A LOW IMPACT LONG DISTANCE CRUISER
In 2016 my wife, Jean, and I took a trip down the Intracoastal Waterway from Brooklin, Maine to the Northern Bahamas. We used a “vintage” 42’ Taiwanese built diesel trawler, a fat old tub with a reliable old Lehman diesel. Knowing the cost of pushing hull speed, we made the whole trip at about 6 ½ to 7 knots, my goal being that we would use no more fuel than it would have taken to heat our Maine house for the winter. An exact accounting was never made, but it was pretty close. It was a very enjoyable trip! We spent almost two months in the warm arms of the Abacos and made it back to Maine in time to plant our vegetable garden.
SOMBRERO is a concept sketch to propose a boat that could make the same trip with electric power. She is longer, but lighter than our trawler and has a long, full width cabin top to provide room for a solar array that can produce 3500 watts in full sun. The idea was to make the boat independent of fuel docks, but on the autumn trip south, when the days are short and the sun is low in the sky, it will be necessary to spend some nights in marinas to top up the batteries. Coming north in the spring, a careful skipper could make it on solar alone.
SOMBRERO has accommodations for four adults and possibly a couple of kids up in the fo’c’sle. The pilothouse will be a fine place to watch the world go by, with easy access forward for anchor handling. Three step down bring you to the main deck, with the head immediately to port. Next aft is the skipper’s stateroom with double berth. Then comes another stateroom with upper and lower single bunks. The galley and dinette are at the back of the cabin, where motion is least. Finally, a step up brings you to the aft cockpit, fine for reading underway or dining on the hook.
As with most efforts at efficient hull design, SOMBRERO employs narrow waterline beam and lightweight construction. This combination can allow a boat to “cheat” the usual hull speed limits for displacement boats –- SOMBRERO will be capable of exceeding 11 knots. But I believe this is not a realistic goal for long distance electric cruising , at least until the next breakthrough in battery technology. As any sailor knows, hull speed is difficult to achieve – it takes a lot of wind! Real efficiency, the kind that makes today’s electric propulsion a viable alternative, comes at slightly lower speeds – the kind of speed/length ratios that commercial cargo carriers use to move goods all over the world at low cost.
The same philosophy and design perimeters that make SOMBRERO appropriate for electric power would make her a very low impact fossil fuel cruiser. A 60 hp diesel would allow her to punch into a headwind at hull speed, or push her along all day at 8 knots using a bit over 2 gallons per hour.
Since the dawning of the internal combustion age, power boat design has been laser focused on hull designs intended to pack the most horsepower available. But high speed boat travel is one of the most energy intensive of human endeavors, the offspring of cheap petroleum, people who think they need to be in a hurry, and a boatbuilding industries that make more money by obliging. Efficiency has been cast aside, and low impact power boating has been the victim. The result is that there are virtually no modern powerboat designs that embrace the kind of efficiency that is compatible with boating in the era of climate change. Let’s hope we will see more boats like SOMBRERO on the water soon.
LOA – 50 ft.
LWL – 47 ft.
BEAM, max – 12 ft.
BEAM, wl – 10’ 3″
DRAFT – 3’ 5″
DISP – 20,000 lb.
D/L – 86