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Posted by Designer on 19 March 2014 - 08:46 PM
I have just about finished making the first CS17 mk3 kit, I made the centerboard today. I am working on final tweaking and finishing up the plans and should have them available soon. There is a lot of detail and it takes time to get it all together.
I have been sneaking in a few duplicate parts so that I can have one.
Posted by Designer on 13 January 2014 - 09:40 PM
We waved farewell to Doug today as he drove off with his new Mk3. We were happy to get her out of the shop to get a good look at her rather than being too close all of the time. I feel that she more than met my expectations and you can still see the Core Sound heritage.
There is decent headroom, without the trunk cabin. It is very comfortable laying back against the hull, at 5' 7" sitting as tall as I could, my head was not touching the deck. I think that a 6 footer could find a comfortable position.
Posted by Designer on 04 October 2013 - 08:12 PM
Rather than hijack the mk2 thread I will start a new one.
Chick asked that I post some pictures of the mk3.
I started on a cabin version of the CS17 at least 5 years ago. I got involved in the big cat project and shelved it for a while. One night after work I was showing Alan some drawings that never made it. When we came upon the CS17 with the raised deck, Alan became excited by it's potential.
I cyber dusted off the oiginal drawings and imported them into Rhino and modified them a bit to fit my current thinking. Then I thought, this might work on the CS20. The CS20 mk3 was born. Here are a couple of views of her.
Posted by PAR on 14 February 2014 - 09:03 AM
Long boards come in various shapes, lengths and sizes, usually geared to match the job. A 1/2" plywood board is too stiff for most boats, except in large expanses of relatively flat areas. I've got a number of boards, one of my favorites is made from 1/8" Lexan. It's 4" wide, about 20" long and fairly flexible, so I can work compound curves. I have ones that are 1/8" and 1/4" plywood too and even one made from 14 gauge aluminum sheet. I buy paper on rolls and cut to length, using a spray adhesive to mount them, though you can just as easily use a clip or slot at each end, to hold the paper to the board.
Technique is key with a boogie board (board-'o-pain). Typically you work from one end of the area (or hull side) in a single direction, across it's full length. You select an appropriate angle, which often seems to be about 30 degrees to the centerline and stroke the board at this angle the full length of the area. All strokes are at this angle, leaving a series of angled scratches. You then come back at the opposite angle, in the other direction, netting a cross hatched pattern of scratches. The low spots will be clearly visible, not having scratches in them and the high spots will be knocked down a touch. At this point, you mark the low spots and apply a little filler in these areas. The next pass with the torture board is focused on the now filled low spots, so you can knock them down to surrounding areas. I often use a very light dusting of primer at this point to fine tune the surface and help see what needs what. Again, working a common angle, you run from one end, to the other, placing a new diagonal scratch pattern and come back on the reciprocal angle for the cross hatch pattern. Each pass will continue to knock down the high spots and reveal the lows you've missed on previous passes.
A pro will make three passes with the cross hatched, long board pattern. The first to find the lows, the second to knock the lows back once filled and the final pass, to even everything up. The backyard fairer, can make a career out of this process, with many passes and filling sessions. The more you work this set of steps, the fairer and smoother the hull will be. The same process is used with paint, if you want a baby's butt surface, just with finer grits, usually wet. It helps a lot to have the right lighting for this process. You can have too much light, particularly if it's directly over head. You want a low angle of light, so you can see the shadows in the low spots.
The biggest mistakes novices make are not using a long board, thinking a palm sander or orbital will do and over working the surface. The Harbor Freight "in line sander" linked above shouldn't be used. It will remove material at an alarming rate and it's not flexible enough to conform to curved surfaces. That particular Harbor Fright tool is a single piston design and you'll be in serious pain, with just a 1/2 hour of use. It's a real piece of crap and if you want one, get a duel action/piston design so it doesn't tear your elbows off. Try not to get aggressive with material removal, just lightly scratch the surface, so you can see what's high and what needs to be filled. On plywood hulls you'll bring the lows up to the highs for the most part, so skim coat the lows with some filler and knock these filled areas back locally at first, then with the long board passes. A jitter bug (palm sander), DA or orbital sander will not fair a surface, just smooth it. Fairing and smoothing operations are wholly different. The long board fairs. Once the surface is fair, then you can move onto smoothing operations. Fair is what you can see, while smooth is what you feel. A surface can be smooth, but quite unfair. A dent in a car door is a classic example of this. The dent can be polished and really smooth, but the light reflection will clearly show it's not fair.
