Wind Turbine Mast Design Considerations

[RBEmerson]

I'm trying to work up a design for a mast to mount a Fourwinds on our Baba 35. For a number of reasons, I will need to keep the braces or support struts lower than seems to be typical (usually the struts mount on the mast just below the edge of the rotor disk). While the Fourwinds needs 1 1/2" (or is it 1 1/4"?) tubing, I'm thinking about using 2" tubing with a reducer to mount the Fourwinds. With the larger tube cross-section, I'm hoping everything will be stiff enough to allow putting the braces where I want them. Also, because the mast will pass through the stern pulpit (it flairs out), I'm thinking about typing the mast to the pulpit with added struts. To add to the fun, we need a hoist for the outboard (nominally 75 lbs). I've looked at Kato's mast and the Fourwinds mast (which doesn't include the o/b hoist) and they don't seem to fit our needs. Comments? Suggestions? Engineering studies?

[captjcook]

I previously owned a Formosa 44/ Spindrift 43 double ender, It came with davits all polished SS, as an option the davits could be ordered with a radar arch. On my present boat "Siren" the stern comes in quite narrow (3/4 ton cup racer) My first attempt for my windgen pole was to attach the pole to the hull with a bend, taking the vertical pole outside my bimini, struts forward and athwartship. The struts were ultimately too short and made for horrible harmonics in addition to the noisy blades. I think the best solution might be to attach a four legged, two hooped (an upside down stethascope?), braced, "radar" arch thru bolted to the bulwarks going out side your canopy (mounting similarly to a wind vane on a canoe stern). This could be fabricated using 1" SS heavy wall tubing and a 1-1/4/1-1/12 vertical mast, struted/gusseted back to the arch. With a bit of thought it might not be too ugly.

[RBEmerson]

Which wind gen was on the mast?

[imagine2frolic]

I had a mast on the stern of my 30ft. Columbia for the radar. I used the stern pulpit as extra support with small struts. The struts were in 3 different direction, and I never had a problem of the mast moving,

I used the back of the boom as a crane to life the dink's outboard. A block on the boom with a block forward, so I could run the line to a winch on the coaming. After a couple of attempts of raising, and lowering the motor. I refined my motion, and it was very simple with no cost. Blocks, and line are already on the boat. I was single-handing at the time too.

Between my head, and the ob you can see a strut running back. Above the life ring you can see a strut running forward. Over my head was another strut running to strbrd......i2f

[RBEmerson]

This is encouraging, as you've done much of the same sort of work that I have in mind. BTW, same question about the wind gen: which one did you use? Also, in the attached image... um... is that a Navy destroyer off the port quarter??

[witzgall]

I am guessing that the Four winds takes Schedule 40 1/5" IPS pipe for a mount. You could make it with Schedule 80 pipe, which is thicker, and if needed bore the end to accept the wind generator.

Chris

[RBEmerson]

Digging around in the old Fourwinds manual (haven't seen the current one), the mast is called out as either schedule 40 or schedule 80 1 1/4" aluminum tubing (both are listed in one spec in the manual). However, that also assumes bracing ending, on the mast, about 1" below the edge of the rotor disk. That, for a number of reasons, comes pretty close to being a deal-breaker. Which is why I'm looking into stiffening the mast to at least avoid seeing it bend appreciably in normal conditions.

[SV_Gonzo]

I recently realized that windsurfing masts are made of carbon...

Perfect, long, bulletproof tubes that don't weigh a thing... and cheap

I've picked up a few now for various projects, including replacing my wind gen mast. Paid $20 for two 8 foot long 1.5 inch wide carbon tubes. Im mounting the wind gen mast through the deck, straight into the battery locker in the stern. It will be strong, with no above deck support needed.

Im thinking of building an arch between hulls out of these... the stuffs great.

Its much cheaper buying the old windsurfing stuff than anything labeled marine. I could see these poles going for 1000 at west marine...

[Evan]

Have a look at my blog then. I did built a windsurfing mast/fiberglass ladder arch. Quite stiff with the diagonal cross braces. The more carbon in the mast the better. I used 2 masts that were mostly fiberglass and they got an extra layer of carbon uni.

http://www.maiaaboard.blogspot.com

[RBEmerson]

Carbon windsurfer masts... v. cool idea! Now if I could find a single mast about 9-10' long...