IM has been very helpful about getting us the information about bending the
mast. The manufacturer rep for the mast company is getting an answer from her
QC department to the questions: how much can you bend the mast without
damaging it?
In the meantime, I talked to Mr. Dwyer of Dwyer Aluminum Mast Company. His DM5
mast is similar (identical?) in dimensions to the mast IM puts on the newer
Potters. He says that you can put a 4-6" bow into the DM5 without any fear of
damaging it. We defined the 4" like this: Imagine you put a bowstring from
the top of the mast to the bottom and bent the mast. At the middle, measure
the distance between the "string" and the mast to get the amount of "bowing".
He said that you would probably pull out a deck fitting before you damaged the
mast., so I guess the Dwyer DM5 mast is plenty strong enough, not only for a
fixed backstay, but also an adjustable backstay.
However, we don't know if the mast IM uses is the same alloy and temper as the
DM5 by Dwyer, so it's not safe to rely on this information in making your
decision about bending the mast.
I have used my adjustable backstay on my P19 with the heavy mast. With the
lower shrouds loosened at neutral, I can bend the middle of my mast forward
about 4" before the lower shrouds limit me. 4 inches of bowing is enough on
my P19 to flatten the draft of the mainsail to about one half of its original
depth. It'll make the boat alot more managable in heavy winds.
I'll let you know as soon as I hear some news from IM's mast manufacturer.
Regards,
Judy B.
Judith Blumhorst, DC
HMS18/P19 Fleet Cap'n, Potters Yachters
1985 WWP #266 "Red Wing"
SF Bay, CA