Creating purchase specifications for your small swiftwater/flood rescue inflatable boat can be a daunting task. Just like fire suppression apparatus, inflatable boats have very different features and must be specified correctly to ensure the equipment is appropriate for each agency’s unique operational needs.
Once needs have been established, you can the find the boat that fits those needs. This article will focus on motorized swiftwater/flood search and rescue boats. But before making the decision to go with a motorized boat, you need to answer a few questions:
- Do you need a motor?
- Can you support the training and maintenance on it?
- Are you willing to meet the standards set forth by the Federal Emergency Management Agency, the United States Coast Guard, and the National Fire Protection Association?
Motorized boats are expensive and difficult to maintain. Recreational owners have a saying that the two best days of owning a boat are the day they bought it and the day they sold it.
The first thing you must realize is that one boat cannot do it all. What may be right for one agency could be a disaster for another. You must look at your own needs.
Horsepower
First, decide what engine you need. Before looking at type or style of the outboard engine, you must determine the horsepower (hp) you need. A 25-hp engine will do well in most static or slow moving flat water and is recommended for the most common 12-foot inflatables boats. However, you must realize that this is a rescue craft. You will run into scenarios that will quickly reach the limits of your load capacities. You must plan for the worst case scenario. There really is no such thing as too much horsepower–just too much throttle. The worst thing you can do is provide an untrained operator and crew in a swiftwater/flood rescue boat. The second most common mistake is not providing enough horsepower to allow the crew to operate safely. A 30-hp engine is the recommended minimum for swiftwater/flood rescue operation and may be the minimum standard for credentialing in your state.
When we reference horsepower, we talk about the horsepower that you are getting at the end of the propulsion unit. The concept of the output vs. the head power is a critical one, as all manufacturers do not rate advertised horsepower the same. When we reference output horsepower, we use propeller drive as the base for comparison. There are three types of outboard propulsion units: propeller, pump jet, and jet outboards.
Propeller
Propeller is the most common type of propulsion unit made by a wide range of manufacturers. Propeller units are easy to find, have low maintenance, and are the least expensive. They can be found in aluminum, stainless, and composite materials. Aluminum props come standard and are probably the most financially sound decision. If underwater obstructions are not a concern, then the performance from a stainless-steel prop is worth the additional money.
Composite propellers are on the market but have not become mainstream because they are not widely used in the recreational world. Composite propellers have the ability to change pitch and replace an individual fin in the field. Composites have been unable to match the power and speed of aluminum without exceeding the cost. The main downside of propellers is that they are extremely dangerous around subjects in the water. Propeller strikes are nothing to shrug off and have caused severe injury to rescuers. Propeller drive outboards can be outfitted with cages or reinforcement to protect a subject from a propeller strike or to protect the propeller from striking an object. Every aftermarket option will change how the engine performs, and most will affect steering. You must know how it will work before you make the financial commitment as well as making irreversible changes to the outboard structure.
The anti-ventilation or anti-cavitation plate is another factor to consider when looking at propeller drives. Propellers need to be submerged to bite properly, much like the impeller on a fire pump. If the suction hose is too close to the surface, a whirlpool forms and draws air into the pump, reducing output.
The anti-ventilation or cavitation plates prevent the same thing from happening. While these plates are formed and can’t be moved up or down, aftermarket versions can be bolted onto the existing ant-cavitation plate to decrease cavitation during quick turns. Aftermarket anti-cavitation plates are similar in shape and just bigger in the sides and rear or all the way around. If your boat cavitates during quick turns, first adjust the height of your engine before adding a plate. A higher performance propeller will help to decrease cavitation but can get pricey after bouncing it off a few underwater obstructions. Full coverage anti-cavitation plates will also reduce spray in the back of the boat.
Hydrofoils can also be used to enhance performance. Hydrofoils provide lift to get the boat up on plane faster and keep the boat at plane with slower speeds. Hydrofoils are very large triangular shaped devices with a “U” to fit around the lower unit. Most hydrofoils bolt onto the stock anti-cavitation plate, but some are available with sturdy clips. Bolting through a stock anti-cavitation plate for any reason should not be taken lightly as the holes may crack and cause significant damage to small lower units. Plates are more useful for larger boats and will reduce the ease with which you back up.