Posted by Designer on 30 January 2014 - 10:27 AM
Posted by Howard on 29 November 2013 - 10:45 AM
Not entirely sure I understand the source of "shear" load, so I drew up some sketches of this to better visualize what is being suggested.
As I understood Graham and Travis's comments on what happened, if the pivot pin is not tightened to take out all the side to side slop, when the mast bends under load, only one side of the tabernacle takes the load, thus transferring most of the leverage force to the leeward side of the tabernacle. Essentially, the top of the tabernacle then becomes the fulcrum, and the end of the long lever that is the mast then ends at deck level. Under the load of the long lever, the entire face of the centerpiece is in tension and if enough load is applied........easy to do with the vastly increased leverage.....the fulcrum is what gives way and bends, taking a segment of the centerpiece with it when the centerpiece splits.
(Howard's Edit: Side to side slop does not appear to be the primary issue. Loose bolt is. A tight bolt shares the push on the leeward upright with pull on the windward one. Loose bolt does not. Side to side slop is still an issue as the push and pull levers against the fixed centerpiece to the side with a racking force or turning moment........close fit is still needed).
If the pivot pin is tight, both side uprights share the load equally. The force in tension transfers from the centerpiece to the outside edge of the windward upright and the whole apparatus starts acting more like an I-beam. The top of the tabernacle then remains an extension of the mast, and the fulcrum moves down to deck level, with the end of the long lever going all the way to the keel.
Not sure where "shear" load factors into this. I can see how a flat or plain sawn centerpiece would resist side to side bending better than vertical grain or quartersawn, at least in the middle, but I would not think that to be the case on the ends.
The affect from several wraps of glass around the joint essentially works to immobilize the joint, tying both sides together much as the pivot pin does. The strength of the glass handles all the forces of tension and compression to hold it together?
Lastly, there may be an additional force I have not considered and that would be in a vertical plane acting on the sides.. Perhaps when the mast bends, there is a compression force pushing the pivot pin down on the leeward side and an equal force in compression pushing up on the windward side as the mast attempts to rotate. The epoxy bushings take that load and spread it over a wide area of the upright.
But back to those "shear" forces, I'm still not certain where the loads are coming from that a flat sawn or plain sawn board is going to help overcome? Not doubting, just trying to understand.
Posted by wkisting on 11 October 2013 - 01:03 PM
Very nice! I have often said that if I was going to make any modifications to our CS20 (mk 1), I would raise the foredeck by about 8" and create a crawl-in cuddy space up front. This version looks much more spacious with a higher deck than I had in mind, but is right in line with the spirit of what I was envisioning. Almost tempts me to build one, but I'm so attached to the boat we have. The CS20, in any guise, is such a fine boat!
Posted by wkisting on 26 August 2013 - 11:27 AM
I use a loop of bungee that attaches to a hook on the underside of each hatch cover. I spent a long time dreaming up other solutions because for some reason I didn't like the idea of using bungee cording, but once I finally tried it, I was impressed how well it holds the hatches shut (once you get the length right for proper tension) and yet how easy it is to stretch to unhook the loop and open the hatch. It's simple, cheap, and works great--especially for how rarely we need to access the fore and aft compartments. (I only stow the anchor in the forward compartment, and lifejackets and a few floatie chairs in the rear one.) I certainly like the "uncluttered" look of having no latch mechanism visible on the outside of the hatch.
Posted by Alex on 28 June 2013 - 01:44 PM
This is exactly why I bought the plans for the Coresound 17. I live on the Gold Coast and first plan to sail out to Moreton Island which is quite a bit further out than the Whitsundays.
Later on I do plan to sail the Whitsundays since they are so close to the mainland and you can easily island hop from one to another. Having seen Peter's Coresound 17 there seems
to be heaps of space to store stuff and the fact that you can still sail it by yourself fairly easily. You will have to let us all know when you are thinking of heading up there as it would be
great to get a few boats together for a cruise or should that be a race around the Whitsundays.
Posted by Alex on 15 June 2013 - 05:58 AM
Just thought I would share some photos of the Spindrift 12 that I built for my 11 year old son. We use this boat extensively for fishing and sailing. I took most of these photos today when I went for a sail by myself in 15 to 20 knot winds. I was quite surprised sailing downwind and doing what I would think to be 10 knots plus with water spraying everywhere and I was having a ball. I have never sailed this fast in this boat before. Just as well I was by myself as my son would have been crapping himself. What a boat. I can't wait to build the Coresound17. I saw a pod of about 20 to 30 dolphins today with what looked to be 2 or 3 babies as well that were flopping all over the place. What a great day.
Hope you enjoy.
Posted by Chick Ludwig on 13 September 2012 - 07:27 PM