Hi Bob and All, You do some nice work Bob, Thanks.
A few details to lower boat drag. 1 hull will almost? always have lower wetted surface drag as has less surface/lb. Why Pontoon boats use less is they make less bow wave drag. Since wetted surface is more at lower speeds, under 4mph or so, monohulls are better. Once you get into higher hull speed, above the sq root of the waterline length, the lower wave drag become dominate making pontoon, multihulls much lower drag than semi planning a wider monohull has to do. Vs hulls 8 x's longer than wide, just keep going faster rather than making wave drag because it gently parts the water and bring it back together making much smaller bow wave, drag. Thus why the old electric launches were all canoe shapes, long and lean. As are most 3rd world boats. As to wooden boats being heavier while it's mostly true of older boats, older racing and modern wood boats can be lighter by a good amount than FG, other materials. My 34' trimaran 22' wide will only weight 2k lbs dry show how light they can be using well designed epoxy/plywood technics. This greatly reduces cost One of the best WW2 planes was made from wood, the Mosquito Bomber, the second fastest plane in WW2. PO'd the Nazi's getting beat by planes made in piano factories of wood. It was actually a fighter but no orders for them so they/ Mitchell put in a small bomb bay and called it a bomber!! Was good at that too. So if you want a nice E boat and don't mind 4 mph use a lightweight monohull sailboat hull to start. If you want faster a multihull/pontoon is better. I use to make tidal power for liveaboard/cruising boats and so much power was made it had to be turned of much of the time to keep the batteries from overcharging. In the 70's I was doing racing boat, etc electrical, mechanical and it turned out props made less drag stopped than left spinning while sailing/racing. So we needed to lock them stopped. The problem as the prop torque was so high it broke nearly everything we tried!! Many ended up using 10'' disc brakes from cars as about the only thing that could safely stop a turning prop. This plus the water turbine rigs used by singlehanded transatlantic racing sailers of the day it dawn on me to use a double V belt step up gearing to a car alternator ended up making too much power despite such ineff gearing, alt. Another was take a six HP Evinrude outboard prop put on a 3-4' SS shaft with a braided line of 40' tossed overboard and hooked to a wind generator generator spinning it to make power. Many of these were used. Some windgenerators came with them as an option. My favorite was Motorola made an outboard looking one that worked well but didn't sell many. I'd love to get my hands on one. Another detail is a prop has the wrong foil direction so inherently not eff yet they still work as so much power is available in moving water. To be most eff a special turbine needs to be made. I've made a 1' dia one for testing from composites. I'll be doing a 2 kw tidal generator so when I get it going I'll give out the data. I've always wanted to do a tide powered boat, anchoring/charging when the tide is against you, and motoring when with it. The east coast intercoastal waterway is near perfect for this from the Fla Keys to Maine. I hope these examples will help make better EV boating as a great place for EV's. Jerry Dycus On Saturday, December 28, 2013 9:25 AM, Bob Batson <[email protected]> wrote: To all: Electric Vehicles of America, Inc. (EVA) has been doing electric boats for 20 years; we have worked with a number of boat manufacturers as well as hobbyists. We have provided DC drive systems for up to a 40 ft sailboat and a pure electric that was displayed at the Annapolis Boat Show in the summer of 1995 (?). The key is understanding how the electric power will be used and how much hp is required based on the boat (water line length, displacement), wind and current in the waters selected. Naturally, a wooden boat has much more displacement than a fiberglas boat; therefore, more hp is required. The equations for calculating hp are readily available from various sources. The hp will most likely determine the minimum voltage required. AC drives are also available, but to be honest I have never seen any actual data on regen capability from a slow turning sailboat propellor. Lots of claims but never any data. I would love to see the data to verify the claims. If the boat is for hire, then you need to meet U.S. Coast Guard regulations. We have also helped with pontoon boats. Our on-road specialty is light-weight trucks because of space; pontoon boats have similar space advantages. But most important, pontoon boats require about 1/2 the hp of the same length sailboat because of less wetted surface. Our most popular pontoon boat was an ice cream vendor http://shantyboatliving.com/2013/sale-35-foot-ice-cream-sternwheeler/ The 48V DC electric drive drove the sternwheeler. This was a 35 ft pontoon boat. Most popular because it served ice cream and more. We have also helped with pure electrics. Silver Bay Marina on Lake George, NY converted a Hacker-Craft, similar to a vintage Chris Craft, to electric for use at a resort in the Southeast. The electric would give sunset cruises. The obvious advantages were lack of noise and pollution. I think it has been operating for about 10-15 years with our system. So reliability is another advantage; low maintenance compared to other options. Hope this helps others see the advanatges of electric boats and electric auxiliaries. Our website has a page dedicated to boats. I do not contribute often to the EV Digest, so I hope I did this properly. Bob Batson (603) 569-2100 www.EVAmerica.com -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20131228/29795ce3/attachment.htm> _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA) -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20131229/fe5be687/attachment.htm> _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA)
