Fast cruising boats are all the rage these days. Pod drives, planing hulls, powerful twin turbo diesels, and even giant supercharged outboards deliver copious quantities of cruising knots to boaters with deep pockets and a need to Get There Now. Modern cruisers don’t have time to wait around, apparently. They’ve got people to see and places to be – and if a few hundred horsepower can lop several hours off that time-in-transit, pour in the diesel (or gas)!
There are plenty of good reasons to go fast in a cruising boat. Tides and currents wait for no man (or woman); and if you can sleep in, eat your omelette, sip your cappuccino, take a leisurely shower, and still show up at the rapids in time for slack, well – life must be tough for those slow-boating trawler types. In fact, who needs slack? If you can beat a six knot current and still make double-digit headway, why wait for slack at all? Strap into your captain’s chair, push the throttle balls to the firewall, and shove some serious water out of your path.
As fun as fast pleasure cruising might be, we are here today to make the case for slow. We like seven or eight knots more than fourteen or twenty one, and we have several solid reasons for our preference. Sure, we enjoy the thrill of sending several tons of fiberglass skimming across the surface as much as anyone (well, almost), but let’s look at the flip side of the coin. For a few paragraphs here, let’s pull back the throttle levers, let the knot meter drop to displacement speed, and see what we might be missing.
First, a little physics. I know, WHAM! We sucker you in with a lot of alliterative language and as soon as you agree to come along on the ride, in waltzes Newton and all his friends with their formulas and laws. Ugh! Forget it. I’m going boating. But – hang in with us for a minute here. Every boat hull has a wonderfully efficient “displacement” speed at which it daintily sips fuel while sliding smoothly through the water – leaving hardly a wake in its path. As you may know, that displacement speed depends primarily on the length of the boat, and longer is better. (See, we’re making an argument for a bigger boat now. We’re on your side!)
At any speed up to displacement speed, the boat is wonderfully efficient. Water virtually volunteers to move out of the way before the vessel arrives, leaving a downhill coast into the void. This is the realm of trawlers – round-bottomed boats that can practically cross the ocean on a single tank of fuel. These cruisers can achieve fuel efficiency many times greater than their planing-hull cousins. If you want to go far in a power boat without stopping for fuel – a trawler is your friend.
If you try to exceed displacement speed in a trawler, however, a nasty thing happens – physics kicks in. While your huge trawler may slide along using only 20 horsepower to make six or seven knots, you could add hundreds or even thousands more horsepower to the stern and you won’t go much faster.
All that extra power and fuel ends up just slamming your boat into a wall of water. In order to remain efficient at displacement speeds, trawler hulls don’t have any “lift” designed into them. They stubbornly sit there in their hole striving to shove the entire ocean out of the way. Try to power up and push harder and your reward is a bigger wake and not much more. Nordhavns are gorgeous cruising boats that can circle the globe, but they’re definitely not designed for racing.
If you ever want to go faster than displacement speeds, you need a planing hull, or a compromise “semi-displacement” hull (which we’ll discuss later). These hulls are designed to generate lift as the speed increases, causing the boat to rise out of the water, which ultimately reduces the drag – allowing faster speeds. In these types of boats, more power yields more speed. Horsepower is your ally, and weight is your enemy – particularly if there is high enough power-to-weight ratio to get you up “on plane” where the flat bottom is skimming the surface. Then, the game changes, and adding more speed no longer requires doubling or tripling the fuel burn for each additional knot.
Now, with all this talk of fuel burning you may think we’re on a mission of arboreal embracement here, but that’s not what this is about. The Case for Slow is about enjoying the experience of boating. We drive boats that are capable of more than double their displacement speeds, but we choose to throttle back and cruise slowly the vast majority of the time – not to save the environment or the bank account (although both are worthy goals), but to get more enjoyment out of our cruise. We travel the Inside Passage – from Puget Sound, Washington to Southeast Alaska – one of the most spectacular cruising grounds in the world. The Inside Passage is brimming with breathtaking scenery, vast unspoiled wilderness, and abundant wildlife. Enjoying all of those elements is about spending the maximum time underway. Cruising for three hours a day at fourteen knots versus six hours at seven is like leaving Disneyland at lunchtime. You’re simply not getting the most fun out of your ticket. In this area, the cruise IS the destination. There’s no big reward for arriving at the anchorage first. If you do – you simply left the party too early.
