a ultimate MotorSailer idea, Dynarig motorsailer

Interesting, some of the experimenting that went on in those early days,.....

"Cunningham became famous for the invention of the self-reefing topsail, which he manufactured in the Gosport Foundry at The Green. The agent for this invention was William Henry Lapthorn, sail maker, ship chandler, of 29 Broad Street Portsmouth. The self reefing topsail was exhibited in a model of a fully-rigged ship at the Great Exhibition in 1862, amongst the section on Naval architecture and Admiralty models. “They roll up like common blinds, and almost entirely obviate the necessity of sending men aloft.” In the 1862 International Exhibition Cunningham was both a medallist and juror."

Clipper Rigs https://doriccolumns.wordpress.com/industry/shipbuilding/clipper-ships/clipper-plans/clipper-rigs/

I found this passage particularly interesting,...
Mr Cargill, an old Shipmaster, who has Commanded Ships for 40-yrs, states, with reference to Navigating the Ship Christina Thompson from Aberdeen to London, in very heavy Weather Beating all the way, that he found 4-hands sufficient to work the Foreyard with ease; he says that he considers the Invention a very valuable one. This Ship was 1,079-Tons Register. It was reported that by May 1856 it had been fitted to upwards of 1,000 Ships, reducing the dangers to Seamen in unfurling & furling Topsails in bad weather

As I was looking back thru some old postings of mine on that other forum, I ran across this possibility that I never took the chance to explore more thoroughly upon.


Unlike my 'single-masted ketch' design that I feel is not necessarily appropriate for a vessel of less than 45 feet, the DynaRig is appropriate for this smaller size vessel. In fact a ‘3-panel’ dynarig might be considered rather than the 4 panels of my new 63 foot DynaRig cat design, or the 5 panels of Falcon. However, I would still favor the 4 panel configuration, as it offers more variation in reef-able sail areas. And with my simplified sail furling mechanisms, it doesn’t add that much weight or complication to the overall rig.

Falcon’s dynarig was complicated by requiring the sails to be furled up inside the mast thru a hollow slot on one side;
1) the mast itself needed a slot in itself all the way down one side of the already weaker side of an elliptical cross-section. This necessitated an internal structure be built into the carbon mast section to reinforce it at the slot area

2) the furling mechanism then needed to be built inside the mast section, and a complicated track mechanism was required to guide the edges of the sails out onto the bridges to the yardarms & the yardarms themselves



I am proposing a much simpler furling and track mechanism for this modern square-rigger concept:
1) The mast will not have internal stowage of the sails, so no slot is required, nor internal support structure. It will be a simple elliptical section that will taper at either end to a smaller section at the top and a circular section at the bottom….not that much more complicated than an ordinary carbon mast for a sloop rigged vessel with a mainsail attached. It might also be a ‘sealed unit’ for ultimate flotation purposes.

2) Each rectangular sail will furl around a ‘wire’ (PBO, Kevlar, Spectra, carbon, etc) sewn across its mid-girth, and having eyes at both ends that clevis pin into ‘continuous line furling drums’ as you might find on ‘Code’ type reaching sails. The sails are constructed of low-tech, light-weight ordinary Dacron, and are of such relatively small dimensions that when furled around a very small diameter ‘wire’, they present a very small diameter package to the elements when ‘stowed away’. Each individual sail panel can be quickly and easily replaced, and inexpensively as well.

3) The furling drums are incorporated into the leading edges of the yardarms/bridges so as to present less windage, and they are’ stacked’ up vertically end to end in a line such that they ‘share’ bearings at either end. One small electric motor drives each panel for furling. For each panel of sail there are two (top & bottom) additional motors to unfurl the sail.

4) The yardarm ‘bridges’ can be shorter in length than Falcon’s with many inherent advantages including the more readily usable ‘forestay arrangement’ with or without a ‘code’ type reaching sail. Shorter lever arms requires less power to rotate the rig as a whole.

5) Three of the yardarms are of equal length thus less production cost…in fact probably these three would be only slightly more expensive than the elaborate furling/stowing booms now found on many ‘ordinary’, modern, short-handed sloop rigs.

6) The low-tech, Dacron sails of this rig should present some considerable savings over those modern sails for Bermudan rigs, and help offset the other initial extra cost of the Dynarig.

7) The sealed mast and yardarms could offer the flotation for the ultimate non-capsizing protection.

These proposed changes to the original Falcon’s interpretation of the DynaRig concept should result in a less expensive version, which is just as viable in sailing characteristics as the Maltese Falcon is proving to be.

Some details from one of the original discussions of MF on this forum site


| Perini Navi | 88M | "-Maltese Falcon" | 2006/23 |

How it works,..
https://www.yachtforums.com/threads/perini-navi-88m-maltese-falcon-2006-23.2487/page-5#post-30282

A Stayed Dynarig concept

https://www.yachtforums.com/threads/perini-navi-88m-maltese-falcon-2006-23.2487/page-13#post-147408

Combination of Fore/Aft Headsails with Square Sails

https://www.yachtforums.com/threads/perini-navi-88m-maltese-falcon-2006-23.2487/page-13#post-147410

Hi again HTMO9,
Have a look at this design,....twin free standing mast, one in each hull.
Listen to what the owners were looking for, and achieved with this design! I am really impressed !!
The simplicity of handling this rig, as well as the cost to build it compared to other designs could be significant.

And the shortened sail area and fully rotating mast ALL ADD UP TO SAFETY .

Very interesting write up on how the design developed,..
https://www.cruisingworld.com/people/a-dream-takes-flight/

@HTMO9
I realize that by now you have already chosen a new direction in search of your family sailing yacht.
And I know one of your major concerns about a multihull design was capsize potential.

Have a look at this twin masted design that allows a sizable sail are to be carried on a vessel that can dump that sail area very easily,..








....the motorsailing advantage,...one engine at basically high idle creating a little apparent wind that doubles the speed apparent


no accidental jibes,...

This twin masted rig would be so much cheaper to build, so much simpler to maintain, so much simpler to handle than the dynarig,

This is now my ultimate catamaran motorsailer