According to Georgs, our listmeister, a small number of trawlers have circumnavigated, albeit with frequent fuel stops.?

According to Georgs, our listmeister, a small number of trawlers have circumnavigated, albeit with frequent fuel stops.? http://www.trawlersandtrawlering.com/circumnavigators/circumnavigators.html <http://www.trawlersandtrawlering.com/circumnavigators/circumnavigators.html> But since Rutan and Jaeger flew around the world non stop in a small airplane the question has been asked if an average sized trawler, say not much bigger than 40 ft., can make a similar trip without refueling. My calculations show that it can be done, but not easily. Let's start with an assumed speed of 4kt. With no favorable lift from wind or current the 24,000 NM trip would take 6000 hours or 250 days. The trip requires 3000 lb. of supplies (food and water) for two crew members. Also assume a LWL of 36 ft. and a boat structure weighing 12,000 lbs. A hull could be constructed this light with sufficient strength to withstand the rigors of a circumnavigation although not providing many creature comforts. If we average 10 NM per gallon of diesel fuel, the total fuel load would be 2400 gallons or about 17,000 lbs. The gross weight of hull, supplies and fuel would be about 32,000 lbs. Using Keith's formula as given in Skene's "Elements of Yacht Design", the fully loaded boat would require 5.62 hp to make 4 kt. A well tuned diesel engine will generate 1 hp per .06 gal. of fuel per hour. This is .34 gal. per hour or 11.86 NM per gal. This is better mileage than anticipated so we can either shorten the boat or carry less fuel.? If we choose to skimp on the fuel, we need only 2000 gallons for a fuel weight of about 14,400 lbs. Also, the boat will require 5.6 hp only when fully loaded. As the fuel is consumed, power requirements drop. If we use a watermaker operating off mechanical power or waste heat, 2000 lbs of water can be eliminated at the cost of a little additional fuel. Rainwater collection and fishing are additional sources of food and water without a weight penalty.? Aluminum construction will permit a lighter hull structure, say 10,000 lbs. The total gross weight is now 24,400 lbs and the boat requires only 4.3 hp to average 4 kt. The new fuel consumption estimate is 15.5 NM per gallon or only 1548 gallons. If we go with the 2000 gallons, we will have reserve fuel for unanticipated conditions. Alternatively, we can decrease the length of the boat to 30 ft. LWL. ?Maybe we can even take a case of beer for an Equatorial celebration. The 2000 gallons of fuel will need about 260 cu. ft. of tankage. A tank 9 ft. long by 5 ft. high and 6 ft. wide will suffice. It would be better if the tank were divided into several compartments and occupied the bilge area for most of the length of the boat. The weight when full would add stability and water ballast could be added to keep the boat stable as compartments were emptied.? Thus the circumnavigator would be a 30 to 36 LWL boat of about 10 ft. beam, powered by a small, very reliable, 10 hp diesel, driving a single large diameter slow turning screw. For safety, the shape should resemble a Coast Guard surf boat or a fully covered lifeboat, capable of handling rough seas and surviving a rollover. Top speed would be about 6 kt, hence there is little possibility of outrunning bad weather. Bon voyage anyone? Larry Z