Dear Boat Doctor,

I am installing some new Harken winches on my boat, and I was told to clean the fasteners and use Loctite to prevent them from “galling.” I agreed, but I’m not entirely sure I know what galling is or why I need to clean perfectly good, brand new fasteners. What should I do?

Henry Anderson

Newport, Rhode Island

Dear Henry,

Whether you really understood it or not, the advice you got was good. 

Galling, also known as cold welding, occurs when metal threads are placed under pressure. As the threads engage, the parts can seize. This can jam the fastener, rip threads or even break off the bolt. Unfortunately, sometimes just the act of threading a bolt and nut together can cause this to happen. It can occur with any metal but stainless steel is particularly susceptible. The nyloc nuts—nuts with nylon inserts—we use for security on critical marine fasteners makes the problem even worse.

The answer is to control the heat and pressure, and the best way to do this is by going slowly and lowering the friction. As tempted as you may be to use a power tool to install the bolts, use hand tools because the lower speed will keep things cooler.

Lubrication is tricky; you want to make the bolts easy to install but you don’t want them to loosen later. The best solution I have found is a thread locker like Loctite. This material will act as a light lubricant when you first install it, but will cure into the thread locker.

Loctite comes in colors that indicate the strength of the materials. Blue is the most common color and fasteners locked with it can be removed with normal hand tools. Red is the more permanent version—once locked, fasteners need to be heated to 500 degrees to be removed. In your case, Blue Loctite will suffice.

The cleaning is for a completely different reason: Proper preparation will keep those through bolts from leaking. Bolt manufacturers will sometimes lubricate bolts, to prevent galling, and some dirt/oil is left from the manufacturing process. If you leave this oil behind, it can prevent a good seal at the deck. 

A quick wipe with a solvent will prevent any problems. You’ll be surprised how much dirt comes off shiny new fasteners. I like to wipe down all the surfaces of the bolts, nuts and washers with acetone. Just make sure they are completely dry before you install them.