Originally Posted by Icarus
Ultrasonic testing is certainly the go, and yes it works, we use sonic testing in the mining industry ..and yes it works
350 is cheap
and a good starting point.
Trouble is some keel bolts might be imbedded and attached to an internal reinforcement structure of the ballast and cant be removed. especially in lead ballasts.
if the ballast is cast steel they most likely will be screwed in to it and can be removed one by one, possibly without dropping the ballast
What is the material of the keel bolts? SS, bronze
, Monel, steel?
SS is the worst.
Thanks for the post. I put in a phone
call to Catalina in Florida
last week and spoke to a very helpful guy called Warren. He explained that the keel bolts are either L-shaped or J-shaped and are embedded into the lead at the time of keel construction. The L or J shapes mean that the bolts cannot be inadvertently pulled out of the keel due to large forces which may be applied through a grounding or similar. The bolts are made from 316 stainless steel
and 1 inch in diameter, with 1.5 inch nuts. Warren advised that he had never heard of anyone doing ultrasonic testing on the bolts, but advised that I should ask the ultrasonic testing contractor to provide me with sample reports, graphs or images
, showing what type of report I might expect from him. That was good advice
. Warren was keen for me to take photos of the bolts as they presently are (i.e. crusted up with some surface rust) from inside the bilge
and then clean up the bolts with a wire brush, or circular wire brush attached to the chuck of a battery
operated drill, and take additional photos after the clean-up. He was keen to see both before and after photos, which I will take and send to him. He also explained that the keel was bonded to the hull
with a very strong bonding material and that material alone would in all likelihood keep the keel attached to the hull. He further explained that the hull was about 3 inches thick where the keel bolts passed through the hull and that during manufacture, bonding material was applied to each each keel bolt in a teepee tent-like shape and while the bonding material was still uncured, the keel and hull were brought together forcing the uncured bonding material up into the holes in the hull for the keel bolts thereby binding the bolts into the hull supposedly making a very strong and water-tight join. He further explained that while at manufacture the nuts were tightened to around 150 ft-lbs, when I next did a haul-out I should remove each nut in turn, inspect and possibly replace each nut and then retighten each nut to at least 105 to 110 ft-lbs. My next step is to get sample reports from the ultrasonic testing operator to determine whether the testing is likely to produce reports which are usable for drawing conclusions about the condition of the bolts.