Deck mounted versus keel mounted masts - Page 3 - SailNet Community
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post #21 of 36 Old 02-15-2012
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The difference between the deck stepped mast and a keel stepped mast goes back to the structural decisions made by the yacht designer.

The keel stepped mast is more rigid and uses lower stress levels resulting in a robust and stable system.

The advantage of the deck stepped mast is it can be more flexible, with the corresponding increases in stress and potential for more failures.

Technology and the experience of making production yachts where the deck stepped masts are thoroughly trialed before the design is sold on mass have changed the design and operating environment.

Racing yachts have provided cruising yachts with huge technical improvements in a very short period.

A few decades ago, the mast and standing rigging was designed to be a fixed structure and the sails were added to it then adjusted.

Now yacht design balances the whole system including hull rig and sails so they work in harmony so the yacht works efficiently in real sailing conditions.

Anyone who has sailed a modern yacht with a flexible fractional rig will understand the need for sail changes as wind conditions change are becoming less often. Modern fractional rigs which are bent and tuned for varying conditions are efficient, reliable and easy to handle.

There may be room for more rigid rigs on cruising applications but the greater understanding of yacht structure means there is less need or value for keel stepped masts. Decked stepped masts have lots of advantages and keel stepped masts do not offer any advantage on newer designs.

There are issues with lighter rigs such as maintaining rig tension to hold furlers straight on a flexible mast. Its all compromises.
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post #22 of 36 Old 02-15-2012
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Interesting thread so far. I'm not a too familiar with a reinforced arch design. Would someone elaborate a bit on those?
Thanks in advance.

Brad
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post #23 of 36 Old 02-15-2012
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Thank you so much for the very kind words. A lot of kind people have helped me throughout my sailing career and I try to return the favor when I can.

Jeff


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I mainly quoted the above to give the link back, I deleted most of Jeff's post.

Jeff_H, I want to state that I greatly admire your posts, and make a point to read all that I see. You personify the old saying of "he's forgotten more than I'll ever know". You also write well, express yourself clearly, and don't try to talk over our heads. You are interested in imparting knowledge, not showing off. Thank you for taking the time to educate us and share some of your insights.

I'm a novice in comparison to many, but I have had both types of mast steps. I will never own another keel stepped mast. The amount of water that streams down a mast during wind and rain is incredible, lots of it goes into the bilge with a keel stepped mast no matter how you try to keep it out. I've had one dismasting with a keel step, and it tore the cabin top as it came down. I was able to limp home under sail, using the boom to "sort of" hold up the main.

Raising and lowering a deck stepped mast is so much easier and safer that there is no comparison.


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post #24 of 36 Old 02-15-2012
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Thank you so much for the very kind words. A lot of kind people have helped me throughout my sailing career and I try to return the favor when I can.

Jeff
And you do a superb job!
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post #25 of 36 Old 02-15-2012
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A bendy mast , while having it's advantage on a racing yacht , is a liability on a cruising boat. A mast failure in a racing boat is nowhere near as dangerous as a mast failure in mid Pacific, where it could mean months of slow sailing under a jury rig , while running out of food and water. The much greater consequences of mast failure on a cruising yacht are just to great to make a bendy mast worth the risk.
Some racing boats have been showing up at races with several bendy masts on a trailer , expecting to break one or two. No offshore cruising boat could afford to be that cavalier about rig safety.
It was interesting , tho, to see a Kiwi boat win the America's cup with a mast as stiff as a brick Brings into question the value of a bendy mast.
My mast arch is a half inch steel plate on edge under a steel deck; no chance of any water ingression.

Brent Swain, Boat designer, Builder, and author of "Origami Metal Boatbuilding"
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post #26 of 36 Old 02-16-2012
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I've had both and have had a total dismasting with the deck stepped mast. A keel stepped mast most like would have failed also under the circumstances. My current keel stepped mast does take in a little water but it seems a little more stable in a seaway. I like the fact that I can adjust the rake on the keel stepped mast which wasn't possible with the deck stepped ( I race). I guess it is to each his own.

PS- For any of those who think you might be able to salvage your mast during a storm think again. I can see saving your mast when it falls down due to a rigging failure in moderate conditions but in a seaway with high winds and waves it is dangerous at best. I can tell you, from experience, that a broken mast over the side with sails submerged and the rig pounding on your hull is a powerful motivator to cut everything away as quick as possible. I can also tell you it is not easy to do especially at night with the boat pitching and rolling. When that mast goes and you are beam to the wind you really don't care what kind of mast you have. Your only consideration is how fast you can get rid of it.
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post #27 of 36 Old 02-16-2012
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Quote:
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I can tell you, from experience, that a broken mast over the side with sails submerged and the rig pounding on your hull is a powerful motivator to cut everything away as quick as possible. I can also tell you it is not easy to do especially at night with the boat pitching and rolling. When that mast goes and you are beam to the wind you really don't care what kind of mast you have. Your only consideration is how fast you can get rid of it.
You raise an important concern. In the (good?) old days they kept an axe handy to cut away rigging. I'm not sure what the best tool choices would be with today's steel cables and metal masts. Any suggestions or thoughts of what you wished you'd had on hand during your dreadful experience? I've always found steel cable to be incredibly difficult to cut, I don't know what the correct tool for it is.
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post #28 of 36 Old 02-16-2012
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Quote:
Originally Posted by Sanduskysailor View Post
I've had both and have had a total dismasting with the deck stepped mast. A keel stepped mast most like would have failed also under the circumstances. My current keel stepped mast does take in a little water but it seems a little more stable in a seaway. I like the fact that I can adjust the rake on the keel stepped mast which wasn't possible with the deck stepped ( I race). I guess it is to each his own.

PS- For any of those who think you might be able to salvage your mast during a storm think again. I can see saving your mast when it falls down due to a rigging failure in moderate conditions but in a seaway with high winds and waves it is dangerous at best. I can tell you, from experience, that a broken mast over the side with sails submerged and the rig pounding on your hull is a powerful motivator to cut everything away as quick as possible. I can also tell you it is not easy to do especially at night with the boat pitching and rolling. When that mast goes and you are beam to the wind you really don't care what kind of mast you have. Your only consideration is how fast you can get rid of it.
Agreed, my dismasting was in very extreme conditions and there was no choice, really but to cut. I did manage to save the boom, however.
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post #29 of 36 Old 02-16-2012
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Originally Posted by skygazer View Post
You raise an important concern. In the (good?) old days they kept an axe handy to cut away rigging. I'm not sure what the best tool choices would be with today's steel cables and metal masts. Any suggestions or thoughts of what you wished you'd had on hand during your dreadful experience? I've always found steel cable to be incredibly difficult to cut, I don't know what the correct tool for it is.
We carry a pair of bolt cutters and a hacksaw, but I keep meaning to source some good carbide blades for the hacksaw.

Ron

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post #30 of 36 Old 02-16-2012
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Quote:
Originally Posted by skygazer View Post
You raise an important concern. In the (good?) old days they kept an axe handy to cut away rigging. I'm not sure what the best tool choices would be with today's steel cables and metal masts. Any suggestions or thoughts of what you wished you'd had on hand during your dreadful experience? I've always found steel cable to be incredibly difficult to cut, I don't know what the correct tool for it is.
Yachting Monthly has some great videos- here is one on demasting:
YachtingMonthly's Channel - YouTube
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