Forums > Land Yacht Sailing Construction

mast mount....

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Created by greenE > 9 months ago, 16 Apr 2013
greenE
47 posts
16 Apr 2013 4:53PM
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hello people,im new to this and the forum so a big hello from not so sunny england lol.
i have a question regarding the mast support,i know the mast should be able to rotate but wouldnt the tube rub and wear the mast and cause it to fail? i see in the construction plans that people are using non seemless tube? surely the seam will aid in trashing the mast? what other ways are there to allow the mast to rotate but not rub in the tube? best regards,greenE.

sn
WA, 2775 posts
16 Apr 2013 5:11PM
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The very top of the mast step is flared a little to reduce wear.
My masts are a loose fit in the step, and I use a piece of plastic swv pipe with a 10mm [approx] slice cut down its length.
The slice on the plastic pipe locates on the welded seam preventing the seam from chewing up the mast.

Dont forget to add a stiffener to the lower 1m or so of the mast.
It can be timber, aluminium tube, or a piece of broken mast.
they all do the job.

stephen

greenE
47 posts
16 Apr 2013 5:54PM
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so your mast goes into the plastic tube then? okydokey,thankyou ;-)

landyacht
WA, 5921 posts
16 Apr 2013 9:23PM
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the mast only rotates if you are using a windsurfer wishbone boom AND it is clamped to the mast ,otherwise the mast doesnt move ,and to boom does

greenE
47 posts
17 Apr 2013 1:20AM
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aha,i see,ill be using a ws sail/boom so i think ill try the above method,cheers ;-)

Chook2
WA, 1244 posts
17 Apr 2013 5:33PM
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It only takes 10 mins with a large half round file, to remove the seam before the mast step is welded on (so you can get to both ends easily).

I can get my air die grinder right down inside with a large diameter, 30mm grinding mounted stone on it. In from both ends and it's finished.

A "dremel" with a mounted stone tool, would do the same job as well.

As Stephen has said, a very slight flair at the top, as in Pauls plans, protects the mast.

greenE
47 posts
17 Apr 2013 5:46PM
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i dont like the thought of my carbon mast rubbing on steel so think ill use plastic tube insert or make a swivvling mast base with the mast clamped secure inside the mast support/base. (forgot tech name for it sorry)

Gizmo
SA, 2865 posts
17 Apr 2013 7:25PM
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'swiveling mast base' what advantage? .... there is a LOT of stress in the mast step area. (suggestion.... keep it as per plans) others have also added a steel strap from one side of the mast tube, underneath the spine tube and up the other side.

landyacht
WA, 5921 posts
17 Apr 2013 8:41PM
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greenE said...
i dont like the thought of my carbon mast rubbing on steel so think ill use plastic tube insert or make a swivvling mast base with the mast clamped secure inside the mast support/base. (forgot tech name for it sorry)


you can get sufficient swivelling movement by machining up a plastic cone shaped plug to fit in the base of the mast and then leave the mast step pipe as per the plans. ive seen this set up work well. there is a photo in my pics ,I will see if I can find it

landyacht
WA, 5921 posts
17 Apr 2013 9:03PM
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sorry the pics and thread are too old, so Ive whipped up a sketch.
the clever chap who built this was pete greeves so all credit to him

oldMXer
130 posts
17 Apr 2013 10:59PM
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We have found when using windsurf sail and boom there is not any mast rotation if proper downhaul is applied to sail. Boom will rotate on mast, rubber cushions and all. Boom is not designed to do that, but thats what happens. Using 2.25 OD, .065 sidewall seamless mast step material, 30" wood dowel inserted in mast base (close sanded fit, epoxyed, with one steel screw thru mast and dowel cut and filed flush), one racquetball in base of mast step to act as cushion and squeak reduction. All is needed because of downhaul tension applied, have crushed bottom of mast several times just setting downhaul. On my yachts the interaction between mast bottom and spine was a constant noise generator, racquetball solved it. There is excellent speed to be found using an unmodified w/s sail and boom, good luck.

greenE
47 posts
18 Apr 2013 2:13AM
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thankyou for ur input,advise taken ;-)

greenE
47 posts
18 Apr 2013 5:31PM
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does the wooden stiffener or alu tube etc inside mast have to be flexible? just thinking about which wood will be best,also thought of pvc pip in a pipe in a pipe ,by slotting them lenght wise so they fit snug inside each other,would this be enough ? cheers,

landyacht
WA, 5921 posts
18 Apr 2013 6:46PM
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If all the pvc sections were glued together I suspect it would work fine.
I would suggest making the stiffener and then doing some kind of bend test to see what the result is. we would award credit points for detailed measurements and of course photos for analysis by our esteemed panel of experts

greenE
47 posts
18 Apr 2013 7:15PM
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lol, ive seen the idea on youtube to make a pvc bow,i tell u what it was pretty powerfull and that was just 2 pipes together the second being roughly 1.5" diamiter and a thin glass fiber dowel in middle,so id say 3 pipes or more together would be stiff,could stagger them along the length too to make stiffer or softer,just an idea?...but yes i will post pics of my build,ive got 3 sails and a mast n booms,just collecting chassis materials now and ill start ;-)

desertyank
1260 posts
19 Apr 2013 8:09AM
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landyacht said...
sorry the pics and thread are too old, so Ive whipped up a sketch.
the clever chap who built this was pete greeves so all credit to him




"2014"?!?!?!?!?! Did I miss a year?

wokelliott
WA, 179 posts
19 Apr 2013 8:41AM
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Just shows that Paul is a "Forward Thinker" and way ahead of us.

I have brought my mini up to Shark Bay to find some decent wind between working on my house, have my eye on the airport but have to be careful as they have two commercial flights per week in the busy time!! Otherwise plenty of dry salt lakes here. Actually I'm sussing out the possibility of a long 200k moonlight sail when the sealed road is practically unused and Mr Plod is asleep. Meanwhile I'll go catch some Snapper and crabs.
..wok



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