Shorty's Loaner Boat Design for 2006 World Championships
About This Hull Configuration
Back in 2006, I had already moved from Texas and was flying back in to host and attend the 2006 PDRacer World Championships at Magnolia Beach Texas. Two of these were built to be "loaner" boats for visiting people to use.
Since duckers use different sail rigs, the idea is that this hull configuration would be able to accept different types of sail rigs and still be balanced and competitive.
The centerboard was concealed in the full length side airboxes so when sailing up to the beach in the shallow water, the board would fold up into the trunk.
16" high hull
Having sailed 24", 18", 16", and 12" high hulls before, a 16" tall hull seems to be a great middle compromise for sailing in the waters around Magnolia Beach.
12" tall hulls are very short, such as you will see on a board boat hull. They can have the tendancy to dive under a wave, so having a decent sized bow transom will fix that, it will let the hull bounce off waves instead of diving under them.
24" tall hulls are are incredibly huge. If you are building a cruising version with a cabin, you will be amazed at how much interior space is inside a 24" hull. But for racing, the problem with tall hulls is they create resistance to the wind and will hamper your windward performance.
18" high hulls are fine, but 16" seems to be the best compromise for the pdracer. It is that just tall enough, but not too tall size, and since 2006, it seems to be the most popular size that duckers built.
Mast Sleeves
2 Mast sleeves are mounted in the deck, one at 12" from the bow, and the other at 24" from the bow. These sleeves are rectangular in shape with a drain hole in the bottom which drains the water to the interior of the hull. The sleeves will accomodate a 2.75" square.
The reason there are 2 mast sleeves, is so a mutton sail could be used in the forward sleeve, or a lug type sail will be used in the aft sleeve. And again, depending on which sail rig you use, you will need to figure how far down to pivot your board to balance with the sail being used.
And another advantage of having two sleeves is that if you break one, you have a backup. The mast sleeve is under huge amounts of stress, especially when hiking out on windy days, and they are a vulnerable to breakage. I have accidentally ripped out 4 mast sleeves in my ducks.
Offset Centerboard
A single, large centerboard mounted inside a trunk, on the inside of the starboard air tank. Lead weight melted into board so it drops on it's own. A pendant line and cleat to allow it to drop all the way, or partially so can adjust the CLR to match your sail(s).
I gotta tell you, I love the offset centerboard. It works just as good as a centered one, but hidden in the side air tank, it leaves the center of the cockpit completely open so you have plenty of room to move around while tacking quickly, take passengers with you, lounge around etc.
Please note, this board pivot location is at 36" back from the bow, and the reason is so that it could be used with a variety of sail rigs. Depending on the location of the sail's center of effort (CE), you will lower the centerboard to match that location. Ideally, you will experiment so that when you find the right dept to lower the board, the Center of Lateral Resistance (CLR) balances with the CE so that the hull doesn't have lee or weather helm. See: Leeboard Placement & Balance on the Make Your Duck Go Fast page.
Another advantage of mounting the pivot so far forward, is that gives you a bigger board that you can hide in the trunk.
Detail Sketch Of Side Airboxes
If the boat gets knocked over in the race, these types of airboxes make it so you can right the boat quickly, and there will not be any water left inside the hull.
Notice how the chine log at the top inside of the airbox is mounted on the side of the cockpit side of the airbox. This will double as a toe rail, meaning that you put your toes under it and then lean way back over the side to hike out.
You will also want to mount a hiking strap in the cockpit. The amount your body can hike out with just a toe rail is limited by the length of your legs. A hiking strap is a cloth strap you put your feet under, so you can position your body further outside of the windward side as you hike out.
The centerboard trunk detail is not shown, it is basically just another side panel with chine logs and you will cut a slot in the bottom to let the board pivot down. You will need to add some kind of backup structure for the pivot bolt, the same you would do for an external leeboard.
Personally, I prefer external leeboards and I have won enough races with them that I know they are just as competitive as centerboards, BUT, everyone has different preferences and internal centerboards look more conventional, so if that is what you prefer then that is great.
I also want to point out that when the board is deployed, the trunk which holds the board now has an empty slot behind the board and will create vortexes and resistance. Where as the external pivoting leeboard has no slot.
Michalak Rudder
This is the most popular type of rudder used on home built boats. The design has been around for many years, it is simple to make, but functions very well. See the rudder page for more info.
Tiller
The tiller is 22" overall length, of that only 18" is in the boat. This is a racing length tiller though, it is about as short as you can get so it is easy to switch from side to side. You will want to attach a hiking stick to the end of the tiller so you can lean way over the side and still be able to steer.
Rigging
Depending on what type of sail rig you use, you can rig her as you see fit. I would suggest running all lines and the main sheet to the forward end of the cockpit and use cam cleats to hold them. On conventional racing dinghies, they have an array of cloth bags near the front where the spare line can be easily stuffed inside. But optimizing rigging and control lines are a whole different story...