Michael Storer Boat Design

PD RACERS - OZ Style

Sailing a PDRacer fast - Methods and Performance.





For general information about detailed OZ PDRacer Plans and construction click PDRacer.info

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I thought I would write a bit of a spiel about how the little boats are going...

We (and several other people) have been sailing them over the last few days.

The performance is pretty much how I expected when I drew up our version.

In light winds they move along really nicely - as you can see from the videos which were all filmed in under 8 knots of breeze.

We had decided to put heaps of sail on them 80sq ft vs the more normal 60 sq feet - the rules restrict the hullshape only. We wanted the performance to really sparkle in the light stuff.

As you can see from the vids they steer pretty well and are capable of turning in their own lengths - far faster in fact than this sailor can move!
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Planing

One of the points I wanted to prove is that the original designer said that the boats wouldn't plane - and that was the opinion of (it seemed) many of the American Sailors.

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Going fast

Headed
for a sail upstream in the Mooloola River - spent a coupla pleasant hours exploring and trying to make headway against the outgoing tide in the light winds.

In the end I gave up in one particularly light area (lots of trees both sides of the river - the tops were waving in a reasonable breeze, but there was nothing at water level where I needed it.

Anyway, headed back and the wind had picked up to between 10 to 13 knots.

This is the sort of wind speed where I expected to start having problems from the big rig.

No Problems and on the upside got the boat planing a couple of times in some of the stronger gusts.

The main reasons for us being able to do it is that our boats are about 1/3 the weight of the average, they have lots of sail, they have carefully shaped centreboards and rudders and though the sails are made of crap material (polytarp) the mast and boom and resulting sail shape are quite efficient in light and moderate conditions and downwind in these stronger breezes - though I am not happy with the amount of stretch distortion in the sails upwind in the stronger stuff.

Oh, yes - both Midge and I have a background in performance sailing craft too - so we both know how to cajole a boat onto a plane.
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Holding together in stronger winds

The next day brought winds of around 10 to 15 knots - so the peak of the gusts was greater than the previous day.

So I spent some time generally getting a feel for the boat upwind and down.

Upwind the boat points quite well sailing at close to 45 degrees to the wind (that's those foils working). In a gust the mast bends as it was designed to do and spill some of the excess wind pressure automatically.

I was worried that the masts - made from radiata pine floorboards - would be two week because of the poor grade of the timber - They stood up OK before breaking at a knot.  The plans have been revised with a slightly larger cross section for the mast.

I was also worried that the boats would become a handful in a breeze - all that sail area - but in 15 knot gusts when they should be well and truly starting to give us a hard time - no probs at all.

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Capsize

The OZ PD Racers work well in capsize.



This picture shows how they float on their sides with the cockpit well clear of the water - it was taken by the shore,but the mast top is in the water being supported by its natural buoyancy.

When they come up they have little or no water inside so can be sailed immediately and effectively - there is no need to bail the boat out before it can be sailed.  This is a pic from immediately after the capsize.



The boat is so light it can be easily pulled upright from in the water - there is no need to climb up on the centreboard - just pull it down as in the video right and the pic below.



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Going fast

Reaching is where the fun starts - going across the wind. As soon as there is enough wind pressure for me to put my feet under the straps and start hiking (not going for a walk with a backpack, but stretching my body out from the side of the boat to keep it flat and stop it from capsizing from wind pressure) - as soon as there is enough wind to hike out on a reach the boat planes efforlessly - at least in the smooth water in front of Peter's house on the Mooloola River in Queensland

The only thing that you have to remember is to move about a foot further back just as you start hiking to stop the bow digging in.

The planing video on the right shows the sequence- gust hits - because I wasn't fast enough the bow digs in a little - I move aft - bow comes up and boat accelerates - as it accelerates the bow comes up more.

If the bow digs in the boat stops suddenly and is going too slow for the rudder to be very effective. But if you hike and move aft that little bit the boat accelerates, the bow rises into the air mightily (that's all the excess curvature of the bottom toward the back of the boat starting to suck the stern down) and you are moving along quite nicely.
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Easy to sail

Almost anyone can jump in and have a great deal of fun - they feel faster than they are and behave just like little modern dinghies.

They are not too hard to hold up and with only one sail and the steering to take care of they are simple.

On launch day one of the ppl there took his two little girls out for a sail - he hadn't sailed a keelboat or dinghy before - only windsurfers - and he had no trouble at all.



Don from up the road dropped in the day after to take one out for a sail. The last time he sailed a small boat was when he was racing VJ dinghies about 30 years ago - he came back beaming.

These little boats are a hoot!
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Rigging and unrigging

The other advantage is that they take about 5 minutes (tops) to get ready to go sailing.

Put hull upright.

Drop mast in hole. Unwrap the sail from around the mast and stretch it out.

One end of the boom is already attached at the back end of the sail - but you have to thread the rope on the other end through a pulley (nautical = a block) and then tie it off around a cleat.

Thread the mainsheet (rope that controls the sail) through two blocks

Put the rudder in its housing.

Put the elastic shock cord line on the centreboard

Put the boat in the water and go sailing.

It's faster than me typing this.
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For the performance minded

If there is anything "wrong" with the boats it is the attention required to stay in the right place fore and aft for whatever conditions you are in.

This will be one of the main skills required to sail these boats efficiently when racing. When cruising around it doesn't matter at all.

The PDRs are very sensitive to fore and aft crew placement - the huge curve of the bottom makes them like a rocking horse. Move too far forward and you can hear the bow starting to kick up water (in light winds) or the sudden deceleration of the bow digging in (in strong winds).

If you time the move aft so the bow doesn't dig in the boat accelerates and the bow rises mightily because of the hullshape - so you can move close to your original position to trim the boat a bit better for speed.

You can just sit in the back position all the time but it means the boat will be going slower because the stern is dragging in the water - you can see the turbulence in the wake (turbulence always means lost energy that could have been used to drive the boat forward).

The optimum solution is just watch what happens and move fore and aft as needed.

Link to a letter written to Richard about how the boats were in the water.  here


How Good a Job did we do?

VIDEO CLIPS

Click the link above for all the youtube clips



Video - 2 PD Racers in light wind



Video - PD Racer Doing Donuts



Video - PD Racer Capsized for the First Time



Video PD Racer Upwind in Breeze


Video - PD Racer Planing on a Reach




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