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Steve W

Core Sound 20 Mark III #3 "Skeena"

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Every night is an adventure. Tonight I shaved a bit off the hull stringers. I used eastern white pine for them, but they were pretty sturdy. The hull unfolded pretty well, but I got thinking the only thing that could be causing that problem after checking the cradle was the stringers. So I just removed the bulkheads and skimmed a bit off the tapered part forward and thinned it back just a bit. Night and Day! My gap is about 1/2 inch naturally and I can hold together easily with tape, so I think we are good. Reading and studying to see what's next.

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Not much progress in the last 10 days, but a major breakthrough. It was just bugging me that the module just wouldn't sit down tight like I thought it should. The kit is CNC cut, and I knew it should fit really nice. Fortunately before I glued the module down I had a lot of family priorities and such. I kept walking by the boat and thinking. Eventually I pulled each of the cradle boards out and rechecked the dimensions and they were right on.  I'd set up a laser level and checked my shop for level, and while it is sloped ever so slightly, the pad is very flat. Within about 1/8" on the half of my shop the boat is in. I had selected the driest cradle material I could find, and made as precise of a cradle as I could and called it good.

 

In the middle of the night Friday I had a thought. What if the cradle itself wasn't perfectly flat anymore? In the middle of the night, I went down to the shop, flipped all the lights on and there it was. See picture.

 

2016-03-27%2B08.28.37.jpg

 

The basement is cool and in the summer has high humidity even though we have a dehumidifier. Somehow between the time I built the cradle and the almost full year until I used it the 2 x 8's I d used on the sides had warped just a bit. About 1/2 inch  in the center cradle spot on both sides. This made the front of the module hit and the bulkhead just above the module loose and all the stringers loose. I would have notice this easily if I hadn't introduced the variable of glassing the center and just assuming this was the problem.

 

Yesterday I took a tape measure and shimmed up the cradle to an even 20" all around (I'm tall and don't want to stoop taping the outer parts from over the side). Luckily I didn't shave enough off to really matter and the module fits almost perfect. I'm a bit embarrassed I didn't notice this earlier, but happy I just stared at it for awhile. For anyone going about this in the future this may help.

 

We have Easter plans all day, but I'm reinvigorated to get back to it tomorrow.

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Chick, I am sort of a perfectionist which works for and against me. My Spindrift 11N took me a very long time to build because I was very cautious. It turned out beautifully and sails like a dream. I am not going to rush this boat. Everyday in the shop is fun, especially when my boys are with me. And I know any people enjoy building as much or more than sailing. Not me. I already have a 5 day trip to the Chesapeake in May (on a Joel White Marsh Cat), a family trip to the North Channel on a bare boat charter in July, the Small Reach regatta in my Sea Pearl, the MASCF and I want to make the B & B gathering this fall. I will bring my 11N and steal a lot of ideas for finishing my 20.3.

 

I am jealous of you and Pete's focus.

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I posted this in the Carlita thread, but it was at a time when C-boards were the talk of the day. Maybe this will get better action.

 

"Graham, one question I have about Carlita is how well your system works for filling and emptying the water ballast. I am a fan of simplicity and I am hoping not to have a complicated electrical system. The tank on the 20.3 holds about 45 gallons of water. I can see letting gravity do it's thing and then taking a few buckets and topping it off, letting any water that splashes run out the self bailing cockpit. Or if necessary adding a whale gusher style pump to top it off. I look forward to your observations now that you've had experience."

 

I have the module out of the boat again doing some last minute stuff that is easier now than later (centerboard pennant, and all it's hardware). I'd like to have a system that requires no power. The thoughts are to mount a whale style pump in the lazerette by the centerboard if Graham's system requires too many buckets to top off. Sort of like Jay did, but I'd go arm-strong for power. I'd use the self-bailer to empty, or see if I could put some valving that allowed pumping out.

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Steve,

 

I believe that I mentioned that I bailed the tank full. I showed a picture earlier in the Carlita build of the 3/4" PVC tube that I set horizontally through the fore and aft tank baffle and into the trunk to let in the water. It filled the ballast tank to within about 3" - 4" of the top before I needed to bail. To empty the ballast tank, I opened the bailer and the tank fill until the water dropped to where it stopped filling and then the transom drain plug was reinstalled. In spite of John's comment that he needs 6 knots to make his Anderson bailer work. I emptied the tank while doing 3-4 knots. The fill tube was installed in the trunk to save parasitic drag rather than going into the bottom. It is reached, just to the left of the hatch. I am happy with the installation.

 

I was pleased with the height of the cockpit and drains. In the worst conditions, I did not have water running back into the cockpit from the drains. I enlarged the 3/4" PVC pipe to take standard transom drain plugs, I can plug the drains if she back floods with a bunch of people sitting in the cockpit. I have not seen the need so far. I have since had a four people plus Mandy in the cockpit with the tank full without issue. 

 

I also have a diaphragm pump but ran out of time to install it. I will see if I ever get around to it. 

 

As I mentioned earlier, I like to fill the tank all of the way. This is to prevent the water from going to leeward as the boat heels lessening it's effect.

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QUESTION: I wonder if an Anderson Bailer installed reversed with the flapper removed -- and the boat moving (by wind or motor) at about 4 knots -- would that [motion] create enough "head" to completely fill the tank and, perhaps, overfill it into the footwell ?? In the ordinary position it apparently creates enough negative head (- 9 inches of water) to suck water completely out of the ballast and into in infinite pool 9 inches higher. Anyone know the answer? Maybe no pump is needed. Doesn't "pitot tube" move a pointer (or a column of fluid) by moving thru a fluid?

