I am not an engineer or capable of designing a model yacht, but I am curious–why has no one designed an RC sailboat with a scow hull? Now this is just my imagination running a little wild, but I could see having bilgeboards that are raised and lowered with servos (like a real scow) and the cat-type rig… is this just the daydreams of an amateur RC sailboat sailor/builder or is there some merit to the basic principal? The thought just occured to me and I thought it might make for some interesting speculation/debate. If I’m not mistaken, in big boat terms, a scow is the next best thing to a multi-hull for speed right?
Andy, I 've built and tested a small 36" scow using a movable ballast system–it was too small to work well. A scow must have some form of movable ballast so that it can be controllably sailed at an optimum angle of heel. If you just use a fixed keel you have a problem with the thing sitting flat in light air which is real slow and when it heels with a single keel fin then the fin breaks the surface which causes a lot of drag as the boat heels.
A few years back I remember reading in MY about some guys that built some longer scows.
My opinion is that to make a really fast rc scow it would have to be around 60" in length using bilge boards like the real thing and would absolutely require a movable ballast system to prevent having a keel fin and bulb which is HUGE drag. You probably would be able to incorporate “sissy floats”–training floats) to keep the thing from capsizing while you learn how to handle it. This type of scow model at that length would be very fast I think especially if it used a tunnel hull.
Being able to use the movable ballast system to heel it controllably in light and medium air and stabilize it in heavy air would give control similar to the real boat…
High Technology Sailing/Racing
Sorry for being slow here but is a scow a US development class? In the UK a scow is a type of hull shape like the hull of a Topper or Fireball (I don’t know if you have those classes in the US so i might just be addiing to the confusion!)
If its not blowing it sucks!
Scow’s are not a development class here. There are several One Design scow classes sailed mainly in the midwest. They range from the MC which is a 16 ft singlehander to the A-Scow which is I think 37ft and a crew of 7. I’ve sailed a lot on the E-Scow which is 28ft and sailed with 4. I don’t know what the hull shape of a Topper of Fireball looks like. Scow hulls ave an unusual hull. The profile is sort of pan shaped. They have bilge boards and are designed too and must be sailed with a 15 to 20 degree heel all the time so that the bilge board is vertical and the wetted surface is reduced. Sailed flat they are very slow.
Ahh right, I see why Toppers and Fireballs are reffered to a scows now, they have a similar hull shape. Am i right in thinking it helps the boat plane downwind if crew weight stays forward?
If its not blowing it sucks!
When my dad had his boat business back in the 80’s he was a Topper dealer–he sold 2, but I don’t think that you can get a Topper here anymore. They were pretty neat little boats–injection molded plastic if I’m not mistaken–they have a bendy mast like a Laser (smaller though) and were almost indestructable. I kind of wish he had sold more and that there were more around here. I saw one on Ebay about 6 months ago–California boat I think. I think it’s still actively sailed/raced in England, where it is manufactured.
I think the Fireball is an Olympic class isn’t it? There used to be some active Fireball racing at our local race many years ago… they were beautiful boats–most of them were mahogany. The bow is not a scow design in the classical sense… it has sharp chines in that area. The topper is a more traditional scow (like and MC or an E) just a lot smaller and with a traditional centerboard, not bilge boards. Kind of a plastic version of the Butterfly.
The topper class is huge over here, its like the main kids singlehanded class apart from the oppie, the nationals gets close on 350 boats and growing each year. The fireballs are still strong too despite the assametric revolution thats killing most of the old symetrical spnni classes over here, mainly because its still fast even by todays standards. It isnt an Olympic class and i dont think it ever has been.
If its not blowing it sucks!
I crewed on an e-scow as a kid and it was a blast! To give you an idea of the difficulty of scaling one down here are some dimensions: a 5’ e-scow model would have to weigh no more than 9.68lb.'s includng “crew”
and would need 1483 sq. inches of sail. It would be 12" wide…
High Technology Sailing/Racing
Noticed a plan in the AMYA One Meter Construction Guide by Bob De Bow of “Scowndrel 3”. Here in NE Ohio we either have 3-7 mph or 15+ mph winds. I thought that a scow could work on the 15+ days. Anyone have experience with this scratchbuilt? Clyde
Scows are spectacular boats that have been around for years and are the boats of choice of Buddy Melges. They range in size from the Butterfly (~12 ft) to the A Class (38 ft). They plane in minimal wind but require a lot of rail meat to keep upright. A fellow named Ralph Smith in Indiana has a mold for a small model of an A Scow with an interesting mechanism for lee board lifting etc. (only the leeward board is down at any time). He has not gotten the ballast problem down yet.
