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About capnrazz

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  • Birthday 01/01/1

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    Greenville, SC
  1. Princess 28 model progress (slow)

    Oops! Turned on the e-mail address in my profile. David Rasberry taoistinsc@yahoo.com CapnRazz
  2. Princess 28 model progress (slow)

    Hi Garry, et al I have plans for Princess 26 #7, but the P28 is closer to what I really want. I have been planning a similar electric propulsion installation for the 26. Haven't checked in with you guys in a while. I have been doing research on electric propulsion for the past year and hanging out on the Yahoo electric boats forum. Good forum with lots of practical experience and knowledge about things electric. I have developed a fairly sophisticated mathematical model for designing and predicting the performance of electric propulsion systems for displacement hulls. It folows a logical process from estimating hull power requirements to modelling the power curve and current consumption of specified propellor, motor , drive train systems, to estimating runtime for various battery configurations. This model has been refined with real perfomance data from several converted boats so far, including a Catalina 27, an Islander 36, a 42' Fontaine Pajot charter cat and a 33' Italian gondola. It is tracking the performance of these boats within an accuracy range of +/-15%. Good enough to be useful as a practical planning tool. If anyone on the B&B forum is interested in using this model I will be glad to email you the latest Excel spreadsheet version if you send me hull specs for your boat. All I ask in return is that you provide me actual performance data on your boat if you do an electric installation and that you keep the spreadsheet confidential as I am not ready to publish it. This is still a work in progress. I am an audio engineer by trade, used to using mathematial models to accurately predict performance of commerical sound systems. It struck me one day that the underlying physics of high power sound systems and electric propulsion systems in boats are very similar. Both involve a power source modulated by an amplfier/controller, driving a transducer (speaker/motor-prop) coupled to a fluid medium (air/water.) This lead to a lot of fun research and development of the electric propulsion model. David Rasberry Greenville, SC
  3. belt-and-suspenders reefing conflict

    I have seen examples of vertical jiffy reefing or brailes on laced sharpie rigs in photos of the old working New Haven sharpies. They fold a section of the sail up to the mast and ease the sprit forward to reef. Has anyone tried these? Razz
  4. What do you think? Belhaven cockpit decking

    You should probably use a flexible sealant between the boards if you seal the gaps. Expansion and contraction from heat and sun exposure will cause an epoxy filler to crack pretty quickly. Some form or another of polysulfide is usually used to bed and seal joints in laid teak decks. Teak is a much better decking wood as it can be left unfinished and provides a good antiskid surface. Razz
  5. How to keep varnish fresh?

    I have a can of the West Marine varnish that I use for my tiller. Its about 3 years old and I'm down to about 1/3rd of a can. When this stuff sits for a year there is definitely some settling of ingredients, maybe the UV inhibitors or some part of the resin. Straight clear varnish doesn't need to be stirred, but this stuff sure does. That may just be the West brand, it seems to be thinner out of the can than the Pettit or Zspar that I have bought in the past. Or it may just be the result of some degree of oxidation over time. I like the idea of storing in smaller cans. It only takes about 1/3 cup to do two refresher coats each year. Probably buy a new can of something this year. a piece of saran wrap floated on top of the varnish seems to work to reduce the skimming. Razz
  6. It is freakin SNOWIN in south Texas

    Some fool on Ebay just paid $92.00 for a snowball from Brownsville Texas. :roll: Razz
  7. How to keep varnish fresh?

    Varnish will tend to skim over in the original container when stored. You can skim the surface with a strainer to remove the gunk. Then stir gently but thoroughly to remix the resins before pouring. Pour just what you need into a separate container thru a cheesecloth or paper paint filter to remove solids and air bubbles. I have also cut a piece of plastic wrap to cover the surface and keep air out before storing. Make sure the original can is clean and tightly sealed and store in a cool place like a basement. Razz
  8. Electric Princess 26

    Northstar battery Link: http://www.northstarbattery.com/index.php Razz
  9. Princess 22 Engine size?

    I have a Gloucester 22' sailboat about 800lbs heavier than a P22. A 6hp 2 stroke Evinrude produces more than enough power to drive the boat to hull speed even with a strong headwind. A fellow sailor powers his lighter 21' Mcgregor with a 4hp Yamaha 4-stroke with equally good results. Both of these boats are significantly heavier than a P22. Several friends who have Rhodes 22's use 8 or 9.9 hp Yamahas and Tohatsus but that boat is about 3200lbs in cruising trim. Ted Brewer NA recommends powering at 3-5hp per ton of displacement, the higher figure is better if you anticipate bucking strong currents in coastal areas. I would figure 4hp minimum. Razz
  10. Electric Princess 26

    Hi Mike, We're thinking along the same lines regarding the box keel. My dream setup would be a somewhat larger boat, around 30' with a Solomon Technologies ST37 inboard motor and about a ton of batteries in a ballast keel. The Solomon motor has a regen mode to charge the batteries under sail with a freewheeling prop. I will look at the possibility of using NiMH D cells for the Princess, but they are likely to be rather expensive compared to 8D AGMs for the capacity required. Finding or building a proper charger for them would be a challenge too. Trolling motors would work OK for short distances on boats up to the size of a Princess 22, but are not built for continuous operation as primary propulsion units. The controllers will overheat and fail if run for more than 20 minutes or so at a time at near maximum current. This is a much discussed problem on the eboats.org forum. By contrast the OEC motor has pushed an 8000lb sailboat to 7.5 knots and will run continously at 80% of maximum current for as long as your battery lasts, producing nearly 200lbs of thrust, compared to about 60lb max for a heavy duty trolling motor. The trolling motor would be good for only 3-1/2 knots or so on a 2 ton boat maxed out. The OEC outboard equals the thrust of a 9hp gas motor.
  11. Electric Princess 26

