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Friday, April 22, 2016
Remember this Vega?
Sailed around the America's, via the Northwest Passage and Cape Horn, this Vega 27 lived an adventurous life. Now she can be found in the "broken dreams" are of the Herrington Harbor North boat yard, worn out and done.
Kinna sad. Simple boats, but a number of Vegas had traveled far.
Solo the Americas
Thursday, April 14, 2016
A Lot of Hidden Work
Rev. 7-25-2024
Installing air air conditioning is like a lot of projects; all the hard work is hidden, and if you do it right, it doesn't look like you did anything. I put in a good 20 hours worth on this, not counting head-scratching time. And I work fast.
The short version is that the installation work is considerable, but it is MUCH quieter, easier to use, delivers 50% more BTUs, and consumes 23% fewer amps. Best of all, it does not leak rain, freeze the person sitting under it, snag sheets, or block the helm view. The weight is slightly less and is carried lower.It actually takes a little more space, just hidden in lockers. It can actually run it off the batteries for 4-6 hours once the cabin is cooled down (meaning I can leave a marina in the morning and leave it one until we are out in the breeze). Fortunately, I kept the lockers pretty cleaned out, so I still have far more storage than I need.
Detailed write-up coming to Good Old Boat Magazine. Meanwhile, if you're looking for AC, I've got nothing but good things to say about the folks at Dometic. Great unit and great tech support (I had no trouble with the installation, but I had a lot of tech questions for the article). The toughest part is running the ducts to the optimum positions, which is very important. Not as difficult, but also very important, is plumbing the water intake so that the pipe rises steadily, without loops, through the strainer and through the pump. If there are loops, the system will air lock after hard sailing. Finally, place the temperature sensor in the warm return, out of the cold blast, to avoid short cycling. Don't draw the return air from bilge space; you can pick-up odors, fuel fumes and even CO. Run a separate plenum from the cabin.
And the obvious. Keep the door closed to reduce humidity and icing. Don't expect it to work in water over 90F (check the manual for limitations) and separate the intake and discharge. Reflective window covers and awnings will greatly reduce the work load. Insulate if possible.
Saturday, April 9, 2016
The Drogue Collection Grows
rev. 7-24-2024
A few loaners round out the field...
... which led to more 1/3-scale models (not factory authorized, but as faithful as I could make them). Cone, Shark, Delta, Galerider, Seabrake.
Interestingly, the 1/3-scale models behave exactly like their big brothers. Drag is proportional to cross section, so the models product 9 times less drag. Drag ~ velocity^2 up to 14 knots, the limit of our testing. They also have very similar surfacing behavior, which lead to the premise that testing these with scale rode in Force 7 conditions, with steep waves and a little engine assist, is equivalent to gale conditions with a full scale drogue. Instead of loads approaching a ton, they stay below 150 pounds, and hand-over-hand recovery is 5-20 pounds instead of 50-200 pounds; makes a real difference when there are 100-300 feet of line out! The result is practical testing at more speeds and with more combinations, allowing full-scale testing to focus on the right questions.
I since made a few scaled to my F-24 trimaran, primarily for emergency steering experiments . In proportion, they perform right in between their big and little brothers. Very scalable.
If you want to try DIY, the Delta Drogue is by far the simplest. Basically, it is a triangle of fabric of the dimensions of the model number (a Delta Drogue 72 is made from a triangle 72inches on a side). Cut about 20% of the length off each corner, rim the fabric with strong webbing, and then sew the edges together up into a balute (Google it) with about 50% of the edge sewn and 50% open (there shdould be three long slots for the water to blast out). The webbing along the sides should be long enough (about 50% of the length of a side before cutting) to joint at the apex. Complicated to describe, but easy to fabricate.
After testing full scale drogues at speeds up to 7.5 knots and confirming scalablity, I built a universal cross reference table (Practical Sailor) so that you can pick a drogue for your boat, whether for steering or speed reduction. Generally it agrees with manufacturers, but they often have different theories regarding how much drag is best.
Now I am starting to focus on tandem drogues; does it make sense to trail 2 drogues on the same rode, as conditions get worse? The answer seems to be a resounding yes. Unlike anchors where rode forces destabilize anchors, in this case they seem to stabilize each other. Doesn't a second drogue add a lot of expense? Not really. Because stability is less of a problem, less expensive drogues like the Delta or Seabrake are valid. The rode and bridles are already paid for. Basically, you get the advantages of a series drogue, with more adjustability, flexibility, and easier handling.
The real bargain? It may be a surplus aircraft drogue I bought on E-Bay 15 years ago for $40. To my eye it is just as well built as the Paradrogue, and it gives a lot of stopping force for the buck. Too much for steering, too much for running a bar, but maybe just the thing for parking to drift fish.