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Alex

CS 17 water ballast

8 posts in this topic

Hi All, I will be starting my build of a CS 17 soon and was wondering if anyone has tried or at least thought about putting in a false self draining floor for the water ballast like the MK 3 models? If Alan or Graham could respond with some info on how deep the floor would have to be to be self righting that would be great. Thanks.

 

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My thoughts: The boat is not designed to carry the extra weight of water ballast. If you did add it, the boat boat would float lower in the water and sink deeper than the design water line. It would also trim down by the stern more. The Mk-3 versions have added buoyancy to carry the weight. If you are aware of these details, and how they would affect performance, it could still be done. I'm sure Graham or Alan could help you.

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It all depends on how you'll sail it and the general condisions it'll be sailed in. If you're sailing solo and/or in heavy air a lot, some consideration to ballast might be useful. I'm not a big water ballast fan (it's just not very heavy for its volume), but in can be handy. Alternatively, consider some ballast castings. These take up much less room are, much denser and they can be removed from the boat for trailering too, though I fail to see the need. Simply, the amount of ballast a CS-17 would need to compensate for a light crew compliment, just isn't enough to be concerned about storing aboard the boat all the time, so draining it out or offloading in just another launch ramp chore, in my way of looking at things. Now a CS-20 or 22 may need a fairly hefty amount of ballast (I don't know the exact figures). I have a ballasted 23' and it needs 900 pounds, 400 of which are in lead castings, fitted into trays around the centerboard case. 99% of the time they remain in their trays, though they could be removed if desired. 

   The CS-17 sails well solo, though in brisk winds you'll need to reef early. The design is quite stable and capable of relaxed sailing, without a need to hike out on every tack.

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Alex,

 

There is very little gain to adding water ballast to a mark 1. If the goal is to prevent a capsize, it will not help much. The issue is what is called the down flooding angle. It is when you are shipping water over the lowest point which is the side deck. When you reach that point, the water starts to flood the boat and you are over. The problem is that the CG of the water ballast is not that far below the heeled center of buoyancy to have much of an effect.

 

The mark 3 has much higher freeboard and a greater down flooding angle allowing the water ballast to bring the CG below the higher heeled CB.

 

With that said, the mark 1 is a very stable boat with a higher than average down flooding angle. I have sailed 2 EC's in a 17 mk1 plus a lot of other trips and never capsized or even felt that I was close. 20 # of lead on the tip of the centerboard would probably have more effect in lowering the CG than adding water ballast.

 

One of the most important safety features that you can do to your boat is to put in the time to make your hatches water tight. This will change your ability to self rescue quicker than any other factor and it is probably the most neglected item I see when I inspect one of our boats. My boat took on zero water and Alan reported dry cockpit lockers after the EC. When I looked at Water boys boat, I was pleased with the Lennies work until I checked his hatches. I dragged him over to my boat to inspect my hatches. He reported up to 3" of water in his cockpit lockers during the race. It is miserable having to cope with that in an EC not to mention getting gear ruined or at least wet. 

 

About a year ago we put in more time on the hatch plans to make them clearer. If anyone does not have the latest upgraded hatch plans let us know and we will get them to you.

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Thanks Graham for the great explanation and also to you Par.

 

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Agreed, in my time with the CS-17, I wasn't remotely bothered by heel angle, her tenderness or feeling threatened by a capsize. In fact, my first conversation with Graham after the launch, his first question was how I felt about her stability. My version of the CS-17 included a 20 pound ballast on the board, spread along the leading edge, which certainly contributed to her steadiness. I was just starting to play with foil equipped Moth like beasts at the time and the CS-17 felt like a rock compairtivly. She's sturdy, hearty, stable and well rounded, a good boat to learn on, as well as test yourself with. She's not a performance skiff, where you have to constantly hike out just to stay upright, but she would be a fine raid boat and you're not going to get embarrassed by any production boat, unless in a tacking duel.

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PAR, based on the video of Alan in the CS 15, the CS's shouldn't be afraid of the tacking part, or are you saying that the production boats point higher?

On 13/03/2017 at 6:19 PM, PAR said:

she would be a fine raid boat and you're not going to get embarrassed by any production boat, unless in a tacking duel.

 

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A cat ketch is at a disadvantage uphill and though you can tack a wee bit faster with some practice on this rig, you're just not going to be as high, so you'd get clobbered to the mark.

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