April 1, 1998
At the 1997 505 Class Governors meeting, and the 1997 505 Class
Annual General Meeting (both in Gilleleje, Denmark), it was decided that a commitee should
be set up to consider and evaluate changes to the sailplan, and report back to the
membership on these possible changes at the 1998 AGM. We chose to evaluate an asymmetric
spinnaker on a 505. These are the initial impressions; we will have a more detailed report
at the AGM.
Allan Johnson
and I have spent much of the early spring evaluating an assymetric spinnaker on a 505.
With hands-on assistance from 505 designer John Westell, sail development with Ethan Bixby
at North Sails Gulf Coast, and of course engineering and construction from Waterat Sailing
Equipment, we implemented a mast head spinnaker with a short bowsprit.
The North Sails asymmetric spinnaker is quite a bit larger in area
than the current medium 505 spinnakers. North was able to apply their experience with
asymmetric spinnakers in other classes to quickly come up with what appears to be a very
nice assymetric design for the 505.
The Waterat designed and built fixed bowsprit is made of a blend of
carbon fibre and other exotic fibres. It weighs only 0.1kg, and has no noticeable effect
on pitching when sailing upwind. It is quickly removeable so the boat can be returned to a
standard 505 configuration, but is not retractable while sailing.
We used our standard Proctor D rig, without any alterations other
than adding a spinnaker halyard and sheave at the top of the mast. We are considering the
addition of a backstay, running backstays, and/or upper diamonds to support the mast tip.
A stiffer mast may suffice.
Cost
The bowsprit took some time to develop and being a one-off custom
part, was expensive. However, in production we expect it to cost under US$500. The good
news is that so far it has been bulletproof, showing no tendency to bend under high load,
and actually withstanding some unfortunate collisions with a dock and another 505
unscathed (unfortunately, the same cannot be said for the other 505 or the dock; by the
way, we believe the other 505 was on port tack, but have been unable to find any
witnesses).
Being substantially larger than a conventional 505 spinnaker, and
using rather more cloth, the spinnaker costs rather more than a standard spinnaker. In
production we antitipate a retail price of approximately US $1000 for the poly version
from North Sails Gulf Coast, compared to US$640 for the current North sails Medium
Bi-Radial AP Poly.
Sailing Impressions
Incredible! The boat is so damned fast with the kite up we are
sheeted in to close hauled almost all the time (as you can see in the photo).
The increased area and greater offwind speed (and relative wind from
more forward) mean that the boat cannot sail high angles. We were unable to get up to the
standard 505 gybe mark in anything over 3 knots of wind. Asymmetric 505s will require
windward-leeward courses.
Visibility to leeward was a problem. As you can see the foot of the
sail is quite a bit lower than with the current symmetrical spinnakers and this did
adversely affect our ability to see in the quadrant ahead and to leeward while the kite
was up. While disconcerting at first, one gets used to it. However, it will be important
to control traffic across 505 race courses to minimize the chances of collisions. This is
how the collision mentioned earlier took place... we never even saw him! The dock incident
took place without the spinnaker, and was simply due to being unfamiliar with the new
length of the boat.
As many of you who know the boat are aware, 505 8263 is a Waterat
forward tack bag boat, without a spinnaker launcher. This worked well, as the standard
bags were large enough to hold the larger spinnaker. We expect that many launcher equipped
505s will have difficulty getting these large spinnakers into the launcher tube, and that
spinnaker longevity will be adversly affected. As many of you are aware, the original 505
design was for a forward tack bag boat. The launchers came later, and launcher
"kits" were sold to allow launchers to be retrofitted to existing boats.
Similarly, we expect that asymmetric "kits" including the bowsprit, a piece of
foredeck to cover up the hole left by removal of the launcher tube, and an extension to
the foredeck centerline beam will be available from the major 505 builders.
Finally, apologies for this report being late, we were hoping to
publish it on the web page and to the e-mail list on
,
in time for consideration for early spring projects.
Cheers,
Ali