Posted by Jay Glen (svfantasy@…>)
Michel,
Thanks for your opinion on the mast stress question. It just seemed to me that if you are trying to move a vessel (weighing a specific amount) through the water, it would take a certain amount of force to move that weight. If the entire force required to move the vessel is placed on one mast (main sail alone) then, of course, all the force is applied to the main mast. If, however, you have both main & mizzen up, the force required to move the vessel is now distributed between the two masts, causing less loading on the main mast. In a document from Freedom Yachts titled, “Sail Handlling Hints” authored by Garry Hoyt, he states the following;
" Each one of the Freedom spars is designed to singlely be able to lever the boat over - to cover the contingency that you might be sailing on one spar. However, it would far better from the point of view of sail balance - and of distributing the heeling loads - to carry the heeling loads on both spars - rather than loading up one".
This, in my mind, confirms that sailing under main alone does increase the load on this mast. Although as Garry states the mast are designed to accept this loading.
I do not know that date of this document but it came with the owners manual when I bought the boat.
The PO lost the main mast on “Fantasy” while motorsailing in 20 kts and head seas about 100 miles South of San Diego. They only had the main up at the time. After making port it was determined that due to frequent anchoring while in Mexico, the chain had abraded the side of the main mast near the mast step. This cause sea water to wick up between the lay-ups of fiberglass in the mast, weakening it to the point of failure at deck level. The new mast was installed with a rubber matting wrapped and tied around the mast in the chain locker. Sorry for the lengthy response everyone.
Jay Glen
F-40 “Fantasy” SF Bay
----- Original Message -----
From: michel.capel
To: freedomyachts2003@yahoogroups.com
Sent: Saturday, June 10, 2006 5:42 AM
Subject: [freedomyachts2003] Re: Mast Stress on a Cat-Ketch
Jay,I agree with Lance’s observations; there is no effect of using two or just one sail on the forces of each individual mast. I also use the same reefing drill as Lance does. Deciding when to reef is easy: a long keeled Freedom such as the F40 and F33 should never heel more than 20*. 20* is approximately when the outer edge of windward side of the coachroof top becomes horizontal. So then you reef. I am very curious to know the cause of the mast breakage of your boat’s PO. Even hacking up and down in a seaway, when the mast is shaken foreward and backward with force, the mast should not break. There must be other, structural reasons why this breakage occured, such as an abundance of screw- or rivet holes in the lower 10’ of the mast, weakening the mast.Michel— In freedomyachts2003@yahoogroups.com, “lance_ryley” <lance_ryley@…> wrote:>> Jay,> I don’t believe this is correct, although some other CK owners may > have a differing opinion. My guess is that the difference in pressure > on the mast of, say, traveling 7 kts with both sails up or 4 kts with > one sail up is negligible at the pressures of mast loading. It’s not > like a Freedom 40 gets up on a plane in 20kts. And also remember that > there are very few points of sail where the mizzen is going to even > partially blanket the main.> > When sailing the F-40, it is good to heed the advice “Reef Early, Reef > Often.” On Bright Star, the reefing routine is usually 1st reef in > Mizzen (reduces weather helm), 1st reef in Main (reduces mainmast > stresses), 2nd Reef in Mizzen (usually again to maintain steering), > 2nd Reef Main, Drop Mizzen. the new main only has two reef points, but > they’re very deep. It seems more likely that if the PO was > motorsailing in 20 kts with pounding seas, he may have been > overcanvased for the conditions.> > Lance> Bright Star> — In freedomyachts2003@yahoogroups.com, “Jay Glen” <svfantasy@> > wrote:> >> > Being relatively new to freestanding Cat-Ketches, is it correct to > > assume that you would reduce the stress to the foremast by sailing > > with the mizzen and main together? It seems to me that sailing with > > only the main up would place all the load on this one mast. The > > previous owner lost the main mast while motorsailing in strong head > > seas in 20 kts of wind. It seems the stresses could have been > reduced > > by having both sails pulling the vessel along. Any thoughts.> > > > Thanks,> > > > Jay> >>