Greetings. We have a 1980 fin keel 33. Some work had been done before we bought the boat and I believe the keel bolts may've been broken loose during the repair. Now, over the last few seasons I have been seeing a fine crack appear where the forward part of the keel attaches to the hull. This does not go through or leak. Anyway, I was considering torquing the keel bolts as a matter of drill. Is there a torquing pattern? How many foot/pounds are required? Any advise would be greatly appreciated! Thanks! Garry Elmer Mystic, CT
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Foot-pounds.
When I wanted to tighten the keel bolts on my H37C I called Hunter. They could not provide any torque values. So I simply "snugged" them up using a 12" handle. The small forward crack(about 6" long) was dremmeled and filled with 5200. In two seasons there is no sign of movement.
When I wanted to tighten the keel bolts on my H37C I called Hunter. They could not provide any torque values. So I simply "snugged" them up using a 12" handle. The small forward crack(about 6" long) was dremmeled and filled with 5200. In two seasons there is no sign of movement.
Some Torque Info
For our H-35 the torque values are 275 ft-lbs for the small bolts and 400 ft-lbs for the large bolts based on what Hunter told me. If you get a person who doesn't know maybe try calling around until you find someone who knows. Perhaps contacting the keel manufacturer and asking what they recommend or what the upper limit is. The small bolts (actually nuts) are 1-1/2 but I forgot what the large bolt size was; I think they were 1-3/4. For keel bolts the proper torque is generally a function of the bolt size. Hopefully this should give you an indication of how much torque to apply. I used 3/4 inch drive sockets, a couple extentions and a breaker bar with a cheater bar. To clear the keel bolts that stick out I had to cut the sockets in half and weld a section of pipe in between. It's too difficult to use a torque wrench so I winged it. For example, a three foot cheater bar and a 100 lb pull will provide 300 ft-lbs of torque. It's hard to find room to work!
For our H-35 the torque values are 275 ft-lbs for the small bolts and 400 ft-lbs for the large bolts based on what Hunter told me. If you get a person who doesn't know maybe try calling around until you find someone who knows. Perhaps contacting the keel manufacturer and asking what they recommend or what the upper limit is. The small bolts (actually nuts) are 1-1/2 but I forgot what the large bolt size was; I think they were 1-3/4. For keel bolts the proper torque is generally a function of the bolt size. Hopefully this should give you an indication of how much torque to apply. I used 3/4 inch drive sockets, a couple extentions and a breaker bar with a cheater bar. To clear the keel bolts that stick out I had to cut the sockets in half and weld a section of pipe in between. It's too difficult to use a torque wrench so I winged it. For example, a three foot cheater bar and a 100 lb pull will provide 300 ft-lbs of torque. It's hard to find room to work!
Crack
My 78 has that small crack and the bolts are torqued tight. I was told at the yard that that is very normal for a boat with lead attached to a skeg.
My 78 has that small crack and the bolts are torqued tight. I was told at the yard that that is very normal for a boat with lead attached to a skeg.
Torque, schmork.
