Re: [PCW] Catamaran MotorSailer with DynaRig
I must say I am very impressed by your Dynarig motorsailer design, Clearly
you have put a lot of thought into it. My only reservations are about the
weight and windage when not in use, but you have obviously thought about
those
issues.
I don't see why a Dynarig boat could not use conventional furling gear just
ahead of the mast. There would be quite a large number of sail control lines
which I assume could go down inside the mast, and I imagine the loadings
would
not be too heavy.
Kind Regards,
Grahame Shannon
Brian replied:
Thanks for your compliments. I just kept watching the developments on Maltese
Falcon and said, there are features here that lend themselves to a catamaran
motorsailer. Sure would be a fun project.
Interestingly the communications that had existed about the Maltese Falcon
from both interested parties and some of the crew over on the Yachtforums
site
has dried up....almost like some sort of 'gag-order' had been put out.
http://www.yachtforums.com/forums/40470-post166.html
<http://www.yachtforums.com/forums/general-sailing-discussion/2487-perini-nav
i-maltese-falcon-sailing-yacht.html>
I haven't thought of everything Grahame. I think a little consulting with
Maltese's designers could go a long way. They spent a lot of time and money
on
this project. I just hope they don't try to hold everything as 'proprietary'
and request licenses. Tom Perkins certainly has enough money to not require
this need, that might stifle further development of the concept.
I've never tried to patent any of my rig ideas, as the market is just too
small for it to make sense. And openning up such subjects to the public can
produce interesting alternatives.
I think you are right about a form of 'conventional furling gear' utilization
rather than in-mast, but I also do not think it requires a great number of
loose lines down the mast. I think a form of their sheeting method is
fine....just don't need to furl such lt-weight sail cloths into the
mast...looks nicer, but EXPENSIVE.
Brian Eiland
beiland@usa.net
www.RunningTideYachts.com
distinctive expedition yachts
I like the Dynarig on your motorsailer cat, but would be concerned about the
expense. I spoke with the builder of a Shuttleworth Aerorig 52. I believe he
said he was into that rig for $250,000.00. What would you expect the
Dynarig to cost?
Brian Leonard
-----Original Message-----
From: power-catamaran-bounces@lists.samurai.com
[mailto:power-catamaran-bounces@lists.samurai.com] On Behalf Of brian eiland
Sent: Friday, March 16, 2007 7:44 AM
To: Power Catamaran List
Subject: Re: [PCW] Catamaran MotorSailer with DynaRig
I must say I am very impressed by your Dynarig motorsailer design, Clearly
you have put a lot of thought into it. My only reservations are about the
weight and windage when not in use, but you have obviously thought about
those
issues.
I don't see why a Dynarig boat could not use conventional furling gear
just
ahead of the mast. There would be quite a large number of sail control lines
which I assume could go down inside the mast, and I imagine the loadings
would
not be too heavy.
Kind Regards,
Grahame Shannon
Brian replied:
Thanks for your compliments. I just kept watching the developments on
Maltese
Falcon and said, there are features here that lend themselves to a catamaran
motorsailer. Sure would be a fun project.
Interestingly the communications that had existed about the Maltese Falcon
from both interested parties and some of the crew over on the Yachtforums
site
has dried up....almost like some sort of 'gag-order' had been put out.
http://www.yachtforums.com/forums/40470-post166.html
<http://www.yachtforums.com/forums/general-sailing-discussion/2487-perini-na
v
i-maltese-falcon-sailing-yacht.html>
I haven't thought of everything Grahame. I think a little consulting with
Maltese's designers could go a long way. They spent a lot of time and money
on
this project. I just hope they don't try to hold everything as 'proprietary'
and request licenses. Tom Perkins certainly has enough money to not require
this need, that might stifle further development of the concept.
I've never tried to patent any of my rig ideas, as the market is just too
small for it to make sense. And openning up such subjects to the public can
produce interesting alternatives.
I think you are right about a form of 'conventional furling gear'
utilization
rather than in-mast, but I also do not think it requires a great number of
loose lines down the mast. I think a form of their sheeting method is
fine....just don't need to furl such lt-weight sail cloths into the
mast...looks nicer, but EXPENSIVE.
Brian Eiland
beiland@usa.net
www.RunningTideYachts.com
distinctive expedition yachts
Power-Catamaran Mailing List
My experiences with free standing masts housed in the cabin structure of
catamarans has made me a little cautious about their application. They do
reduce the compression load from the standing rigging of a mast but a
"normally" rigged mast on a catamaran has low compression courtesy of the
staying angles of 30 to 45 degrees that are obtainable because of the extreme
beam. The normal stayed rig is therefore considerably lighter and much, much
cheaper. But of course the stayed mast cannot rotate 360 degrees to depower as
can the free standing one. On the Maltese Falcon they are talking about a
bending load of around 13.28 MILLION lbs ft at deck level! This is some load.
Brian is proposing to handle this cantilever load with a carbon compression
structure. We used a Kevlar tension structure which is potentially lighter.
The mast we had experience with was our motor sailer of 1992, the Revolution,
in which an 18m diameter propeller was attached to an 18m freestanding spar.
This drove two in the water propellers via a shaft and hydraulics. Today this
could be replaced by off the shelf components of a wind turbine driving
electric motors. The cantilever load was not in the same order as that of the
Maltese Falcon but it was enough to continually destroy the roller bearings
used as collars at deck level. This gave me a real appreciation of the loads
imposed by free standing masts when you have a relatively restricted bury as
occurs with the deck cabin of a catamaran.
A phenomenon occured which we hadn't anticipated,. Though in hindsight perhaps
we should
have. The rotating propeller had a major gyroscopic effect and the boat had a
tendency to want to keep going in a straight line.
Maybe the free standing bi-plane rig might be a better option as it would have
a deeper bury and would only have half the height. Two side by side Dynarigs
perhaps, or as on team phillips?
The major problem with the Revolution was that it did not have the "romance of
sail" even though it was wind driven. This would appear to be a real stumbling
block to acceptance [see the Walker wingsail also]
MALCOLM TENNANT MULTIHULL DESIGN LTD
PO Box 60513, Titirangi.
Waitakere 0642
NEW ZEALAND
Ph: +64 9 817 1988
e-mail: malcolm@tennantdesign.co.nz
www.tennantdesign.co.nz
www.catdesigners.com