Keel bolt torque values.

B

BAD ORCA

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Nov 6, 2020
386
Mariner 36 California
I know this one comes up regularly, but curious for those of you that know your keel bolt diameter, material and torque value...what torque are you using?

I'm guessing I have 304 or 316 stainless bolts, possibly Monel (im 100% sure they are stainless but not exactly sure grade), 3/4 x 10, and get torque values all over the place, depending on what calculator or chart im looking at. I have tried my best through much research to sort through all the info and determine the best torque value for my keel. The values I have settled on ranged from about 95 ft/lbs to about 125 ft/lbs based on what i could best determine from charts etc...and some very limited anecdotal info from fellow Mariner owners. I settled at about 100ft/lbs with clean, lubricated bolts and nuts while the boat was resting on the keel, but am wondering after more research if thats a little low. I have seen some suggestions recently for 316 stainless that are a lot higher, mid 300's which seems crazy high, so am interested to see if i can get some input from other sailors.
 
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Johnb

Johnb

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Jan 22, 2008
1,457
Hunter 37-cutter Richmond CA
Look up the thread "Keel Bolts" and pay particular attention to what "Diana of Burlington" wrote.
 
D

dlochner

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Jan 11, 2014
12,757
Sabre 362 113 Fair Haven, NY
Sabre recommends 90 ft/lbs for all its boats. The torque value is not based on bolt strength rather it considers the fiberglass and it what it tasks to start crushing the layup and the strength of the lead to resist stripping the threads or pulling the bolt out of the lead.
 
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Tom J

Tom J

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Sep 30, 2008
2,323
Catalina 310 Quincy, MA
dlochner said:
Sabre recommends 90 ft/lbs for all its boats. The torque value is not based on bolt strength rather it considers the fiberglass and it what it tasks to start crushing the layup and the strength of the lead to resist stripping the threads or pulling the bolt out of the lead.
Click to expand
Good point! Years ago, I had an older O'Day 23 that needed the keel re-installed after being refurbished. I used the recommended torque values, and everything was fine for a number of years. Eventually, the boat had a leak at the keel and when I dropped the keel, I found that the thin layer of fiberglass of the hull had been crushed by the washers of the bolts being torqued. I blamed O'Day for this, since they had counter bored the keel bed and used short keel bolts. Yikes! I filled the bolt holes with epoxy and drilled new holes and used full length keel bolts.
 
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B

BAD ORCA

.
Nov 6, 2020
386
Mariner 36 California
dlochner said:
Sabre recommends 90 ft/lbs for all its boats. The torque value is not based on bolt strength rather it considers the fiberglass and it what it tasks to start crushing the layup and the strength of the lead to resist stripping the threads or pulling the bolt out of the lead.
Click to expand
Interesting, thanks. I had not known this but came across this in another thread this afternoon as well. I would not have considered this as part of keel bolt torque.
 
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