re-bedding keels
- Thread starter p.boon
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What type boat and keel do you have? I would assume the keel you are asking about is bolted on, externally hung.
Bolted-on Cast Iron
I have the same question, so I will jump in too. I am experiencing minor leakage into the bildge, and I am suspecting the keel joint. My boat is an O'Day 23, 1973, with the bolted-on shoal draft cast iron keel (weight about 1200lbs). - Under what circumstances should you actually remove and re-bed/re-bolt the keel? - Does anyone know the torque for the bolts? - Can small leaks be resolved by tightening bolts and/or running a bead of below-waterline sealant around the keel? Appreciate any experience anyone can offer.
I have the same question, so I will jump in too. I am experiencing minor leakage into the bildge, and I am suspecting the keel joint. My boat is an O'Day 23, 1973, with the bolted-on shoal draft cast iron keel (weight about 1200lbs). - Under what circumstances should you actually remove and re-bed/re-bolt the keel? - Does anyone know the torque for the bolts? - Can small leaks be resolved by tightening bolts and/or running a bead of below-waterline sealant around the keel? Appreciate any experience anyone can offer.
Our yard will lift the boat off the keel...
leaving it on raised jack stands while the keel is left to the side for any refinishing and joint repair and cleaning. After the boat's keel stub joint is cleaned the yard will apply 3M5200 to the joint and then set the boat back down onto the keel. With the weight of the boat resting on the keel they will torque the nuts on the keel bolts and let the sealant cure over night. The next day they will torque the nuts again then apply several coats of epoxy paint to seal the entire keel and stub joint. Then the yard will apply one coat of hard bottom paint followed by two coats of ablative bottom paint. After this procedure the boat is ready for splash. Terry P.S. While the boat is on the hard you can create a trough by scraping away some of the old sealant from the keel stub joint and then fill the trough with fresh 3M5200 sealant. This may (emphasis on may) fix the joint leak, assuming the joint is the source of your leak.
leaving it on raised jack stands while the keel is left to the side for any refinishing and joint repair and cleaning. After the boat's keel stub joint is cleaned the yard will apply 3M5200 to the joint and then set the boat back down onto the keel. With the weight of the boat resting on the keel they will torque the nuts on the keel bolts and let the sealant cure over night. The next day they will torque the nuts again then apply several coats of epoxy paint to seal the entire keel and stub joint. Then the yard will apply one coat of hard bottom paint followed by two coats of ablative bottom paint. After this procedure the boat is ready for splash. Terry P.S. While the boat is on the hard you can create a trough by scraping away some of the old sealant from the keel stub joint and then fill the trough with fresh 3M5200 sealant. This may (emphasis on may) fix the joint leak, assuming the joint is the source of your leak.
Torque
General Guidelines for Keel Bolt Nut Torque: 1/2" Dia. Bolt ~ 180 Ft/Lbs Nut Torque 3/4" ~ 250# 1" ~ 350# 1-1/4" ~ 450#
General Guidelines for Keel Bolt Nut Torque: 1/2" Dia. Bolt ~ 180 Ft/Lbs Nut Torque 3/4" ~ 250# 1" ~ 350# 1-1/4" ~ 450#
didn't get some of the numbers
Gord: This is really useful, since I'm going to be changing my keelbolts this winter (Cal 20: 30 year old heavily corroded galvanized bolts being replaced by stainless steel). What does 250# mean? Are you saying 250 ft/lbs for a 3/4" bolt? I don't think so - seems too much of a stepup from 80 for a 1/2" bolt. Sorry to be dense. Dick
Gord: This is really useful, since I'm going to be changing my keelbolts this winter (Cal 20: 30 year old heavily corroded galvanized bolts being replaced by stainless steel). What does 250# mean? Are you saying 250 ft/lbs for a 3/4" bolt? I don't think so - seems too much of a stepup from 80 for a 1/2" bolt. Sorry to be dense. Dick
