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Tech Tuesday #16: Wakeboard Ballast Systems Explained

Tech Tuesday: Ballast Pumps Explained

Wakeboard ballast is defined as the storage of mass within a boat to displace the hull deeper in the water which in turn changes both the wake size and shape. There are two common designs for a wakeboard boat ballast system depending on what type of pumps are used.

The aerator pump system is the first and still most common ballast system used. An aerator pump only pushes water in one direction. This system is configured so that one pump will fill the tank from the top port and another separate pump will be used to drain the tank from a bottom port. This design has the fastest fill and drain times, is the least expensive, but does require more space for the additional hose lengths needed to work correctly.

The second ballast system design relies on a flexible impeller driven pump. The flexible impeller pumps are reversible meaning one pump can both fill and drain through the same bottom port in the ballast tank. This system is usually more expensive but is easier to install and takes up less space. This system's on off switch can be controlled by a timer that will shut off the pump when the tank is both full or empty. The impeller pump ballast system is truly automatic in this respect.

Aerator Pumps: Quieter, Longer Lasting, Less Energy ConsumptionAttwood Tsunami 1200 GPH

The aerator ballast pump (Example: Attwood Tsunami, Shurflo Piranha, Rule Livewell) was initially developed to fill livewell tanks in fishing boats. When wakeboarding became popular and riders were looking to enhance their wake size, the livewell pumps were found to work really well to fill portable ballast bags. Boat manufacturers saw this and began integrating the pumps into their boats to fill strategically placed hard plastic tanks.

The aerator pump is flow-through and works by propelling or pushing the water at a faster velocity in one direction. This means when the pump is off it does not act as a check valve allowing water to travel either direction unrestricted. When the pump is turned on water in the inlet is accelerated through the pump to the outlet. Aerator pumps are not self priming and need to be mounted below the waterline in the hull to maintain a consistent supply of water. If the water supply is limited the pump can lose prime and will air lock. No damage will be caused by running the pump dry since an aerator pump uses a hard impeller and is not water lubricated.

Aerator Pump System Design: (
Aerator Pump Ballast System Diagram)
Water Source
We DO NOT recommend using the engine’s raw water intake as the source of water for the ballast system. The risk of damage to the engine is not worth the small amount of convenience during the installation.

Aerator Ballast Pump SchematicThe number of pumps that will be using a single water intake will determine the correct size of the bronze thru-hull fitting. When only suppling water to a single pump a 3/4” or 1” thru-hull intake will be sufficient. If the water needs to be distributed to more than one pump the intake should be at a minimum of 1” and should probably be 1-1/4” to 1-1/2”. Once the intake comes through the hull into the boat a bronze ball valved must be placed on top as an emergency shut off. If the intake is suppling a single pump it can be connected directly to the ball valve. When using multiple pumps the intake will need to feed water into a manifold that can be shared by the fill pumps for a continuous water supply. (NOTE: All pumps must be below the water level.) The more pumps that are connected the larger the manifold will need to be but a good rule of thumb is to construct it with the same size fittings as the thru-hull intake. The fill lines should be run to the ballast bag in the least restrictive route possible to avoid tight radiuses that could crush or kink the hose. Before the fill hose is connected to the sac a Vented Loop Anti Syphon Valve must be added in line. This valve prevents passive filling and draining by eliminating the vacuum in the system. (NOTE: This fitting needs to be mounted higher than the intake of the ballast bag when the bag is completely full.) The fill line will then need to be connected to a top port on the ballast bag.

Vent / Overflow
The second fitting that will be used on top of the ballast bag is for the vent or overflow connection. This is a necessary part of the ballast system because without it the bag will either trap air and not fill to capacity or grow larger than the compartment and potentially cause damage. By adding a vent the soft structured bag will only grow as large as the confines that it is given. The bag will also discharge when full alerting the driver to turn the pump off. The vent hose needs to be routed above the sac and the thru-hull fitting needs to be at a level that is higher than the bag fitting when it is filled completely. (NOTE: Installing the thru-hull fitting as far forward toward the bow will ensure that the bag does not drain when wakesurfing since the boat is heavily weighted on one side.)

Draining
The drain port on any ballast bag is always at the end on the bottom. The drain pump must be at or below the bag's port to ensure that gravity will do the job of keeping the pump primed. The proximity of the pump is also a huge factor in how well the system will drain. If the pump is close to the water source and primed at all times the chances of an air lock are less likely. The hose connected to the outlet on the drain pump must run up beyond the height of the ballast bag just like the vent line. It is also advised to loop the hose before connecting it to the thru-hull fitting to ensure that the bag does not drain due to the force of water pressure from a full ballast bag.

