fatehunter1972

Up here 'Hydrotec' Meranti BS 1088 runs at US$ 60. The issue really isn't the cost so much as the durability. I thought that MDO was a type of resin impregnated OSB (oriented strand board) but I am starting to think that it is plywood, that is multiple veneers glued togetther What I really should do is go and look at the stuff and soak it, kick it, bang it around, take a hammer to it, boil it, and give it to my dog (ok, not the dog due to the glue). when I see what is left I could make a choice. I thought that I have heard of someone building a Core Sound in aluminum? For all those who abhor my taste for metal, my father built four wooden boats from 40 to 65 feet to fish and trade the South Pacific with before I was born. Hope that redeems me.

Hello, I will admit I've mostly been a lurker with just a few posts but I am absolutely sold on the Core Sound series. I live on the east side of Vancouver Island, BC, Canada and it seems to me to be the ideal boat for around here. By the way if there are any other core sound aficionados around these parts please let me know. First let me thank all of your for posting everything you do. I will not be building this boat only by myself and all that I have learned will make it easier to shell out the dollars. Here's a question. Has anyone built a core sound out of MDO? That's the stuff highway signs are made of. What do you think of the stuff? Does it bend well etc. I ask because I am really a workboat kind of guy. I crossed the Atlantic as a toddler in a 65 ft steel freighter (sail powered, on the way to Tuamoto). Spent my summers as a youth on a steel freighter in Europe. Worked as deckhand/Mate/Master on steel tugs and freighters and now command a ferry (steel) that I bash into the dock regularly. Please note the common theme here; steel and banging things around. Since I plan to use this boat to travel all over this coast, land on rocky beaches, go over rocky shoals, it is gonna get scratched, dented and banged around. My thoughts are to have the best and most practical material in the hull. Michael

insult? it hasn't sold yet and the reserve has not been met.

That was Kilometers per hour?

I have heard of the stay sail for the CS series. Are there any pictures or plan drawings out there? Michael Dreaming of a CS 17

Jeff and Tom, There are many different factors that can affect the boundary layer. I don't profess to be an expert on this, I just like to read. Look at a golf ball. It has dimples on its' surface that enhances its' directional stability. Does it affect the drag? I have no idea. The fact it is a sphere though makes it a very draggy shape allready. And the submarine with a non-smooth surface. I think that that surface is more likely that way for its acoustic proerties; being silent in the water, than it's hydrodynamic properties. These types of subs probably value their silence more than their efficiency. Many airplanes have vortex generators on the top lifting surface. These vortex generators re-energize the air layer and allow it to stick better to the wing at high angles of attack. You don't notice these devices on the bottom surface though. NASA conducted experiments where they actually had a dedicated jet engine sucking air off the wing aft of the point of maximum thickness in an effort to reduce the depth of the boundary layer. While very effective in reducing drag and increasing lift (less turbulent flow) it was inefficient on the whole. As for your rudder and centerboard. I really don't think it matters. On my first 40 ft steel tug there was a flat plate rudder with barnacles, rough paint, and zinc anodes hanging off it. It still worked. Mind you there was an extra trim tab on the back (a becker rudder) and a horizontal plate on the bottom to reduce vortices peeling off the bottom of the rudder. I would not go to the trouble of resurfacing your foils, unless you have something to compare them to and they are obviously deficient. Just get out there and sail and have a blast. As my father says: Do what you can while you can, before you know it you will be an old man. when I get some time I'll desribe a rudder that I had on a cargo ship that was very obviously inefficient for drag purposes but excellent as a rudder. I love this site and forum. I have learned so much about the CS series and all the adventures people have had with them. I still find myself going back through all the old posts. cheers, Michael Dreaming of a CS 17

The qualities of the surface over which water flows always matter. With my current command, a 200 ft ferry, we notice a decrease in speed and increase in fuel consumption between bottom cleanings as the hull gets weeded up. On my previous command, a 380 ft ferry, we had bottom cleaning done by divers in the dock between regular drydockings. Those bottom cleanings payed for themselves in a few weeks by decreasing fuel consumption. The flow of a fluid of a fluid, such as water, is always zero at the surface and increases to the the full hull speed at a certain distance away from the hull. This layer is called the boundary layer. It is the depth of this layer that is so important. The more water that you drag along, ie. the thicker the boundary layer, the greater the drag. Now the CS17 is quite small but even so a weeded up skiff will still be slower than a smooth one. A rudder is a foil, not a hull, so some other factors come into play. On a foil, at some point aft of the leading edge, the nice smooth flow of fluid over the surface (called a laminar flow) will break up into a turbulent flow. On most foils this will occur a little distance back from the point of greatest foil thickness. There are various different foils shapes that have different characteristics but they all have turbulent flow at some point. You use a foil, the rudder, to generate lift, such as turning the rudder to create a force to turn the boat. When this happers the flow over the top surface, (the face of the rudder away from the boat) will try to separate from the surface. When this flow separates completely, when all the laminar flow becomes turbulent, that is when your rudder, or any foil, becomes stalled and loses all effectiveness. Surface qualities matter greatly in this case by affecting the angle at which this separation will occur. That's why airplanes can't fly very well with frost on the wings. Even a 1 mm layer of frost on a wing will dramatically reduce the capacity of the wing to generate lift. Your rudder will be similarly affected. Now for the surface area of a rudder, likely you would never be able to measure the difference in speed through the water. However when you use the rudder to turn the boat your rudder may lose lift and effectiveness at a smaller angle than a nice smooth one. This may not be noticeable at slower speeds. I don't think that it mattered much that the rudders on big old sailing ships were made of rough boards and were of a flate plate construction. however if you would be surfing down the face of a wave at ten knots and you turned the rudder to the same angle that you would normally turn it at slower speeds, you may very well stall the rudder, due to the large increase in forces involved. I encourage you to to experiment with this. Also pick a up a book on flying. Almost any book on planes will give very good descriptions of laminar flow, stalls, how lift is generated etc. Sorry for getting such a case of typing diarhea, but I think it always helps to know the science behind the stuff we do. Michael Dreaming of a CS 17

Hello All, I am from the Pacific North-West (BC) and looking for a camp cruiser that can handle quite a few different conditions. Ideally I would like a boat that could circumnavigate Vancouver Island while staying under 20 feet. This would require a weatherly, seaworthy and esentially simple boat. I have recently found out about the Core Sound series and am very impressed. Accolades to the designer of the CS 17. I like the fact that your boat has actually proven itself in various conditions, as per the many races the boat has won. I am curious as to the boats performance as it relates to its' carrying capacity. What kind of loads was the boat carrying in the various races that were won? I see on the website the baot is shown as 350-400 lbs. and the total sailing condition weight (full load displacement)is 1000 lbs. That would be be 600-650 lbs of cargo. Does the top speed or the average speed vary significantly with load? I woul welcome anyone's comments on their experience. Thanks for your comments. Here's a link to peruse. http://www.tadroberts.ca/services/small-boats/ratty.php