Comparing wood and aluminum masts

[okawbow]

I am wrestling with the desision of what to do with my wooden masts from my Cheoy Lee 31. The old masts are off and stripped of all hardware. The mizzen is rotten for 2 feet at the base and has joint separations in several places farther up. The main mast has a small amount of rot at the base, and also a few bad glue joints. Many of the screws were loose or stripped, leading me to believe the 40 year old masts may have reached the end of their days.

I have thought about building new masts. I have the tools and skills, but I'm having a really hard time finding wood within driving distance,( near St. Louis) and I don't feel comfortable taking what someone else picks out for me.

Another alternative is aluminum. For those that know about such things; how does the size of an aluminum mast compare to a hollow rectangular wood mast? My main is 5" X 7" at the base, and tapers to 4" x 4 1/2" at the top. The top and bottoms are 1 3/8" thick, and the sides are 3/4" thick. I don't think most aluminum masts are tapered. If I buy an aluminum mast to replace the wooden one of the same height; will it be the same diameter as the wood? Will it look too bulky at the top with out taper? Can I use a smaller diameter aluminum mast and get the same strength as the wooden mast?

[rbgarr]

Aluminum masts are often tapered. How tall is yours?

[StevenBauer]

Carbon fiber? With fake wood grain.

Or buying aircraft grade spruce so you know it will be good without picking it out yourself.


Steven

[JimConlin]

Aluminum masts are generally made from extrusions which start out with uniform dimensions. These extrusions are often anodized shortly after being extruded. Getting a taper into an extrusion is done by sawing a tapered slit in the extrusion, welding it back together, grinding it fair and anodizing again. Not surprisingly, mast builders have wanted to avoid this considerable effort and the majority of aluminum masts are not tapered. The weight savings of tapering are small. For a boat with a masthead foretriangle like the Cheoy Lee Offshore 31, tapered aluminum spars are uncommon.
I suggest that you ask a yacht designer or mast builder about scantlings for aluminum spars. I think you'll end up with spars that are modestly skinnier but (more importantly) considerably lighter.

Carbon fiber spars can be considerably lighter than aluminum, but at a cost that would be hard to justify for a vintage cruising boat. A faux finish on an aluminum spar could be done, too. Same comment re cost.

[kc8pql]

Or buying aircraft grade spruce so you know it will be good without picking it out yourself.

That's what I did, from Public Lumber in Detroit. Including shipping it cost about a third of what Rig-Rite quoted for a 50' aluminum mast.

[kc8pql]

I think you'll end up with spars that are... considerably lighter.

Maybe, maybe not. The 50' aluminum bare spar quoted by Rig Rite, a Kenyon Spar suitable for offshore cruising weighed about 300 lbs. The round, hollow, tapered, 1 5/8" wall sitka bare spar I built weighs about 200 lbs. Yeah, I know. It surprised me too. I suspect though that the bronze fittings on my spar ate up maybe half or more of the weight difference.

[JimConlin]

Ask another spar manufacturer and tell him that weight matters.

[JimConlin]

Sounds heavy.
Ask another spar designer and tell him that weight matters.

[okawbow]

Aluminum masts are often tapered. How tall is yours?

My main mast is just over 30 feet tall. The mizzen, just over 23 feet.

[RFNK]

I hope I'm not too far off the topic here but why would a mast with a masthead rig be tapered? Is it a little bit of weight saving or another reason? Rick

[allene222]

Before I knew that it wasn't the right way to do things, I carved out all the seams in my mast with a sharpened bent screwdriver. The seams were all coming apart. I filled them with West Systems. That was 20 years ago. I have had to do a couple of places that I didn't originally do since then but it has been fine. Now I spline the seams I repair. Have you considered just replacing the rotten section and re-glueing the joints? By the way, if it falls down, don't blame me, it is your decision on what to do. If it were my mast, I would repair it.

Allen

[ssor]

Aluminum flag poles are tapered and very available. They would still need to be made into masts but they do make pretty nice sticks.