Strange Rig

[kenJ]

I saw a different rig this weekend when I was working on the boat. It was european I think, steel hull, twin keels, hydraulic powered screws out of each keel. The mast was a bit aft of midships and it had a strange boom mounted on a pivot in the center of the foredeck for the head sail. I didn't have a camera so my crude drawing is the best I can do. Any idea what this rig is all about?

[bistros]

Originally Posted by kenJ

I saw a different rig this weekend when I was working on the boat. It was european I think, steel hull, twin keels, hydraulic powered screws out of each keel. The mast was a bit aft of midships and it had a strange boom mounted on a pivot in the center of the foredeck for the head sail. I didn't have a camera so my crude drawing is the best I can do. Any idea what this rig is all about?

Going REALLY slow?

[messabout]

Drawing not too clear. Maybe you are talking about a jib club. Some clubs are pivoted at the front at the jib stay location. Some are pivoted some distance aft of the jib tack. That arrangement is standard practice on RC model sailboats. The pivot point is usually about 20 to 25% aft of the tack and often made adjustable. The function is to gain control of the jib stay tension. A topping lift is almost always used on such rigs to keep the jib leach tension under control. In any case the jib is self tending, which can be a convenience when sailing short handed. In addition the foresail seems to perform better on down wind legs, because of the way it orients itself with respect to the main.The down side of it is that the jib boom is called a club. It can and does live up to its' name. Many of these rigs will have the boom close to the deck, whereupon the term "deck sweeper" is to be acknowledged

[PAR]

The boat you saw was likely an aft mast rig with a balanced club headsail. An interesting approach, but like everything else in yacht design, full of compromise.

[kenJ]

Had not heard that term before. Did a little reading and you are correct. I'll try to get some pictures this weekend.

Thanks

[RonR]

http://s109.photobucket.com/albums/n...t=IMG_0215.jpg

Should this come through ok it shows what I did to my 26x MacGregor jib . As already mentioned earlier it makes the jib self-tending and is a real plus going wing on wing. One down side is that the 110 jib now only opens to 95 % now, but I would never change it.

[rwatson]

Why the steel pillar to support the bow end of the boom ?

Looks like a pain when furling as well, but being self tending is a major bonus, expecially with no, or untrained crew.

[RonR]

rwatson,
The steel stub mast is the fulcrum support for the boom, which can swing on a loosely hinged connection.

No pain with the furler going in or out. The port sheet controls amount of jib unfurling, the s'brd sheet controls angle of jib to the wind

Try Google for: Hoyt Jib Boom Data Sheet, which shows a 1-piece construction(and expensive) similar with mine.

[rwatson]

Hi Ron
It appears that your boom can pivot up and down on the steel pole. (unlike the Hoyt Jib boom, which is rigid) Is that correct ?, or has the photo fooled me.

The reason I am interested in the detail is that it is in line with the plans I have for my project, and the details interest me a lot.

The Hoyt concept is very usefull indeed.

For everyone, you might be interested in checking out the "boom" arrangements used in
http://www.harryproa.com/designs.htm
harry proa designes. The Jib is mounted on the boom extension.

[kenJ]

The boat is Lucky Palima home port is Hamburg. Hard to tell how it is acutally rigged because no sails are present and lines are laying everywhere. Picture 065 shows the Club jib, looks like it has it's own head stay. Picture 066 show the hard chine and twin keels. Pic 067 aft view of keels with shaft logs for twin props. 068 shows the overall set up, with pilot house and aft main mast.
LOA 55-60' draft about 6' beam about 12' Looks like it is built like a tank.

[RonR]

RWatson,
Yes, the hinged boom is free in all directions. Simply a quick release shackle bolted loosely into the boom end that snaps onto a 6mm bolt on a teak yoke which is set into the the stub mast. Nicely very sloppy, intended that way,and when not in use I can unsnap it and re-attach it to the clew ring of the furled up jib(lets me get at the forward hatch more easily).

BTW The harryproa stuff is pretty neat............Thanks

[rwatson]

Hi Ronr

Thats what I thought! - the whole idea of the Hoyt Jib boom is that it is rigid, and cant move up and down. - as they say - like a vang.

The need for a steel pole is probably not that great then, you could simply mount the boom on the deck, which is what I was planning until I saw the Hoyt boom.

I suppose the height above deck might make it easier to store gear there, get anchors etc

All food for thought. I wonder how easy it would be to rig a 'wishbone' boom on a jib? especially a furling jib? With another forestay perhaps?

[RonR]

RW

You are correct, there are the advantages you mentioned-storage etc, but additionally the stub mast is high enough to allow making use of the front hatch especially singlehanding in nasty weather, also necessary to allow the boom to clear the side legs of the bow pulpit when reaching or running.

I've no idea about the 'wishbone' application. Is this something quite common?

[rwatson]

The 'wishbone rig' is what windsurfers use. Its advantage is that there isnt a boom to sweep the deck, and it shouldnt restrict roller furling. Its also 'self vanging', but clearing the pulpit and side rails could be a problem.

I will think about it a bit , but your stories have given me a great insight into the possibilities.

[sharpii2]

I once had a similar rig to the one shown. It was on a scow sailboard designed in 1948. The balanced jib accounted for 55 sf of the 85 sf total. The hold down was placed considerably aft, about 40 %.

The interesting thing about this rig was that it was not only self tending but self trimming as well. I removed the jib sheet and let it point itself into the wind. It did so most efficiently.

The boat, though grossly overweight (skipper too at the time), plained routinely and went quite fast.

The mast was set almost as far back as the one in the drawing. That may been one of the secrets of its success. The mast did not help encourage the low, wide, square bow to dig in, when running before the wind.

As to its upwind performance, let me say it was far more than adequate. Especially considering the sails were made of polyethylene drop cloths bordered with duct tape.

I have even sketched a yacht with a similar rig.

The big disadvantage is that such a rig would be difficult to reef.

Other than that, I see mostly upsides to it.

No running to the extreme bow to take in the jib, no endless adjustments to the jib sheets to get the sail to set right, and no need for whisker poles when running down wind.

Though my sketch shows a fore stay, the jib does not attach to it. The forestay is there only to help support the mast.

Oops! Don't have that file anymore.

Instead, let me show you a proposed design for a 'Puddle Duck Racer"' class boat.

Here, the jib is much smaller, but it shares the same virtues I just mentioned.