Graham Faulkner has launched his Periwinkle named Entropy. She is the first Periwinkle to to carry the gaff-headed Cat rig, and here is Graham's initial report: -
Hello Ross, Well finally she was launched. I picked a dead calm day and put her in at Poona, very light steering as we sailed out into a 5kn n.e drifter, perfect manners. Helm response was good, and pointing ability appears great., Tried out the 3.5 hp outboard and speed was impessive. Now out in the straits we could see quite a storm building from the south so we hoped for say 10-15 to give her a try on the shakedown. Well we had that and more.probably 20 but with little chop as the conditions immediately prior were calm.
On all points sailed well but I was not comfortable running square. Quite a bit of rudder pressure and the boom [loose foot] looked like it may sky so I backed off and ran a full shy. Also grannied rather than jybed in the 20knts. Mast bent at the head maybe 2" but the sail shape was generally good apart from a modification I will make at the throat [need to cut a bit out]. No indication of wanting to bury the bow although my crew and self were well aft.
Q. I need to find a way to slide the sail up and down the mast. At the moment I lace it on but that would be far to slow in the event of an emergency sail drop. Also difficult at sea standing on the foredeck. Any suggestions.
A friend on a cruising yacht took plenty of photos but they will take while to get back so for now a back yard photo and a sail down retrieval photo in the weather. More later
Thanks very much indeed for the photos and for the report.
To answer your question I would suggest mast hoops as the first option (either made from laminated timber, or made from rope like a quoit), with them being loose enough for the sail to always drop reliably. If that doesn't appeal to you, then I'd use a diagonal lacing pattern which automatically loosens off as the halyard is released.
There are two systems I know of which work well - see attached files. The pdf file is two pages out of Harold Payson's book, "Build the New Instant Boats" in which he describes a lacing method promoted by Phil Bolger. It works really well, but takes a bit of setting up.
The jpeg is a sketch I just did to explain the other method. Note that the diagonal lacing always comes back on the same side as it came around. You would expect it to pull the luff into a zig-zag shape, but it doesn't.
Regarding the downwind manners, the first thing I'd look into would be a vang, although that is an additional complication in the rig, and may cause problems fouling the side decks. N.G. Herreshoff used to use a diagonal sprit set between the mast and the boom to form a sort of vang that worked in compression rather than tension, using a snotter to provide the compression. I notice that they use similar systems these days on ocean racers, but the struts are hydralically controlled.
Periwinkle is a small boat, despite her length, and I'd be thinking about reefing for downwind work in those conditions. Lazy jacks and a jiffy reefing system make that sort of sail easy to reef, once you get the hang of it. By the way, with a narrow boat and a free-standing rig, it is absoloutely vital that the head of the sail is not allowed to swing out to more than 90 degrees to the centreline of the boat. If the head of the sail swings forward of the beam, you will quickly get out of control in what is called the "Death Roll". What hapens is that the head of the sail drives the boat over to windward, and it quickly leads to loss of control. I used to sail a Finn in competition, and if the head of the sail went forward of the beam it meant an instant capsise - it was over before you even knew it was starting! With an easily-driven hull like Periwinkle, you don't need much sail to make her get up to quite high speed in the sort of winds that you described. Reefing is the key.
I'm really looking forward to more photos if you get the chance, but in the meantime, I strongly suggest that you try one or other of the luff systems I've mentioned, and that you stay off the foredeck - as soon as she gets weight up forrard and up high like that, she will be quite unstable because of her fine forrard sections. However, those same fine sections make her a relatively dry, easily-driven, and soft-riding boat.
Ross Lillistone www.baysidewoodenboats.com.au
This my rough sketch for Graham