Oops
Dick: Thanks for pointing out my typo’ (I like critical readers) - I should have said 180 Ft/Lbs for ½" diameter Stainless Bolts. These are typical torques, representative of modern fin-keeled boats. Check with your particular manufacturer for their recommended spec’s. BTW: Tighten keel bolts sequentially - alternately tighten up at one end; then switch to bolts at the other end; take a few turns on the center bolts, and so forth so that the keel is uniformly snugged up to the hull of the boat. ½" ~ 180 Ft/Lbs 3/4" 250 Ft/Lbs 1" 350 Ft/Lbs Gord
Dick: Thanks for pointing out my typo’ (I like critical readers) - I should have said 180 Ft/Lbs for ½" diameter Stainless Bolts. These are typical torques, representative of modern fin-keeled boats. Check with your particular manufacturer for their recommended spec’s. BTW: Tighten keel bolts sequentially - alternately tighten up at one end; then switch to bolts at the other end; take a few turns on the center bolts, and so forth so that the keel is uniformly snugged up to the hull of the boat. ½" ~ 180 Ft/Lbs 3/4" 250 Ft/Lbs 1" 350 Ft/Lbs Gord
fastener torque
Max Torque (foot-pounds) for clean, dry threads Bolt size - Thread pitch Grade 2 Grade 5 Grade 8 Special Alloy 1/4-20 6 10 12 14 1/4-28 7 12 15 17 5/16-18 13 20 24 29 5/16-24 14 22 27 35 3/8-16 23 36 44 58 3/8-24 26 40 48 69 7/16-14 37 52 63 98 7/16-20 41 57 70 110 1/2-13 57 80 98 145 1/2-20 64 90 110 160 9/16-12 82 120 145 200 9/16-18 91 135 165 220 5/8-11 111 165 210 280 5/8-18 128 200 245 310 3/4-10 200 285 335 490 3/4-16 223 315 370 530 7/8-9 315 430 500 760 7/8-14 340 470 550 800 1-8 400 650 760 1130 1-14 460 710 835 1210 Copyright © AutoWare 1998 I hope that this saves a few bolts. http://www.auto-ware.com/techref/bolttorque.htm With the link. Ross in Bel Air
Max Torque (foot-pounds) for clean, dry threads Bolt size - Thread pitch Grade 2 Grade 5 Grade 8 Special Alloy 1/4-20 6 10 12 14 1/4-28 7 12 15 17 5/16-18 13 20 24 29 5/16-24 14 22 27 35 3/8-16 23 36 44 58 3/8-24 26 40 48 69 7/16-14 37 52 63 98 7/16-20 41 57 70 110 1/2-13 57 80 98 145 1/2-20 64 90 110 160 9/16-12 82 120 145 200 9/16-18 91 135 165 220 5/8-11 111 165 210 280 5/8-18 128 200 245 310 3/4-10 200 285 335 490 3/4-16 223 315 370 530 7/8-9 315 430 500 760 7/8-14 340 470 550 800 1-8 400 650 760 1130 1-14 460 710 835 1210 Copyright © AutoWare 1998 I hope that this saves a few bolts. http://www.auto-ware.com/techref/bolttorque.htm With the link. Ross in Bel Air
Torque
The mechanics of the screw thread are actually very complex, and have numerous interacting variables. Sliding friction is affected by materials (dissimilar metals), surface roughness, bearing area, material hardness, lubrication (lubricated threads decrease torque by 10-55% over dry), and load orientation (shear loads reduce torque by 30-40% over tensioned), etc. The importance of correct application cannot be overemphasized. Undertorque can result in unnecessary wear of nuts and bolts as well as the parts they hold together. When insufficient pressures are applied, uneven loads will be transmitted throughout the assembly which may result in excessive wear or premature failure due to fatigue. Overtorque can be equally damaging because of failure (yield or deformation) of the bolt or nut from overstressing the thread areas. Accuracy: Tightening is not an accurate science. From the “preloading accuracy” published in the "Machinery's Handbook”: Method ~ Accuracy By Feel ~ +/- 35% Torque Wrench ~ +/- 25% Turn-of-nut ~ +/- 15% Preload washers ~ +/- 10% Bolt elongation ~ +/- 3% Strain gauges ~ +/- 1% Given the inaccuracy of Torque figures, in determining the actual loading, any tabular specifications should be regarded as an approximation - a starting guidance only. Sailboat manufacturers (should) specify the recommended torque for each model, based upon their actual experience in use. Take all of these recommendations (including mine, which come from C&C/Tartan) with a grain of salt.
