Hi all,
After 3 years of intensive use, it is time for Shui Jen to get a new mast.
Her hinged one is a very smart piece, made of two parts connected by a hinge and with an alloy tube sliding on the hinge. Folding and unfolding are easy procedures that I can manage alone making the boat ready for crane and trailer in about 45 min. The hinged mast transforms this pocket cruiser into a trailer sailler which is an intiguing feature that expands the range of our costal sailing. Last but not least, the folded mast enables an easy inspection of the top gears and works as a support for the boat cover.
Unfortunately the mast is 50+ years old, is quite heavy and has a lot of sign of intensive use. My aging iliosacral joint and multiple reports about old alloy spars snapping suddenly make me think about replacing it.
I’m thinking about an hybrid one: 1) the lower alloy part will be reinforced with an internal carbon tube making it double and stronger; 2) the upper part will be replaced with a new carbone spare; 3) the hinge will remain the same one; 4) the sliding tube will be also replaced with one of carbon fibre. The idea is to make the mast lighter to fold and unfold but stronger. I’ve already found a company that would make the job.
I am also thinking to incorporate the mast top in one piece and to make the upper part of the mast a bit longer in order to reduce tension at the halyard blocks and give me the opportunity to increase the sail area in the future. This is the second point: Shui Jen appears to me a bit undercanvassed (actual SA/D 16.8) and with a bit too much weatherhelm.
Shui Jen is a KF 20+JR and like Pilmer (the last boat of Blondie Hasler) is a JR production boat. Her mast has been probably set a bit too far aft and her original mast from needlespar is thin. Nevertheless, I’d prefer to work on mast materials and sail balance rather than starting a major surgery project by changing mast position and its diameter.
In a former post on this thread Arne wrote: “Maybe that tactics could be used on your boat as well? Now I checked. If we start with one of my master sails, the one at AR=2.20 and remove the lowest panel, and then scale it down until B=3.65m, the AR will drop to 1.94 and the sail area to 20.1sqm. It will look like a close cousin of Frøken Sørensen’s sail, only with six panels. Then, later you may find that you can fit a taller mast and set a seventh panel. This will bring the sail area up in 23.4sqm and the SA/disp. to 19.4, which is not bad. Moreover, the sail’s fairly high AR will give a tall leading edge for better upwind performance“.
Would be such a sail with a lower yard angle a good solution for me? How much higher should be the new mast to get her? Any suggestion about dimensions of the top gear support?
Dimension of the mast: 8,3 meters, 7 m above the deck; 10 cm diameter at the base and 6 cm at the top, 3mm thickness.
Actual dimrension of the boat: LOA 6.58; displacement 1315 kg;
Actual dimension of the sail (same of Frøken Sørensen): 20.2 sqm, 70 deg. yard, batten length 365 cm.
Sailing ground: the Adriatic sea, light winds and sudden squalls.
Thank you for the inputs,
Mauro