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Old 21-05-2014, 01:20   #16
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Re: Keel Bolt torque specs

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Originally Posted by Guy View Post
Well, often times, someone who has no clue hides behind that kind of statement. Sometimes boat yard workers do have a clue. I would put lots of them way above lots of owners.
Perhaps you will note that I did not suggest asking "owners". Indeed some boat yard workers are very knowledgeable. Many are not. They all talk a great game. Hard sometimes to distinguish between those categories.

So, instead of "hiding behind that kind of statement", i suggested contacting the builders. You would agree that they should know, wouldn't you? And, because I am not sure if they are still in business, then a naval architect, one who designs yachts, should also be a valid source of info, far better informed than the average boatyard guy. Or the forum "Guy".

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Jim
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Old 21-05-2014, 03:16   #17
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Re: Keel Bolt torque specs

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Originally Posted by Guy View Post
Well, often times, someone who has no clue hides behind that kind of statement. Sometimes boat yard workers do have a clue. I would put lots of them way above lots of owners.
That being said, consider whether you would trust a naval architect over the yard worker. Assuming that you do not know either's knowledge base, which one do you think has the better chance of serving you well?

Over the years we've met many boat yard workers: some of them have been stupid and known little; others, smart and have known lots. With the naval architect, at least you know he's been to school! Not saying your boat yard worker isn't knowledgeable [I don't know him], but Jim's mechanical knowledge has kept us safe since 1983, so I trust it, even if you do not.

Either way it will be a learning experience.

Good luck with it.

Ann
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Old 21-05-2014, 08:28   #18
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Re: Keel Bolt torque specs

Quote:
Originally Posted by Jim Cate View Post
Perhaps you will note that I did not suggest asking "owners". Indeed some boat yard workers are very knowledgeable. Many are not. They all talk a great game. Hard sometimes to distinguish between those categories.

So, instead of "hiding behind that kind of statement", i suggested contacting the builders. You would agree that they should know, wouldn't you? And, because I am not sure if they are still in business, then a naval architect, one who designs yachts, should also be a valid source of info, far better informed than the average boatyard guy. Or the forum "Guy".

Cheers,

Jim
Jim, the comment was made by the boat yard owner. I know he's been in the industry a long time - longer than I've owned a boat, so I need to take that into consideration.

The boat in question is a new to me Lippincott 30. The boat builders lay built one in 1986, so tough to get their opinion.

It is just that I'm used to higher torque values, but to be fair, those come from a vehicle perspective. Hence my surprise at only 80 lbs.

There are forum guys here who have expertise in a number of areas, but yes, one must sperate the wheat from the chaff.
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Old 21-05-2014, 08:45   #19
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Re: Keel Bolt torque specs

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Originally Posted by avb3 View Post
Jim, the comment was made by the boat yard owner. I know he's been in the industry a long time - longer than I've owned a boat, so I need to take that into consideration.

The boat in question is a new to me Lippincott 30. The boat builders lay built one in 1986, so tough to get their opinion.

It is just that I'm used to higher torque values, but to be fair, those come from a vehicle perspective. Hence my surprise at only 80 lbs.

There are forum guys here who have expertise in a number of areas, but yes, one must sperate the wheat from the chaff.
When considering the lead keel, one also has to consider the keel-bolt material, thread pitch and dimension. Even though 80# may seem low, it's worth remembering that ANY torque is also pre-utilizing the material to some extent. To take it to the extreme, if somebody over-torqued their bolts to the point that 70% of the apparent material yield strength was already utilized through pre-tension. Then this would not leave a great deal of headroom for the material to handle the much larger loads of righting-moments and forces associated with fluid-differentials while sailing.
Admittedly, 80# shouldn't be a great deal of utilization as long as the bolts are correctly sized and of sufficient material quality. There was a comment earlier, that the minimum torque only needs to ensure that the keel is adequately supported and that any moments on the keel cannot result in movement of the keel in the bedding materials between hull and keel (causing leaks and fatigue) - then plus a bit more torque to account for temperature/expansion. I'd concur with this statement.
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