Well, now that winter is upon us I have been thinking about some ideas that are appearing in big boats that I thought might suit RC boats. Mainly, after reading several reviews about the Kyosho Seawind, it seems to be very good boat, but like most rc boats, it has a hard time down wind, maybe worse than most from the readings. I was thinking about buying just the hull and attempting to add, spray rails to it, similar to the Russian VOR boat. Now I know there is a lot of R&D that goes into all modern racing yachts, but I think the simple idea could be of great benefit to our little boats. See photo for What the rails look like on the Russian boat.
Additonally, I found some of my older designs (still in CAD form) and I am going to attempt to add a hard chine from about the 70% mark to the stern. I will let everyone know how it turns out. This too requires alot of R&D in the big boat world, but I just wanted to see if there is any discernible difference when added to an RC yacht.
No canting keel. After reading an article in Sail magazine about the purpose of strakes and spray rails it sounded well suited for RC boats. Basically, they allow a more bow up attitude, especially when off the wind, which allows them to run their bigger sails higher in the wind range, because the boat does not have the nose diving tendency through waves rather they tend to ride up and over the waves.
As for the chines, it is really just my attempt to mimic some of the ultra-modern racing boats (i.e. Dan Meyers’ Numbers). I know that they certainly serve a purpose on big boats, but I do not know if that purpose would carry over to RC sailing, and more importantly, what factors go into the placement of said chine. I may have some .pdf’s of the stations soon which I will post.
the strakes (like diving planes on a sub) are small "winglets (for lack of a better word) mounted to the sides of the bow and angled from high to low looking from the bow. Originally intended to help act as an “up foil” and keep bows high.
Was tried on the Mini40/48 multihull scene and results were, well, questionable. Not required in light winds, worked well in medium winds and contributed to pitchpole in heavy winds when sterns rose and their “upwards angle” relative to water surface became negative as sterns rose higher. Thus, like diving planes on a sub, one you were headed down the 'mine shaft" no way you was “gonna” come back up! Perhaps with your lead keel, slower speeds it may help. The biggest problem is that stick and sail area way up there acting like a lever and overcoming both bow buoyancy and ability to accelerate quickly!
The hard chines are on the after body of the hull and are (supposed) to increase initial stability, as well as resistance to easy heeling. Like any hard chine boat (Star, RG-65, etc.) they will be resistant to heel, and also the chine seems (seems ??) to increase lateral resistance from the hull.
Thanks for the input Dick. One of the VOR Telefonica boats has (what SAIL magazine calls) strakes. Not quite as radical as the Russian boat’s “spray rails”, but supposedly serve the same purpose, maybe not to the extreme degree of the Russian boat. I am not sure. I’m not calling your terminology incorrect, I was clarifying, why I chose the word strakes.
As for the hard chine comments that make sense now that you mention it.
Yar- I guess it would be 6 of one, half a dozen of the other. My thought was to use a hull that we know has a significant deficiency, so once the project is complete, there might be a measurable difference. Using an existing hull would give me a baseline. But the same argument could be had for most boats, I guess it doesn’t matter what “was” if the end result is a boat that resists nose diving downwind. Would save me some $$ so maybe I will go down that path. Thanks for the input guys.
Niel and Martin,
I had seen something like that before. It turns out my current USOM is going to be a perfect candidate. I am going to use (2) strakes, the bottom one will be only slightly above the waterline and about 1/3 the length of the boat, the top one will be about a 1/2" higher than the first and will be about 1/4 the length of the boat. Not only do I hope this solves the nose diving problem, but it should also help with a more “bow up” attitude on all points of sail. The strakes may cause some extra drag, but if it keeps the boat moving forward rather than downward, it is worth it to me. I hope to get started this weekend so I will be sure to post pics of the progress. Thanks for all the input.