Bimini/Rail SS 316 or 304 or what?

[AMFE]

I need to build a bimini for my boat and was also thinking of replacing cable lifelines on the aft end of boat with stainless tubing rather than wire.

What are people using, polished 316 or 304? The prices I am seeing for a 20' stick of 1" 316 is about 500$. surely I am not looking in the right places. I figured 304 would stain but noticed that is what Jamestown is selling from Taco.

any recommendations on where to procure materials? local industrial stores are off that chart also. Or I may just be a tight wad.

Also.....Can a guy order material from say jamestown and then pick up the 20' sticks from taco to save the ridiculous shipping charges?

I currently live in oklahoma so I understand that limits me.

[robert sailor]

Forget 304 unless you sail on fresh water

[AMFE]

thats what I was thinking robert..........looking for a supply house for 316. 500$ unshipped for 20' surely isnt the going price?

[pdxsailordiver]

I just priced 1" 304 and 316 .062 wall thickness at Alaska Cooper and brass in Portland,OR an industrial supply house.
304 $3.02/ ft 316 $6.10 / ft.
I want to build a bimini.

[AMFE]

thanks pdx I have not tried alaska cooper. Will look into that.

[roverhi]

304 won't rust out but will probably show more rust stains than 316. That is not to say that 316 won't also stain. Occasional cleaning with Barkeeper's Friend, oxalic acid, or some other rust converter/polish will keep it shiny. If you really don't want rust staining get 316L It's the most rust free 3 series alloy.

Most production boat hardware is 304 from chainplates to bow rails. Higher end boats may have used 316 but wouldn't guarantee it. There has not been good quality SS available in the US since the late '60s. Remember sitting in Papeete in the mid '70s comparing the ss on US built boats and those from Europe. Euro boats stainless was almost always bright and shiney while our boats were dull and often rusty. Rerigged my boat with 316 wire from one of the biggest yards in SF Bay a few years ago. Had to have a rigging survey done a year later. The surveyor questioned the alloy and age of the rigging because of the staining.

[Stumble]

So I just had to look...

Typical Bimini rails are made from 1" .049 wall stainless. But prices are all over the map...

West marine 304 - 20' $150 - $7.50/ft
Online metals 304 - 8' $74.73 - $9.34/ft (welded)
Online metals 304 - 8' $80.77 - $10.09/ft (seamless)

So I went and priced some carbon fiber tubing just to see.

RockWest will sell you 1"x.036 wall for $14.66/ft.
Dragon Plate has the same size for $14.75/ft.

Both will give you a 10% discount for ordering 36' or more.

Not that I advocate CF for Bimini frames, or thatthis is the right size, but I had to look.

[AMFE]

Thanks guys,

Is there a way to test stainless to determine weather it is 304 or 316?

[Cheechako]

304 is fine. Most boat rails in the past were 304. What is more important is how good the polishing is.

[doc_cj]

This might be a good place to ask, will the common pipe bending jig work well with the smaller walls on 304? I've done aluminum and othe qualities of SS, but no experience with 304.

Also, I don't know the name of the overhead rig setup at the aft and used to hold solar panels and other goodies. My new (1978) Hunter 27 doesn't have a Bimini top and the single solar panel is mounted on a safe rail that is in the port pulpit position. I'd like to reclaim the rail so that I can install a real pulpit/seat on each corner. Since i'm adding the Bimini top I assume the rig will allow me to move the single (soon to be double) panels up and out of the way.

[Dan_K]

Consider ensuring whichever stainless steel is ordered, it is passivated (this is the removal of anodic contaminates from the surface, iron being the most common). Passivation is an industrial process nearly impossible to do at home. If the tubing is not passivated, it will corrode (stain) fairly quickly. Mechanically polishing, if it does not remove the imbedded iron, will stain again. Electro-polishing (another industrial process) will passivate the surface.

[a64pilot]

Originally Posted by robert sailor

Forget 304 unless you sail on fresh water

Not so sure. Kato Marine, uses 304 for their davits, Radar poles and such, and they are considered to be a high end product.
However if I have a choice I would go with 316

[Cheechako]

Originally Posted by doc_cj

This might be a good place to ask, will the common pipe bending jig work well with the smaller walls on 304? I've done aluminum and othe qualities of SS, but no experience with 304.

Also, I don't know the name of the overhead rig setup at the aft and used to hold solar panels and other goodies. My new (1978) Hunter 27 doesn't have a Bimini top and the single solar panel is mounted on a safe rail that is in the port pulpit position. I'd like to reclaim the rail so that I can install a real pulpit/seat on each corner. Since i'm adding the Bimini top I assume the rig will allow me to move the single (soon to be double) panels up and out of the way.

Are you talking about a hand conduit bender? Not sure if you can get a good match tool to tubing...?
Generally, the thinner the wall, the more likely to get some wrinkling, but moderate bends not bending too far and on a fairly large radius bend are usually not a problem with small tubing and thinner walls. IF the bender OD cavity fits the tube OD well. 1" x .049 wall is a pretty good ratio actually if your bend block radius is over 6".

[robert sailor]

Originally Posted by a64pilot

Not so sure. Kato Marine, uses 304 for their davits, Radar poles and such, and they are considered to be a high end product.
However if I have a choice I would go with 316

I have screws and the odd fitting that's made of 304 and after a short passage, say 2 or 3 days they are rusted. On a crossing 304 will be bleeding rust. Just won't have anymore of that on our boat. It's a British boat and all the original stainless was high end 316 and it always looks good with the odd rinse. Friend just bought a so called high end combo davit and solar panel arch made by a reputable builder in Florida and it's always rusting. He's polished it over and hates it. He was told it was carefully polished and lots of satisfied customers when he bought it during a boat show. You can't give me 304 for a sailboat that is actually being sailed. Here's our high end Caribe dingy with crap 304 stainless. I clean these with acid once a month and they end up just like this. The exterior facing ones are twice as bad with rust running down several inches. I'll change these out after I'm back home where I can buy some quality stainless. If your boat is sitting in a marina and your using it on weekends and short holidays then fine 304 is ok because your rinsing the boat of continually and it's not getting exposed to salt spray but if your a full time cruiser do yourself a big favor and spend the extra money.

[Cheechako]

As others have mentioned and myself... regardless of 316 or 304, it's important about surface treatment, passivation, polishing etc to a large extent. Screws are rough cut, never passivated, work hardened and may have been in contact with steel. This is why they may rust quickly. Both alloys have a large percentage of iron in them. If SS is work hardened, it corrodes faster and actually may become magnetic like steel, which in the solution treated and passivated condition it will not be. A SS flat bar which had a final cold pass when rolled will be magnetic. That doesn't mean it's bad material, but it's in a different state than it should be for some uses. It will also be much stronger than soft SS. Just because your 304 is rusting, doesn't mean it couldn't be made to be much less rust prone.