Thread: Oklahoma OZ PDR

How about stepping the mast a bit off-center so the boom is on-center? Bad idea? -- Grant

Howdy Grant,

Not worthwhile. It is easy enough just to feel if the boat is moving along nicely as per normal.

Also it is currently set up for a couple of different sailing rigs and it works for both of them.

Probably if I was doing a reall raceboat of a lug I would put stops on the traveller that took account of this.

MIK

"Even a blind squirrel finds a nut now and then"

It took two shots but I managed to get lucky enough win the SDDP (Same Day Different Place) race Saturday.

When I started the wind was 16 gusting to 22 mph but the lake was flatter than usual for those speeds. I used permanent marks the club has placed around the lake for my course and wanted to do a beam reach on both tacks. I chose mark #1 and mark #5 thinking they would work best but when I tacked at mark #5 I was on a close reach. I sailed to mark 3 and the course between it and 1 was perfect. I was using my Ronstan racing watch for timing, it has a large red start/stop button so it's easy to press when you have both the sheet and tiller in your gloved hands. Everything was going well until I looked at the watch on my last leg and noticed I'd inadvertently bumped the button and stopped the watch.

I was disappointed and too tired to start over at that time so I rested two hours while watching the wind readout in the clubhouse. I knew to finish before dark I would need to start a little after 6:00 pm. The wind station was showing speeds higher that what I wanted but I decided go out anyway, I had a watch on both wrists this time. When I got on the lake the wind was perfect and the boat was on plane the majority of the time. I completed four legs for a total of 5.44 miles in 1:03:58 for an average speed of 5.1 mph.

The watch stopping on the first run turned out to be a blessing, the second time out was much better.

I think the extra controls I put on the boat helped. I had the outhaul let out to the stopper knot which gave the 1 in 7 draft Mik recommends for reaching, the vang was tensioned to take most of the twist out of the sail and the 8:1 downhaul was pulled in hard.

I'd like to thank both Mik and Brian for taking the time to answer the many questions I've asked. Without their help I couldn't have done it.

Brad

Hi Brad, That is a pretty good average speed.

In the early days of speed sailing trials over 500 metres all the fast class racing boats and catamarans were more or less expecting that they would be able to duplicate their peak speeds of around 20 knots.

Their averages of regular class boats were often down around the 12 to 16 knot range.

With your longer distance the averages are even harder to keep up.

The point where drag starts increasing badly for the PDR is around the 4 knot mark so to have an average around 5 knots aint bad at all. Most of us who have sailed with GPSs have found that the OZ is pretty happy sailing at around the 4.7 knot range on a reach.

A good measure of efficiency.

How did the control feel Brad?

I would have loved to have seen you set off the two watches in synchrony as you passed the first mark.

You must have been busy!

MIK

The boat felt good. There were a few brief moments when I had some weather helm due to the hull getting off balance but other than that the helm felt balanced and it required very little movement of the tiller to hold a straight line. I didn't feel quite as good, my knees, thighs, shoulders, and arms all ached.

Starting two stop watches would have been a good trick with a tiller and sheet in my hands. I left one in clock mode and noted the time when I started the stopwatch.

Brad

Mik,

Do you think 5.1 mph over five miles sounds reasonable?

I know my timing was accurate but I got the distances from this table: http://okcboatclub.com/race/permanent_marks.pdf

A survey was done three weeks ago by a certified race officer but it's possible one of the marks could have moved off station since then. I did discover the distances listed as nautical miles in the table are actually statute miles so I corrected that in my calculations.

The boat was on plane all but a fraction of the time. At one point something happened I've not experienced in the PDR before, the bow was up and the boat was heeling very little when it felt like the boat started leveling out and accelerating as the stern lifted and I didn't hear the backwash at the transom like I normally do. It felt like a powerboat going over the hump and leveling off on plane. Waves could have had something to do with it but it felt like the boat was flying.

Thanks,
Brad

Brad sent me the above as an email - he hadn't seen that I thought that his speed was quite a good effort.

In reality there is no strict phenomenon we can call "planing".

But it has a common language use.

In some ways you can say you start "planing" when the boat exceeds "hull speed" (which also doesn't really exist as a strict limit on any boat) - about 3.5 knots for the PDRacer.

There are a couple of things that happen when the boat is planing - in the way sailors use the term.

One is the single boat starts moving considerably faster than "hull speed".

The second is that instead of the water behind the boat having a bubbly swirly "grain" it goes quite smooth - like a sheet of glass with some streaks in it.

Sometimes this "separation" can be only a little bit behind the boat and is not truly "planing", but by the time it goes two or four feet back, then you really are in a dinghy.

MIK