…to my surprise, it sailed pretty well.
This is the first RC boat I’ve made. I used the carved insulation, fairly-quick-and-dirty method for the hull, although there isn’t any of the blue stuff around here so I used white expanded polystyrene. EPS resists attempts at refinement very successfully. I’m aware that every boat needs an excuse, so I have that covered already.
I thought there was an interesting challenge presented by the footy rule, and the easy entry cost. As far as I know, there aren’t any others around here in So Cal?
Anyway, here’s where I went with it:
I figured in a length-defined rule, sailing length is king. I went with a diagonal boat, and used a fairly blunt, large-radiused nose to avoid “wasting” sailing length on such niceties as a cute bow. I read about Humphries doing this with the Russian VOR entry, and the reasoning seemed, uh, reasonable.
I thought a plumb bow with some wave-piercing characteristics might be interesting, and together with a low-volume, narrow hull would be effective at dampening the waves. My max-beam is a ways aft, so the bow is a low volume, high leverage trade. The static trim is set to place the bow knuckle just in the water, and fully immerse the pinched tail, with the ballast and “stuff” all centered fairly far aft.
Since the narrow hull rides so low, I used a pinched stern to avoid a large immersed transom, and get the max length in the diagonal box.
With almost no form stability, I went with max depth, fairly heavy ballast.
So far I have a McRig on the boat, with “looks about right” sizing.
The numbers are:
All up weight: 480g
Rig weight: 30g
Hull only (with batteries=4xAAA, servos, and rudder): 140g
Sail area: 231 sq. in.
My initial sailing observations in 2-8kts are that it presses the bow down fairly aggressively upwind, achieving approximately “level” trim. With just an hour of playing at a pond, I get tacking angles somewhere around 100 degrees. It’ll get stuck in irons if I tack in a lull, and it’s tough to get it going again since I can’t push the boom to weather!
Downwind, it’ll go bow down with a bow wave coming about two inches back along the deck, like pictures of subs motoring on the surface. When bigger puffs hit, it’ll dig in a little further but seems to maintain about the same speed. I didn’t have any wipeouts or broaches. I do need to spend a little more time on waterproofing, though!
Any wisdom gratefully received!