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mamero
Joined: 25 Aug 2013 Posts: 380 Location: Vancouver, Canada
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Posted: Sun Jan 24, 2021 4:12 pm Post subject: Shortening a Mast Extension? |
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Any of you have success cutting a mast extension down? I sail Sailworks NX's and use Chinook SDM extensions. For some reason, Chinook only makes SDM in either 28CM or 48CM. The 7.8 and 8.6 NX call for 30cm so the 28's are JUST a little too short but you can kind of make do. However, you can't do a good downhaul for strong conditions or, you must use their 48cm and end up with a LOT of excess extension up the mast which may not be ideal? Chinook should make their extensions in a 38cm as well.
Anyhoo, I have an older 48cm Chinook extension. I'm thinking about making a custom 38cm extension. Any of you done something like this? Remove the base part, cut off 10cm from the bottom with a pipe cutter, put the base back on, relabel the numbers and voila, 38cm. Is the base part pressed fit on or will it come off by just by removing the screw? Perhaps I can use an engraver to put new reference numbers on the tube. It should be an easy job... in theory. Anything to consider before I potentially destroy a perfectly good 48cm extension? |
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dllee
Joined: 03 Jul 2009 Posts: 5330 Location: East Bay
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Posted: Sun Jan 24, 2021 4:21 pm Post subject: |
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Cut the top |
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mamero
Joined: 25 Aug 2013 Posts: 380 Location: Vancouver, Canada
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Posted: Sun Jan 24, 2021 4:31 pm Post subject: |
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Certainly easier. But, the holes running right to the top would drive the perfectionist in me crazy. |
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dllee
Joined: 03 Jul 2009 Posts: 5330 Location: East Bay
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Posted: Sun Jan 24, 2021 4:36 pm Post subject: |
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Cut between holes. |
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westender
Joined: 02 Aug 2007 Posts: 1288 Location: Portland / Gorge
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Posted: Sun Jan 24, 2021 4:42 pm Post subject: |
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OMG |
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isobars
Joined: 12 Dec 1999 Posts: 20946
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Posted: Sun Jan 24, 2021 11:59 pm Post subject: |
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Since you apparently love dweebing, why not just:
1. go take welding classes,
2. advance to whatever the heck they use to weld aluminum,
3. hone your welding skills to include filling holes in aluminum,
4. fill the ones you don't want,
5. turn the welds down on a lathe so you can't see or feel them,
6. re-anodize the whole damned thing so the color match is perfect,
7. put the cap back on, and
8. go sailing.
That, or just cut the dang top off and skip to step 7.
The first lesson I was taught in industry and the military was that the only job worth doing perfectly is performing triage ... i.e., deciding which jobs aren't worth doing at all, discarding them, and doing the rest as well as necessary. Both careers drummed that into us by deliberately overloading our plates and expecting us to make wise choices. Even then, very few jobs worth doing are worth doing perfectly. |
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swchandler
Joined: 08 Nov 1993 Posts: 10588
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Posted: Mon Jan 25, 2021 1:49 am Post subject: |
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Just use the 48cm extension and don't worry about it. Having 13" (assuming 6" above the last hole location) of the mast extension extending into the mast isn't a problem. It certainly won't hurt the mast or adversely affect its bend curve. |
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bred2shred
Joined: 02 May 2000 Posts: 989 Location: Jersey Shore
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Posted: Mon Jan 25, 2021 8:51 pm Post subject: |
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I agree, save yourself a lot of grief and just cut from the top. I’ve done this before to salvage mast bases that have bent. I would recommend that you disable the holes at the top 6” of the base so the adjustment pin won’t fit in and allow you to accidentally run the base without enough insertion into the mast. You can use a center punch to create a little bump on the edge of the hole that makes it impossible to fit the pin in.
sm |
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joethewindsufa
Joined: 10 Oct 2010 Posts: 1190 Location: Montréal
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Posted: Tue Jan 26, 2021 7:12 am Post subject: |
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Many years ago I wrote to Barry Spanier then of Maui Sails and now of S2Maui and asked him about using shorter mast extensions in sails and whether it made ANY difference ??
He replied that they ALWAYS used the 48 cm extensions no matter what
and if I did experiments to let him know the results ...
i just continued with the 48 cm extensions |
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mamero
Joined: 25 Aug 2013 Posts: 380 Location: Vancouver, Canada
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Posted: Tue Jan 26, 2021 9:43 am Post subject: |
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joethewindsufa wrote: | Many years ago I wrote to Barry Spanier then of Maui Sails and now of S2Maui and asked him about using shorter mast extensions in sails and whether it made ANY difference ??
He replied that they ALWAYS used the 48 cm extensions no matter what
and if I did experiments to let him know the results ...
i just continued with the 48 cm extensions |
Thanks for the feedback folks. I'll stick with the 48 and if I need to I'll cut from the top. |
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