Bolt Strength Differences for jackplate, help needed

[johnw91]

Hey Guys,

I got a fixed 10 inch slidemaster jack plate. It uses 4 S30400 bolts to hold it together currently. Unfortunately These bolts are going to be too short when I add power pole plates on the side of the jackplate. Lowes has stainless steel bolts in the same size and a longer length, but they are marked with F593C. I have tried to do some research online but cannot find a ton of information. Does anyone know the difference in strength between these two bolt types, and if going with the F593C would be sufficient? Thanks.

[Cheeseman]

Here's one discussion.

https://www.scribd.com/doc/139128082...-F593C-Article

304 is standard 18/8 stainless. F593C bolts are also made from 18/8 stainless, but they have a higher tensil strength that S30400 bolts. Either should be fine since you probably will not be subjecting them to salt water.

[gehol]

Whew, a little confusing but, let me take a stab at it. The 593C is an ASTM specification. The S304 is an alloy designation. So the F933C has certain characteristics such as 65 KSI. If the 304 is made to 593C specifications then it will have the 65KSI tensile strength (65 kilopounds per sq. in.). It would APPEAR to me any stainless bolt that met the 593C ASTM spec would be fine. I know clear as mud. Maybe someone will show up shortly that can explain it better.

[Melton Jason]

Check out this post in the Stroker forum.

http://www.bbcboards.net/showthread.php?t=959112

[Skeeterbait]

Buy TH Marine mounting bolts with brass no gall nuts and you wont have to worry about it. Even better would be to buy Mercury fine thread bolts with brass nuts but they will cost more. You are supposed to tighten jack plate to engine bolts to 90 ft lbs. I would not trust a bolt not designed for that purpose.

[johnw91]

Buy TH Marine mounting bolts with brass no gall nuts and you wont have to worry about it. Even better would be to buy Mercury fine thread bolts with brass nuts but they will cost more. You are supposed to tighten jack plate to engine bolts to 90 ft lbs. I would not trust a bolt not designed for that purpose.

I thought about doing that, Ill have to see if the current bolts are 1/2 inch . The bolts in question are not the engine to jackplate bolts, but are instead the 2 bolts on either side of the jack plate that hold the two pieces of the fixed jackplate together, I would think that these would have less force on them, but obviously want to use whatever is the best.

[DougL58]

Won't grade 8 SS bolts do the trick?

[OH_Ranger]

Won't grade 8 SS bolts do the trick?

No such thing.
Get on McMaster Carr website. There is a section all about bolt grades. Have to use a computer. Can't load website on a phone.
A local Fastenal store could get whatever you need also.

[DewRonInc]

Grade 9 ecoguard is way

[Riccochet]

Grade 8 or 9 will work just fine.

[gehol]

Not SS, but appears with that ecoguard coating it would be fine.

[Jumping Jimmy]

Those bolts that thread into the side of the plate only clamp the sliding section to prevent any up or down movement. I don't (think) you would have an issue using the bolts you mentioned to mount your poles.

[Bassnailer]

I'd like to add to this discussion by saying that, out of convenience, I bought new stainless steel bolts from Menards when I added a spacer to my jack plate. While the boats were stainless steel and rated high enough for the load they carried, they quickly rusted on the surface first time out with them. The rust was not bad, and it appeared to just be surface rust, but still annoying that a "stainless" steel bolt quickly acquired rust stains. We have a Fastenall in town, and I've learned to just buy all my stainless steel bolts from them. The bolts from Fastenall did not rust when I installed them, so I am guessing they are probably a higher quality stainless steel than the ones carried at the big retailers like Lowes and Menards.

[DrewFlu33]

Just buy the kit from Bob's. $35, so basically as cheap or cheaper than you can buy the bolts and stuff at the hardware store, and you'll know you're getting components that are up to the task. Comes with everything you need.

https://bobsmachine.com/product/jack...olt-kit-bolts/

[Ranger519VS]

I'd like to add to this discussion by saying that, out of convenience, I bought new stainless steel bolts from Menards when I added a spacer to my jack plate. While the boats were stainless steel and rated high enough for the load they carried, they quickly rusted on the surface first time out with them. The rust was not bad, and it appeared to just be surface rust, but still annoying that a "stainless" steel bolt quickly acquired rust stains. We have a Fastenall in town, and I've learned to just buy all my stainless steel bolts from them. The bolts from Fastenall did not rust when I installed them, so I am guessing they are probably a higher quality stainless steel than the ones carried at the big retailers like Lowes and Menards.

The stainless bolts that won't rust may or may not be of higher tensile strength as the ones that do rust. It all depends on what spec they meet. In fact if you use carbon steel bolts you can get them with much higher tensile than SS bolts. That's the problem, compounded by the confusing array of bolt specs. A sales clerk at West marine explained to me that their bolts and screws are all 316L SS and those from Ace Hardware or Menards are 304 SS. Theirs will not rust in marine applications. The 304SS bolts not so much. That's why theirs cost more.

Another problem is that most of the bolts will come from China or India and you are on your own when it comes to whether or not the bolts actually meet the spec that is stamped on them. Buying from Menards or Lowes; they tend to buy big lots and job them out to the lowest bidder so there you go.
In the construction industry we went thru problems with bad crosby cable clamps and shackles. Even tho they were marked properly the metal they were made of didn't make spec and there were a lot of failures. This endangered life and limb. We had to inspect every one carefully and check for proper manufactures stamping etc. to make sure they were genuine.