Tune a Typhoon
Moderator: Jim Walsh
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BarbiS
- Posts: 1
- Joined: Jul 14th, '19, 19:57
- Location: 1967 Cape Dory Typhoon Weekender, Hull #49, keel-stepped mast
Tune a Typhoon
I wish to know the manufacturer-recommended tension for the standing rigging of a 1967 Cape Dory Typhoon Weekender with a keel-stepped mast. The cable size is 1/8" diameter (302/304 1x19 stainless steel cable) with a breaking strength of 2100 pounds. I'm using a Loos Professional Tension Guage, Model PT-1. What should be the tension of the forestay and shrouds in pounds or per cent of breaking strength? The boat's manual is unavailable. Online manuals for later vintage CDs don't give this information. The Loos manual recommends an initial tension setting of 320 pounds (forestay) and 240 pounds (shrouds) but defers to the boat maker for a better number. We sail out of Woods Hole, Massachusetts; the current is a mighty river, the weather can suddenly scream. Just bought the boat, the mast has been stepped by a crane. Now to tune the mast. Thank you!
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Megunticook
- Posts: 352
- Joined: Sep 2nd, '12, 17:59
- Location: Cape Dory Typhoon Senior #11
Re: Tune a Typhoon
I have a Ty Senior, same basic rig but scaled up slightly. Mine uses 5/32 wire.
Like you, I looked in vain for CD recommendations--the manual is pretty vague.
First year I had a professional do it while I watched, plus I did research online and talked with other riggers.
The fractional rig requires a surprising amount of tension to get everything in balance.
While there is disagreement about this, most pros I talked with/read say you really don't want leeward shrouds going loose under sail as it is hard on the rig.
My forestay is generally around 18% breaking strength, upper shrouds at 15%, lower shrouds a bit less, and backstay only at 9% or so. If I tension the backstay any more, it just bends the mast too much.
Key thing I learned is the swept back spreaders mean the forestay is balanced more by the upper shrouds than the backstay. So those upper shrouds are tight.
Selden has a useful guide: http://www.seldenmast.com/files/1456145 ... -540-E.pdf
Good luck! Definitely an art not a science!
Like you, I looked in vain for CD recommendations--the manual is pretty vague.
First year I had a professional do it while I watched, plus I did research online and talked with other riggers.
The fractional rig requires a surprising amount of tension to get everything in balance.
While there is disagreement about this, most pros I talked with/read say you really don't want leeward shrouds going loose under sail as it is hard on the rig.
My forestay is generally around 18% breaking strength, upper shrouds at 15%, lower shrouds a bit less, and backstay only at 9% or so. If I tension the backstay any more, it just bends the mast too much.
Key thing I learned is the swept back spreaders mean the forestay is balanced more by the upper shrouds than the backstay. So those upper shrouds are tight.
Selden has a useful guide: http://www.seldenmast.com/files/1456145 ... -540-E.pdf
Good luck! Definitely an art not a science!
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Interlude
- Posts: 20
- Joined: Apr 21st, '15, 20:27
- Location: INTERLUDE, Naugus Alberg Typhoon Daysailer #22
Re: Tune a Typhoon
I would agree tuning is more art than science.
We have an early Naugus Typhoon (#22 Circa 1964) which has a tapered mast and different shroud chainplate locations, so I cannot provide specifics for your CD Typhoon, but here is some information for you to consider.
First, Carl Alberg expected his boats to sail with a slight weather helm. To achieve this the mast must be raked aft around 4 degrees. To check your rake mast rake, tie a weight to your main halyard and let it hang below the boom. On our boat, I have found the halyard hangs ~5-6" behind the mast at the boom - I'm till playing with it, but so far this amount of rake works for us. Also recognize this is not pre-bend of the mast, but rather rake - top of the mast leaning to the aft. Also, given the diameter and length of the mast it's difficult to put much pre-bend in a Cape Dory Typhoon mast. Here's some background/folklore on Alberg's view of rake: http://www.pearsonariel.org/discussion/ ... -2455.html
Second, here are a few relevant articles on tuning:
https://ensignclass.clubexpress.com/con ... 1297649585
https://www.quantumsails.com/QuantumSai ... -final.pdf
https://attilavedo.files.wordpress.com/ ... ur-rig.pdf
Third, recognize Typhoons, Ensigns, Pearsons, and other small, full keel displacement hull boats like to have some headstay sag going to windward. Newer planning hull boats behave differently, so much of what you read about tuning modern wraceboats does not directly translate with what is best for a Typhoon. The boat does not accelerate as quickly as newer boats, so tuning and trimming to optimize and maintain boat speed is priority one.
