Tager, You are correct. I remember that from A&P school.
03-30-2010 11:33 PM
Well, The boat, a W.D. Schock Santana 27 is a fairly well known boat built by a reputable company and designed by Gary Mull who was a very well respected designer. The company still builds the Santana line and still uses the same bolts some 40 years after they were installed in the keel I now own.
Considering the condition of the bolts I would say that they certainly know what they are doing. At least from an engineering standpoint anyway.
03-30-2010 11:32 PM
I don't believe that the bolts are buried or tapped into the keel, mitiempo, they are countersunk into a flange on the top of the keel. The shear strength of the bolt is still the same, and the amount of thread engagement necessary to obtain full tensile strength is only as large as the nut. It was surprising for me to learn how little thread engagement is necessary to obtain full strength in a bolt.
03-30-2010 11:15 PM
I would think that the bury in the keel itself should be 5" to 6" minimum for the keel bolts. 2.5" sounds very light to me.
03-30-2010 09:26 PM
"If it ain't broke, you're not trying . . . "
03-30-2010 09:05 PM
These are 1" diameter x 2.5" length. The keel is countersunk so the bolts sit flush to it. Apparently Schock is still using the same bolts with the exception that the new ones are now 3" length. This means I will have to cut them which will be no small job considering they are SS.
I am a big believer in the theory of "if it's not broke, don't fix it." which is why if I pull another and it looks as good as the first then I will delay cutting and installing the remaining 8.
03-30-2010 08:56 PM
that does not look like any keel bolt i have ever seen before. normally they are around 1 inch dia and 10 to 12 inches long with no head, just a long thread.
03-30-2010 08:34 PM
I would say you are lucky to be able to remove the the old keel bolts. There are boat maintenance companies that simply drill (bringing a modified drill press inside the boat) and tap brand new holes in cast iron keels - next to the old/original bolts at a cost 100 times what you spent above.
Way to go!
03-30-2010 08:19 PM
Replacing the Keel Bolts
After reading this forum I decided to inspect the keel bolts on my newly purchased 1971 Schock Santana 27.
I read somewhere that inspection after 15 years and replacement after 35 was called for. The previous owner had sailed her on Lake Erie but as her history beyond this owner is unknown to me I decided that after 40 years a look was in order.
I contacted W.D. Schock and they were very helpful considering the age of the boat. They told me that the original hardware was zink coated steel but that they now use stainless steel. They offered to sell me a complete new set of 10 each bolts, nuts, and washers for $10.
I removed the first bolt by cutting the nut using a chisel and large maul. After about thirty or so whacks the nut cracked and I was able to drift the bolt out.
surprisingly enough the bolt was in excellent condition considering it's age. As you can see by the attached picture aside from some rust on the threads above the nut, the bolt and load bearing threads are in great shape. The only damage visible is that caused by the cutting of the nut.
Based upon what I found I am now thinking that I will pull one more bolt and if it's condition is the same I will replace those two this year and then replace the balance in the future.
Due to the condition of this bolt I am guessing that this boat has had little saltwater history.