moveable ballast

im currently building a (hopefully) high performance sloop thats slightly larger than a 1m. The rig on this thing is 75 inches tall, while the hull is 42 inches. With the amount of pressure that would be generated on the rig and hull, which would make more sense- a canting keel or a heavy moveable weight(on deck)?

Just out of curiosity, why are you planning on a boat bigger than 1m. Im about to commence the building of my own custom boat and I am still debating on whether to follow the F100 rules or not. Just curious what your thought it, maybe it will help mine. Thanks for the time.
Andrew Miller
Im gonna start cutting foam tomorrow so I will post pics when available.

I was planning on using a 1 meter hull, but wasnt sure whether it was stable to support a huge mast like the one I have. Also, the reason Im building this boat is to race it against a EC-12 in light air, so Im trying to see whether the shorter boat would be faster with the super-large rig and the moveable ballast. I guess you could call this project an experiment.

That sounds interesting. Im tryin to build a scale rendition of Pyewacket, it will have the twin foil design, but im not sure if I will have the canting ballast. I was thinking of maybe [putting a canting mechanism on the keel, then just keeping it centered until I felt like changing it. I roughed out a 42/43" plug tonight out of insulation foam, but that was just practice for for the 1m design. I may play around with the larger hull and see what I can come up with. Good luck, im sure Ill be bac with some more posts in the next few days.

im now currently thinking of extending the hull even longer so i can put more ballast on. When its finished, the hull should loook similar to a ACC sloop. Im leaning toward the moveable ballast on deck because I dont want to risk having a canting keel fail or snap with at least 7 pounds of lead on the end of it. The hull is ABS plastic and wood, the mast is wood, and the underwater appendages are carbon fiber. The keel box is right now being reinforced to handle higher loads, and prevent the hull from flexing with the keels weight. This thing is probably going to be a very tender boat, so hopefully it sails well in light air.

The movable ballast on the deck should allow you to build an all around lighter boat. The deck ballast will have its greatest righting moment effectiveness near 0 heel whereas the canting keel will have its greatest righting moment at 30 - 40 degrees of heel (depending on how far it cants).

If you use the canting keel, you will need to find some way of generating extra lateral resistance as well. This might mean a forward rudder or daggerboard. Or it might mean wings on the keel. Either way, you will be adding extra drag creating underwater surface area.

The biggest concern with moving ballast on deck is stability in the event that the ballast is in the wrong position. I would try to maintain a positive stability in the condition where the ballast is on low side and the wind is blowing you over. Make sure you have enough lead in the keel bulb so that you can recover from a mast-tip-in-the-water broach.

If you are feeling really spunky, try something like this:

Good Luck and keep us posted.

  • Will

Will Gorgen

Sometimes, simple works better. I don’t think you have to go nearly as far as you are proposing to make a one meter boat competitive with an EC12, particularly in light air. Frankly, in the light stuff a current generation IOM or US1M should already be able to keep up with an EC12. If you are looking for a horsepower boost, a slightly larger sailplan than currently allowed on the IOM or US1M should work fine without having to engineer and perfect moving ballast systems. Also, in all events I would suggest you look at either a carbon fiber or aluminum mast.

But simple is no fun!

Luff 'em & leave 'em.

KISS (keep it simple stupid) is for the GIRLS[:X]

ok, so ive sorta figured out what this thing is going to be like. The rig will stay at 75", the hull will be about 50 inches with the extensions, and its 9 inches wide. The bulb will be a 6 pounds on a 20 inch fin, with a to be determined moveable weight on deck. That will be attatched to 2 Hitec giant scale servos, which will cant it to the appropriate side. If this can be built as i have envisoned it on paper, the weight, which will also be a bulb, will be several inches outboard when fully canted. Has anyone used a system like that before?


Here’s a spreadsheet that I knocked sometime ago when I was play with the design of my F100CBTF (ok i have been calling it F100CKTF)

I look at a normal keel, moving ballast and canting ballast.
Just change the yellow coloured cells draft, weight, sail area & height of CoE, then change red cells the wind strength & angle of heel,

It calculates the righting moments and heeling moments. Ok someones going to say it doesnot take in the hydrodyamics of the hullform centre og buoyance CZ and all those nautical terms the yacht designers used. I just wanted a simple thing to show the difference between the setups.

Have problems attaching the spreadsheet, will try to put in the file option

Still no lucky, can anyone help, how can you attach a xls (excel) file to a post or upload to Resoures/Files???

50 inches long with a 75 inch mast–you’ve now come pretty close to describing a contemporary Marblehead (50/800). There are a great number of these designs available, all can carry the sail area you are talking about with no trouble and don’t need a nine inch beam or moving ballast to work. Also, they can pretty much beat an EC12 in most conditions. Check the AMYA site for some more info.

A minor word of caution, particularly if you are knew to design and building r/c yachts. While there is some talk on the internet about r/c sail moving ballast systems, (and even a few experiments here and there), no one has yet produced a fast, reliable r/c moving ballast system that has proven itself out on the racecourse.