I hate to be the bearer of either bad tidings or cynical attitude, but I have never heard of a 'spec' for keel-bolt torque and have a suspicion that many engineer-types (like my aerospace brother!) worry too much about this stuff. It just shows you guys have never worked in the boat business! [laugh] The boat business gets a bad rep for being a 'black art' that defies technical explanation, usually by techies. They just can't seem to fathom how something that just reeks of scientific concepts, what with all that water and angle-of-attack and displacement stuff, is done by people with so little apparent knowledge of the technology aspects of it! And I know it sounds incongruous, but the truth is, it just IS. Ask the average boatbuilder-- a guy, by the way, who is not at all dumb-- what the keel-bolt spec is, and he will say, 'Until they're tight'. And the techie will go, 'Arrrrrgh!!!!' -- as if that never got a boat to float or a sail to draw air. But-- and you guys all know I am right-- your boat floats, it sails, it takes a very good beating, and the keel does not fall off. And there it is. Stick that in your Strengths and Stresses of Materials textbook and stuff it! [laugh] I know this is disappointing and frustrating to many people. Others are laughing and still don't care. The fact is that there is SO much seat-of-the-pants stuff going on in the boatbuilding industry, and the success rates of this are so phenomenally good, that it gets to seem like a waste of time to determine mathematical specs for keel-bolt torque when we all know that tightening them up till the mish-mash oozes about an inch all the way round is good enough. Wipe off the mish-mash before it hardens there and call in the bottom-painters. Done. And it will not require another look for 15 or 20 years. I am not really a Luddite and really do respect all you tech-heads. [smile] Really. I just have to warn you that not everything is done by the book-- not everything even HAS a book. The guys who built your boat knew how to do it because that's what they do. I assure you not one would ever question your job. Tighten the keel bolts till the mish-mash oozes sufficiently to indicate that there are no voids between the hull and the lead. Tighten them another half-turn if it lets you sleep better. We once did a serious test and found out the polyester mish-mash alone held the 11,000-lb keel of a Cherubini 44 on better than all the bolts together. (The chemical bond blows the tensile strength away. Half of all boatbuilding is chemistry.) Once we knew that we stopped worrying about it. Trust me. [wink] JC Cherubini Art & Nautical Design Org. JComet@aol.com
I hate to be the bearer of either bad tidings or cynical attitude, but I have never heard of a 'spec' for keel-bolt torque and have a suspicion that many engineer-types (like my aerospace brother!) worry too much about this stuff. It just shows you guys have never worked in the boat business! [laugh] The boat business gets a bad rep for being a 'black art' that defies technical explanation, usually by techies. They just can't seem to fathom how something that just reeks of scientific concepts, what with all that water and angle-of-attack and displacement stuff, is done by people with so little apparent knowledge of the technology aspects of it! And I know it sounds incongruous, but the truth is, it just IS. Ask the average boatbuilder-- a guy, by the way, who is not at all dumb-- what the keel-bolt spec is, and he will say, 'Until they're tight'. And the techie will go, 'Arrrrrgh!!!!' -- as if that never got a boat to float or a sail to draw air. But-- and you guys all know I am right-- your boat floats, it sails, it takes a very good beating, and the keel does not fall off. And there it is. Stick that in your Strengths and Stresses of Materials textbook and stuff it! [laugh] I know this is disappointing and frustrating to many people. Others are laughing and still don't care. The fact is that there is SO much seat-of-the-pants stuff going on in the boatbuilding industry, and the success rates of this are so phenomenally good, that it gets to seem like a waste of time to determine mathematical specs for keel-bolt torque when we all know that tightening them up till the mish-mash oozes about an inch all the way round is good enough. Wipe off the mish-mash before it hardens there and call in the bottom-painters. Done. And it will not require another look for 15 or 20 years. I am not really a Luddite and really do respect all you tech-heads. [smile] Really. I just have to warn you that not everything is done by the book-- not everything even HAS a book. The guys who built your boat knew how to do it because that's what they do. I assure you not one would ever question your job. Tighten the keel bolts till the mish-mash oozes sufficiently to indicate that there are no voids between the hull and the lead. Tighten them another half-turn if it lets you sleep better. We once did a serious test and found out the polyester mish-mash alone held the 11,000-lb keel of a Cherubini 44 on better than all the bolts together. (The chemical bond blows the tensile strength away. Half of all boatbuilding is chemistry.) Once we knew that we stopped worrying about it. Trust me. [wink] JC Cherubini Art & Nautical Design Org. JComet@aol.com
But seriousl, folks.
