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Bluemansailor · 30-07-2012, 11:49

Am in the process of re-bedding my chain plates and am replacing all the bolts. Have searched on all the website chandleries for these bolts but can't seem to find them. I have found plenty of standard stainless carriage bolts but none with a slotted head. Anyone seen any of these around?

Their 2 1/2 inches long and 3/8" diameter.

thanks

rtbates · 30-07-2012, 12:24

why in the world do you want a slotted head?? They SUCK...The application could care less about head type, slotted or phillips...or the best a hex socket...

Bluemansailor · 30-07-2012, 12:29

Quote:

Originally Posted by rtbates

why in the world do you want a slotted head?? They SUCK...The application could care less about head type, slotted or phillips...or the best a hex socket...

why do you feel they "suck"

Fortytwo · 30-07-2012, 12:47

http://www.mcmaster.com/

Bluemansailor · 30-07-2012, 12:55

Quote:

Originally Posted by Fortytwo

McMaster-Carr

yep they have them thanks Fortytwo!

Freerider · 30-07-2012, 13:06

I find them hard to tighten, and un-tighten. A flathead screwdriver is no match for the socket wrench on the other side.

When i disassembled my boat for her refit, all the lifelines were through bolted with slotted bolts and it made me want to inflict pain on the builders.

ArtM · 30-07-2012, 13:30

Newbie question, since I have a recently developed interest in chainplate integrity -
Is there a need to regularly replace bolts like these? Are they subject to stress fracturing, or anything like that?

In other applications (not sailboats) I have been recommended to NOT change out bolts which are in good condition because the original bolts may have engineering or design specs which are not apparent and may not be present in a newly purchased bolt.

**skipmac** · 30-07-2012, 13:47

Agree with previous opinions. Slotted screws are a pain and the application does not care at all what kind of head is on the bolt.

Slotted heads are hard to tighten, screw driver can easily slip out of the slot and scratch your wood or gouge your hand. Any high torque application it is almost certain the slot will end up damaged and if you have to remove these after a few years of marinating in salt air a slotted screw head is about ten times more likely to strip out.

Plus if you are trying to install short handed you can clamp vice grips onto a hex head to hold it while you work on the other side or hold one side with a wrench while you turn the other side socket.

Bluemansailor · 30-07-2012, 13:55

I guess I should have posted a photo of how my chain plates are attached- I have to disagree as I had no problem removing the bolts nor the chain plate.
If my bolts where hidden inside my boat I would have no problem using a hex headed bolt, but as they are on the outside of the boat -- I'd like to replace them with the original bolt and look. - I found them and have ordered them.

As far as ArtM 's question "In other applications (not sailboats) I have been recommended to NOT change out bolts which are in good condition because the original bolts may have engineering or design specs which are not apparent and may not be present in a newly purchased bolt."
I don't think that would matter here as most boat builders use standard bolts.

barnakiel · 30-07-2012, 14:05

If your plates are thick and external, you may consider countersunk (wording?) heads - they could be made flush with correctly drilled / countersunk plates.

b.

Stumble · 30-07-2012, 14:27

ArtM,

Stainless bolts on a sailboat are often the first thing that sufferes from crevice corrosion. They are typically under enough stress to cause what's called stress crack corrosion, plus the threads are prime candidates to start crevice corrosion. This is a pretty big subject, and there are a lot of seperate things that work together to cause stainless corrosion.

There aren't really the same type of proof bolts in stainless as there are in steel. That is because the stainless grades are much more descriptive than occurs with steel alloys. So for instance a 316 bolt from almost anyone is going to be very close in properties to a 316 bolt from anyone else. With steel that isn't true, there are hundreds of steel alloys (if not thousands) so proofing is pretty necessary.

That being said, there are a number of stainless grades, and you need to know what you are replacing to match it. Or go with the strongest option you have available. That being said most boat manufacturers use either 304 or 316.

**roverhi** · 30-07-2012, 15:37

If these bolts are external, I'd change them. These fasteners are classic examples of places where crevice corrosion will occur. AFAIK, carriage bolts have a round head with no screw slot. Under the head is a square bolster that fits into a square recess in what the head is seated against that keeps the bolt from turning.

Straight slot machine screws can be a major problem to get out if you have to unscrew them. Having said that, straight slots are a lot better because you can put more torque on the fastener than with a Phillips head which strip out real easy. In your case, all you probably had to do was remove the nuts on the inside and punch the screws out. If they fell out, they are definitely candidates for crevice corrosion because that would mean the caulk had failed and undoubtedly allowed salt walter to infiltrate. Stainless bolts that are not subject to salt water immersion/infiltration are usually good to go.

Sailor_Russell · 01-10-2016, 13:23

Are there any other sources people know of for Slotted Truss Head bolts made of 316, larger than what's available on McMaster. Additionally, they only have 18-8 in the larger sizes. By large I mean 1/2" bolts by 9 inches long. Thanks!