Footy Class Catamaran possible within the rules? - Page 2 - RC Groups
Thread Tools
Nov 26, 2008, 02:51 PM
Registered User
nigelpheron's Avatar
Oh my. Nice yours is ready for a maiden.

How much ya displacing? I'm getting around 300gm on my proto sponsons together.

I have one sponson/cross member made, and will have the others probably by next week. I wish I had mine ready to try now, but oh well

Keep us posted
Sign up now
to remove ads between posts
Nov 26, 2008, 03:37 PM
Registered User
200g so far, but as I mentioned the batteries aren't right. I guess it would be around 230-250g if I would balance it with normal batteries.

But there are new LiPo batteries out, (although I haven't found them yet) wheighting a third less than normal batteries so I guess I will end up around 180-200g.

I hope we get better weather soon.
Nov 26, 2008, 05:36 PM
Registered User
nigelpheron's Avatar
Those batteries are nice. I bought my first set in April, and they still work fine. 65gm with my wire solder job too. better than the 110gm average of the cells I was using earlier.
Nov 27, 2008, 03:26 PM
Registered User
"Finally" (after nearly 20 hours of waiting ) I got the batteries. Quite expensive but at least the wheight was worth it. No lead neaded to trim the boat (Ok probably I will need 5g or so to make it perfect).
Around 200g

The boat is realy light and the smallest breeze pushes it forward (at least in my bathtube).

I don't think it will capsize, at least not sideways. I can push the mast down about 70 before one hull starts to submerge. Sadly I don't think it can go on one hull, not enough lift.

It might get a little bit critical on broad reaching and running couses in strong winds. It may somersault. I will probably add 2cm high styrofoam to the top of the forwad third of the hulls to prevent this.

Here some pics of the bathtube test. Enough wind but not enough space to turn .

Nigel what's the size of your hulls?
Nov 27, 2008, 05:31 PM
Registered User
nigelpheron's Avatar
Looking good.

My hulls...Uh...no more for the moment. I jumped on the prototypes in a fit of wee rage. I rushed, and they didn't turn out the way I wanted.

I will carve some new ones over the weekend or so.
Nov 29, 2008, 09:14 PM
Registered User
nigelpheron's Avatar
Got some new sponsons carved, and they are getting glassed tonight.

I had some after thoughts that I wanted to put on the other ones anyway.

Had yours out on the pond yet??
Nov 29, 2008, 11:34 PM
Registered User
nigelpheron's Avatar
Hulls were carved from a block 2" wide x 12" long x 2.5" high.

When I get some pics up, you'll see how much of that block was removed.
These new carvings should displace around the same as the last protos (around 300gm).
Nov 30, 2008, 08:04 AM
Footy Pie-Rat
AndyTrewin's Avatar

FootyCat


Must get round to finishing mine off soon
Rgds
AndyT
Nov 30, 2008, 11:45 AM
Registered User
Not yet.

Today whould have been good (well lets say not to bad) weather, but I had a little bicycle accident yesterday and my knee is swollen. Nothing serious but it stops me form walking to the pont.

Your specs look nice but I think foam might be a little bit heavy

@Andy

Come on you ARE allmost finished Only 2 or 3 hours to go, but I know sometimes its hard to move on.

It looks a little bit narrow are you planing on using a ballastkeel?
Nov 30, 2008, 01:04 PM
Registered User
Dick L.'s Avatar
Quote:
Originally Posted by Whiskysour
It may somersault. I will probably add 2cm high styrofoam to the top of the forwad third of the hulls to prevent this.
Only a technical comment/observation here......

When sailing downwind, and hit by a gust, a 2cm. added height to bows will only help so much. From a technical point of view, the entire boat MUST accelerate as quickly as possible to react to the wind gust. Monohulls - like multihulls will have the same tendency to "trip" over the bows, but monohulls, with their added lead keel, acceleration is much slower. It is really the lead keel that keeps them from nose-diving more than they do.

From a physics point of view (very basic) the mast/sail/rig acts as a lever. When hit by a gust, they tend to react faster, trying to go forward in the air which has less resistance than the water on the hull. Thus as the rig accelerates and the hull doesn't, the mast/sail will move forward faster and acting as that "lever" will tend to push the bows down. If the hull doesn't have a counteracting lead keel, and if the hulls aren't narrow enough to allow acceleration, then the mast will eventually "pass" the hull bows and a somersault/pitchpole will result.

