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kayaker
10-22-2000, 10:53 PM
My Brother and I are rebuilding a Formosa Ketch, 41'. We need plans or books on building masts for this beauty out of wood. Also any leads to plans, specs for this Ketch?? Thanks.

BIRD
10-23-2000, 03:11 PM
kayake : Racing Cruising & design by Uffa Fox, published by Peter Davies Ltd. London 1937 and reprint 1943 has some great yacht designs and mast / spar sections too. Similarly I believe Uffa's earlier works ~ Sailing, seamanship and Yacht construction would be of benefit. Personally I had a 35' wooden yawl with spruce spars, which astounded me by the amount of bend when off the boat. The construction was simple 4 piece hollow box, but earlier designs were two piece routered or otherwise planed out.
For your immediate information I quote for Uffa's book ; 'Ortac's cutter rig stands 55ft above the deck and her oval mast is 9-3/4" x 7-1/2" tapering at the top to 4-7/8" x 3-3/4" and to 9-1/4" x 7" at the goose band. From just above the goose band to the heel this mast is solid, and has 1-7/8" walls, which taper to 1-1/4" at the top, but an extra 1/8" has been left on all the way up the after side of this mast to take the track.' This shows the fine engineering of these masts. The illustrations show the aft face to be straight down to the goose band, the mast is pretty well parallel between the goose band and the stay sail halyard, there-after the taper is being from the forward edge. TonyH mentioned an article in wooden boat magazine, my copy is in storage but it was between one and three years ago. If this is the same article then the builder (at home) added a flat strip of carbon into each side, epoxy glued (sandwiched transversely) between the wooden components (if my recollection is correct). as the author said this added greatly to the rigidity of the whole, I would add that carbon would do more for the strength. Regarding loading, it is crucial for you to use similar mast fittings, the modern variety would impose too local a stress. The goose band for example is not just a simple eye ring screwed on, it has bands above and below the goose neck which both dissipate the load and allow for better spacing of the fastenings screws. Ortacís mast uses three cross trees (spreaders) and is naturally keel stepped and deck chocked (at this point in development cabin were still being stopped short of the mast (as the deck was the stronger support), in fact this book gives two of the first examples where the mast came through the cabin tops. It may be useful for you to know that Ortac carried 940 sq ft of sail, on a 14 ton yacht with 11ft 1inch beam. Sorry I am not familiar with your Formosa Ketch, design but I hope this information helps. regards, Pete.

BIRD
10-23-2000, 03:12 PM
kayake : Racing Cruising & design by Uffa Fox, published by Peter Davies Ltd. London 1937 and reprint 1943 has some great yacht designs and mast / spar sections too. Similarly I believe Uffa's earlier works ~ Sailing, seamanship and Yacht construction would be of benefit. Personally I had a 35' wooden yawl with spruce spars, which astounded me by the amount of bend when off the boat. The construction was simple 4 piece hollow box, but earlier designs were two piece routered or otherwise planed out.
For your immediate information I quote for Uffa's book ; 'Ortac's cutter rig stands 55ft above the deck and her oval mast is 9-3/4" x 7-1/2" tapering at the top to 4-7/8" x 3-3/4" and to 9-1/4" x 7" at the goose band. From just above the goose band to the heel this mast is solid, and has 1-7/8" walls, which taper to 1-1/4" at the top, but an extra 1/8" has been left on all the way up the after side of this mast to take the track.' This shows the fine engineering of these masts. The illustrations show the aft face to be straight down to the goose band, the mast is pretty well parallel between the goose band and the stay sail halyard, there-after the taper is being from the forward edge. TonyH mentioned an article in wooden boat magazine, my copy is in storage but it was between one and three years ago. If this is the same article then the builder (at home) added a flat strip of carbon into each side, epoxy glued (sandwiched transversely) between the wooden components (if my recollection is correct). as the author said this added greatly to the rigidity of the whole, I would add that carbon would do more for the strength. Regarding loading, it is crucial for you to use similar mast fittings, the modern variety would impose too local a stress. The goose band for example is not just a simple eye ring screwed on, it has bands above and below the goose neck which both dissipate the load and allow for better spacing of the fastenings screws. Ortacís mast uses three cross trees (spreaders) and is naturally keel stepped and deck chocked (at this point in development cabin were still being stopped short of the mast (as the deck was the stronger support), in fact this book gives two of the first examples where the mast came through the cabin tops. It may be useful for you to know that Ortac carried 940 sq ft of sail, on a 14 ton yacht with 11ft 1inch beam. Sorry I am not familiar with your Formosa Ketch, design but I hope this information helps. regards, Pete.