Jet Pump
The second and most expensive propulsion option is called a jet pump. Jet pumps are impeller units that are installed on a lower unit to decrease possible injury to a subject in the water. These units are highly recommended for crews working with divers. The lower unit has the same draft as a propeller unit and five to eight percent horsepower output decrease compared to a propeller unit.
The pump jet is not supplied by the engine manufacturer but installed by a third-party vendor. Pump jet manufacturers prefer to install their units on specific engines because the internal drives are built better for heavy duty use. The engine is drop shipped to the pump jet manufacturer then delivered to you or your boat vendor. While pump jets are the most expensive, upfront cost repairs are usually cheaper with upfront flat fees from the manufacturer.
Jet Outboard
The third and safest option is called a jet outboard, not to be confused with an inboard jet. Inboard jet drives are more common among larger swiftwater rescue boats (18 feet plus) or recreational boats because the engine is actually inside the boat vs. on the transom. Jet drives do not have propellers and are similar to pump jets because they run with an impeller. Pump jet impellers’ intake and discharge are inline, making them more efficient than jet outboards that take the water in and discharge it at nearly 90 degrees. This is why a pump jet has a six percent power reduction and a jet has a 30 percent power reduction when compared to a prop.
Jet thrust comes from the pressure discharged, not the impeller of a jet pump or a propeller, so expect a decreased throttle response time. You must be very careful when looking at jet outboards to see how the manufacturer rates the listed horsepower. Some rate it at discharge while some rate it at the power unit. For example, Yamaha’s 40-hp jet is a 40-hp power head and results in 30 hp at discharge, while Tohatsu’s 40-hp jet is a 60-hp power head and results in 40 hp at discharge. It is very important to understand the listed horsepower may not be what you get at discharge. Read engine specifications carefully, as not many vendors are familiar with jet outboards unless they sell them on a regular basis.
Another option is to purchase a prop outboard and drop ship it to an aftermarket jet manufacturer. The aftermarket option will give you more variety of engines and weights. Besides safety, the major benefit is decreased draft. Jet outboards only draft two inches below the hull compared to the 14 inches of a prop or pump jet. Jet outboards have greater access capability and fewer “Dear Chief” letters with properly trained operators.
Jet outboard stabilizers are attached where the intake housing mounts to the pump housing. The stabilizers branch out to both sides in various shapes. Jet outboard stabilizers are similar in function to propeller outboard hydrofoils but look different. The wings help the boat get up on plane faster and stay there longer with slower speeds but are prone to breaking in a flood environment.
Intake fins are bolted or welded to the side of the intake and stick out and down only an inch or two. Intake fins are used to increase the amount of water being applied to the intake. The intake wings push more water into the intake to reduce cavitation, especially during tight turns.
Now you need to find a boat that fits that engine. Two key factors for outboard fit are weight and transom height. Every boat has a maximum load capacity for passengers and equipment including the outboard engine and a maximum transom weight. Every boat will have a recommended horsepower, but remember that this recommendation is for recreational use. In rescue operations, expect to be at the maximum allowable maximums for both horsepower and transom weight.
Don’t be disappointed if you can’t find a boat that can handle the engine you want. Good manufacturers have an extra five to 10 percent rule for safety and will grant exceptions in writing to well-trained agencies to exceed the advertised maximums. Before moving forward, make sure the letter will suffice when questions are asked by your administration and boat enforcement agencies. Don’t be afraid to talk with the manufacturers about your project. If you need your boat to be portable, realize that a five- to 10-hp increase may increase the weight of the engine dramatically.
Start Up
No matter what type of propulsion unit you choose, they all have similar power heads. To go anywhere, the engine has to start. Starting options are limited to either rope pull start or electric start.
Rope pull starting is more reliable than electric starting because it requires less maintenance and has fewer problems. If you have ever tried to pull over a 40-hp or greater engine, you know why electric start is available. It is difficult to pull over a 40-hp motor, and most engines above 40 hp don’t have a rope option because it is too difficult. Replacement ropes and pull handles should be inspected often and stocked for replacement on the boat trailer.
Electric start is a welcomed addition to any operator familiar with a pull start. It also prevents facial injury to unprepared occupants when an operator pulls the rope back. The electric start requires a couple of changes. The first is a battery. The battery is required to turn the electric starter. The electric starter will add some weight to the engine. The battery will need to be securely mounted to the floor in an area that will not hamper rescue efforts or allow damage to the battery.
