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Sep 23, 2009, 04:19 PM
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oldpilot's Avatar
Please Nigel.
These little boats are Catamarans or Trimarans.
As such they have HULLS ----not SPONSONS.

Respectfully. Paddy.
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Sep 23, 2009, 04:46 PM
Registered User
Dick L.'s Avatar
Andy -

sail area is too far forward, and a bit much for that width of cat.

If boat tipped to side, you need a faster sail winc to let sail out, or steer closer to wind.

If boat tipped forward (pitchpole) the sail a bit further back will help. Also don't "RUN" downwind - deep reaching and gybing is faster. It tendency to pitch forward, also inhauling sial to reduce sail area exposed to wind will help (if running).

My old 18 Square Meter cat was very fast, and for it's 5.5 meter (18 foot) length, it carried a nearly 10 meter (31 foot) mast with 18 sq. meters (194 sq. feet) of sail area. You can do the math ratios, but from looks of your boat, a uni-rig - main only might solve some problems. Biggest challenge is to watch and identify just at the point the windward hull is about to leave the water. What makes this difficult is you are on shore, not on the boat and you can't feel the hull getting "light".

In the case of multihulls - it is much easier to sail them as they get bigger (to a point) but in reality, they all carry too much sail!

Good luck.


Nigel - I have to agree - "hulls"!!!
"Sponsons" are usually reseved for aircraft with landing "floats" (or sponsons)
Sep 23, 2009, 05:55 PM
Footy Pie-Rat
AndyTrewin's Avatar
lookin cool
Sep 24, 2009, 09:16 AM
Registered User
nigelpheron's Avatar
Sponsons, hulls, floats, pontoons, amas, whatever works...

I used to hear the term used a lot on the powerboat side of things, so I fugured to use it here.

I'm mostly concerned with shape/size/location of fins. And then there'sthe rig mounting....

A question to the much more experienced.

To start, should the CLR of the daggerfoil be on the CLR of the hull (I figure to aid in the ability to turn)? Or put the CLR of the daggerfoil trailing the CLR of the hull, Like the resistance was pulling something?
Sep 24, 2009, 04:23 PM
Registered User
Dick L.'s Avatar
Nigel
foil or daggerboard?

Beach cats have their boards behind centerline of hull (side view) and some are getting really close to the rudder. Most uni-rig cats have slight to moderate weather helm that is NOT taken out for a neutral helm. This allows the boat to "seek" an optimum windward point of sail. The speed generated by a hull without lead is usually sufficient to cause apparent wind to move forward, which in turn "seems" to want to pull the cat into a "footing" mode. As the cat slows slightly, apparent wind swings back to the side, the cat begins to point and speed again increases. It is finding the happy medium in this process that results in decent VMG.

If you add a jib it will add lee helm, which means the boards must come further forward, which then adds weather helm, and you are back to same pointing/footing issue as above. As I noted elsewhere - if you have a slab-side hull (assymetric) the need for dagger boards is eliminated - although pointing ability will suffer.

I will need to sit down and calculate but the boards usually are a percentage behind the mast and I think depends on actual sail area. Cats seldom reef their sails, so if you take a cat with a jib, and roller furl the jib, the boat points much higher and the boards just resist sideways slippage until they get a good stream of water flowing over their boards.

ADDED: See photo below and note how far back toward stern, the boards are located on this uni-rig cat. Hull is 5.5 meters (18 feet) long for reference. Might be able to scale ratio/percent from photo, although vantage point it is not exactly perpendicular to the boat. Trampoline is approximately 7-8 feet long, so boards are less than 8 foot from stern rudders. Assuming it is just 8 feet, then there is 10 feet of hulls in front.

Foils ? I sailed one of the MicroSail boats, but don't feel qualified/experienced enough to comment.
Last edited by Dick L.; Sep 24, 2009 at 04:32 PM.
Sep 24, 2009, 08:59 PM
Registered User
nigelpheron's Avatar
Eh Dick.

Foils is what they are. I guess foil-shaped daggers.