Hope this helps.
We have an early Naugus Typhoon (#22 Circa 1964) which has a tapered mast and different shroud chainplate locations, so I cannot provide specifics for your CD Typhoon, but here is some information for you to consider.
First, Carl Alberg expected his boats to sail with a slight weather helm. To achieve this the mast must be raked aft around 4 degrees. To check your rake mast rake, tie a weight to your main halyard and let it hang below the boom. On our boat, I have found the halyard hangs ~5-6" behind the mast at the boom - I'm till playing with it, but so far this amount of rake works for us. Also recognize this is not pre-bend of the mast, but rather rake - top of the mast leaning to the aft. Also, given the diameter and length of the mast it's difficult to put much pre-bend in a Cape Dory Typhoon mast. Here's some background/folklore on Alberg's view of rake: http://www.pearsonariel.org/discussion/ ... -2455.html
Second, here are a few relevant articles on tuning:
https://ensignclass.clubexpress.com/con ... 1297649585
https://www.quantumsails.com/QuantumSai ... -final.pdf
https://attilavedo.files.wordpress.com/ ... ur-rig.pdf
Third, recognize Typhoons, Ensigns, Pearsons, and other small, full keel displacement hull boats like to have some headstay sag going to windward. Newer planning hull boats behave differently, so much of what you read about tuning modern wraceboats does not directly translate with what is best for a Typhoon. The boat does not accelerate as quickly as newer boats, so tuning and trimming to optimize and maintain boat speed is priority one.
Hope this helps.
Mark Lay
INTERLUDE
Naugus Alberg Typhoon #22 (1964)
Irvington, Virginia
INTERLUDE
Naugus Alberg Typhoon #22 (1964)
Irvington, Virginia
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rjnale
- Posts: 58
- Joined: Sep 15th, '14, 22:09
- Location: 1982 CD Typhoon Daysailer "Typhoon Mary" Hull #97 model K Syracuse NY
Re: Tune a Typhoon
Sorry for late reply its been a busy summer including some sailing!
I sail a CD Typhoon Daysailer. The mast steps thru the deck to the floor of the cockpit.
I also use the Loos Pro Model PT-1. I have wrestled with the same questions of tension. I've read a lot of articles (including those attached), asked countless "professionals" and played with different settings.
I have landed on 10-14% of break strength based on the many conversations and even the pamphlet that comes with the tension guide. I start at 12% and go for a sail to see if there's any slack or give on the leeward stays. I continue to monitor the tension thru out the season and adjust if needed based on wind conditions too. But I find I'm running in that 10-14% break strength range that works.
I run a jib furler so I don't have a fore stay reading. But I adjust the back stay to get the rake I need. As someone mentioned is important to helm responsiveness. When I started using a tension guide I did have to take the furler apart to adjust the fore stay turnbuckle to get the rake angle correct.
I sail a CD Typhoon Daysailer. The mast steps thru the deck to the floor of the cockpit.
I also use the Loos Pro Model PT-1. I have wrestled with the same questions of tension. I've read a lot of articles (including those attached), asked countless "professionals" and played with different settings.
I have landed on 10-14% of break strength based on the many conversations and even the pamphlet that comes with the tension guide. I start at 12% and go for a sail to see if there's any slack or give on the leeward stays. I continue to monitor the tension thru out the season and adjust if needed based on wind conditions too. But I find I'm running in that 10-14% break strength range that works.
I run a jib furler so I don't have a fore stay reading. But I adjust the back stay to get the rake I need. As someone mentioned is important to helm responsiveness. When I started using a tension guide I did have to take the furler apart to adjust the fore stay turnbuckle to get the rake angle correct.