Then, there’s the stress factor. Piloting a boat at double the speed requires much more constant attention – avoiding other boats, logs, crab traps, rocks (both charted and uncharted) and generally keeping your vessel on a safe course. Not only does this deprive the skipper from enjoying the view, it takes its toll in terms of emotional stress. The obstacles appear at a much more leisurely pace with the throttles pulled back, and the captain has time to contemplate the options rather than relying on quick reflexes to keep the ship safe. And, nobody goes cruising with the goal of increasing their stress and anxiety.
And, on the subject of logs and uncharted rocks, let’s dive into physics again. The damage from hitting an obstacle at double the speed is not just double. More like four times the force is delivered at twice the speed. The odds of critical damage to your boat and its occupants rises exponentially as the speeds increase. Slowing down saves lives – and insurance claims. If we all wanted to be cruising along at fifty knots with death zooming past mere meters away, we’d be driving RVs on the freeway instead of boating.
In the areas where we cruise, fuel burn matters more for range than for expense. At near-displacement speeds, we can easily make it through the remote sections of British Columbia and Alaska with ample fuel to reach the next marina. If we throttled up to “get-‘er-done” we’d soon be wishing for a tow service (Spoiler: there isn’t one). Regardless of your budget, fuel efficiency is important for cruising range, and burning too much too fast can leave you short. Sometimes, going faster doesn’t even get you there as quickly. Racing from fuel dock to fuel dock can actually result in longer total transit times because of detours and waiting. We have cruised the Inside Passage with many “faster” boats who regularly arrived at the anchorage later than we did, owing to reroutes to locate scarce fuel docks.
And, even though cost isn’t a big factor for us, fast cruising can certainly make it so. On a typical summer cruise to Alaska and back, we will travel around 3,000 nautical miles. In our boats, we burn around 2.5 gallons per hour at 7.5 knots. That gives about 3 nautical miles per gallon, so those 3,000 miles burn around a thousand gallons of diesel. At $3 per gallon, that gives us a fuel cost of $3K for a summer. Double our speed, though, and we drop to 1 nautical mile per gallon and we’d be coughing up $9K for fuel instead – for the same trip. That also means that enjoying an hour underway suddenly costs six times as much.
For our own use in the PNW, we haven’t chosen full-displacement trawlers, however. Since we’re not crossing oceans, absolute maximum efficiency and range isn’t as important. And, there are many places we frequent where a little extra speed comes in handy. If you’re late for a date with slack current at a rapids, want to beat a weather system into port, or need to get across the shipping lane well clear of commercial traffic – it can pay to throttle up, warm up the oil, blow out the carbon, and make some time. For that, we have semi-displacement hulls – compromises between the efficiency of a full-displacement trawler and a planing hull. We don’t get quite as much efficiency at displacement speeds as a trawler, and we don’t ever get quite the high-speed planing of a planing hull. In return, the semi-displacement hull gives versatility – the ability to efficiently go long distances at displacement speeds and to power up occasionally to double that speed as needed. For some, this would be the worst of both worlds, but for our mission – cruising the Inside Passage with numerous other types of boats – we like it the best.
We have the luxury of time on our side. We’re seldom needing to skate out to a fishing hole, get the maximum time with bait in the water, and speed back home by dark. We don’t have the kind of jobs where we want to race to the “good” location on Friday night, enjoy a full weekend in the water, and rush back home on Sunday, ready for work Monday morning. In those situations, fast boats are just the ticket. But, for getting the most enjoyment out of extended long-range cruising, we recommend slowing down and settling in for the leisurely ride. Try it. You won’t be sorry.