Lot's to think about. I'll worry about getting one built, then worry about making it move right. Just post-poning headaches I plan on using this rig (pictured). Basically a buch of rigs made up, that will plug and play with all my personal footies.
Sep 25, 2009, 09:01 AM
Registered User
Dick L.'s Avatar
Hi Nigel - sorry - and thanks for clarification.

For what it's worth, here are a couple of photos (circa early 2000) that may offer some ideas or suggestions. As noted, beyond this and my sailing experiences witht he Microsail foiler - I have not engaged in any deep discussion or conceptual thought.

Not sure whose boat isin the first photo, as I've lost touch with some who dabbled, then went on to something else. I have an idea, based on what looks to be "Kenny" (from South Park cartoons) as skipper.

Good luck with your experiments. All I can suggest (based on the Microsail boat) is the the width greatly exceeded the length of 1.2 meters.

Dick
Feb 21, 2016, 12:10 PM
Registered User
chiwea's Avatar
This may have already been stated, and I doubt anyone will read this. I saw a cat that it's rig went around the side of the box, the boat was inthe box side ways but the mast went around the box. Like the bottom of a 5 on a digital watch
Mar 20, 2017, 11:40 AM
Registered User
Chiwea, that would be my Proa you mentioned. A cat cannot effectively fit in a Footy box with the rig upright and have the hulls far enough apart to have enough resistance to capsizing unless there is a keel and bulb. That sort of defeats the whole purpose of a light weight weight multihull Footy.

So, I came up with a solution that I initially had little faith in, having never designed a multihull before, some very fast monohull Footys, but this was new to me. My prototype was rather heavy at 320 grams, a pretty good weight since it was a pair of chine hulls in 32nd ply. The Proa was western style in that it sailed on either tack with the same bows headed forward (unlike the Pacific Proas). The rig, sail winch, rudder servo and receiver were all mounted in the main hull and the battery in the outlying hull. The hulls were asymmetrical mirrors of each other, slab sided on the outer faces of the hulls. The slab side on the main hull allowed the mast tubes to be mounted flush to the inside of the hull. When placed in the Footy box on it's side the main hull was below the top edge of the box but the rig fit over the long side of the box and could swing in both directions satisfying the sailing trim rule. In the box, on edge, the hulls were far enough apart so that the boat is just under 12 inches wide and 12 inches long. No need for a new box for multihulls!

Slab sided hulls should not need fins, but not a trusting type I included a small fin in the center of the main hull. I figured it would be needed since the rig was at the outer edge of the main hull and might turn the boat in one direction. Wrong! It seems that power pushing a slippery set of hulls doesn't need come from the center of a boat (as on a monohull). My Proa tracked straight, and as she was legal, dusted my best monohull Footy. I made this boat several years ago but shelved it for lack of interest.

My Proa had one flaw which I am working on to fix. Going off wind I broad reach, I don't go directly on a run like I do with a monohull. But in strong winds (and with gusts) a jibe can lead to a pitch-pole. Bringing in the sail before a jibe can result in a wild broach to windward once on the new tack. It is quite a riddle, not one the bodes well for racing. Like all the hurdles I tackled in making this Proa sail, this I am sure can be solved or at least mitigated so the average sailor can use it with confidence.
Mar 20, 2017, 06:48 PM
Thomas Armstrong
Quote:
Originally Posted by Niel1055
Chiwea, that would be my Proa you mentioned. A cat cannot effectively fit in a Footy box with the rig upright and have the hulls far enough apart to have enough resistance to capsizing unless there is a keel and bulb. That sort of defeats the whole purpose of a light weight weight multihull Footy.