The second change is an ignition. Key ignition is the most common and can be very troublesome in small boats. Keys get lost, they break in the ignition when objects are jostled around in whitewater, and mounting can be difficult. Keyless push button ignitions with battery switches are preferred, much like with fire apparatus, but are rarely available. If you do have a key, secure it to the ignition with a small cable. Keep needle-nose pliers in your maintenance kit to remove or turn a broken key. If your engine comes with a pull start backup make sure you can access it. Some require tools to access the rope and handle. A jumper kit will also be a valuable addition to your tow vehicle equipment cache. Battery conditioners are highly recommended for agencies that experience different seasons with reduced call volumes.
Steering
Steering control also falls under consideration of the engine. Types of steering control will change how the boat handles and how the crew operates. Steering controls are broken down into either remote or tiller control. Remote steering control is when an operator uses a steering wheel to direct the boat. The steering wheel is either center mounted or side mounted. A center-mount remote wheel is in the center of the boat either on a console or a console with a seat or bench. Throttle lever and ignition are mounted close by. Side mounted is a console mounted in the middle of the boat but off to one side with a lighter weight console and seat. Center console is best for weight distribution over side console and tiller operation. Side console allows for easier forward/aft movement within the boat and long storage such as a litter.
Both remote steering styles operate with use of pulleys and cables that must be inspected and maintained regularly to avoid catastrophic directional results. Cable and pulley movement will create a slight response delay in steering but is easy to get used to. Operators will quickly get used to driving with one hand to have one hand on the throttle at all times. The steering wheel increases the amount of input needed to make a change in direction. Some agencies have installed suicide knobs to make steering input faster. The best reason for a remote steering application is a significantly reduced training curve. Operators that have experience operating any vehicle with a wheel will take to it much more quickly than tiller operations.
Tiller operation is more common to swiftwater/flood rescue boats as it is cheaper, requires less maintenance, is more interchangeable, and is easier to portage or transport. Tillers provide an immediate steering response but increase the weight of an engine. Tillers also have a greater training curve than remote steering but allow the operator to control direction and throttle with one hand while the other hand stabilizes the operator inside the boat. Tiller operation requires the operator to be at the rear of the boat changing the weight distribution but provides the most space for victims and equipment. Higher horsepower models do not have a tiller standard, and they may need to be specified. Tillers come in a variety of styles. We recommend a straight tiller vs. an offset tiller to allow ease of operation for left-hand or right-hand operation. The length of the tiller should be short but long enough to allow needed leverage.
Older and very low horsepower models have forward, neutral, and reverse controlled in the same throttle. Most have a paddle to control transmission or gate position for safety. Make sure the shifter paddle is easy to locate without looking. The tiller can be loaded with options such as electric trim, ignition, and kill switches. An electric tiller will make it impossible to get the lower unit up fast enough to avoid an underwater obstacle unless it has a quick-release lever. Even if the engine has a quick-release lever, the amount of force you need to apply may be greater than what you have available.
No matter what type of steering you choose, you must pay attention to the locations of kill switches and buttons. Buttons should be easy to find in a hurry but not easy to bump accidentally. Kill switches are designed to be used with a tether in case the operator is ejected or moves away from the controls. Kill switches use specific tether mounts. One tether must be kept with the boat at all times and every personal flotation device (PFD) should be outfitted with one as well. If you have different kill switch mounts, look for a universal tether. Spare tethers mounted to the underside of the engine cowl or in the battery compartment are recommended.
Fully Inflatable
Now that we’ve determined what engine you need, let’s look at what boat you need. Fully inflatable boats are most commonly used for access and egress issues. Whitewater rafts and other rescue inflatables have become commonplace on swiftwater rescue teams and are therefore used when teams are deployed in flood areas. Nonmotorized inflatable boats are significantly lighter than motorized inflatables and are used in flood water for wading evacuation of victims. These boats do not have hard floors and are self-bailing for swiftwater use resulting in wet floors during evacuation. The benefit is that these boats have flat bottoms and very little draft when compared to motor capable inflatables.
