twin masts on cat thoughts on

Do any of u have thoughts on using 2 masts on a cat? What I'm wondering is if you put a smaller mast on each hull instead of one large one on the bridge deck.

 

It sounds more complicated. But that is an uninformed opinion.

 

Been done before.......... For starters

http://www.schionningdesigns.com.au/www/welcome.cfm look for Radical Bay under sailing designs

http://www.ikarus342000.com/DUO660page.htm

http://www.kelsall.com/Designs/KSS54.htm

http://www.tcdesign.co.nz/TC_Design/Sailing_Designs/Pages/TC_750.html

http://www.multihulldesigns.com/designs_other/cat2fold36.htm

 

As Jamez said, It has been done before ----and has been done to death.
As the old saying says, "Why use two when one will do".
If the idea was so good you have to ask your self, why don't you see them all over the place today. All the complications of cost, rigging complexity, control, trim balance, airflow interference------the list goes on.

 

I disagree. I sail on a boat that has a whole other spare boat tied alongside.
No rigging on my masts means simpler. Maybe costlier, but definitely simpler.
Redundancy is cool!
And... I'm a rookie sailor, but it doesn't take a rocket scientist to learn which strings to pull to make the boat go, which strings to ease when the windward sail interrupts the flow over the leeward, and how good it feels to have a cruising boat that is safer/easier/faster/more comfortable than most other boats out there.
...of course, I am biased.

 

I would love to have a couple of days on one of the little Schionning RB8000's to try the whole deal out. There would seem to be some limitations for racing (harder to fly a hull and limitations in size of any extras) which is probably why there aren't so many around. Also they are 'different' and sailors tend to be conservative when it comes to their own money. That said, the idea of a cruising boat with only two sails and two strings to pull (like the Radical bay) has some attraction.

Tom F Jones wrote at length on his experience with a biplane rig on his 25' Dandy. However Jones' approach was to fit a complete stayed rig to each hull which effectively doubled all the cost and complexity. In the end he changed the boat to a single mast. If you read around a bit there have been some successful biplane rigged cats but they all seem to be based on free standing masts of some type or other, which most of the modern iterations seem to be based around - usually carbon these days.

Casting the clock back, a friend of mine built the boat (blue topsides) in the pic around 30 years ago. Designer Bernard Rhodes helped modify the plans (pahi 31) and designed the rig - with freestanding wood/glass masts - which it still carries, through several subsequent owners (pics were taken long after the original owner sold her). Rhodes went on to design and build 'Flying Carpet' a biplane rigged cat of around 11 metres, which he sailed from NZ to Japan and back and then used as a charter boat (white cat below).

 

Thank u all for your responses. I checked out the sites Jamez referred me to. Great information. My original thought was that 2 smaller masts would mean smaller sails with less rigging meaning easier to handle. I hadn't taken into account the shadowing effect one sail would have on the other, or the different driving forces on the separate hulls. I imagine it would be much like having a motor in each hull, were one is running at full speed while the other is at half speed, with the boat constantly trying to turn towards the slower motor.

I truly appreciate your patience with my basic sailing questions. This is my first foray into multihulls after many years with planing power boats. Now that i have retired i'm ready to slow down and smell the roses, so to speak.

My next boat will definitely be a cat. Now my mission is to define what i really want to do with it, find one that fits, and get back on the water.

 

I just remembered that the creative & innovative french designer and builder Dennis Kergomard also designed some catamarans with 2 masts.
Al his boats are inspiring and its worth to look around on his website Imo.

Homepage:
http://www.alibi-architecture.eu/

twin masts catamarans:
RV7:
http://www.alibi-architecture.eu/delirs/dossiers/RV7.pdf

Catamixt:
http://www.alibi-architecture.eu/cata%20croisiere/dossiers/catamixt.pdf

Catcotcot:
http://www.alibi-architecture.eu/cata%20croisiere/dossiers/catcotcot.pdf

 

Looks like each mast is combination of a stayed and unstayed mast. An interesting idea.

This one is odd. How does this thing work?!

Here one can see that stayed twin masts add a lot of complexity. Look at all those wires!!

 

thanks hasyb. Very interesting concepts. The catamixt appears to use two fixed wing type sails that rotate around the deck house. I wonder if one of these was ever built.

Lol..now i have to research fixed wing type sails.

 

and don't forget 50/50!

http://www.boatdesign.net/forums/multihulls/50-50-biplane-cat-43793.html

and then there's my "Bad Kitty" design for the Ultimate Florida Challenge.

 

the fastest sailboats built, all of the record breakers, all have single sloop rigged sails. two smaller sails are less efficient that one large one of the same area. Meaning you get more speed out of the same amount of sail area with one large sail.

There are other reason to go to twin sails, that is one to make it easier to handle two smallish sails by a single crew. Also, as noted, smaller rigs are easier to make unstayed masts and simpler rigging without being overly heavy. And there is also something to be said for redundancy on a long distance cruiser.

Do it to have something unique, but not because it actually performs better. Me, I think simpler is better, which ever one has the few parts and costs less is the one I go for. fewer parts also means more reliable, few parts to break or wear out.

 

Actually twin rigs did break several records: Yves Parlier with his hydroplaneur broke 24hour record, above mentioned 50/50 broke Lake Balaton record, and also Radical Bay is said (by people who sail it) that it has superior performance.

This is true, but main+jib = 2 sails, not one, so this statement doesn't really tell us anything about the matter. It's also worth to mention that mainsail is more efficient then jib, so you can't say that main+jib is more efficient then 2 mains. You just don't know that, you'd have run tests (and as mentioned: not all record breakers have standard sloop rig).

I think the biggest downside of twin rig is added cost, if it is stayed then added complexity, but if it is unstayed then being unable to attach more sails to it (which could deteriorate performance in light winds). Although I'm not really sure about the latter, because Radical Bay does use jib, and Cat2Fold too and noone really proved that luff must be super tight to get good performance out of it.

 

Here's a Radical Bay 8000 that claims to have been a winner in international regattas: Crazy Horse. (doing chartering at the moment)

 

prograd,

yes, you are correct, there are some narrowly defined records that often use unconventional rigs. Perhaps I should clarify, as far I am aware, all of the open ocean records are currently held by multi-hulls with conventional sloop rigs. They are advanced design, yes, but the basic configuration is a sloop.

It would seem from a pure efficiency standpoint a large single sail should be the most efficient at producing trust. But all of the open ocean records are held by sloops, even the single handed ones. Perhaps the higher pointing ability of the sloop gives it an edge in open water sailing from point to point.