Um, seriously--- the keel cracks described ARE normal. Getting room to work WILL result in loss of torque due to twisting moment on an extension, so the torque specs have to be applied exactly as the factory did or they are mu. My advice to mind the ooze of the bedding agent is serious and won't fail you. Cracks only round the front edge are almost certainly due to shock, which fibreglass does not take well, probably from bumping something about 4 ft down (imagine the available leverage and force. Something HAD to happen). But like most stress cracks in fibreglass it tends to be cosmetic. Forget about it. Filling with 5200 or polyester-based filling compound, as you would any other crack for any other reason, is fine. Pay attention for fairing for speed just as much as for filling the void. If the bolts are not loose now, they won't improve the crack situation. Stand the boat on the keel and see if the crack gets smaller. (Put a loose wedge in and see if it gets tighter.) If it does, lift it, fill it, set it down, and tighten the bolts. If they move at all I'll be surprised, or it's a VERY old and/or abused boat. Fibreglass is flexible but it does not tend to shrink in thickness or under compression. If they got loose it may indicate another problem-- the keel was off once and not installed right, or the bedding agent was not right for the task, but I would NOT jump to the alarmist's conclusion and say that the keel is slowly falling off. I'd just fix it and forget it. Dropping a keel is like pulling a car engine-- sounds like a nightmare but it is possible and not as bad as you'd think when you know what you're doing. And when you have to do it, it's the only thing you can do. But, a caveat-- investigate appropriate bedding agents before visiting Home Depot, PLEASE!!!!! BTW-- At Cherubini, until we went to internal ballast, we put the keels on for eternity, using polyester-based mish-mash-- basically a really nasty goo made up of resin, filler, and sand (which does not compress), patiently kicked off (it went on blue) and applied over a few layers of saturated mat and cloth. Very goopy. Believe it or not it adheres chemically to the lead as well as the raw Fabmat of the hull. Then we lowered the hull onto the lead shoe and the weight did more work than the bolts in drawing the hull and keel together. I have never heard of an older Cherubini 44 built by us that had a loosened keel. Some cheaper production boats could have had corners cut. I don't know. I don't suspect Hunters after about 1978 to have been anything but solidly built in this area because they learned from my dad's experience at Cherubini about this and other areas as well. JC
Um, seriously--- the keel cracks described ARE normal. Getting room to work WILL result in loss of torque due to twisting moment on an extension, so the torque specs have to be applied exactly as the factory did or they are mu. My advice to mind the ooze of the bedding agent is serious and won't fail you. Cracks only round the front edge are almost certainly due to shock, which fibreglass does not take well, probably from bumping something about 4 ft down (imagine the available leverage and force. Something HAD to happen). But like most stress cracks in fibreglass it tends to be cosmetic. Forget about it. Filling with 5200 or polyester-based filling compound, as you would any other crack for any other reason, is fine. Pay attention for fairing for speed just as much as for filling the void. If the bolts are not loose now, they won't improve the crack situation. Stand the boat on the keel and see if the crack gets smaller. (Put a loose wedge in and see if it gets tighter.) If it does, lift it, fill it, set it down, and tighten the bolts. If they move at all I'll be surprised, or it's a VERY old and/or abused boat. Fibreglass is flexible but it does not tend to shrink in thickness or under compression. If they got loose it may indicate another problem-- the keel was off once and not installed right, or the bedding agent was not right for the task, but I would NOT jump to the alarmist's conclusion and say that the keel is slowly falling off. I'd just fix it and forget it. Dropping a keel is like pulling a car engine-- sounds like a nightmare but it is possible and not as bad as you'd think when you know what you're doing. And when you have to do it, it's the only thing you can do. But, a caveat-- investigate appropriate bedding agents before visiting Home Depot, PLEASE!!!!! BTW-- At Cherubini, until we went to internal ballast, we put the keels on for eternity, using polyester-based mish-mash-- basically a really nasty goo made up of resin, filler, and sand (which does not compress), patiently kicked off (it went on blue) and applied over a few layers of saturated mat and cloth. Very goopy. Believe it or not it adheres chemically to the lead as well as the raw Fabmat of the hull. Then we lowered the hull onto the lead shoe and the weight did more work than the bolts in drawing the hull and keel together. I have never heard of an older Cherubini 44 built by us that had a loosened keel. Some cheaper production boats could have had corners cut. I don't know. I don't suspect Hunters after about 1978 to have been anything but solidly built in this area because they learned from my dad's experience at Cherubini about this and other areas as well. JC
drop keel
Has anybody ever heard of the keel actually falling off on one of these boats? How bout it becoming so loose that it just flops around? Major trauma to the keel doesn't count...
Has anybody ever heard of the keel actually falling off on one of these boats? How bout it becoming so loose that it just flops around? Major trauma to the keel doesn't count...
Thanks
I just wanted to thank everyone for their responses. "5200 and forget it". The more I sail this boat, the more I like it! Thanks again! Garry Elmer Mystic, CT
I just wanted to thank everyone for their responses. "5200 and forget it". The more I sail this boat, the more I like it! Thanks again! Garry Elmer Mystic, CT
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