mainsail (think faux-leg o' mutton) to a gaff-jaw boom.

The new boom allows reefing and greater control when reaching, but adds a LOT of complexity and additional hardware, lines tangling around crew, and fiddling with same.

Simplicity is one of the main virtues of small open boats, and adding any additional rigging or parts needs to be considered in that light as well as how it may improve performance under some conditions.

[bateaux]

We went to a loose footed spritsail when we built a little 16' crab scrape - I got the idea from looking at old photos of open workboats and pleasure craft on the Chesapeake from Betterton on south. Every old photo - late 1800's thru about 1935, contained spritsails, most loose footed. The sail we built drove that beamy scrape like a damn tank before the wind, she literally hummed a deep bass note when she started cranking along, and it was just grommetted dropcloth canvas on a sandwiched 2 x 4 mast, with a ground down 10' 2 x 4 sprit - (we still do a little serious shadetree boatbuilding over here on the Shore).

http://www.redlionstudio.com/radcliffecreekseadogs/

[Pernicious Atavist]

I used a boomless sprits'l on my sharpie and was never happy with it until I added a boom. Now I'm happy with it.

[mizzenman]

http://www.jwboatdesigns.co.nz/plans/6m_whaler/6m.gif
Oh yeah! I'm thinkin' of something like this, sans jib.
I'll go and search through Todd Bradshaws posts pronto! Always a nice read:)

[Frank E. Price]

You understand of course that if you sail a boat rigged so simply other boaters will stare, snigger and point. Only sailors dare put to sea in such craft.

The reason we don't see more of such rigs is that the yachting rags' advertisers don't make any sales on them; and most boaters have been so brainwashed by the advertisers and their shills that they shudder at the sight of a simple traditional small boat rig. Sailors of traditional rigs are a minority and though a large proportion are readers of WB, even here we are a minority.

I'm making all this up of course.

Frank

[Eric Hvalsoe]

Speaking from experience with spritsails on the HV 13 and 16, always loose footed, never percieved any reason to add a boom. In my case the boom could be a head banger, not a problem in the case above. Not much experience with lugs. At some point the sail may be large enough, I think significantly more than 85 sq ft which is the area for the HV 16, to benefit from a boom for a little more control downwind. Sometimes a boom will be necessary for proper sheeting - that is, if the sheeting angle for a loose footed sail does not work out conveniently with the layout of the cockpit or hull interior - with a loose foot the sheeting angle has got to trim the sail correctly. I like simplicity and the idea of the loose foot - but it all depends on running that sheet. Hey, you could use the boom for a boom tent as well as trimming the sail!

[Thorne]

Mizzenman -

We should also define our terms here, as it can get confusing quickly. I prefer to call the spar in question a "sprit-boom", leaving the term "sprit" for the spar that angles up to the top of spritsails.

As above, I'd try it without and see how it goes. Remember that adding a boom means you'll have to raise the sail on the mast, or do a lot of very low ducking to avoid headbanging.

My friends John & Pia added a spritboom to their spritsailed Tortuga, and report better performance on most points of sail. However they are young and flexible, so manage to crawl about under the boom fairly easily with only a little complaining.

http://www.luckhardt.com/bl_tortuga1.jpg

[mizzenman]

We should also define our terms here,


You are right Thorne. Let me spesify that I'm talking about a basic boom less lug rig witch would have a sprit-boom aded so as to hold the sheet clew out.

[Frank E. Price]

I sailed my sharpie skiff loose-footed for the first three years or so and it worked OK. Then I added the sprit-boom that Chapelle shows in his sail plan and I would not go without it again given the choice. The skiff has no standing rigging, so the routine when stopping for a minute or several is to simply let go the sheet, letting the sail go over the bow while the boat drifts stern to the breeze. With the sprit-boom the sail is a lot quieter in this operation, which also gives the benefit of less wear on the sail. The sail shape is easier to control on almost all points. Probably less so in a sail with a short foot. If you have the sprit-boom on board you can use it or not, whereas if you don't have it . . .

We're talking about almost no investment. Can't see why anyone would not try it.

