Dboards
While the surface of the boat's dboard surely factors into the wetted area and drag computations, for some reason the D model is acknowledged to be just slightly faster overall than the S model which is faster than the X or M. The S and the D models are the Classics. The Ida dboard is a short run type of product: Joel will only build 4 at a time, and only with 4 committed buyers, and only when production time permits. This is the time of the year that Joel will typically do short run requests. The Ida dboard is made of a material that is lighter than water, floats, and so needs encapsulated lead in the bottom of the dboard. I am talking about the D model here. One consideration about the strength of the dboard is that the dboard needs to weaker than the well it is sticking out of, or you will tear the fiberglass hull in a grounding. Ida will machine a kerf into your custom dboard if you wish, as a weak point. I do a lot of camping and beaching on my boat, I have just developed the skills to get the dboard up before ground strike. I used to use a depth finder, but it is currently inop, so I just make sure I get it up when I get anywhere near the bottom. Sailing in the Boise area is done mostly on Lucky Peak reservoir and Lake Lowell. Both are about a half an hour from here. In the greater area is Cascade reservoir, Lower Payette Lake, Redfish, and then large impoundments in Hell's Canyon. My boat is right now ready to go down the highway. We spent as week on Lake Mead in April, and a week on Yellowstone in August. Because of the ease of towing, we have been trying to cover ever greater circles to see the bodies of water around here. I am looking at Flathead Lake for next year. The strength of HDPE is sometimes challenged when used as a rudder, but for a dboard it is strong enough. Example: at Yellowstone Lake I was sailing along the edge of the lake watching a herd of swimming elk and I ran agound at about 5 knots. When this happens, the dboard will not retract (I tried) because the weight of the entire boat is cocking it in the well. It stopped the boat (with a ton of people and camp gear, supplies), and then I had to rock the boat to one side to get the weight off of it. I examined the dboard later: no damage. Bottom material was volcanic geyser muck and gravel. I don't know about the X or M, but on the D model the original dboard was made of fiberglass with wooden stringers. It was designed to be filled with water and sunk down the well. The wooden stringers separate from the fiberglass over time reducing the strength of the dboard. Once any damage is suffered by the fiberglass, the dboard starts to stick in well, going up or down. By contrast, the self lubricated plastic of the HDPE is easilly sanded to remove imperfections, and it slips up and down in the well easily, so easily that I often forget when excited and I slam the dboard up against the deck block. It is easy to adjust on any point of sail. It also has a superior shape than the stock oval, and the benefits of the Ida rudder apply here for the dboard, but are more difficult to quantify. Since I have the nice airfoil, and because I can adjust this beauty so easily, I have determined to take advantage of this dboard in the upcoming season. I am going to do some GPS speed calculations, try to figure in VMG, make marks on my dboard line, and record what works for my boat.
Schoolhouse Steve, Ida does make rudders for the M. Check out the link. http://www.idasailor.com/catalog/product_info.php?cPath=25&products_id=480