Building a Wooden Mast

[lohwaikin]

I forgot to take pictures, but there's actually a shallow groove cut into each 3.5" wide slope to capture the "sail-track bulkhead", which is a scarfed-up 26-feet stripe of 1" x 1/8" timber. Then some epoxy fillet about the radius of the doctor's tongue depresser...

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[lohwaikin]

Stiffening the "sail-track bulkhead"...

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[lohwaikin]

By 01 JUN '13....

The 2 triangular sections (wedges) were glued on next.
There's a slight change in my cross section design in an attempt to achieve a slightly larger 96 x 70 mm size.
Therefore some 1/8" spacers are temporarily stapled to these wedges to lower them on the sloped planks.
The internal corners were filleted to the doctor's tongue depresser's radius.
Photo seems to show some "jagged" edges but they are actually the "fill-in" of the edges of the biax tape that went in earlier.
The inside surfaces have to be reasonably smooth to prevent catching or fraying a braided line.

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[lohwaikin]

And then got hijacked by work.....

By 21 JUL '13, preparing to close up the hollow section:

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[lohwaikin]

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[lohwaikin]

The top plank went on.
Quite a stressful operation.
I have to resort to mixing into the thixotropic epoxy some glass microballoons to delay the kick-off.
It managed to extend the useable pot-life from usual 20 minutes to 45 minutes.

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[lohwaikin]

Marked out the first 4 corners.
Then plane them off.
Took about 4 hours to cut 4 corners, maybe the planer blades are blunt...

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[lohwaikin]

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[jray]

Very nice job, looking great! Are you planning on glassing the outside after shaping? What wood did you use, looks very clear and uniform.

[slowpoke]

I recommend against glassing over the outside. My old ketch had wooden masts that had been glassed over, it led to serious problems later.

[lohwaikin]

I'm using Kapur, the Malay name for Dryanbalanops Aromatica, medium hard wood of 0.75 SG.

Rocky, can you elaborate the mast problem you experienced with glassed-over timber mast? My intention was to do just that, with single 6oz plain weave glass cloth. Then epoxy prime & PU finish, and maybe UVR clearcoat.

[slowpoke]

The glass cracked and delaminated due to the expansion and contraction of the wood over time, something that I think would happen even faster with a flexible mast. The glass hides potential problems with the wood, especially if you plan on painting it to protect the epoxy. And, you really don't need to.

[lohwaikin]

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Done with sanding the mast to the desired teardrop shape, encapsulating with epoxy and nylon peel-ply.

[jray]

What do you think the finished weight will be.

[lohwaikin]

So I finally managed to weigh the completed wooden mast with a digital bathroom scale.
That's after 1 layer of 6oz glass cloth.
At the mast-step, and at both spreader bracket position, I reinforced with 17oz 4-inch wide biax glass tape left over from the hull build nearly 2 years ago.
5 coats of epoxy primer, the first 3 coats nearly all sanded off.
2 coats of Hempathane 55210 white.
So it's 9.1 kg at the masthead end, 8.5 kg on tthe mast-step end.
That totals up to 17.6 kg (38.7 lbs).

Very heavy....

I was hoping it'll be stiffer laterally than fore-aft, but it's the other way round physically.

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[lohwaikin]

Oh I remember that's because the sail track "bulkhead" of 1" wide 1/8" thick Kapur plank was actually reinforced with generous epoxy fillets on both sides and topped with continuous 17oz biax.

And somehow I started with 26.5 ft full length and ended up 25 ft, because there's some imperfection in the section form-up at one end which prompted me into a trimming frenzy. By the time I come to my senses 1.5 feet worth of mast was gone...

[jray]

Loh
Still, with the small things. You have crafted a beautiful wooden mast. Congratulations!
Far beyond what anyone else has done, I wish I had the skills to do the same. Well done!

[i550sailor@aol.com]

Loh,

Thats a great looking mast, well done!. I am going to use a cut down U20 mast, until I feel comfortable enough with my carbon fiber work, to build mine. Great job. How many hours do you think you have in the mast?

[lohwaikin]

On hingsight, it is cheaper and faster to pay GBP 825 for a complete Z-spar Z170 mast assembly (with spreaders, masthead, step, gooseneck, exits), and additional GBP 395 to have them shipped to Singapore. I spent about 3 nights flipping thru'' the Z-spar catalog, and 4 emails later concluded the price plus shipping. By today's rate GBP 1220 will be about SGD 2550. For this price I can have a complete set of professionally manufactured mast system.

Instead I spent an accumulated time of 14 weeks of evenings (averaging 3~5 hours each) just producing the wooden section, and countless nights designing and drafting custom mast brackets (they are still stuck at the metal worker shop now...). As you know I am renting this workshop space to fulfill my boat-building dream, and there goes avoidable expense of rent. Material wise I did not spend more than SGD 300.

I know I'm not stingy; just plain stubborn with a dash of stretched optimism. This is indeed a good lesson learnt for me, both in life and in profession.

[micah202]

.
....don't feel bad...if -any- of us add up the hours we spend and put a $ value to it,,we'd -all- be in shock!

....but that's not the point,,is it?