The late Helmer Peterson had a marblehead with a scow hull at one time if my memory serves me correct.
Also the “Firecracker” IOM was based on the Fireball hull.
The International Moth class was dominated by Scow type hulls back in the 70’s, most had 3 inch concave in the bottom near the bow making them a sort of tunnel hull…no one serious would dare show up with one now.
I regularly race on E-scows. Up until a few years ago I sailed an M-20 scow with my father and have also raced on A-scows, C-scows, and several other classes.
I can tell you a few things about these boats. They will plane upwind or downwind. They tip over. You need to ease the sails to keep them from tipping over (crew weight alone will not do it). They do not handle waves well (they are designed for inland lakes where waves are small). They are wet, wet, wet.
They are some of the fastest boats around. They are also quite popular. The E scow Nationals will regularly draw more than 60 boats - sometimes 80 or 90. Put 80 boats capable of 20+ knots boatspeed and capsizing on a starting line together and things get pretty exciting to say the least…
I have seen several attempts to make an RC scow. Generally they have not worked well.
Scows are capable of such extreme speeds because of their massive sail area to displacement ratio. For example, the E scow carries 323 square feet of sail area plus another 550 square feet in the spinnaker and the boat only weighs 965 lbs. what other boat can you waterski behind???
Download Attachment: waterski.jpg
So in order for an RC model to have a similar perfomance advantage, you would need to make it very light weight (around 1 to 1.5 lbs or so), be able to heel the boat with movable ballast in light air, be able to “hike” with movable ballast in heavy air and be able to keep the boat from tipping by responding with sail eases. I think the laws of scaling are working against you. At least that is what I have seen in all the models I have seen attempted…
I think if I weren’t into cat sailing it would be scows… before I bought my Nacra and got back in to sailing I considered buying an MC scow–looked like a lot of fun. Perhaps someday I still will. Oh, and by the way–we used to water ski behind my father’s Nacra 5.8–talk about a ride!
Since several of you have indicated that you sailed on E scows, I thought you might enjoy some eyecandy. It does not really have anything to do with building an RC scow, but perhaps it shows the speed potential and poularity of the full sized boats…
Download Attachment: escow_start2.jpg
That is a picture of one of the starts from the 2002 E scow Nationals held at Torch Lake. If memory serves there were 86 boats registered. Yours truely is somewhere in that pile-up at the starboard end of the line yelling for rights…
Download Attachment: wwmark.jpg
That is a typical windward mark rounding… Yikes!!!
those boats seem to be holding a lot of sail? i have never sail a scow before but they look like flying dutchman. are they a take off of the design?
Yes, Scows carry a lot of sail. Th E-scow in those pictures are less than 1000 lbs (plus crew weight) and carry 325 square feet of sail area with another 550 sq. ft. in the spinnaker. That is a pretty huge SA/Disp ratio.
Scows have been around since the 1800 in some form or another. They are flat bottomed boats so they really do not bear that much resemblance to the Dutchman. THe class scantlings were solidified around 1880 and have not changed much since then. The E-scow in particular has remained relatively unchanged since the 1920s. In fact there are some wood boats from the 40s and 50s that are relatively competitive.
I’m not sure when the FD was designed but I think it was much more recently than that (in the 1950s, I think), so if there is any resemblance, the FD was probably designed as a takeoff of a scow.
BTW, I was in a regatta in florida about 10 years ago where we (the M-20 scow - 20 foot long, so similar in size to the dutchman) shared a starting line with the FD class. They started 5 minutes ahead of us and every one of the M-20s beat all of the Dutchmen to the finish. So even the slowest M-20 was more than 5 minutes faster around a 7 mile course than the fastest FD. The wind in that regatta ranged from quite light to 15 to 20 knots between the 4 days of the regatta and the M-20 was faster in all conditions, but most so in lighter winds. The thing that really suprised me was how slow the FD was downwind. We were about the same speed as the FDs upwind, but downwind we were able to sail past them with ease.
Here is a good reference for the M-20: http://www.m20scow.com/ScowBuilders/M20Specs.pdf
Cougar ,there is a major design difference between the FD and a scow: scows are designedto sail at an angle of heel to reduce wetted surface whereas the FD isdesigned to sail almost dead flat.
I believe the M20 is a tunnel hulled scow: the tunnel was introduced o lower wetted surface more rapidly at the same angle of heel. A scow sailing essentially on one side has a waterplane that has a high beam to length ratio reducing drag a lot.
–High Technology Sailing/Racing