Fully inflatable boats have very limited engine weight and horsepower capabilities. Common lengths max out around 10 feet and 15 hp. Fully inflatable boats are more susceptible to flood debris because they are made with lighter fabrics. Benefits include portability, cost, and options for high-pressure filling with an octopus regulator that fully inflates the boat with one 30-minute self-contained breathing apparatus bottle.
Ridged floors are different than ridged hulls. Ridged floors are interior and they serve two functions: They support everything inside the boat (including people, equipment, and the transom), and they serve an important structural function in the fabric hull. The fabric hull starts as a loose piece of fabric glued to the sponsons to form a watertight seal. A long cylindrical air bladder similar to a log is inflated along the keel pressing downward from the underside of the ridged floor boards, stretching the fabric hull into a “V” shape.
The first type of inflatable with hard floors uses marine plywood with aluminum hinges or slats. Marine plywood is light and cheaper than most alternatives. It is important to note that without proper maintenance and oiling, the plywood is prone to mold and splintering from sun damage and use. The marine plywood repairs and any securing of interior objects such as fuel cells, batteries, or straps for paddles can be made in house, keeping costs down. The marine plywood tends to be slippery when wet but can be treated with friction compounds to reduce slippage.
Aluminum floors are more common in the 12- to 16-foot range and are much more durable than marine plywood. They are lightweight, require little maintenance, and have a decent traction surface. Aluminum is more commonly used than other metals because it does not rust and resists corrosion well. Aluminum floors are more expensive than marine plywood and need to be inspected for splintering as well as jagged rivets on the bottom. Aluminum is more difficult to repair, and rivets are recommended for mounting equipment such as fuel tank and battery straps.
Inflatable boats are available with ridged plastic, fiberglass, or aluminum hulls. Ridged hulls are more expensive than inflatable hulls because of their materials. Ridged hulls are 30 to 50 percent heavier than fabric models with the same length, significantly limiting portability. Stay away from the minimum horsepower range on ridged-hull boats. Underpowered ridged-hull boats will have difficulty making plane with a rescue load and have decreased agility.
The weight and deep “V” hulls of most ridged hull inflatables require the use of trailers and boat ramps. The deep “V” hull design significantly improves ride and handling over inflatable hulls. Recently, rigid-hull manufacturers have designed shallow water ridged hulls that significantly reduce the draft of the boat. The ridged hull is more resistant to flood-prone objects and has much less friction than an inflatable hull.
Reinforced plastic hulls are the lightest but are not reliable in rescue use because they crack easily against hard objects. Plastic hulls are used by recreational operators with little workloads. Plastic is the most difficult to repair out of the three. Fiberglass is the heaviest of the three but gives the best ride. Aluminum hulls are light and durable, making them the first choice for swiftwater and flood work in a ridged hull series.
Inflatable Pontoon
Inflatable pontoon or “cat” catamaran boats are popular with agencies that work medium-sized rivers with turbulent white water. Cat boats have two inflatable hulls, similar to a pontoon boat. The riding surface can be a fiberglass mold or some type of netting supported by frame rails. Cat boats, like their namesake, can be very nimble with very little surface area when compared to a standard inflatable boat. The decreased surface area allows these boats to be much faster on plane and in operation than standard boat styles. Some cat boats have a riding surface on or just above the water surface at idle, while others have a flat deck across the top of the tubes. The lower riding cat boats are prone to swamping in whitewater because they don’t have a “V” style bow pushing the bow upward. High-riding cat boats have large tubes, increasing the difficulty of retrieving a victim over the freeboard. Cat boats are best known for their stability and agility while paddling in white water because of their setup. The stability comes at a cost, with longer turning radiuses when under power.
The inflatable tubes that form a “U” around the hull in standard inflatable rescue boats and the hulls of cat boats are called sponsons. The sponson is an inflatable tube that gives the boat buoyancy and stability and protects the floor from being swamped. The sponson is broken up into different sections called chambers. The number of chambers is determined by the manufacturer for types of use and size. Chambers are high-volume/low-pressure and are filled at 1.5 psi to 3.5 psi. Some chambers come with relief valves that blow off unwanted pressure so the chamber will not fail. Relief valves are highly recommended for swiftwater/flood rescue operations. Relief valves are commonly found in the sponson but not in a keel or speed tubes.
