Hey, long time lurker here, and this is my first post in a long time.
I'm needing some wisdom!
While this isn't my boat (I wish!), it shows exactly the railing I need to make for a customer. I've tried welding similar things before, and heat distortion made the main rail bend in toward the braces (short rails). When this piece is done, it will be clamped down in the gunnel of a boat and welded to the boat.
Any advice in how to keep the main rail from warping?
Your welding on one side of a tube so it's not really possible without some distortion in my experience - the lower the heat input & welding in small lengths will reduce it to some degree but when I've done these rails I either pre-deflect the rail prior to welding which I prefer or straighten afterwards - stainless is the worst material for it but any one sided weld will do this - it's sometimes possible to clamp the two rails back to back & try to use one to dissipate the pull from the other while welding but I doubt this is practical for this application - never tried it as almost all the rails I do have all sorts of curves & height changes in their shape.
If the top rail has no return to a fixed mounting plate, or connection point, you’ll have trouble no matter what.
To me, it looks as though the verticals have base plates, the top rail a forward plate to mount behind the console? If so, screw the plates down to your table/jig, tack the bases up, tack the top rail to the verticals. Start in the middle, and weld out your first vertical, then proceed outward, base plates first. By the time you’ve reached the ends, you should be welding the tubing that is pulling itself toward the vertical anyway.
Hint: make sure you drill a small vent hole in the top rail where the vertical intersects. This will allow the pressure and gas to dissipate when closing the top of the vertical. Make sure you use an ample postflow and that your tacks are strong enough. Ally tacks are very weak and under that much welding, you’ll probably hear them pop if they’re stressed too heavily.