    Greg L wrote: "What sort of Northstar batteries are you speaking of?" I ran across these during a web search on battery technology. They are a sealed VRLA absorbed glass mat type lead acid battery, so they can be installed in any orientation except upside down. PDF attached. Razz [attachment over 4 years old deleted by admin]
  12. Electric Princess 26

    Mike wrote: "Just an out-of-the-box thought. I work at a research lab where we build undersea vehicles. We have one that is powered by over 9,000 (yep, that many) D-cell alkaline batteries. They could be rechargables. They are slotted in tubes for easy placement. The D-cells allowed the designers to fit them into the form of the vehicle much better than larger cells." Interesting idea. The Honda Insight hybrid uses a battery pack of 120 NiMH D-cells. Cost Vs capacity Vs cycle life is too high currently for the more exotic battery chemistries for this application. There is an interesting new lead acid technology that has been spun off from Caterpillar as a startup called Firefly Energy. It reduces the weight for a given capacity by 70% using some kind of lead/polymer matrix for the grid plates. There is also some reduction in size vs capacity too and the polymer grids are impervious to sulfation and positive plate corrosion that limit the life of conventional batteries. Supposedly they can be manufactured on existing lead acid infrastructure at comparable cost. These may be available by the time this boat is built.
  13. Electric Princess 26

    Greg Luckett wrote: Assuming you were able to do this, how would it affect the displacement of the boat and the number of possible passengers? If I'm interpreting the specs correctly the boat has a payload capacity of around 1000lbs at 3700 lb design displacement with 700lbs of ballast in place. The pounds per inch immersion is listed as 498. So if I built it with the 700lb ballast keel as designed, the total weight of the electric installation + 2 crew and gear for a week's cruise would probably push displacement to around 4500lbs for about 2 inch increase in waterline depth. I imagine this would nail the boat firmly in the displacement speed range. Without the ballast keel and sailing light she would be more likely to plane in a breeze. My intended use is primarily daysailing and weekending out of Big Water marina on Lake Hartwell, SC-GA border where I currently keep a Gloucester 22. A few times a year I may make longer cruises between marinas on the lake or trailer to the coast for inshore vacation cruises. The freestanding tabernacled rig will make it possible to get under bridges on the lake, opening up 1100 miles of shoreline and 60 miles of lake to camp cruising. From Big Water I have 14 miles of open water until you hit the first bridge on the main body of the lake. A 12kWh battery on either an OEC or RAY electric outboard should give around a 25 mile range under power alone at 5 knots, that increases to 40 miles at 4 knots and shrinks to about 8 miles at 7 knots based on calculations for a 2 long ton boat with 25' lwl. This is roughly equal to the range of my Gloucester with a 6hp 2 stroke and 6 gallons of gas, except the the Gloucester will only make about 6 knots max with the Evinrude. So 650lbs of lead acid battery is about equal to 6 gallons of gasoline. Question for Graham: If the boat is built with the shoal keel and ballast shoe as designed and I use the Northstar batteries (650lbs) turned on their side under the settees so the height above hull is about 5 inches what would the displacement and stability curve look like? Razz
  14. It is freakin SNOWIN in south Texas

    I apologize for the rant. But everything I outlined is published in peer reviewed scientific journals and has been reported often in TV documentaries and the popular scientific press as well. It is not new, most of it was well established by the late 70s. What is more recent is the determination of prehistoric atmospheric conditions that triggered major past climate changes. This came from analysis of polar region soil and ice cores in comparison with modern atmospheric and earth science records, which only go back about 100 years. Most of this work was done in the 80's and 90's. The science is sound enough that current recorded average increases in ocean and atmospheric temperatures were accurately predicted in college courses I took in the early 70's. Scientists can accurately model the warming trend, but not what the resulting climate changes will be. Only that the more extreme the average temperature increase, the more extreme the changes will be. The science is real, the politics is what we choose to make of it. Razz
  15. It is freakin SNOWIN in south Texas

    The science on global warming is solid. It is happening and we are major contributors to it over the last 200 years. It doesn't mean everything is going to get uniformly warmer on a local macro weather basis. The increase in atmospheric energy will result in more extreme weather patterns, both warm and cold. At the same time it was snowing on Charlie the east coast was setting high temp records for this time of year. We will also be facing more active hurricane seasons like the one we just had for the same reason. Do we really think we can dump billions of pounds of greenhouse gasses into the atmosphere every year for centuries and not have an effect? Two major prehistoric extinctions, one was the pre-cambrian, I forget what the other was, were triggered by warming cycles caused by increased methane concentrations in the atmosphere. The methane came from living sources existing at the time. Both caused major climate catastrophies when the temperature rise hit about 5-7 degrees C. In one case ocean warming released huge quantities of frozen methane beneath the ocean floors which kicked the temperature up another 10 degrees and turned most of the planet into a desert. Wiped out 90% of all species existing at the time. The other catastrophe triggered a northern hemisphere ice age when fresh melt water from the polar regions stopped the gulf stream, wiping out 70% of all existing species. Gulf stream flow has diminished by about 20% over the last decade due to polar warming. At the current rates of accelerating warming we could hit the critical 5-7 degree range before the end of this century at the polar regions. The sad thing is that even if we had the political will to make the drastic changes to curb emissions, its probably already too late to reverse the current warming trend in time. But make no mistake about it, atmospheric changes are caused by the contributions of all living things to the biosphere. When serious imbalances occur for whatever reasons, major disasters will follow. Right now human activity is the major source of change in our biosphere. Razz