Speed tubes are small-diameter inflatable tubes that are attached to the lowest portion of the sponson in line with the keel only. Speed tubes are used to decrease surface area when the boat is on plane. Speed tubes decrease drag, thus increasing speed. When not on idle, speed tubes increase the draft of a boat and grab changes in current more aggressively. Eddy turns and peel outs are not as forgiving and turning radius is larger than without speed tubes. Speed tubes are more commonly found on static water, salt water, and class I whitewater.
Planning strips are applied to the outside of the sponson to bring the boat up on plane faster and maintain plane at slower speeds. Victim retrieval from the water over planning strips is difficult but can be fixed by par buckling.
Materials
There are several main types of fabric used in inflatable boats.
Hypalon is a rubber impregnated fabric that is much easier to repair in the field than other materials. A synthetic weave of materials is used to make the material light and durable.
Polyvinyl coated (PVC) fabric is more durable and used often in ocean operations. PVC is harder than hypalon and will cause the boat to slide off physical objects easier than hypalon. PVC will slip off rocks easier, causing less damage. The firmness makes is difficult to hold position when transferring patients from water bound objects such as flooded cars.
Plastic is very similar to PVC. Both plastic and PVC are difficult to repair in the field because the fabric must be perfectly dry.
Polyurethane is the newest material in the inflatable boat realm. It is slightly more resistant to abrasions than hypalon and is the most puncture resistant of all. Polyurethane appears to be more chemically resistant and easier to clean than other materials, but more testing is needed on this new material. It is the most environmentally friendly, but field repairs are more difficult than with PVC or plastic.
Boat Length and Width
The length of the boat is determined by the horsepower you need because engine weight and capacity increase with boat length. Capacity is determined by available buoyancy; the longer and wider your boat is, the more capacity it will be rated for. Every swiftwater/flood rescue boat must have a boat operator and agile bowman. Beyond that, capacity is meant for victims and whatever they may bring. The only exception to this rule is the transportation of a rescue swimmer. Three adults combined with an outboard engine get very close to the maximum capacity of the boat. You will not find a boat less than 12 feet that can meet those needs.
A 12-foot boat is more nimble and agile when weighed and powered correctly. It moves in and out of tight flood passages with ease. In general, 16-foot boats are considered the maximum size for swiftwater/flood rescue operations. However, some locations with sparse vegetation and deep channels are more accommodating to large boats. Agility is very useful in swiftwater/flood rescue conditions, and 16-foot boats have a larger turning radius. Additionally, 16-foot boats are heavy, and most require trailering to get into the water. The ability to use a trailer for launching and retrieving in flood conditions is a rare luxury. Most often, the trailer can’t get deep enough for the boat to float and there are not enough resources to pick a large boat onto a trailer. Therefore, you must weigh your capacity need with your available resources when considering the length of your next boat. When comparing different manufacturers, consider the weight-to-length ratio, which will help you determine the length-to-horsepower ratio needed.
Boat width and tube size are commonly associated with length based on manufacturer testing. You don’t want anything less than five feet wide because it will tip side to side. Beyond seven feet wide, it is hard to find a trailer that is narrow enough to fit in a traffic lane while keeping the boat low enough to deploy in shallow water conditions.
Put It Together
Once you have determined your engine and boat, you have to fit them together. The next step is to identify what the available shaft size of your engine is. This information can be provided by the manufacturer or by measuring from the top of the transom mounting bracket to the anti-ventilation plate. This measurement will work on prop and pump jet models. Measure the shaft length of a jet outboard by measuring from the top of the transom mounting bracket to the bottom of the intake. The transom height is measured from the top of the transom to the bottom of the keel. Measurements of 15 to 17 inches are considered short, and measurements of 20 to 22 inches are considered long. Anything greater than 25 inches is extra-long and is not used for swiftwater/flood rescue applications.
If the transom height falls in the range of 17 to 20 inches, refer to manufacturer’s recommendations or use a jack plate. Installation of a jack plate may be required to raise the height of an engine on a short transom. Do not cut the transom or install jack plates to lower the engine.
We recommend 25 to 30 hp for 12-foot boats, 40 to 50 hp for 14-foot boats, and 60 to 80 hp for 16-foot boats. Anything less and you will find performance issues with an operator, agile bowman, gear, and a couple of victims. Weight distribution is key with heavy engines, so make sure to have the weight forward to reduce the time it takes to get up on plane and the draft of your boat while accelerating.