Frank

[Todd Bradshaw]

As you can also see in the sailplan for the yawl posted above, the sprit-boom's addition can also make the question of sheeting angle for the main much easier to get worked out. Without the boom, the sheet angle would need to be farther aft and possibly complicating the area where the mizzen lives. This way, the boom takes care of getting decent sailshape and tension along the foot and leech and the sheet's role is largely reduced to easing or trimming the whole works outboard or inboard as needed.

It should be noted that the foot of a sprit-boom-equipped sail should ideally be cut straight. The sail doesn't necessarily need to be flat in that general area, but the lower edge should be straight with no round and by the time the sailcloth reaches that lower edge, all draft should have been tapered out. This is the old "triangle of tension" thing that a sprit-boom creates with the triangle's three sides running along the sprit, along the luff, and in a straight line between the tack and clew grommets. Any round, as shown here, which falls below the tack to clew line will generally be little more than a useless flap - and it will usually cause a long tension wrinkle from tack to clew, leaving the round bottom to flap in the breeze. This is often more of an annoyance than a serious problem, but if you're retro-fitting your loose-footed sail with a sprit-boom, you may get some flapping down there that can't be corrected. Sailmakers don't usually cut loose-footed sails straight on the bottom because it looks funny and rather chopped-off. If you have a sail made with the intention of fitting a sprit-boom, let the sailmaker know ahead of time so that he can delete the foot round.

http://webpages.charter.net/tbradshaw/sprit%20boom%20triangle.jpg

Also note the other big change that the sprit-boom has made. It has made the sail self-vanging and greatly reduced the clew corner's ability to lift. This is good if your intent is to keep the entire sail working - since clew lift increases the amount of sail twist to leeward up high. It's not so good if you're getting overpowered and want to be able to ease the sheet, briefly letting the top twist to leeward to spill some wind. If you sail most or all of the time with the sprit-boom installed, you may find that you need to reef a bit earlier than you would (or used to) without the boom. You may also find that if your layout allows the mainsheet lead to be set in a position that works reasonably well either with or without the boom, that in windy conditions you may have more boat control with the boom stowed and more twist available, instantly at your fingertips, by simply easing the sheet. This can be handy on those days when the wind is all over the place and you find yourself thinking seriously about reefing one moment and glad you didn't the next.

[Eric Hvalsoe]

Todd, very interesting comments.

[johngsandusky]

I've only had my dory out twice, with her boomless spits'l. But I'm adding a sprit boom, to give better shape downwind, and less strain on the sheet (and my arthritic hands). I don't mind ducking, and I don't let the loose sail slap my head either. She's a bit slow downwind now, with the jib blanketed and the main curled.

[J. Dillon]

John , why not a whisker pole for the Jib ?

JD

[Cedric Rhyn]

This is the 6M Whaler design of John Ws that was featured on the cover and within a recent issue of the English magazine Watercraft, there are a number of pics of her sailing, and you'd get a good idea of how the rig is set up from those pics. JW commented on one group that while the boat was lovely, the builders when rigging her had omitted the tack parrell that stops the outhaul on the forward end of the sprit boom from pulling the main tack away from the mast thus reducing the vanging effect and also the control over sail shape.
There are a couple of his Rogue Designs sailing near here and they have that same mainsail setup, but just in a cat rig and those boats are seriously quick even in amongst aspiring racing dingies.

Cedric


http://www.jwboatdesigns.co.nz/plans/6m_whaler/6m.gif
Oh yeah! I'm thinkin' of something like this, sans jib.
I'll go and search through Todd Bradshaws posts pronto! Always a nice read:)

[johngsandusky]

JD, my jib's small, only about 24sqft. And I'm steering and trimming all the while. I did put a club on the jib, and tack it down as a balance jib so I could use one sheet.

[Frank E. Price]

Has anyone tried putting a mast parrel on the spritboom?

Frank

[mizzenman]

So to sumarize:

1 Althought fairly seldom seen, its a well-proven combo.
2 Performance is improved.
3 Foot must be straight.
4 I'll get loadsa atention with my unusual non-yachting-rag-rig

Sounds like winner, Only thing left is to finish the hull!!:)