So, I came up with a solution that I initially had little faith in, having never designed a multihull before, some very fast monohull Footys, but this was new to me. My prototype was rather heavy at 320 grams, a pretty good weight since it was a pair of chine hulls in 32nd ply. The Proa was western style in that it sailed on either tack with the same bows headed forward (unlike the Pacific Proas). The rig, sail winch, rudder servo and receiver were all mounted in the main hull and the battery in the outlying hull. The hulls were asymmetrical mirrors of each other, slab sided on the outer faces of the hulls. The slab side on the main hull allowed the mast tubes to be mounted flush to the inside of the hull. When placed in the Footy box on it's side the main hull was below the top edge of the box but the rig fit over the long side of the box and could swing in both directions satisfying the sailing trim rule. In the box, on edge, the hulls were far enough apart so that the boat is just under 12 inches wide and 12 inches long. No need for a new box for multihulls!

Slab sided hulls should not need fins, but not a trusting type I included a small fin in the center of the main hull. I figured it would be needed since the rig was at the outer edge of the main hull and might turn the boat in one direction. Wrong! It seems that power pushing a slippery set of hulls doesn't need come from the center of a boat (as on a monohull). My Proa tracked straight, and as she was legal, dusted my best monohull Footy. I made this boat several years ago but shelved it for lack of interest.

My Proa had one flaw which I am working on to fix. Going off wind I broad reach, I don't go directly on a run like I do with a monohull. But in strong winds (and with gusts) a jibe can lead to a pitch-pole. Bringing in the sail before a jibe can result in a wild broach to windward once on the new tack. It is quite a riddle, not one the bodes well for racing. Like all the hurdles I tackled in making this Proa sail, this I am sure can be solved or at least mitigated so the average sailor can use it with confidence.
That was some good read!! I would be glad to add the Proa here: http://www.allradiosailboats.com/class/footy

Do you have photos? Can you detail some dimensions??

Thanks
Mar 20, 2017, 08:35 PM
Registered User
Dick L.'s Avatar
Downwind heavy air gybes are possible but much is in the timing.

Sheet in main
Slight tiller to get main to cross wind
Don't bear away
Allow main to fill
Then steer downwind but on your new reaching angle

Your gybe should limit amount of sail projected to the wind as mainsail crosses wind. In essence the effort is to only allow the mainsail leech to move to other side snd then follow up by controlling your boom moving to new side. Don't try to gybe from a full out main to a full out main - especially in heavy wind downwind. You will invite a pitchpole at worst and a roundup at best.
Mar 21, 2017, 10:21 AM
Registered User
Tarmstro, by all means if you think that my Proa would be of interest to other Footy sailors. And yes, I do have pictures but they are jpegs which are not supported by rcgroups. I need to find out what file types are accepted and then I can show you how it sails and how it fits in the Footy measurement box.

Hey Dick, it has been a while since I've posted, but it is good to see you are still out there! I recall your giving me the jibing advice on a private text years ago. That is just what I have been doing but you are right, it is all in the timing and a fast winch and fingers!
Mar 23, 2017, 07:22 PM
Registered User
Proa Photos to give you all an idea what the prototype looks like and how it sails. Also how it fits in the Footy measurement box.
Mar 24, 2017, 01:21 PM
Registered User
Dick L.'s Avatar
Hi Neil
Good to see your post and hear of your tests with a boat design that doesn't require the use of " Lead" !!!

I'm still doing some building, but it has been slow going. I've been sucked into the world of HO scale model railroads as I work on a layout for my youngest grandson.

In your photos, it "seems" there is a lot of camber in the sail which can easily overpower the small hulls. Just an observation, but if the design is easy to manage, keep going on the testing.

Good luck,
Dick
Mar 24, 2017, 01:58 PM
Registered User
Hi Dick,

The sail on the Proa is actually a B rig from my monohull Footy. I didn't really put much effort into the boat because I had no idea if a Proa would work or not. Coming up with a multihull design that would fit in the measurement box that was a little odd looking for a multihull and a Footy too! There were a whole bunch of mistakes I made in this design but my head was in what worked for monohulls so I applied them here. Despite my goofs this boat surprised me with its performance. Which showed me that this can do even better if I start to think multihulls. Also, hard chine is a good, fast way to test an idea. But if you go back and look at the clunky early hard chine Footies you can forgive this prototype for not being very elegant.


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