Making the hulls very narrow, and the entire platform very light will help with the acceleration - meanwhile running a shorter, low aspect rig/sail combination will allow the bows to stay up longer as you are in effect shortening that "lever". Likewise, running downwind - all you will ever be able to accomplish is the speed of the wind. If you "crack off" on a deep reach, not only will you sail faster than the true wind, the apparent wind will shift forward so you can begin to sheet in. You will find - like an ice boat or land yacht with less drag/surface friction, close-hauled both upwind and downwind would be the norm.

Not trying to say you are wrong - just trying to provide a bit of multihull sailing experience so you understand "why" things happen and what the cause/reaction will usually be.

Good luck with your efforts. (PS - chunk of foam on mast is a "good" idea to prevent a "turtle" of the multihull. Remember, multihull platforms are very stable - right-side up or upside down)
Dec 01, 2008, 12:26 PM
Registered User
Hi Dick

Thanks for the commant, you are right and I was already thinking about building a smaller rig (now I'm sure)

But actually I'm not worried about gusts. The eqillibrium rig helps a lot when dealing with gust. Its the the lift of the hulls that make me worry. One hull can only lift a little more than 200g (probably 250 at the most) and I think in stronger winds and on broad reach the bow of the leeward hull could be pressed under water resulting in increased resistance on one side flipping the boad over.

Still the foam might only be helpfull as floats because the wind might then be strong enough to push the footy at its hullspeed and leed to a pitchpole anyway. So I guess I will add a "foammast".

P.S.: I have to find a way to make a planing footy hull
Dec 01, 2008, 01:27 PM
Registered User
Dick L.'s Avatar
A couple of Scow type hulls perhaps ? (A, E or M)

Heel them slightly inwards so if they do support sailing on leeward hull, when windward hull is in the air, the leeward hull will lie flat to water. Start at about 10 degrees of hull angle from flat and see if you can get the thing up and sailing, then sheet in slightly and steer to leeward to see if the windward hull will break free of the water. If it does, foot off a bit more, and if windward hull gets too high, steer to windward a bit.

A good, fast winch is also suggested....... along with fast thumbs!
Dec 01, 2008, 02:49 PM
Registered User
I don't think I will get a hull out of the water. But I will keep it in mind if it does!

The bars are fixed and resinified for now but I'll try to make them exchangeable on the next one

Hmm didn't know scows till now, but looks like relatively simple hull designs.

Do you think it will work footysized? Either as a cat or mono? On a cat the hulls might get to thin to plain and as a mono it might have have problems when it heels (but at least faster downwinds.)

Do you have some scow plans?
Dec 05, 2008, 09:49 PM
Registered User
nigelpheron's Avatar
Your right, the foam is heavy. However, these carvings are plugs, intended to make physical, my mental renderings.

From these carvings, flash molds will be made, and then I can make protos for testing. If it all works, propper molds will be made for production. If nothing works, the flashes will be filed under "G" (chrow dem indy gyarbage).

I bonded the crossbeams on today, and over the weekend-(ish), fairing will take place. Starting to look good, and now that some shapes exist, the placement for rigging and electronics now present their problems to be solved. I forsee a lot of bellcranks, or push/pull cables to be used...
Dec 06, 2008, 08:36 AM
Registered User
Fitting the electrics was really a bit challenging and I'm not sure how waterproof the deck realy is. I guess before the first run I'll seal the rx and the batteries in autoclavation bags to protect them.


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Build Log A Footy class scale sailboat. suirendoujin Sailboats 19 Feb 25, 2009 12:10 PM
Discussion 2008 New Zealand postal Footy class race micro sailor Sailboats 0 Jan 17, 2008 02:45 PM
Discussion Footy Class Announcement Angus R Sailboats 1 Feb 18, 2007 07:18 PM
Yippee! FREE plans for a 12inch Footy class yacht micro sailor Sailboats 25 May 27, 2006 07:27 PM
Official Footy class rules micro sailor Sailboats 5 Sep 19, 2005 09:35 PM