A new rig for Leeway

<< First  < Prev   ...   4   5   6   7   8   Next >  Last >> 
  • 19 Jul 2016 04:33
    Reply # 4139097 on 4139059
    Timothy Balcer wrote:

    You could rig up a sort of 'gallows arch' with a bit of crown (would this have a special name?), tall enough to deal with the takeoff angle, perhaps a traveler on top, high enough off the deck to allow space for a dinghy underneath. 

    Yes, an arch for the sheets seems like a natural way to go in order to preserve space for a hard dinghy on deck.  But, it really comes down to the sheets.  The 2P sheeting distance is only 7" (18cm) off the coachroof at its maximum height.  If I built an arch 36" (91 cm) above the coachroof, the new maximum sheeting distance would become 1.36P.  So the only way I could build an arch over the dinghy is to use a sheeting style with a shorter Dmin than 1.36P that is still happy with sheeting a high AR sail.  This is what has me stumped.  I have thought about travellers for both sails and maybe they will be a necessary evil.  Although they add complication, they would improve the sheeting angles on all points of sail.
  • 19 Jul 2016 03:58
    Reply # 4139087 on 4138733
    Treasurer JRA wrote:


    Increasing the forward rake of the foremast could gain you 2-3 ft of space - but then you'd still need to move the mainmast forward by this much to take advantage of it.


    I don't think I could move the mast forward that amount and still maintain a reasonable lead.  Unfortunately, I didn't sail the boat very hard as a staysail schooner, so I don't have a good feel for the lead, but by-the-numbers, 16% was a pretty generous lead and I felt better with 12% (PJR recommends 5%).  I could maybe gain a bit of area for sheeting aft on the deck if I increased the balance in the mainsail a bit in order to grab a half a foot more to place the sheets.
  • 19 Jul 2016 03:27
    Reply # 4139059 on 4138614
    Deleted user

    Just off the top of my head, for the (a) sheets and (b) not wanting to do double sheets, aka port and starboard, to preserve space for a dinghy.. I am assuming you have very little room between mast A and mast B here.

    You could rig up a sort of 'gallows arch' with a bit of crown (would this have a special name?), tall enough to deal with the takeoff angle, perhaps a traveler on top, high enough off the deck to allow space for a dinghy underneath. It would have a bit of strain forward, so you would want to stay it with diagonal tubing facing 45 degrees fore and aft, but they wouldn't have to be too extreme if everything were made up of thick wall stainless pipe, and throughbolted with backing plates. If this is on a cabin top, you might want to beef it up a bit around the areas where it is attached. as well as the cabin sides and under the deck a bit.

    Last modified: 19 Jul 2016 03:28 | Deleted user
  • 18 Jul 2016 22:16
    Reply # 4138733 on 4138614


    Increasing the forward rake of the foremast could gain you 2-3 ft of space - but then you'd still need to move the mainmast forward by this much to take advantage of it.


  • 18 Jul 2016 20:53
    Message # 4138614

    After multiple iterations of PJR, Van Loan, Arne's articles, lots of searching the PJR archive and building a scale model, I've arrived at the the point in sail design where I'm pretty certain that I'm just chasing my own tail and could use some advice. The below post is long, as I try and explain my rational, thanks ahead of time to anyone who takes the time to read and comment.

    The Mission

    Our plan is to sail offshore for two to three years, initially pointing the bow in the direction of a circumnavigation from the West Coast of Canada. The crew will be my wife and myself along with our sons who will be nine and twelve at the time we depart in 2018.

    The Boat

    From a bare hull, we are completely refitting a Brandlmayr 40, which is essentially a Benford Brigantine that has had the beam increased by one foot and the forefoot of the full keel cut away somewhat. Our boat is aluminum, where the original design was steel. Our boat was built with 5000 lb steel ballast, but we have now replaced that with 8000 lb lead. The final cruising displacement (half tanks plus gear) will likely be in the range of 28 000 to 31 000 lbs (13 to 14 tons). The original staysail schooner rig had 940 sqft (87m2) of sail suspended from free-standing aluminum masts (10” (254mm) dia at base, 4”(102mm) dia at head). It looks like the main mast is in about the right place and I'd rather not move it. The foremast has to be moved and there is some longitude of where it could end up.

    The Sails

    I've posted pictures of the original and the junk sailplan in the photo gallery under my profile here. I may have been a bit too greedy in trying to fit in 1200 sq ft (113 m2) sail area (versus the original 940), but having spent enough summers sailing the BC coast, I have an aversion to not having enough sail for light conditions. Working through PJR and modifying Arne's sailplan templates I ended up with near identical sailplans. I've shown the version that is derived from Arne's 2.25AR sailplan with two additional panels added to the mainsail and one additional panel added to the foresail. This results in fairly high AR sails (2.7 and 2.5), but makes good use of the mast height for a fairly heavy displacement boat, and is still within the PJR guidlines. I kept the 70 degree yard on both sails, as the balance of the sails had to be kept low to allow adequate clearance between the sails and to maintain the CE in a reasonable location (the lead on the original sailplan was 16% and the lead on the Junk sailplan is 12%). I did cheat the drift on the sails somewhat, leaving just 24” (610 mm) halyard, but others seem to have got away with this and if necessary we could use a simple two or three part halyard and commit to raising the sail with a winch. I also had to cheat the mainsail topping lifts forward a bit to get adequate clearance for the yard when reefed. I preferred this to lengthening the yard. Although it is not shown in the drawing, I'd like to terminate the topping lifts in an integral fabric sailcatcher/cover.

    I must admit, I'm most confused about how to make the sheeting work (or if it even can work with these sails). On the mainsail the sheeting angles are very steep and there is just a little 6” (152 mm) long patch of deck space aft-most that offers a 2P distance for sheeting. The davits could be incorporated into the sheeting system, but this lessens the sheeting distance to about 1.5P and might also interfere with the wind vane. On the foresail, the sheets land on the coachroof right in the same spot where it would be nice to store a dinghy...... It seems that split (upper and lower) sheets would offer better control of such a high AR sails, but the simplicity of a single sheet would be nice, at least to start as we get used to the Junk sails.

    My main question is, what to do about sheeting a very high AR sail with a steep sheeting angle, minimal deckspace and eight sheeted battens? Has anyone tried the running spanline sheet system from PJR (Fig. 4.52)? It looks like it would offer a sheeting system that requires a fairly low Dmin and that would be fairly easy to convert to split upper and lower sheets later if the need arose.  I would really prefer a single sheet, at least for the early days of sailing the new rig. I worry about breaking battens with a moment of inattention and not carefully balancing the upper an lower split sheets. I really don't want double sheets (port and starboard).

    The sailplan also makes it look like it would be advantageous to remove the steering pedestal and move the wheel to the aft side of the pilothouse. Does anyone have experience with a wheel that proximate to the sheets (our refit is taking a lot of time and I am now trying to add as few things to the to-do list as possible).

    Any comments or thoughts are appreciated,


<< First  < Prev   ...   4   5   6   7   8   Next >  Last >> 
       " ...there is nothing - absolutely nothing - half so much worth doing as simply messing about in junk-rigged boats" 
                                                               - the Chinese Water Rat

                                                              Site contents © the Junk Rig Association and/or individual authors

Powered by Wild Apricot Membership Software