You keep a;uding to teh fact that no one has produced a fast canting keel or moveable ballast boat which may be the fact but there may be other reasons as to building these boats as to teh shaer fact of going out to beat a fixed keel boat.

I have built mine and are in the process of finishing my second canting keel boat and have done this as it is a bit more technical and is a bit more of a challenge to build than a standard fixed keel boat.

My second boat is alot more techincal than my first boat and hopefully will tend to be a bit faster as I have found from how my last boat performed as to what i would change.

The canting keel boats are a lot of fun to sail and put a new twist into the sailing of teh boats.

If anyone wants info on what i have done to make my boat work please feel free to contact me.

Cheers Gappy


how do you attach the keel to the hull. Do you have a sort of hinge like mechanism or something?

Gappy -

I think both Will and I have outlined some specific reasons for NOT going with moving ballast on a multihull. If you aren’t on board, no matter how quick you are - you are still “reacting” to the boats heel. “IF” you were on board (big boat) you certainly would feel the boat reacting to wind and waves, and have a slight chance to be proactive.

Even in it’s simplest form of moveable ballast on a multihull - if you aren’t quick enough and don’t get it right - you are going for a swim/paddle - regardless if big boat or little.

I think what Roy might be pointing out, is that if one was to reduce weight and use a canting keel, would the weight loss (or add on for all the parts, servos, winches, etc.) make the boat that much faster on our small r/c race courses over a non-moving keel/ballast boat of same dimensions - but less complicated to sail?

This is the issue some of us asked well over a year ago (or more) and it still hasn’t been answered - or demonstrated. Will moveable ballast improve performance on a closed course - and by how much? A previous poster always insisted it would, but never seemed able to produce verifiable results. Add in the fact that there seems to be a lack of boats built to a specific sized class where a lot of benchmark boats exist, and I (for one) still seem to be waiting for someone (anyone) to provide a demonstration of on-water performance comparisons against a known class of boat. I’m not saying “M” versus EC12 - but I am strongly suggesting 1 Meter against 1 Meter, “M” Class against “M” Class, etc.

If you really are building to an “M” Class standard size, then I am positive there are “M” owners who would be willing to do some boat-on-boat racing to see if the added complexity results in markedly faster boats.

I am not talking long-distance racing - but racing on our generally accepted course lengths. I think all of us who are asking questions just want to see something demonstrated. How long has the Bantock CK design been out there - and how many have been built and are sailing? What happened to the CK Trainer program? Hate to bring up “flame-type” subjects - but what the heck… !

oh right…I almost forgot the CK trainer…now that you talk about it, I thought the idea was nice, but then again, it was just some “idea” and nothing came…

BUT, new battery technolgy is out (well kind of) LiPos…could save some weight…and easily…might be worth a try!

Just my 0.0000000000000000000000000000000000000002 Yen


_/ if it isn’t broken, don’t fix it! _


You did not read my post i never mentioned anything about multihulls and never have and neither did Roy so where did this come from I am only talking about Monos as this is all that i am involved in i would agree wth you that it would not work on a multi and I was going with the original thread that this started on that it was a mono as last time i heard Pyewacket was a mono hull and he was talking about doing a model of Pyewacket.

I also said that i did not build my boat to go faster than a fixed keel boat it is purely for teh enjoyment of building it so don’t try and twist what I am saying. I have never stated that it would be faster unlike as you put a previous poster did and i did not agree with what he said and i believe that we will never see the CK trainer or the Bantock F100.

So if we can get back to the main thread it would be great.

To answer USA2’s question my first keel went right through the hull and had a pin going through it and the keel extended up inside the hull and was then canted with pulleys and a winch. My lastest boat the keel goings into a shaft which is about 20mm in diameter and the keel fits into it and then the shaft ges through a sealing system and then has another lever on the side of the boat which the servgo attaches to and then it has a gear on it which runs a long a gear quadrant i can post pics which will make it easier to understand. Contact me if you u like and I can e-mail them to you.

Cheers Gappy

I just used the multihull as an illustration of why canting keels “WITHOUT” anyone on board are at best “reactive” (if you are fast enough)- unless of course you are able to “feel” the boat’s reactions through the Tx sticks?

Canting keels work - on big boats and on small… (Wind Warrior) … not an argument there.

I guess my question still remains unanswered - does an r/c canting keel monohull prove to be any faster around a closed course than a non-canting keel boat or is this simply a “GeeWhiz/Cool” option?




I would put it in a gees wize cool option at the moment as it is yet to be proven.

But i have been talking to Grunta thats makes the wind warriors and he lined up his Ultimate warrior which has teh canting keel with Jeff Smales new one metre and Jeff is a very well known and very good one metre sailor and alround RC yachtie. Grunta was pleasently supprised at the results and found that he was quicker sometimes upwind and then Jeff would eb qucker but around teh rtack they tended to be pretty much the same. I am sunre as to what conditions it was but I know the One emtre no.1 rig is quite a bit bigger than Gruntas rig.

Any way we will see what happens in the future.

Cheers Gappy

the canting keel boats would be faster in moderate winds, especially beam reaching. It also would allow you to carry more sail area for the size of the boat, so therefore would almost always be faster