PD Racer South Africa

[Manie B]

Guys we want to start a PD Racer club South Africa

http://www.pdracer.com/

http://www.pdracer.com/site-map.php

http://www.watertribe.com/

Dries has offered to cut the first 5 boats on his CNC router for free.
We will design a nice little kit that goes together easily.
Our boats will comply with the PD Racer rules so that we are part of the international group.
The whole idea is to start a genuinly fun orientated club that is aimed at the first time boat builder and the guys that would like to get the family and kids, or themselves, out there and have fun on the water, easy and cheap.
We can also arrange our own little "raids" where we as a group sail towards Villiers as a 3 day "adventure"
Obviously we can also visit other dams, and party all over.

The main driving force is to do the "Around the Island" next year as a registered class, this would be a great kick off point.
My micro-cruiser will always be on stand-by as well as a PDR that I will build for myself, just to promote the "water experience"

We need to get the kids and the adults into the fresh air, and the PDR is a very easy and cheap way to start, learn to sail, it will change your life, we will be there to help you along.

My estimates are that you could build this for around R2000
here are the pics of the one that I fancy
sleeps two, nice storage for the cooler box
and with a boom tent the whole boat is covered at night time.

These are a collection of pictures that I got off the PDR website and this particular boat simply blew me away, love at first sight!

So - calling all Saffas - lets go sailing! We will help as much as we can.

So even if you own a mega expensive cat with gold taps, build a PDR and let your visitors have fun, join in!

 

[DriesLaas]

proposal

Hey Manie et al,
I attach two images of what I propose to cnc cut as a kit. It is a stock standard PD racer with side tanks and a small foredeck. The height is sixteen inches and not eighteen, as this seems to be the more popular choice.
I faired the terrible bottom profile to still be within tolerance but a lot fairer, it makes very little difference to how the boat will sail.
There is a structure under the mast step to carry mastloads, and the transom is built up with a doubler. The dropouts from the doubler forms the cheeks of the rudderstock.
I have not given thought to the dagger/centerboard trunk, but this is up to the discretion of the invidual builder, as it is driven by his weapon, sorry I mean rig of choice.

So far so good, I want to cut the first simple kit this week from el cheapo 6mm pine ply from boardking at R170 per sheet.
The mass of the wood so far is in the region of 30 kg, for information.

 

[Wynand N]

Manie, what a noble idea if it could work.....
If I may be devil's advocate.

People in SA are different animals than say the British that may love these boats. They are obsessed with hype, like for instance cars - everyone wants to have a Merc, Bmw or Audi (like the plague on the roads), although there are much better cars out there and the Honda Accord comes to mind, but how many do you see on the road?

Same with boats, they want sleek, modern stuff and always bigger than they can afford. I agree that these little boats can put many people on the water at the cheap and add a lot of fun in the package, but again, what would the neighbors and the guy with his sleek machine think of your boxy boat and herein lies the big obstacle to change SA perceptions.

I had the same problem: I built the best 4.5m fishing boat that weight only 180kg (foam filled) with 30hp engine and could only sold 4. Problem? To good a boat with too much flat floor space, properly rigged out for fishing, tiller driven etc. Fisherman would rather buy a fancy looking ski boat with no space, fancy seats/steering station and carpets and nowhere to put their fishing rods and goes fishing with that- again the hype thing and show off factor.

Lastly, it is a buyers market out there in the boating world and people does not have money to spend on nice things, let alone time to build a boat. This was the very reason I scrapped that brand new mold of the planned L18 which was ultra modern compared what is available in SA without pulling one hull. Everyone wanted one but nobody has the kudus to spend.

But, times are a changing and perhaps you and Dries can do the unthinkable and changes peoples point of view here.

Remember that beautiful Flamingo dam I showed you some time ago in my town that is derelict now, lawns and picnic spots just bush and thorns etc. Well, in the seventies and eighties you were pressed for space and the dam a hive of activity with all sailing classes but time and financial circumstance caught up with it. There are also other similar sad stories out there.
Best to start with killing DSTV to try and get people out of their homes can be a good starting point

Again, I tried not to slow you down Manie, but these are facts you have to consider when dealing with Saffas....

