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In my limited experience I had never "planed" a sailboat before, but at times in good wind conditions I felt my Skerry was going pretty fast, and I heard a different steady "rushing" sound instead of the usual gurgling or splashing sound. So yesterday I brought along my portable VHF radio, which includes a GPS.
I was in a broad reach in about an 8 to 10 kt wind, when I felt the boat was planing, and sure enough, the GPS at one point reached 5.5 kts. According to my calculations, if not planing this would require a L.W.L. of 15' 5". Given that the L.O.A. of a Skerry is only 15', then I think the boat had to be planing.
This was without the most efficient sail set or balance (I was leaning against the rear seat rather than sitting on the hull near the middle seat and the snotter was a little loose). Also I have read that you can only plane during a run, not a reach, so I may have been mistaken about being in a broad reach--though I could still feel the wind on the side of my neck and the pennant was flying pretty much parallel to the sail; telltales looked pretty good.
Can the more experienced sailors out there give me some insight? It would be nice to know exactly what was going on and what the little boat is capable of (although I'll never race it, still the experience was exhilarating).
5 replies:
RE: Planing a Skerry?
I guess I don't know the difference between planing and surfing. Will look it up later. The boat was mostly on 5.3 and 5.4 for long enough for the reading to be reliable. Went up to 5.5 briefly, so naturally that is the figure I bragged about! :-) Anyway, I know it was doing at least 5.4 for sure--which is definitely still above hull speed.
Thanks for the info.
RE: Planing a Skerry?
OK, I looked it up. Surfing is . . . surfing! Duh! It does not seem to me it was surfing, there were no appreciable waves in the somewhat protected area where I was--mostly just ripples. I.e., I was not far enough from land for waves to form. Further out, the waves were 8" high at most and not breaking. As I said I estimated the wind at 8 to 10 knots. I was on a small inland reservoir, probably 2.5 miles long by about 1 mile wide.
Whatever I was doing, it was a heck of a lot of fun and I look forward to doing it again. I think it would be exhilirating and not dangerous up to about a 15 or 16 kt wind.
RE: Planing a Skerry?
Having planed a great variety of dinghies on many occasions, I can confirm that when the hull jumps on a plane it looks, feels and sounds like entering a new dimension. I currently sail a Johnson 18 which can plane even going upwind. Most planing dinghies will most readily jump on a plane when beam and broad reaching.
Obviously it is possible to surf waves and plane at the same time. Light planing dinghies will most quickly get on a plane in flat water with a nice gust.
The Skerry is light enough but certainly does not have the typical hull shape of a planing hull which usually features a flat relatively wide bottom going toward the stern. All the same, it does sound as though you had a bit of a plane going. A friend on our local lake build a Skerry which I had a chance to sail and I do believe that it is possible to plane the boat.
If you want to do some serious planing, why not consider building the PaperJet14 designed by Dudley Dix? CLC cuts the kits on his behalf. I had a chance of sailing Dudley's demo boats at the last OkoumeFest and was very impressed with the design.
Several years ago I built a lug-rigged PassageMaker Dinghy and I have had it out in all kinds of winds with gusts in the low 20's. Though this boat has a wide tail end, the significant rocker of the hull works against any planing. Yet, on a broad reach I did actually get it on a "quasi plane".
I agree that 15 knots would be a good and safe target to learn more about the planing abilities of the Skerry. Have someone take a video of that and it might go viral :)
Fresh breezes!
~~~_/)~~ Chris
RE: Planing a Skerry?
With a pointed rather than a transom stern, the Skerry won't plane as readily as some racing dinghies.
Otherwise, it does have the requisites of a planing sailboat: a high sail area-to-displacement ratio and a shallow hull. It would take a lot of wind and smooth water to get a true test of it. That hull WILL plane, given the right conditions.
I suspect the transition from displacement to planing would be much more gradual compared to a dinghy designed for planing---many of those feature an abrupt jolt as they outrun their stern waves and achieve liftoff.
There's no difference between surfing and planing, technically, except that "surfing" means that it was a wave that got you up to the requisite speed, and the boat stops planing when you either outrun the wave or the wave outruns you.
RE: Planing a Skerry?
» Submitted by Laszlo - Thu, 9/12/13 » 1:27 PM
I'm thinking that maybe you were surfing instead of planing. For one thing, that hull shape doesn't look right for planing. For another, GPS is a bit unreliable for instantaneous speed changes. Did it stay at 5.5 for any appreciable length of time? Or did it hit it for a moment and drop back down? If it stayed 5.5 for more than a few seconds that's a more trustworthy number.
Also, the waterline length calculation is for a purely displacement vessel. If you had any kind of lift at all, you'd have been easily able to break the "speed limit" for the Skerry's length.
When my boats have surfed, I've heard that same change in water noise, another reason I'm thinking that that's what was going on. Sounds like fun. I've never had a Skerry go fast for me (always sailed them in light winds).
Laszlo