Just Because...

A hypothetical boat design that Jerry is 'playing with'.
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Joined: Tue Apr 23, 2013 7:45 am
Location: Dearborn, MI

Just Because...

#1 Post by happy_sailor » Wed Apr 24, 2013 11:16 am

So I'm pretty new to the forum, been reading up alot on the Sage 17, really like the design and construction, and I had a few ideas for the 21'er...

I definitely come from a dinghy racing background. I sailed 420s in college and currently I have a 1953 Thistle that I'm bringing back to racing form. So my trailer sailor definitely has to have an emphasis on performance. I believe that it's definitely possible to have a higher performance boat and still have it be extremely seaworthy. I've taken Thistles out on days when it was 25 knots with 4' waves in Lake St. Clair and they handled fine despite their lack of decks. Granted, it was a chore to keep the boat moving and at a decent angle of heel, but I think that you don't necessarily need to build a boat with a huge displacement for it to be seaworthy.

I also would think it would be super awesome to have a boat light enough to row comfortably. I'm not a huge fan of motors and I think it would be unique and neat to have a boat that you can sail off the dock and row during calms. To this end, the boat would have to be very light and have a comfortable rowing station.

The sail plan would be simple, one headsail, one reefable main, and a spinnaker, whether on a sprit or not. Adding more headsails would fill up space in the boat and complicates things. It would be most convenient to have an assymetric spin, but that could limit downwind performance in certain conditions. It's definitely possible to handle a symmetrical kite with a small crew, I've doublehanded Thistles many a times, but singlehanding would be a challenge.

As far as hull shape, I think that there are two options that would provide the speed that I would want in this boat. You could either have a plumb bow, square sterned, wider boat, shaped more modernly (think Thistle, 420, or any higher performance boat these days), or a long, narrow boat (think 3 meter design). The wider boat would have more initial stability, be able to plane and would have more living space, however it would probably have more drag during displacement mode. The long, narrow boat wouldn't have enough surface area to plane, but at the same time would provide less drag in displacement mode. Personally I favor the wide hull model, as I LOVE the ability to plane going downwind, and I think you can overcome the drag in light air by careful weight placement and heeling angles. I like the increased living area it also gives you.

Ballasting this boat would cause a problem, if you were trying to make it fast. Obviously a large SA/D ratio indicates speed, but it also means that you have to use your body weight as ballast, which can be tiring and doesn't give the boat tons of ultimate stability. Basically, if you flip a Thistle over, you're screwed, which is not ideal for a cruising boat. I think this problem could be alleviated by using ballast bags filled with water. Again, this would be more work when tacking, etc, but if you were in an especially light air environment, it could definitely work. Just to be clear, I am a self proclaimed racer so I'm all about speed and safety...

Positive flotation is a must, as well as flotation in the mast, so in the event of a capsize the boat doesn't automatically turtle. A self-draining cockpit would also be a huge bonus.

As far as accomodations go, I think that a hard cabin would be too heavy and cumbersome and would get in the way of sailing FAST (did I mention that I'm a crazy racer yet? Also I'm young so my ideas of roughing it are pretty rough... I also backpack and kayak and canoe camp so sailboat camping seems luxurious to me). In my limited experience boom tents don't provide quite enough reliable protection to keep water out of the boat and ensure a comfortable stay. If you were to set up a deal with like tent poles and such you'd have to have a place to store them and I think you'd still run into the reliability problem. If I'm holed up for a thunderstorm I want to know for sure that my roof isn't about to collapse. I think an ideal solution would be similar to the air supported tents produced by NEMO.

link: http://www.nemoequipment.com/explore/te ... echnology/

They retain their shape due to inflated air chambers. If you had a tent solution that incorporated their air beams with a waterproof/breathable fabric that attached onto the outside of the deck, you could creat a watertight space to live in. At the forward end of the boat, if you had a buoyancy/storage chamber that came up to deck level, the forward end of the tent could attach to that, so that water would run down the outside of the hull to the lake/ocean/river.

I believe Jerry or someone else said this conceptual design would be a one off cold molded hull. I think that's a great idea, but I also think you could gain a lot of weight advantage from using carbon fiber structural members. Using a composite design of thsi nature has been used before in the construction of large super yachts and is a proven technique. For example, if you used carbon fiber for the keel/centerboard support structure you would be able to build them much lighter than with conventional cold molded designs. You could also building the bulkheads and compartments with carbon fiber for additional weight savings.

Using PBO or something similar for standing rigging instead of stainless steel would reduce weight aloft and increase sailing performance. Designed carefully, I think you could create a boat this size for around 1200 lbs, which would be a lot to row, but not overly so, especially if you had two rowing stations.

I know a lot of my ideas are pretty crazy, but I'd love to hear what you guys thought about it...

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