While being able to maintain high planing speeds in rough seas makes a boat safer and more seaworthy, it’s also inevitable that you’ll have to occasionally run at slower speeds to suit the conditions. You may find yourself in a harbor approach that’s rough and crowded with traffic, or you might have to slow to steerageway to study a bar before crossing. The ability to control a boat at low speeds in conditions such as these is fundamental to its overall capability and suitability.
Slow-speed control is first a matter of being able to control your heading, even with a strong wind on the bow, which is the most difficult direction when it comes to relative wind. That’s because your rudders are back aft, and most boats have high freeboard and little hull depth underwater forward. The bow turns into a kite, as a result.
One of the most uncontrollable boats in a strong wind right off the bow is the typical inboard production express cruiser with small props and rudders and prop pockets. Small props produce an equally small discharge race bouncing off small rudders, with little steering control below 20 or 25 knots of headway. The deep prop pocket can make things worse by introducing an eddying and unpredictable water flow off the prop that impinges on the rudders.
If you own such a boat, realize that it’s very limited, and don’t venture out in demanding conditions that may require precise low-speed directional control. It you push your luck, you can quickly find yourself veering off course and hitting another boat or running aground if you’re near shoal water.
The express sportfisherman is better in these conditions than a cruising express — for example, a Hatteras or Viking, both of which have deeper gears, larger and slower-turning props, and bigger rudders. These boats have to be able to maneuver nimbly while working a fish at low speed or even with sternway, so their running gear produces much better responsiveness at low speed. These boats also tend to be heavier, with greater chine immersion, and the extra hull immersion creates keels of the hull sides, with improved directional stability. Their mass also makes them more rooted and less susceptible to wind and waves.
Even if your boat has good-size rudders, they have to be able to turn far enough to deflect prop thrust effectively. Years ago I ran a 35-footer that had rudder stops set at 22 degrees, which I found out after the boat took 75 seconds to turn 360 degrees (about 40 seconds longer than it should have). The axe-head rudders on most planing powerboats, as well as the flat-plate and foil rudders on many displacement vessels, should generally turn 35 degrees to full rudder (70 degrees total arc) and 37 or 38 degrees to the hard stops. Much more angle than that, and they start to stall, losing sideways lift and generating vertical lift. However, any less than 35 degrees, and the rudders won’t generate the side thrust and maintain control as well as they should. Your maneuverability will suffer greatly, and your turning circle will increase so you end up turning like the USS Iowa.
Another issue bearing directly on steering responsiveness is the number of turns it takes to bring the wheel from lock to lock. For me, the typical sterndrive or pod system is ideal at three turns from full left to full right rudder. When you put the wheel over half a turn, the boat responds almost instantly, turning and heeling (if you’re going fast enough) in the direction you want to go. I ran a Fairline 65 that was three turns from lock to lock, with power steering, and it was a revelation — it handled like a runabout. Suddenly, all the American convertibles and cruisers with six turns felt like leaden dinosaurs.
For a given above-to-below (A/B) waterline area, the most controllable boats are those with props that turn to direct thrust, rather than just having fixed props with rudders to deflect thrust. This includes pod drives. With pods that are spaced far enough apart and well forward of the transom, you may be able to get away with using the system’s station-keeping mode, which maintains heading and position. To find out the limits of the system in rough conditions, you’ll have to experiment.
Off the wind
When station-keeping, you might be best off lying with the bow 10 or 20 degrees off the wind and allowing yourself to be slowly blown sideways. When you move far enough to one side, turn across the wind and put the other bow to the wind and seas, basically tacking back and forth as long as you need to. This is much easier than using lots of steering and power and gears to keep her directly into the wind.
The idea is to find a balance between fighting the wind continuously and getting blown sideways too fast, or taking the seas too close to the beam. It may also be possible to find a good balance of rpm and rudder, or perhaps using just one engine, to let the boat find its own way with little steering effort. If you make too much headway upwind, you can even turn off the wind enough to let yourself get blown back to leeward — just don’t let her roll too deeply in the process.
Your boat will lie at a natural angle that’s a function of the ratio between the above and below waterline areas and shapes. A lobster boat with a house forward and big cockpit aft will naturally lie with the bow downwind to some degree, and this is limited in part by the deep keel’s resistance to lateral movement. I’ve done 3 or 4 knots in lobster boats with the engine in idle and the rudder put over just right to hold her with the seas on the quarter. A trawler with an aft deckhouse and low, long foredeck may actually lie bow to, or at least the beam square on to, the seas. Displacement workboats used to have steadying sails precisely because it is so hard to keep a boat pointed into a strong wind, especially one with low power, shoal draft and lots of topside cross section.
Working the throttle
The degree to which your boat will respond to the throttle at low speed is almost entirely a function of the boat’s displacement, sail area balance and the power of the engine and size of the prop. It’s the size of the water column moved by the propeller that determines traction at low speed. A pair of 18-inch props on a 40-footer just can’t do the job as well in demanding rough-water conditions. However, a single 26- or 28-inch prop can do an excellent job if the rest of the drivetrain and boat proportions are right. The more power you have to use to maintain your heading, the more headway you’ll pick up, and that may be the last thing you want.
With a twin-engine boat that has small props and rudders and poor steering control, you may have to resort to using the gears — backing on one engine or the other — to maintain your heading at bare steerageway. This is fraught with peril, however, since you can actually end up making sternway and losing control of your heading altogether, or taking a wave over the stern. It can also be a vicious cycle, like oversteering, with more and more throttle and faster and faster shifting until you’re in a real mess.
