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Clamdigger · 04-01-2017, 06:34

I have a technical question with regard to a 'soft/shallow dent' in my aluminum mast. It is located adjacent to the Mainsail track opening and appears , by eye, to *slightly* pinch the track. the mast shape is an elliptical more than round cross section.

First question is how does one not mar the sail track opening while 'burping' this soft/shallow dent out? What tools to use? I don't have a pair of calipers to measure the sail track to know how far closed it is vs the rest of the sail track opening. We are talking between 1/8th" to 1/4" at most pinched vs the unmarred track opening. What tool should I use to spread the track open, without marring the sides of the opening?

It's about 3-4" in oval diameter size. Will/can this have any structural strength losses in use due to this 'soft dent'? I do not know how this dent occurred in the mast. I am considering it to replace a wooden mast on an available 19ft'er.

**tkeithlu** · 04-01-2017, 08:07

First, aluminum, unlike steel, does not have a "memory." While small dents in a car can be popped out, connecting a slide hammer to the center of the dent in the mast and giving it a whack will just rip the slide hammer out of the mast, leaving a worse mess. Doing body work on aluminum cars is really difficult. You have to hit the dent from the convex side, which in your case probably means hammering a mast-shaped wooden plug up the mast to push out the dent. That's going to be a very challenging task. As for reshaping the track, I think the best rule of thumb is use a hardwood strip sized to the correct track width plus a little to allow for aluminum's slight eleasticity, and tap it up the track slot, small taps at a time. Then, leave it in the track wherever the bent track is too wide, and tap the edge down using another wooden tool, such as a dowel, with the wood strip serving as the anvil. The point is that if you hit it anywhere with a steel hammer, you're going to dent it, not shape it.

I can't imagine getting through a day of boat work without a vernier caliper. They are cheap.

**a64pilot** · 04-01-2017, 08:11

The dent depending on size and depth undoubtedly weakens it, however maybe the best thing is to leave it alone, track like was said, work it out by knocking something soft and slightly over sized through, I can't think of anything significantly better than wood.
Do not use heat.

rognvald · 04-01-2017, 08:23

Clamdigger,
I used a slide hammer(as tk mentions) on a mast dent by my spreader base on my former 25 foot boat. I heated the area with a heat gun and slowly worked the spot with the slide hammer until the dent was barely perceptible. I then prepped the metal, sanded, re-prepped the metal and faired with West System high density filler and painted. The repair was imperceptible when we sold the boat 10 years later and there was never a structural issue. However, the mil of the mast was surely less than those used on a larger vessel. If it is for a 19'. boat, I would give it a try. I believe you will be successful. Good luck and safe sailing. P.S. Can you send some pix??

Cheechako · 04-01-2017, 08:35

For a 19 footer, I wouldn't worry too much. But where? is the dent? top? Bottom near the boom? in the middle? A slide hammer may work on that small mast, I cant imagine the aluminum is very thick on that... which is probably why it dented.

**tkeithlu** · 04-01-2017, 09:54

Hmmm. One person suggests heat and the other says don't. OK, in theory it's a good idea, but be careful - aluminum melts at about 1200F, and you could make a mess if you over heated it in one area.

paulajayne · 04-01-2017, 10:02

Quote:

Originally Posted by tkeithlu

Hmmm. One person suggests heat and the other says don't. OK, in theory it's a good idea, but be careful - aluminum melts at about 1200F, and you could make a mess if you over heated it in one area.

Rub area to be heated with soap.

Heat slowly and when soap turns brown STOP.

Be very careful as the outside surface (oxidised aluminium) has a higher melting point that the aluminium hence using soap as an indicator.

thruska · 04-01-2017, 10:42

You can heat the dent . But dont use a gas torch!
Use a electrical heat gun directly on dent. Then use ice after removing heat source. Its called heat shrinking.
I suggest you research the method . It works.

alaskaflyfish · 04-01-2017, 10:51

You can glue a tab to the dented area using hysol or similar adhesive and then pull the tab. The adhesive that is used to glue rear view mirrors to windshields will work if you don't need a great quantity. Or you could polish the area smooth and use a vacuum assisted suction cup on the end of a puller. Auto shops use these to pull dents.

**a64pilot** · 04-01-2017, 11:56

Quote:

Originally Posted by thruska

You can heat the dent . But dont use a gas torch!
Use a electrical heat gun directly on dent. Then use ice after removing heat source. Its called heat shrinking.
I suggest you research the method . It works.

That might work and can't hurt. I have seen hail dents "pulled" out of cars in Tx with dry ice after letting the car set in the sun.
Aluminum can't take much heat and unlike steel it gives no indication its about to melt, then suddenly you have an aluminum puddle.
When we say heat the metal as an old welder first thing comes to my mind is a rose bud, don't use an oxyacetylene rose bud on aluminum, I seriously doubt you could hurt one with a heat gun though, be tough I think.

**a64pilot** · 04-01-2017, 11:59

I'd like to try the adhesive method myself as I can see it working 5200?

Just joking, the mirror adhesive may do it though

thruska · 04-01-2017, 12:09

Quote:

Originally Posted by Clamdigger

I have a technical question with regard to a 'soft/shallow dent' in my aluminum mast. It is located adjacent to the Mainsail track opening and appears , by eye, to *slightly* pinch the track. the mast shape is an elliptical more than round cross section.

First question is how does one not mar the sail track opening while 'burping' this soft/shallow dent out? What tools to use? I don't have a pair of calipers to measure the sail track to know how far closed it is vs the rest of the sail track opening. We are talking between 1/8th" to 1/4" at most pinched vs the unmarred track opening. What tool should I use to spread the track open, without marring the sides of the opening?

It's about 3-4" in oval diameter size. Will/can this have any structural strength losses in use due to this 'soft dent'? I do not know how this dent occurred in the mast. I am considering it to replace a wooden mast on an available 19ft'er.

Hey. C Lamdigger,
If you could show some pics with a closeup of the dent and track , more precise advice might be able to be given.
Might 'being the operative word there.
Good luck

**Symphony** · 04-01-2017, 14:24

great ideas: soap as thermometer, heat gun, wooden plugs, Hysol.

**tkeithlu** · 04-01-2017, 16:26

Folks, don't be too quick to recommend ways of popping out an aluminum dent based on automotive procedures. Automotive body steel is formulated to take and hold a shape when stamped with considerable force, and to pop back (memory) if dented after it cools. Aluminum doesn't work like that. It has no memory and darned little elasticity. It's soft. It's also plated - what you've got is an aluminum alloy that is stronger than pure aluminum, plated with pure aluminum, because aluminum alloys corrode (filigree - seen it?) while pure aluminum forms a self protective oxide.