 

[Manie B]

Just on a much lighter note

I am looking for a new girlfriend
around 30/35 years old
so this PDR of mine will make FANTASTIC accomodation for the little kids that usually come with this kind of parcel
so you see there is method in my madness

you and Fanie will definately NOT FIT so dont worry

now to get serious :idea:

the idea is just to have a bit of cheap fun
my PDR will be available for anybody in a bikini

sorry I am trying to get serious
want to encourage the prospective boat builders that write to me and want to build a "Micro" that they first build something small, without braking the bank, THEN drag the missus to the wind and rain and the misery that comes with sailing AND THEN come back and talk to me about that 40ft CAT with golden taps

in other words bye bye boating, because the BOSS HAS SPOKEN !

But for the chaps that genuinely would like to get away what a wonderful place to start

 

[Manie B]

Also what may make a difference

we are not trying to sell anything

we are purely there to help

in other words - get off yer lazy @rse - stop the TV - and get busy in the garage :idea:

 

[Wynand N]

Manie, I would love to build one just for the fun of it to compliment the Portuguese dinghy in my garage
But first, I must get my Seven finished that lacks far behind schedule due to other commitments that put bread on the table...so far for retirement

The PDR might make a nice little bass boat for the local river with my little 2hp Suzuki glued to it tail

 

[Wynand N]

I am looking for a new girlfriend
around 30/35 years old
so this PDR of mine will make FANTASTIC accomodation for the little kids that usually come with this kind of parcel
so you see there is method in my madness

Can hook you up to a 37 years old looker (brunette) that loves to wear little black bikini's and comes with 3 children - oldest a young lady of 16 years young that also wears the skimpiest water wear and not shy to say the least. Btw, as an added bonus, this lady had the cut and is bullet proof

 

[Manie B]

Wynand I am glad you have posted the above because I just realised that YOU MUST BUILD A PDR

because here is the challenge

we can start the first PDR "potjie" competition
I will do a beer one
you can do a wine one
and then we wash it down with some "Bells"

howzat !

you just decide on your "camping" layout for your boat!

To the guys a "potjie" = little cast iron three legged pot, in which you make a stew, meat browned at the bottom, then layers of veg, then layers of potato or rice, cook very slowly for around three hours. I will leave the rest to your imagination because we have some serious cooks around here, that folks will beat a path to their door for a plate of this food

Go and look at the PDR website
there are a couple of big boys there that proves that a PDR is a very capable cruiser !

Wynand the guys will love to sit around a camp fire and chat to you about the boats, come on, join us, you have some wonderfull stories to tell.

Here is Wynands pedigree
http://5psi.net/
for the newbees that dont know

Wynand, Anchor Creek is closer to you than me
up the road is the Motorbike Museum and pub
lots of fun

And Then

I will challenge you to a "skottel" breakfast

(a skottel is a round dish plough disc, perfect for bacon and eggs)

So you see Wynand, you have no excuse not to join us!

 

[Angélique]

It looks it's gonna be a lot of fun for you guys Manie, two Saffas so far on the World Wide PDR members list, PDR #17 and #606, last one seems to have found that girlfriend to join his PDR sails

Have lots of fun and smaaklik potjie

Cheers,
Angel

 

[Angélique]

I faired the terrible bottom profile to still be within tolerance but a lot fairer, it makes very little difference to how the boat will sail.

It seems to be meant that way . . . . .

Class Rule Explanations:

Rule 1 - Rocker Shape . . . . .

Another thing you might want to know, is that our curve is not a natural bend from bow to stern, it is a hybrid made by combining 2 batten bends.

