Aluminium sail track welded to mast

[DougR]

Most normal modern marine masts don’t have welded on tracks because during manufacture the mast is extruded thru a die and the recessed sail track is extruded in place along with the rest of the mast.

However there is plenty of other welding done on masts....plates for the gooseneck, plates for the boom vang attachment, winch bases, spreader brackets, masthead fabrications, tapering, etc......common as dirt.

Any decent welder should be able to tack the track to the mast without causing harm to the mast, but I think I would take a foot or two of track and do a little test welding, probably at the base of the mast, and check it out. Is there any distortion of the track? Any internal tube distortions? A little basic material strength calculation can compare fastener tensile strength to weld strength....

[RaymondR]

On the broken boom.

It was an Isomat boom, 6061 T6 I think 2.5mm wall thickness. Not a good combination with a loose footed sail and the main sheet arrangement about 5/8 along the boom from the mast end. The crack on one side had been there for some time as the edges on the inside were corroded. I repaired it by having a 3mm plate sleeve pressed up in three pieces and drilled, threaded and counter sunk about 100 screws.

On the track on your new mast.

If you are going to stitch weld a track on I would not use the track they screw to wooden masts.

I'd buy say 25mm x 25mm x 3mm square hollow section and split it with my panel saw into two U sections. Then I would stitch weld it on it on with the stitches in either side of the U legs. Then I'd set up my saw with a fence and with the blade mostly retracted and saw the slot up the middle of the U. This would form a slot which would use the same slugs as those on the extruded mast sections.

[nik36]

Originally Posted by billgewater

Look at spars that come out of professional spar shops. Do they ever weld the tracks on? I must say I have never seen welded tracks on a mast .... ever.

There must be some reason(s).


I believe that being conservative with boating practices is probably the best path to follow, unless you are into experimenting which can be horrifically expensive.

Cost is probably one factor. You can pay minimum wage for someone to drill holes but a competent welder would be pretty expensive. Probably not enough work for a fulltime welder in a smaller shop so you either need to pay welders wages for routine work or get someone in at double the cost (or send it out).


You can check a minimum wage hole driller/riveters work, but unless you have some equipment/training you need to trust your welder - bit of a risk (but I do trust myself)



Then you have the risk factor of people not accepting the process, remember when they introduced those "plastic" (yuk) boats ie fiberglass 8-)


Also boats (at least where I live) are 90% driven by racing so the masts will be as light and hitech alloy as possible, probably not easily weldable.


Tracks do need repair and replacement occasionally. You probably wouldn't buy a mast that you couldn't do repairs on.



Why change if you are already making money with the existing process.


I would not recommend that a commercial enterprise tried something like this.....


However.....



I am actually into experimenting, the expense is not too bad. The materials are about $500 AUS and my labor is for pleasure so I should actually be paying to do this 8-)


I actually had access to a second hand mast that would have done the job, it was $1000, but because of the length it would have cost me $1500 to get it here.

[Manateeman]

Here is another method...no drilling, no rivets and no TIG so no heat issue.
Call PLEXUS or send them an email.
You will get a free engineering answer to your idea.
It might be possible to glue the track on.
Not what I would do but I do not think TIG is the answer.
Again, you could post this idea on Boatdesign.net and you will get excellent feedback from builders and engineers.
Happy trails to you.
Captain Mark and his Manatees who love Jody on Welding tips and tricks.

[rmlarson1098]

Originally Posted by nik36

Hi all,
I have a 10m mast which will carry a 20m2 mainsail. I intend to tig weld the sail track to the mast but so far have been unable to find an example regarding weld size and spacing. I can understand the 100s of rivets/screws closely spaced normally used because rivets do pull out, but I was considering every 200mm, maybe that's a bit too far apart. It's a balance between overwelding and the track lifting as the sail pull on it.


Any examples/advice appreciated.

If you 'stitch' weld the track along the edges, you'll want to 'backstep', or 'backweld'. Tack it up carefully, as it'll pull like crazy when you start to fit & tack. Whatever spacing you chose; 3" on 12", 2" on 6" (measurements in inches) or whatever understand how to backstep your welds. If unfamiliar with that I could explain it in another post (simple enough) but if you can TIG weld I'm sure you know how it works.
The idea of slot or 'plug' welding is interesting. You have no holes in your sail track, but you could drill your own every foot or so. Make 'em so you can actually get some weld in there. To slot weld with TIG (heli-arc) is a challenge; you've got to feed wire, the TIG torch is in the way...
You'd better be pretty handy with that rig.
Everybody loves TIG welding, but for aluminum in my experience MIG (wire- feed) is the way to go. Find a spool gun set up, with the little (I think 2 pound) spool of aluminum wire right on the gun at your wrist. Prevents that soft wire from kinking, jamming, and much cursing.
If you already have a heli-arc rig, well then there you go.
I'm not certain what you mean by 'over-welding', but I expect your thinking about too many and/or too long stitch welds. But it doesn't do you any good to weld an inch every foot, and have the track break off with the first squall.
Once you strike up an arc on that mast, weld it like you mean it. Backstep!
Fill in those craters at the end of each weld, and hold your shielding gas there for several seconds after breaking the arc.
Better yet weld right to left, then left to right to finish the weld, putting the crater in the middle. A LOT of aluminum stitch welds break at the craters.
I spent over 40 years behind the hood, in construction - oil refineries and powerplants, shipyards and the like. Most of that work was mild steel, stainless and assorted alloys (inconel, etc.) and I don't have a lot of experience welding aluminum. I LOVE to weld! That said, I would probably rivet the thing.

[RaymondR]

The way to emulate an extruded mast section would be to plug weld a piece of flat bar as a chord on the inside of the round 3 mm mast tube then use the panel saw to cut the groove up the back of the mast section. Now that would look neat and just like a store bought mast section.

Where are you situated nik36?