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A pitot tube works by pressurizing a column of air, inside the tube, just past the orifice. This column of air "breaths" on a blader in the back of a speedo or speed sensor, which is connected to a gauge needle or a coil if it's a sensor.

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Great weekend. I probably got 10-12 hours of focused time. I mostly finished filleting the module and bunk supports into the boat. I was watching Alan's videos and thinking how much nicer it would be if I could tape everything and coat everything continuously, but that's not happening. I'm stoked to get to a point where I can fiddle on the smaller stuff. I worked on the rudder between the filleting.

 

A few questions as usual:

  1. The bow eye backing block.....I have a picture from my Spindrift 11N. I'm assuming a similar approach.....right?
  2. The lazerette cover.....is the intent to make this hinge? It seems it really needs to seal pretty well in some way as this area isn't self bailing.  Gasket?
  3. I noticed some of you notched the longitudinal bulkhead to move the motor mount notch closer to the center-line. Graham's seems to be fully outboard of it. It seems like there is pros and cons to both ideas. I'm about ready to make that decision.

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Steve, want pictures!

   1. Not sure about the S-11, but i used a 3/4" thick block shaped to fit into the "V".

   2. I'll hinge the lazerette hatch at the bottom and have a turn screw to hold it closed at the top. Not sure about a gasket yet but it seems like a good idea.

   3. If you get too close to the centerline, the rudder will hit the prop on the motor when they are both down. This could spoil your day. Keep it outboard of your longitudinal bulkhead. 

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Steve,

 

 The reason why the lazerette cover is flat along the bottom is to allow for a length of piano hinge. There is room for a 1/8" soft gasket. If you look at Carlita  pictures that cover that area you will see that I fitted an eyebrow in my cockpit seat to give the hatch some rain protection. I did not have time to fit the gasket for the EC. I was expecting to have to bail out the lazerette at some time. To my amazement, it never got a drop of water in there. As soon as I finish painting the cockpit I will fit a gasket. I used some scrap 6mm Lexan to make my turn buttons. They worked out well.

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Thanks everyone. This tinkering stage is fun. This morning I placed my Suzuki 2.5 on the transom and got serious about how to make it fit. It turns out to not be as hard as I thought. If you cut the transom down like Chick did, the cavitation plate is below the transom about 1/2 inch. I'm not sure if this is enough, so I might go an additional 1/2 inch after I work out the geometry. Lowering has advantage of pushing the motor back a bit. The back of this motor sticks out further than the front and the coaming is a factor, so in order to allow it to spin, it needs to be pretty close to the longitudinal bulkhead. I set the rudder from my Spindrift 11N on it temporarily and I think the only way you would have interference is with the rudder half up and that would be making a crazy sharp turn. The motor will require a pretty deep well that goes forward quite a bit, but not as wide as I feared. 

 

Edit: I just noticed that Pete has a pic showing his motor swung in reverse with it just clearing the transom down by the prop. Can your motor swivel around in reverse Chick without hitting?

 

For Chick:

 

2016-04-13%2B06.51.25.jpg

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Yes, it can swing around. 

 

The transom has wedge shaped plates so that the motor is vertical and not kicked out.

 

Sitting back in the cockpit also lowers the back of the boat so that the prop is deeper in the water. My CS-20 Mk-2 had the motor at the same height on the transom and I had no problems with "sucking air".

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Thanks Chick. Tonight I'm going to make a temporary transom and a wedge to try and sort this out. If you look at Pete's post below, you can see the problem. His mount sits the motor much farther back and it barely clears in reverse. It may be that the 17 transom height is less and makes the problem easier. I really want to do it your way, but I fear it isn't possible.

 

For reference:

 

Pete's pictures:

http://messing-about.com/forums/topic/9519-core-sound-20-mk-3-4-chessie/?p=88650

 

Chick's pictures:

http://messing-about.com/forums/topic/9480-core-sound-17-mk-3-summer-breeze/?p=86687

http://messing-about.com/forums/topic/9480-core-sound-17-mk-3-summer-breeze/?p=89284

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Chick, I noticed your well doesn't extend as far fwd as Graham's does. Will your prop clear the water pretty well? I'm guessing your motor won't fold back to horizontal as it does in Steve's photo?

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frowley, the motor tilts all the way up. Probably the 20 has a higher transom. a question for Graham or Alan.

 

Steve, it's ALWAYS possible---somehow. May require surgery to make the well long enough for the motor's powerhead to lay all the way down in it. Never say "never". You can DO it!

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I have come to the conclusion a long shaft motor would be a better choice for these 20s. I brought the Honda 2HP long shaft in from my Sea Pearl and it would be so much easier to make it work with it's extra 3 inches. But I just hate the noise of it. I made a temporary transom and I've tried to figure out how to do what Chick did, but short of a giant cut out which would look a bit goofy, I think an extension like what Pete did will be best, but I still have t have a cutout and I'll hopefully work that out this weekend.

 

Anyway, thinking is what slows me down the most, so I thought that maybe I'd take a break from thinking about the motor mount and do something fun. Working on the rudder was just the ticket. This morning I took the picture below. My plan is to glass it tonight.

 

2016-04-22%2B06.40.21.jpg

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Thanks Chick. I bet those fancy CNC blades are nice, but I took my time and this thing really came out nice. Something about working with a hand plane that brings me joy.

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Steve,...

Why glass the rudder?

It's not under much stress like the CB and several coats of neat epoxy should keep it dry. And an extra coat on the part within the cheeks will keep the sliding parts from wearing through. Also, if you are not sailing and at anchor, it's often raised out of the water. Am I missing something?

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