You can read more about it on the page: Designing The Puddle Duck Racer

Why the Puddle Duck Rocker is shaped like it is:

- Max rocker closer to the stern -
Water doesn't like to be moved, so the further aft you can put the maximum rocker, the more gradual of a water squishing effort you have. The water is going to get squished either way, but if you can do it more gently, it will cause less resistance, and be a faster hull. However you can't have the maximum rocker at the complete stern, because you have to curve back up and let the water go without dragging a transom corner across it. If you drag the transom corner, it will create vortexes and suck at the stern of the boat. This sucking force is so great, you can actually feel it: try rowing your pdracer around with even trim. Get a feel for how she rows, then have a passenger sit on the stern so it digs in, and row it around some more.

- Look up at sail -
Another advantage of having the max rocker further aft, is so you can look up at the sail. When racing, you look at the sail every 30 seconds or so to read the tell tales and the luff crinkles, to make sure you have laminar air flow. The further aft you can sit, the easier it is to look up.

- 6" Rocker Shape Depth -
The more rocker you have, the more weight the boat can carry. The PDRacer's rocker shape is only 6" deep, which can carry a total of 630 lbs. That should be enough for the weight of 2 adults (or 1 adult and 2 kids), plus the weight of the boat (commonly around 125 lbs).

- Types of rocker shapes -
Generally speaking, there are 2 main types of boat hulls: Displacement hulls, and Planing hulls.

A displacement hull is like a typical sailboat. It is round shaped, and as you sail her a wave is created at the bow. The harder you push the hull, the bigger the wave gets, the longer it's trough extends. When the trough of the wave extends to the full length of the hull, that is called sailing at the hull's full displacement speed. One type of displacement hull shape tries to fit that wave, so as you sail inside of it, the water will match and flow evenly at that speed. After you reach displacement speed, the harder you push, the deeper the wave gets, and those shapes have a difficult time climbing above their bow waves.

A planning hull is shaped like a typical bass boat or jon boat, it has a curved entry and then a long flat run with an abrupt corner at the stern. The way a planning hull works is that as you apply power to the hull, it will create a bow wave just like the displacement hull. However when you apply more power, because of it's flat hull shape, it will rise up on top of the bow wave, and then start to skim on top of water, which is called planning. The compromise of planning hulls is that if you push it at speeds below planning, then the stern corner will drag in the water and create large amounts of resistance. This resistance is so great, that it actually takes more energy to push the hull at below planning speeds, than it does just after you have reached planning.

The Puddle Duck's rocker is a hybrid (semi-displacement or semi-planing) that borrows from both planning and displacement types. It has rounded ends so that it can move through the water at low speeds, but also has a long entry and flat-ish center section. To create this shape, I combined the bends of 2 battens. This compromise results in a hull that can travel at both displacement speeds, and climb up on a plane. In 2008, Kenny Giles was able to sail his duck at 9 mph (picture on mutton sail page) under wind power alone, which is more than double what the displacement speed of an 8' boat is.

I did not invent this type of hybrid shape, I first learned of it when researching boat design related to the Moth class, and am just one of many who uses the technique. Also before launching the pdracer class, I spent a year testing the rocker shape in my Flats Rat design.

- Controversy of the PDRacer 2 batten bends -
One of the great things about the boat building hobby, is that anyone can be a boat designer. There are some famous amateur designers like Noah, but also any native american that cut down a tree and scraped out a canoe technically becomes a "boat designer".

Get out some paper or load up your favorite CAD program, draw a boat. Buy some materials, build your hull, and presto you are a success. Some designers don't even do that, they just make plans and sell them. Of all the hundreds of amateur designed hulls I have seen and taken rides in, none were "bad", because sailboats are very easy to design, and almost anything will work. As for judging if a hull is to be considered "really good", is actually a perception on the part of the builder / owner, and how they feel the hull meets their needs (which may be different than the designer's intended purpose).

Because the Puddle Duck has an odd shaped rocker, a small controversy arose about the creation of it's shape. There is a belief floating around that all displacement hulls must be created in a way that their curve follows that of a single batten, if it is bent from the bow to the stern. The PDRacer is not a displacement hull, she has a hybrid rocker, created by combining the bends of 2 battens. Furthermore, it doesn't matter what the hull shape is -- the only important factor is that we all use the same hull shape, which has always been in rule 1 and explained further at the top of the class rules page.