Flexible Impeller Pumps: Reversible, Built In Check Valve, Easy InstallationJabsco Ballast Puppy Pump

The flexible impeller pump has been used for bilge pumping, livewell circulation, washdown systems and general fluid pumping. The first ballast application using the flexible impeller pump was by MasterCraft when they started using the Jabsco Water Puppy pump to fill and drain ballast bags in their wakeboard boats. Jabsco worked closely with MasterCraft to develop the Jabsco Ballast Puppy Pump and has since emerged has the leading supplier in the industry. The simplicity of the pump is what makes it so appealing. Being able to use the same port to both fill and drain is very convenient.

Unlike the aerator pump a flexible impeller pump is self priming meaning it does not need to be mounted below the water line as it will actually pull water into the system from the thru-hull inlet fitting. This also means the pump will act as a check valve and will not allow water to flow in or out. The impeller is water lubricated so running dry will damage the impeller if not the entire pump. The chance of “run dry” can be almost eliminated by installing an ballast pump timer. Another option is to design a system with a visual and audible indication of when the bag is draining. The best rule to keep in mind is that when the pump is not circulating water be sure to turn it off.

Flexible Impeller Pump System Design: (
Reversible Ballast Pump System Diagram)
Water Source / Draining
We DO NOT recommend using the engine’s raw water intake as the source of water for the ballast system. The risk of damage to the engine is not worth the small amount of convenience during the installation.

The suction that a flexible impeller pump has can create issues if the water intake is shared. By using a 1” bronze thru-hull fitting the pump will have a sufficient source of water. Immediately after the thru-hull intake fitting install a brass ball valve as an emergency shut-off point to allow you to immediately stop the flow of water into the boat if something goes wrong. On top of the ball valve add a 1” hose barb fitting. (NOTE: Using 1” ballast hose throughout the system is preferred and will make later steps easier.) The fill lines should be run toward the ballast bag in the least restrictive route possible to avoid tight radius's that could crush or kink the hose. To implement a system that drains above the water line install (Visual and audible indication of draining) a check valve or non return valve inline to prevent water from draining back through the intake and out the bottom of the boat. Next to this check valve a tee fitting is needed to redirect the flow of water out the thru-hull fitting when the bag is being drained. One of the two unused barbs on the tee will be need to be connected to the flexible impeller pump via a stretch of 1” oem ballast hose. The hose should slide over the inlet on the pump as most are 1” barbs. The other end of the pump will need to be connected to the port on bottom end of the ballast bag. The pump will fill and drain from the bottom part. Proximity between the pump and the bag is not crucial. The last remaining barb on the tee fitting will be for the drain. Run this hose to a thru-hull fitting above where the bag will be when at its capacity.

Vent / Overflow
The only port that will be used on top of the ballast bag is for the vent or overflow connection. This is a necessary part of the ballast system because without it the bag will either trap air and not fill to capacity or grow larger than the compartment and potentially cause damage. By adding a vent the soft structured bag will only grow as large as the confines that it is given. The bag will also discharge when full alerting the driver to turn the pump off. The vent hose needs to be routed above the sac and the thru-hull fitting needs to be at a level that is higher than the bag fitting when it is filled completely. (NOTE: Installing the thru-hull fitting as far forward toward the bow will ensure that the bag does not drain when wakesurfing since the boat is heavily weighted on one side.)

What type of ballast system do I want?
Most riders want to match what was available from the factory when the boat was new or when the manufacturer integrated a ballast system. That concept has always been the best option in our opinion. If there is already a ballast system in the boat it is best to match what the manufacturer had in mind to ensure the entire system functions and looks like it was installed by the factory. Having an entire system that functions the same will also make trouble shooting any issues that arise much easier. If the system that is already installed is not working properly let us help you find the best solution to resolve the issues.

The aerator pump ballast system is the best option for most riders because of its fast speed and low cost. If there is not enough room in the boat to add the vented hose loop fittings and vent lines above the bag this system is not a good choice.Complete Impeller Pump Ballast System

We recommend the flexible impeller reversible pump ballast system for riders that need to fill and drain through the bottom of the boat because of regulations or if they don't have enough room to implement the aerator pump system. When adding an additional stand alone system on top of a existing factory ballast system the flexible impeller pump system will have the best results with the least amount of hassle.

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