The right time to go slow
When running head-on into very steep seas, especially if the waves are breaking, it may be that slowing to displacement speed or steerageway is your only recourse. Steerageway is the slowest speed with the engines in gear at which a vessel’s heading can be controlled. You’ll need more power and speed with a strong bow wind than in calm conditions because the weathervane known as the bow has so much control over the proceedings. It takes more power and speed for the rudders to win the heading argument.
If you’re approaching a bar, you’ll have to get close to read the waves and figure out the timing of the lowest wave cycles. While you’re busy doing this, you may have to make no headway at all to avoid being carried into the worst of the breaker cycle.
The more bow-on you can meet a wave, the better, though you might trade a little more roll, with the wave broader on the bow, for less impact velocity. If you have a boat that steers well, you may well be better off with the seas abaft the beam in terms of boat motions that you and your crew can take for hours on end.
If you’re well offshore and a weather system is coming through, with wind and seas building for the foreseeable future, there’s no substitute for a planing or semidisplacement hull that remains controllable and seakindly at 20 or 25 knots in all directions to the sea. If your boat has full and flat sections forward, with low chine elevation (height above the waterline) in the forward half of the hull, you will have no choice but to slow to a crawl. This is also true of hulls with sharp entries and flat sterns; these boats are dangerous when running down-sea because the bow digs in when running down a trough and the flat stern has no directional stability, or keel effect.
I consider the ability to run 20 to 30 knots an important seaworthiness factor because you can avoid the worst of the weather by beating it home or running around it.
Steering and engine problems
Losing power may be the worst scenario since you can’t control your heading or position — geographical or in relation to local waves — without it. If you have a sea anchor that’s heavy and large enough to be effective, it can help keep the stern pointed higher into the seas. This will reduce the chance of a capsize, but you’re still at the mercy of the elements.
Of course, this argues for a well-maintained main engine, plenty of fuel — more than you’ll need so you have a healthy reserve — and for two engines if you have any doubt as to propulsion reliability. Always be ready to tow and be towed. This calls for 600 feet of hawser, a towing bridle, chaffing gear, and cleats or bitts that are strong enough to handle the load.
Low-speed handling inshore
Challenging low-speed situations such as maneuvering or keeping position within tight channels call for utter predictability in course-keeping. In this situation, you have both other traffic and shoal water to avoid. This requires that you know where you are and where all other vessels are that you could potentially collide with, including those overtaking you. For example, when maneuvering to show an oncoming vessel your intentions by showing the correct target angle in a meeting situation, the last thing you want is to cross his bow, even momentarily, which would certainly confuse him as to your intentions. In these conditions, it’s very important to keep up plenty of speed so you have a responsive helm. It doesn’t do any good to keep slowing down timidly when the result is increased risk of collision or running aground. Often the most prudent action is to increase speed for increased agility and also to keep clear with a quick course change to create a wider berth.
At the dock
Maneuvering around the dock takes the same sort of balance as maneuvering in a crowded channel. Don’t proceed so slowly that you can’t control the boat, but not so fast that things get out of hand. This balance depends a lot on your boat’s power-to-weight ratio and how that power is delivered to the water (its propulsion traction at slow speed); its steering response; whether you have bow or stern thrusters; all-around sightlines from the helm; your crew’s line-handling skills; and your skill as a boat handler.
Of course, joysticks and thrusters can reduce the intimidation factor when docking. But remember, there is still a learning curve, and practice makes perfect.
Having lots of wind and current often make a good case for using more speed, not less, provided you have the boat and the skills to operate safely at higher maneuvering speeds. This might call for a 3- or 4-knot initial approach rather than tentatively trying to make your way in, crabbing at 1 or 2 knots. You have a lot more control over your boat in a beam tide or wind at 5 knots than you do at 2.
Get out and practice
There is no substitute for practicing. The more you run your boat, the better you’ll get at it. Make sure you understand the basics of pivot points, twisting or walking a twin-engine boat, backing and filling a single-screw, and so on. Practice often — approaching a dock, getting underway, picking up a mooring, using spring lines, retrieving a man overboard. You’ll be better prepared and more confident in the process.
December 2014 issue
Last month I discussed the capabilities and limitations of planing, semiplaning and displacement hulls in rough conditions. Now let’s take a look at offshore boat-handling tactics, tips and strategies.
This is the first in a series of stories on rough-water boat handling. Although you might not intend to go out in seas taller than your VHF antenna, you may well find yourself in such conditions if you venture offshore often and far enough. In this first article, I’ll consider the capabilities and limitations of the three basic hull forms: displacement, semidisplacement and planing. I’m assuming in this discussion that each of the examples under consideration is the best of its kind in terms of hull form, seaworthiness, helm sightlines and so on. Each hull form has its pluses and minuses. This overview should help you think more deeply about the issue of seaworthiness.
F. Todd Warner, an authority on classic wooden powerboats who owns the original POSH, approached designer Bill Prince roughly two years ago about building a 21st century version of his 1937 classic.
“I am starting my 40th year specializing in the restoration, sales, service, design and construction of vintage boats and vintage boat design,” says Warner, CEO of Mahogany Bay and RetroModerne Yacht Design in Mound, Minn.
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