For marking up plywood to cut the rocker, it is not an issue, just bend a batten around 3 or more station marks and make sure your pencil line crosses the 7 station marks at their proper dimensions. Or you can bend a single long batten around all the station marks at the same time and clamp them in place.

For CAD drafters that draw the rocker, it can be frustrating if they don't understand that the rocker is a hybrid shape because most try to draw it using a single arc spanning from bow to stern, and the computer typically will not draw it properly.

Good luck !
Angel

P.S. - see also . . .

The OZ has a regular round displacement rocker shape which can be sensitive to the crew sitting position, while the PDRacer has a flatter hybrid hull shape, which also enables the PD to get up on a plane. The fastest puddle ducker was able to go 9.0 mph on wind power alone.

 

[Angélique]

I don't understand the tolerance range of the class rules . . . .

Are those decimals or eighths of inches behind the commas in the Tolerance Range table ? ?

Compare for example the above Defined Hull Shape station measurements with the Ideal line in the Tolerance Range table

And what is meant by the "over to bow" measurements in the Tolerance Range table ? ?

Cheers
Angel

 

[lewisboats]

It is in inches and 8ths. Look at the inch drawing and see that station 1 is 2 5/8 then look at the tolerance drawing and see that ideal is 2,5... same with station 2: 5/8 and ,5 Which means that there is a +/- tolerance of 2/8 or 1/4" for sloppy building practices or those with all thumbs. The over to bow means that not all the boats are the same length...look at the tolerance for length. So this is the remaining distance from station 7 to the bow.

 

[DriesLaas]

Allow me o comment, as I need to put this to rest right right now lest anyone starts believing that we are building a non-standard boat. This type of thing could haunt me forever.

I remember an old piece of software called plyboats, where you could also use a similar concept to compose any curve on the boat. If I remember correctly, it was using some spline data, and one could combine a curve from two different spline "stifnesses," which is sort of what we are talking about here. Is it possible to get plyboats still? I drew a few sweet hulls on that software, and actually built two boats from it myself.

The problem is exactly that most builders would set out points, fit a batten through (maybe spring the batten once to allow for the different stiffnesses required,) and draw the curve.

When I drew the curve on cad, it is clearly unfair, so I had to fair it, otherwise the bottom would be much less fair than one built by hand ( remember I am cutting the panels on a CNC router, which for everything it is, can still not eyeball a curve and adjust it to be sweet......)
Do not fret, I took great care to ensure that the fairing variation was kept within a tolerance band of 6mm. That is not +-6, but rather +-3mm. So I should be somewhere within on eight of an inch from the target on any point on the bottom profile.
In conclusion I also offset the profile on the side panel by 6mm (the panel thickness I want to use on the bottom) to ensure that the lower surface of the hull conforms to the specified hull coordinates. ( Most builders are actually out by 3/8 inches unless they do the same offset exercise.)

So I daresay that this is all completely academic, because the effect it will have on the speed (such as it may be) of the hull is negligible. It just satisfies me that I did things as properly as I could.

As an aside, I think that the native american who "scraped out" a dugout canoe did a fantastic job, and I would like to call my boat "Sitting Duck" in his honour.

 

[sharpii2]

Allow me o comment, as I need to put this to rest right right now lest anyone starts believing that we are building a non-standard boat. This type of thing could haunt me forever.

I remember an old piece of software called plyboats, where you could also use a similar concept to compose any curve on the boat. If I remember correctly, it was using some spline data, and one could combine a curve from two different spline "stifnesses," which is sort of what we are talking about here. Is it possible to get plyboats still? I drew a few sweet hulls on that software, and actually built two boats from it myself.

The problem is exactly that most builders would set out points, fit a batten through (maybe spring the batten once to allow for the different stiffnesses required,) and draw the curve.