Other Things to Consider
Whatever equipment you want in the boat after it accidentally flips needs to be secured to the boat prior to an accident. The fuel tank or fuel bladder needs to be secured in an area where the fuel line will not get pinched. Consider shortening the length of the fuel line to prevent kinking, but don’t make it so short that a falling body would pull it from the engine in a turn. The fuel cell should be brightly colored and labeled to indicate what type of fuel it contains. Hard cells are more common and much cheaper than soft cells but may not be allowed to be transported by air. If air transportation for deployment is a concern, work with your aviation transportation agency to find the fuel cell that will best meet your needs and their standards.
The battery should be secured to the floor in a watertight box. The posts on the battery should be changed out to wing nuts so you don’t need tools to take the battery out. If possible, have a rope backup available, and make sure your jumper cables or jump pack alligator clips fit the small battery terminals.
Paddles are your lifesaver. Do not be stuck upstream without them. Paddles need to be secured to the boat but also be easily accessible as soon as the engine stops. They can also be a great reaching device. Outfitter paddles should be purchased to replace the ones that come with the boat. Outfitter paddles are bright in color and easy to spot when floating in floodwater. Nonexpandable 57- to 62-inch “T” handle paddles will drastically improve the paddling ability of a two-person crew.
Ropes in water rescue should be considered an evil serpent waiting to strike. Ropes will cause mayhem if not controlled. Stern lines should be avoided altogether. Bright colored polypropelene bow lines should only be just shorter than the length from the bow to the transom so they can’t reach the propulsion unit. Flip lines should be securely tied to their anchors and then bundled in a small reflective cinch bag that is attached to the other end. We recommend webbing for flip lines as it is easier to hold and can provide an anchor resource for pins. The flip lines also double for parbuckling if needed. Two bright colored 75-foot reflective polypropylene throw bags should be attached to interior equipment rings with clips that are easy to operate with gloves on.
Drains are extremely important for getting rid of water fast. Drain plugs are used for recreational boats or to clear the last drop of water when the boat is on a trailer. Swiftwater/flood rescue boats should have large-diameter self-bailing drains. One pound of water weighs eight pounds, and a 14-foot standard inflatable boat can carry more than 50 gallons under the floor. That is a lot of extra weight that will significantly decrease the agility of your boat. If your boat gets swamped with that much water, it is an area you want to get out of quickly, and getting rid of the water faster will help.
Arches on inflatable swiftwater/flood rescue boats should be limited to those agencies that need them for radar or emergency signaling in congested navigable waterways. Arches are more common on larger boats and are not recommended for use in swiftwater/flood rescue use. Arches make it very difficult to right an overturned boat and may grab on underwater obstructions. High-vegetation areas common among river banks and in flood conditions can prohibit access to victims on boats with arches.
Always carry PFDs for victims. Remember that not all of your victims will be adults. Youth, child, and infant PFDs are very handy when moving in and out of the boat. Small PFDs are cheap and provide a great public relations tool when extended to a family without one during a training evolution.
Parbuckling nets like snow fence or cargo nets with body bags or body recovery systems should be available to deploy but are not needed in the boat at all times.
Maintenance kits may not have a place in your boat but are needed to correct minor problems so they don’t become major problems. The kit should be waterproof and buoyant and have high visibility. If it is in the boat, don’t make it too big, and make sure you can secure it. Maintenance kit items should include spark plugs and tools; tools to change out the engine if bolted on; cylume sticks or night navigation lights; emergency signal devices; inflation valves; pressure relief valves; a fabric repair kit with patches and glue for your type of fabric; a spare propeller; a floating prop wrench; a dead blow hammer; a castle nut and cotter pin and grease. This list is not an end-all list but it does contain items to consider. Figure out what works best for your operation.
Differing Needs
Remember that no one boat does it all, and each individual agency has different needs. Purchasing a swiftwater/flood rescue boat is a bigger decision than you may realize. Vendors will try to sell you everything they have. You have to do your due diligence to find the right boat for your needs, operations, training, and level of commitment.
Get out to other agencies, go to trainings, and demand hands-on time before committing to a purchase. You wouldn’t make a blind purchase of a specialized apparatus like a tower truck or heavy rescue, so don’t do it for a swiftwater/flood rescue boat.