The mechanics of the screw thread are actually very complex, and have numerous interacting variables. Sliding friction is affected by materials (dissimilar metals), surface roughness, bearing area, material hardness, lubrication (lubricated threads decrease torque by 10-55% over dry), and load orientation (shear loads reduce torque by 30-40% over tensioned), etc. The importance of correct application cannot be overemphasized. Undertorque can result in unnecessary wear of nuts and bolts as well as the parts they hold together. When insufficient pressures are applied, uneven loads will be transmitted throughout the assembly which may result in excessive wear or premature failure due to fatigue. Overtorque can be equally damaging because of failure (yield or deformation) of the bolt or nut from overstressing the thread areas. Accuracy: Tightening is not an accurate science. From the “preloading accuracy” published in the "Machinery's Handbook”: Method ~ Accuracy By Feel ~ +/- 35% Torque Wrench ~ +/- 25% Turn-of-nut ~ +/- 15% Preload washers ~ +/- 10% Bolt elongation ~ +/- 3% Strain gauges ~ +/- 1% Given the inaccuracy of Torque figures, in determining the actual loading, any tabular specifications should be regarded as an approximation - a starting guidance only. Sailboat manufacturers (should) specify the recommended torque for each model, based upon their actual experience in use. Take all of these recommendations (including mine, which come from C&C/Tartan) with a grain of salt.
A grain of salt
I add this as anecdotal evidence. A friend had rebuilt the engine in a car that he used for drag racing. And in the first high speed run threw a connecting rod. One of the bolts on the bearing cap had failed. He told me that he had measured the length of the bolt before tightening and after torqueing( a bolt will stretch a predictable amount when tightened)[( a bolt that is of a lower grade will stretch more than a bolt of the proper grade)] and everything seemed to be right. The bolt was of proper hardness, size, grade, he had magnefluxed the lot. So sometimes ya pays yer money and ya the yer chances
I add this as anecdotal evidence. A friend had rebuilt the engine in a car that he used for drag racing. And in the first high speed run threw a connecting rod. One of the bolts on the bearing cap had failed. He told me that he had measured the length of the bolt before tightening and after torqueing( a bolt will stretch a predictable amount when tightened)[( a bolt that is of a lower grade will stretch more than a bolt of the proper grade)] and everything seemed to be right. The bolt was of proper hardness, size, grade, he had magnefluxed the lot. So sometimes ya pays yer money and ya the yer chances
Rebedding Keels
to All Great converstaion, I wish I had joined earlier. I'm contemplating keel removal of a 22 Catalina. Actually, not contemplating, initiating is a better term. Boat is currently on dry with 5 poppets (stands) and keel on appromately 10 inches of blocks. Does anyone have hull locations to place additional cradle to support hull along with current stands? Bolts are accesible, keel is cast iron, unfortunately. Finally, for the 64K dollar question: Does anyone know if the C22 has a short FRP stub keel or does the keel go all the way up to the fairbody line? It appears, and I only say apperars that there is a change in the surface texture about 6-8 inches below the hull that runs parallel to the hull at what I think is the hull/keel interface. Any help will be appreciated. I learn more stuff here than anywhere else about Catalina's Thanks!
to All Great converstaion, I wish I had joined earlier. I'm contemplating keel removal of a 22 Catalina. Actually, not contemplating, initiating is a better term. Boat is currently on dry with 5 poppets (stands) and keel on appromately 10 inches of blocks. Does anyone have hull locations to place additional cradle to support hull along with current stands? Bolts are accesible, keel is cast iron, unfortunately. Finally, for the 64K dollar question: Does anyone know if the C22 has a short FRP stub keel or does the keel go all the way up to the fairbody line? It appears, and I only say apperars that there is a change in the surface texture about 6-8 inches below the hull that runs parallel to the hull at what I think is the hull/keel interface. Any help will be appreciated. I learn more stuff here than anywhere else about Catalina's Thanks!
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