BIRD
10-23-2000, 03:15 PM
kayake : Racing Cruising & design by Uffa Fox, published by Peter Davies Ltd. London 1937 and reprint 1943 has some great yacht designs and mast / spar sections too. Similarly I believe Uffa's earlier works ~ Sailing, seamanship and Yacht construction would be of benefit. Personally I had a 35' wooden yawl with spruce spars, which astounded me by the amount of bend when off the boat. The construction was simple 4 piece hollow box, but earlier designs were two piece routered or otherwise planed out.
For your immediate information I quote for Uffa's book ; 'Ortac's cutter rig stands 55ft above the deck and her oval mast is 9-3/4" x 7-1/2" tapering at the top to 4-7/8" x 3-3/4" and to 9-1/4" x 7" at the goose band. From just above the goose band to the heel this mast is solid, and has 1-7/8" walls, which taper to 1-1/4" at the top, but an extra 1/8" has been left on all the way up the after side of this mast to take the track.' This shows the fine engineering of these masts. The illustrations show the aft face to be straight down to the goose band, the mast is pretty well parallel between the goose band and the stay sail halyard, there-after the taper is being from the forward edge. TonyH mentioned an article in wooden boat magazine, my copy is in storage but it was between one and three years ago. If this is the same article then the builder (at home) added a flat strip of carbon into each side, epoxy glued (sandwiched transversely) between the wooden components (if my recollection is correct). as the author said this added greatly to the rigidity of the whole, I would add that carbon would do more for the strength. Regarding loading, it is crucial for you to use similar mast fittings, the modern variety would impose too local a stress. The goose band for example is not just a simple eye ring screwed on, it has bands above and below the goose neck which both dissipate the load and allow for better spacing of the fastenings screws. Ortacís mast uses three cross trees (spreaders) and is naturally keel stepped and deck chocked (at this point in development cabin were still being stopped short of the mast (as the deck was the stronger support), in fact this book gives two of the first examples where the mast came through the cabin tops. It may be useful for you to know that Ortac carried 940 sq ft of sail, on a 14 ton yacht with 11ft 1inch beam. Sorry I am not familiar with your Formosa Ketch, design but I hope this information helps. regards, Pete.

Alan D. Hyde
10-23-2000, 04:13 PM
I strongly recommend that you get a copy of "How to Build a Wooden Boat" by David C. "Bud" McIntosh. It is available from the WoodenBoat Store.

April 2000 WoodenBoat had a great piece on Herb & Doris Smith's latest schooner, "Eastwind." Both learned much from working with McIntosh.

Bud's advice is direct and practical. It has been tested, and it works.

Alan

Bob Cleek
10-23-2000, 11:04 PM
Sigh... Well, what's wrong with the one's you've got... or do you? If they are there, bust 'em apart with wedges and reglue them. The wood is probably fine, if not rotten, but the glue they used in the "Taiwan Turkeys" was probably recycled monkey dung.

If you need to build a new spar, check any of the basic texts for openers. McIntosh, Chapelle, Steward. If you don't have spars or spar plans, contact William Garden, NA, up in the San Juans, still, I think. It was his 41' "Porpoise" design that the Taiwanese yards ripped off for the Formosa Ketches and CT-41's and so on. He would have the sail plan that would work.

OR... you could "bite the bullet" and have a local yard build your spars for you. Unless you have access to a spar bench and a gazillion clamps, it may be cheaper and easier to have the pros do it. Remember, you have to have a perfectly flat clamping surface or you will build the bend into the spar! Last spar I did at 36' I used a length of 12" steel I beam and it worked fine, but then, I happened to have the I beam and a crane handy to set it up down at the yard. Take stock of your resources and abilities first... are you sure you can plane a perfect 12:1 scarf? See where it is going? A man's gotta know his limitations, as Clint sez... Good luck!

Ed Harrow
10-25-2000, 05:38 PM
If you've got them, you can rebuild them, as Bob says. If you need to have them designed as you've got nothing to work with, I suggest making them as a box spar. There is quite a bit of information out there on constructing box spars. The scarfing can be accomplished with a jig and router, and I've seen a number of articles on that subject. Bingham (?) Practical Yacht Joinery (?), and WoodenBoats book on Planking both discuss these techniques.

Ian McColgin
10-26-2000, 08:36 AM
I'd go with the bird's mouth approach if you can solve the problem of how to put the notch in such long sticks. I'd scarf up the 8 staves, plane the tapers so that when it goes together the taper is all in the front and sides, and then make the notch with a wormgear driven saw riding along the stave on a jig bolted to the plate.

Easy enough to set up a spar bench outside - just hammer into the ground 2x4 pairs at suitably close intervals, and carefully with good sightlines, string or lasar pointer whatever get the rack cross pieces laid straight.

G'luck