Sport Today

I noticed that a mast base that is advertised to provide up to 16" of
extension would only put 5" into the mast at its maximum extension setting.
I have also noticed that Sailworks advises using a base with at least 6"
extending into the mast.  I am not familiar with other mast brand
recommendations.  I'd like to know of problems experienced, if any, using
similar extension to what I have just described combined with such a short
amount of base inside the mast.

8 years ago I built up a "stubby" extension taking into account 2 concepts:
1) that if you could size the bottom of the mast to fit on the foot (and
keep the rivets from pulling through the mast itself) attaching the cleat to
the mast would probably work; in fact, producing a "0" length extension
2) an engineer friend indicated that when working with tubing (50:1 diameter
to wall thickness) a maximal limit (for insertion)would be about 1.5 times
the diameter.    most people that saw it said it wouldn't work/that it would
break the mast(s), etc.  After all these years (sails up to 6.0) no mast has
broken (fiberspars and easton E9/windsurfing hawaii)

If you're talking about Chinook or Streamlined extensions, you probably
won't have an issue even if you use them fully extended. That is, you
probably won't have to be too concerned about mast breakage if you
don't heap tons of abuse on that particular joint (such as use in
breaking waves, where a lot of torque might be applied to the base of
the mast when you go through the rinse and spin cycle).

There's another issue to consider, however, which is performance. I've
used my 7.9 XT with both a 460 and 490 SW XR mast. The 460 with a 45 cm
extension pretty far out, the 490 with a much shorter extension. The
effect was probably amplified by the fact that I'm 210# and that I
don't really go down to this size from my 9.1 until there's significant
breeze, but the additional control and stability gained from the longer
mast was amazing. I felt a very noticeable increase in range and
pumping response, and the rig just was more dialed in, allowing me to
hold the hammer down going upwind through gnarly chop without constant
adjustments.

As a result, I have resolved to no longer use short masts with long
extensions despite the additional cost of buying the longer spars. Of
course, if you're on the lighter side, you might find the feel of the
shorter and softer mast to be more appealing.

Andreas

Sent via Deja.com http://www.deja.com/
Before you buy.

I've always considered it a rule of thumb to ensure there is 6" of extension
inside the mast.  Guess I've read it on more than one mast type.  When you
consider the stresses and leverage exerted at the point where the extension and
mast share the load, spreading those pressures over a larger area makes sense.

While it might technically work with less, I suspect you'd have a tough time
with any mast warranty claims if the bottom of the mast showed breakage or
excessive wear that indicated a "too-short" extension.

I used to use a long Chinook extension with a 400 mast on a 4.9 sail.  That
was, until the extension broke clean across the adjustment holes about 1/2
mile offshore off the coast hear in Northern California.  That cured me of
that practice right away.

I use as little base extension as possible now.  Though the 400 felt great on
a wave sail, I use 430's for the most part on my typical sails (4.7-5.8).

-Ed