When I drew the curve on cad, it is clearly unfair, so I had to fair it, otherwise the bottom would be much less fair than one built by hand ( remember I am cutting the panels on a CNC router, which for everything it is, can still not eyeball a curve and adjust it to be sweet......)
Do not fret, I took great care to ensure that the fairing variation was kept within a tolerance band of 6mm. That is not +-6, but rather +-3mm. So I should be somewhere within on eight of an inch from the target on any point on the bottom profile.
In conclusion I also offset the profile on the side panel by 6mm (the panel thickness I want to use on the bottom) to ensure that the lower surface of the hull conforms to the specified hull coordinates. ( Most builders are actually out by 3/8 inches unless they do the same offset exercise.)

So I daresay that this is all completely academic, because the effect it will have on the speed (such as it may be) of the hull is negligible. It just satisfies me that I did things as properly as I could.

As an aside, I think that the native american who "scraped out" a dugout canoe did a fantastic job, and I would like to call my boat "Sitting Duck" in his honour.

I don't think you have a thing to worry about.

Having hung around the pdracer site since there were only four boats, I think I can attest to that.

The bottom shape controversy started with the 'oz duck', which seems to have exploited 'builder tolerances' to create 'design tolerances'. This, IMHO, did little if any harm to the class, because these boats still had the cardinal dimensions of a pdracer, including the mildly raked bow transom, 1h to 2v, the location of the deepest section, between St.s 4 and 5, and the depth of rocker, 6 inches, not to mention the same length, beam, and very similar static waterline length.

It is these numbers, more than anything else that dictate the performance of the boat.

The real problem with the 'oz boat' was its superior engineering (I bought a set of plans, just so I could study them). It was built a considerable expense (by pdracer standards) out of very thin plywood (which had to be a notch up in quality) and epoxy everywhere. In short, its hull structure is a functional masterpiece. Add to that, its rudder and dagger board had a professionally designed foil (which, to his credit, the designer posted the offsets to), and a well thought out leg-'o-mutton (which the designer posted as well).

As a consequence, it was it weighed 1/2 to 2/3 as much as the typical pdracer.

Add tho that, it's massive 81 sf of sail (perfectly legal, as sail area is not regulated in this class) compared to the 60 to 70 sf that was typical in the class at that time, and a good tiller nut, you have a practically unbeatable boat.

By then, I had long ago posted the idea of sail area to weight restrictions, but was pretty much ignored. The restrictions I posted could have been handled on site with a cheap calculator. They slightly favored heavier boats, as to get out of using cube roots, and because the hull design itself favors lighter displacements considerably more than most purely non planing hull designs.

For this reason, when an 'oz boat' was built here in the USA, it swept the fleet.

The bottom shape controversy started shortly afterward.

By that time, I was no longer participating in the discussion group, so there were no "I told you so"s from me.

Sadly, what could have become a single global fleet, has now broken off into three separate and unequal parts, pdracers, 'oz ducks' and 'kiwi ducks', when, at worst, some very simple handicapping would have been needed to keep the fleet unified.

when it comes to racing, we all know:

deeper boards are faster than shallow ones, one board is faster than two, air foil shaped boards are faster than taper ended flat ones, a center-line board is faster than an offset one, lighter boats are faster than heavier ones, and the sail to displacement ratio is king.

But most pdracers are not built purely for racing. The two I designed were primarily for comfort and hitting shallow bars and hidden logs with minimal damage.

Getting back to you. It is quite clear that you have made every attempt to keep your design within the perimeters of the rules (something the 'oz boat' designer did not do) and only failed because your software wasn't quite up to the job.

I am sure Shorty will recognize this fact.

I have 'Plyboats' too. It is possible to design a pretty accurate pdracer bottom with it. Just draw with the sides 18 inches high, 7 ft long, and use only seven stations, leaving the flat part out. Then St. '4' becomes your deepest station. Then use the offsets print out to see which spline choice gives you the closest curves for the bow and the stern.

 

[Manie B]

thanks sharpii2
as we are trying our best to get this thing of the ground (our members will be very limited) we are concentrating on the "fun" aspect
we are going to try to make the "kit" easier to assemble and do what we can to make it faster and easier to build and bring costs down to a minimum. Minimal costs is the most important.
This also the concept that I would like to promote as a "first build"
way too many guys start off to big and then run out of steam halfway